NASA SP-2000-4521

NASA History Division

Office of Policy and Plans

NASA Headquarters

Washington, DC 20546

February 2001
Humans to Mars

Fifty Years of Mission Planning, 

1950–2000

by David S. F. Portree

NASA History Division

Office of Policy and Plans

NASA Headquarters

Washington, DC 20546

Monographs in Aerospace History Series

Number 21

February 2001
Library of Congress Cataloging-in-Publication Data

Portree, David S. F.

Humans to Mars: fifty years of mission planning, 1950–2000/by David S. F. Portree.

p. cm.–(Monographs in aerospace history; no. 21) (NASA publication SP)

Includes bibliographical references and index.

1. Space flight to Mars–Planning. 2. United States. National Aeronautics and Space Administration.

I. Title. II. Series. III. NASA SP ; no. 4521.

TL799.M3 P67 2000

629.45’53–dc21 00—062218
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 iii

Contents

Foreword ............................................................................................................................................................v

Preface ..............................................................................................................................................................vii

Chapter 1: On the Grand Scale ............................................................................................................................1

Chapter 2: Earliest NASA Concepts......................................................................................................................5

Chapter 3: EMPIRE and After ............................................................................................................................11

Chapter 4: A Hostile Environment ......................................................................................................................23

Chapter 5: Apogee ............................................................................................................................................33

Chapter 6: Viking and the Resources of Mars ....................................................................................................53

Chapter 7: The Case for Mars ............................................................................................................................57

Chapter 8: Challengers ......................................................................................................................................67

Chapter 9: Space Exploration Initiative ..............................................................................................................77

Chapter 10: Design Reference Mission ..............................................................................................................89

Acronyms ........................................................................................................................................................101

Endnotes..........................................................................................................................................................103

Bibliography ....................................................................................................................................................127

About the Author..............................................................................................................................................141

Index................................................................................................................................................................143

NASA History Monographs ..............................................................................................................................151 
The planet Mars has long held a special fascination

and even mythic status for humans. While not the closest planet to Earth, scientists have considered it to be

the planet that most closely resembles Earth and thus

is the other planet in our solar system most likely to

contain life. Since before the space age began, people

have wondered about the “red planet” and dreamed of

exploring it.

In the twentieth century, robotic spacecraft and then

human space flight became a reality. Those who wanted to explore Mars in person felt that this might finally become a reality as well. The Apollo program, which

put twelve Americans on the surface of the Moon, certainly encouraged the dreamers and planners who

wanted to send astronauts to Mars. Indeed, many people in and out of the National Aeronautics and Space

Administration (NASA) have felt that human exploration of Mars is the next logical step in human space

flight after the Moon.

Clearly, however, many obstacles have remained.

Human travel to and from Mars probably would take

many months at best. Thus the biomedical and psychological implications of such long-duration missions are

daunting. The logistics of getting enough food, water,

and other supplies to Mars are also challenging at best.

What would astronauts do once they got to Mars? How

long would they stay on the planet’s surface and how

would they survive there before returning to Earth?

The financial cost of sending humans to Mars would

almost surely be measured in billions of dollars. Aside

from technical and financial issues, there remains the

political question of why we should send humans to

Mars at all.

David Portree takes on these questions in this monograph. By examining the evolution of 50 mission studies

over the past 50 years, he gives us a sense of the many

options that Mars human space flight planners in the

United States have explored. Portree covers a wide

variety of ideas for human exploration of Mars, ranging

from Wernher von Braun’s of the 1950s to the Space

Exploration Initiative of 1989. These concepts, culled

from a much larger pool of studies, range from hugely

ambitious flotilla-style expeditions to much leaner

plans. This monograph provides historians, space policy

practitioners, and other readers with a very valuable

overview of how much planning has already been done.

If humans do go to Mars any time in the near future, it

is quite conceivable that their mission profile will

resemble one of the plans described here.

A number of people helped to produce this monograph.

In the NASA History Office, M. Louise Alstork edited

and proofread the manuscript, while Stephen J. Garber

and Nadine J. Andreassen also assisted with editing

and production. The Printing and Design Office developed the layout and handled the printing. Shawn

Flowers and Lisa Jirousek handled the design and editing, respectively, while Stanley Artis and Warren

Owens saw this work through the publication process.

This is the twenty-first in a series of special studies

prepared by the NASA History Office. The Monographs

in Aerospace History series is designed to provide a

wide variety of aerospace history investigations. These

publications are intended to be tightly focused in terms

of subject, relatively short in length, and reproduced in

an inexpensive format to allow timely and broad dissemination to researchers. Thus they hopefully serve as

useful starting points for others to do more in-depth

research on various topics. Suggestions for additional

publications in the Monographs in Aerospace History

series are welcome.

Roger D. Launius

Chief Historian

National Aeronautics and 

Space Administrations

October 25, 2000

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 v

Foreword
vii

The story of the dreams and the unbuilt spaceships for flights to Mars should be recorded so

that in the future people can examine past

ideas of space travel just as we can examine the

unconsummated ideas of Leonardo da Vinci by

reading his notebooks. Years from now people

should be able to decide for themselves

whether they want to go to Mars or if they prefer to stay earthbound. But let us not destroy

the dream, simply because we do not wish to

pursue it ourselves. (Edward Ezell, 1979)1

In the past half century, visionary engineers have made

increasingly realistic plans for launching astronauts to

Mars to explore the planet. This monograph traces the

evolution of these plans, taking into account such factors as on-going technological advancement and our

improving knowledge of the red planet.

More than 1,000 piloted Mars mission studies were conducted inside and outside NASA between about 1950

and 2000. Many were the product of NASA and industry study teams, while others were the work of committed individuals or private organizations. Due to space

limitations, only 50 mission studies (one per year, or less

than 5 percent of the total) are described in this monograph. The studies included are believed to be representative of most of the technologies and techniques associated with piloted Mars exploration.2

In addition to tracing the evolution of mission concepts,

this monograph examines piloted Mars mission planning from a policy standpoint. Mars plans are affected

by their societal context and by the policies that grow

from that context. When the human species eventually

decides to send a piloted mission to Mars, the political

environment in which it develops will have at least as

much impact on its shape as technology, human factors,

and the Martian and interplanetary environments.

Hence, it stands to benefit the space technologist to

study the ways in which policy has shaped (and thwarted) past Mars plans. This idea may seem obvious to

some readers, yet the history of piloted Mars mission

planning shows that this truism has often been ignored

or imperfectly understood, usually to the detriment of

Mars exploration.

This history should be seen as a tool for building

toward a future that includes piloted Mars exploration,

not merely as a chronicle of events forgotten and plans

unrealized. The author hopes to update and expand it

in 15 or 20 years so that it tells a story culminating in

the first piloted Mars mission. Perhaps a university

student reading this monograph today will become a

member of the first Mars mission crew tomorrow.

The author gratefully acknowledges the assistance provided by the following: Robert Ash, Donald Beattie,

Ivan Bekey, John Charles, Benton Clark, Aaron Cohen,

John Connolly, Mark Craig, Dwayne Day, Michael

Duke, Louis Friedman, Kent Joosten, Paul Keaton,

Geoffrey Landis, John Logsdon, Humboldt Mandell,

Wendell Mendell, George Morgenthaler, Annie Platoff,

Marvin Portree, Gordon Woodcock, and Robert Zubrin.

Thanks also to the Exploration Faithful at NASA’s

Johnson Space Center for their insights and encouragement these past several years. Finally, thanks to

Roger D. Launius, NASA Senior Historian, for soliciting

this work and providing overall guidance.

David S. F. Portree

Houston, Texas, September 2000

A Note on Measurement

In this monograph, measurements are given in the units

used in the original study. Tons are U.S. tons (short tons)

unless specified as metric tons. Measurements not associated with a specific study are given in the metric system.

Humans to Mars: Fifty Years of Mission Planning, 1950–2000

Preface
Will man ever go to Mars? I am sure he will—

but it will be a century or more before he’s

ready. In that time scientists and engineers

will learn more about the physical and mental

rigors of interplanetary flight—and about the

unknown dangers of life on another planet.

Some of that information may become available

within the next 25 years or so, through the erection of a space station above the Earth . . . and

through the subsequent exploration of the

[M]oon. (Wernher von Braun, 1954)1

Von Braun in the Desert

At the beginning of serious Mars expedition planning in

the United States stands German rocket pioneer

Wernher von Braun. From 1945 to 1950, von Braun was

interned at White Sands Proving Ground in New Mexico

with about 60 other German rocket engineers spirited

out of Nazi Germany by the U.S. Army at the end of the

Second World War. Under Hitler, they had developed the

first large liquid-propellant rocket, the V-2 missile, at the

Nazi rocket base of Peenemünde; in the United States,

they shared their missilery experience by preparing and

launching captured V-2s under Army supervision.

In 1947 and 1948, to relieve boredom, von Braun

wrote a novel about an expedition to Mars. Frederick

Ordway and Mitchell Sharpe wrote in their history

The Rocket Team that von Braun’s novel “proved

beyond doubt that its author was an imaginative scientist but an execrable manufacturer of plot and dialog.”2 Perhaps understandably, the novel never saw

print. In 1952, however, its appendix, a collection of

mathematical proofs supporting its spacecraft

designs and mission plan, was published in West

Germany as Das Marsprojekt. The University of

Illinois Press published the English-language edition

as The Mars Project a year later.3 By then von Braun

and many of his German colleagues were civilian

employees of the Army Ballistic Missile Agency

(ABMA) at Redstone Arsenal in Huntsville, Alabama.

Von Braun described a Mars expedition “on the grand

scale,” with ten 4,000-ton ships and 70 crewmembers.4

He assumed no Earth-orbiting space station assembly

base. His spacecraft were assembled from parts

launched by three-stage winged ferry rockets. Nine

hundred fifty ferry flights would be required to assemble the Mars “flotilla” in Earth orbit. Von Braun estimated that each ferry rocket would need 5,583 tons of

nitric acid and alcohol propellants to place about 40

tons of cargo into orbit, so a total of 5,320,000 tons of

propellants would be required to launch all ten Mars

ships. To provide a sense of scale he pointed out that

“about 10 per cent of an equivalent quantity of high

octane aviation gasoline was burned during the six

months’ operation of the Berlin Airlift” in 1948-49.5 Von

Braun estimated total propellant cost for launching the

expedition into Earth orbit at $500 million.

Seven vessels in von Braun’s plan were assemblages of

girders and spheres without streamlining designed for

the round-trip Mars voyage. Incapable of landing, they

featured inflatable fabric propellant tanks and personnel spheres. Three one-way ships would each have a

winged landing glider in place of a personnel sphere. At

the appointed time, the flotilla’s rocket engines would

ignite to put the ships on a minimum-energy Earth-toMars trajectory. As Earth shrank behind, the Mars ship

crews would discard empty Earth-departure propellant

tanks and settle in for an eight-month weightless coast.

The members of the first Mars expedition would be the

first humans to see the planet up close. No robotic

explorers would precede them; von Braun did not

anticipate the technological advancements that

enabled automated explorers.

From Mars orbit they would turn telescopes toward

Mars’ equator to select a site for a surface exploration

base camp. The first Mars landing site, however, would

be determined at the time the expedition left Earth.

One landing glider would deorbit and glide to a sliding

touchdown on skids on one of the polar ice caps. Von

Braun chose the polar caps because he believed them to

be the only places on Mars where the crew could be certain of finding a smooth landing site. In von Braun’s

plan, the first people on Mars would abandon their

glider on the ice cap and conduct a heroic 4,000-mile

overland trek to the chosen base camp site on Mars’

equator. There they would build a landing strip for the

pair of wheeled gliders waiting in orbit. This Mars

landing approach is unique to von Braun’s work.

The wheeled gliders would touch down bearing the balance of the surface exploration party, leaving a skeleton

crew in orbit to tend the seven remaining ships. As soon

as the glider wheels stopped, the explorers would

unbolt their delta wings and hoist their V-2-shaped

fuselages upright to stand on their tail fins, ready for

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 1

Chapter 1: On the Grand Scale
blast off back to the ships in Mars orbit in case of emergency. They would then set up an inflatable habitat,

their base of operations for a 400-day survey of Mars’

deserts. They would gather samples of native flora and

fauna and explore the mysterious linear “canals”

glimpsed through Earth-based telescopes since the late

nineteenth century. The journey back to Earth orbit

would mirror the flight to Mars. Total expedition duration would be about three years.

In almost every Mars expedition plan from von Braun

to the present, propellant has been potentially the

single heaviest expedition element. Von Braun

attempted to minimize total Mars expedition

weight—and thus the number of expensive rockets

required to launch the expedition from Earth’s surface—by reducing as much as possible the amount of

propellant needed to boost the expedition from Earth

to Mars and back again. His mission profile—a minimum-energy Mars transfer, followed by a long stay

during which the planets moved into position for a

minimum-energy transfer back to Earth—was the

chief means he used to reduce required propellant.

This approach, called a conjunction-class mission, will

be described in more detail in chapter 3. Extensive

use of inflatable fabric structures also helped reduce

spacecraft weight, though von Braun invoked them

primarily because they could be folded to fit within

the cargo bay of his hypothetical ferry rocket.

Use of multiple Mars ships and landers minimized

risk to crew. If one ship failed, its crew could transfer

to the other ships at the price of increased crowding.

Von Braun’s expedition plan boosted science return

through large crews (including professional scientists),

a small fleet of tractors for wide-ranging surface traverses, and ample scientific gear. His thinking was

shaped by large Antarctic expeditions of his day, such

as Operation High Jump (1946-47), which included

4000 men, 13 ships, and 23 aircraft.6 In the days before

satellites, Antarctic explorers were largely cut off from

the world, so experts and technicians had to be on

hand to contend with any situation that might arise.

Von Braun anticipated that Mars explorers would face

a similar situation.

In keeping with his assumption that little automation

would be available for precursor probes, von Braun’s

piloted ships were largely manually controlled, making

large, naval-style crews mandatory. Lack of automated

systems also dictated that some crewmembers remain

in Mars orbit to tend the Earth-return ships.

It is interesting to compare von Braun’s vision with the

Apollo lunar expeditions, when just two astronauts

landed on Earth’s Moon.An army of personnel, including

scientists, formed part of each Apollo expedition, but

remained behind on Earth. This separation was made

possible by communication advances von Braun did not

anticipate. In 1952 von Braun stated that television

transmission between Earth and a lunar expedition

would be impractical.7 Sixteen years later, Neil

Armstrong’s first footsteps on the dusty, cratered Sea of

Tranquillity were televised live to 500 million people.

Collier’s

Von Braun’s slender book of proofs was not widely distributed. His vision, however, won over the editors of the

colorful Collier’s weekly magazine, who commissioned

him to write a series of space exploration articles. The

Collier’s editor for the project, Cornelius Ryan, also

solicited inputs from astronomer Fred Whipple, physicist

Joseph Kaplan, physiologist Heinz Haber, United

Nations lawyer Oscar Schachter, science writer Willy

Ley, and others. Technical and astronomical art by

Chesley Bonestell, Rolf Klep, and Fred Freeman brought

von Braun’s technical descriptions to life. Collier’s, now

defunct, had a circulation of three million, making it one

of America’s most popular magazines. Through the

Collier’s articles, charismatic von Braun became identified with space flight in the minds of Americans—the

quintessential white-coated rocket scientist.

Collier’s published eight articles laying out a logical

space program blueprint. The first, published on 22

March 1952, described von Braun’s winged ferry rockets

and a spinning, wheel-shaped artificial-gravity space

station in Earth orbit.8 Collier’s readers reached the

Moon in October 19529 and explored Mars in the 30

April 1954 issue.10 Each step in von Braun’s program

built infrastructure and experience for the next.

Von Braun’s Collier’s Mars plan was identical to that

described in The Mars Project, except that the ten-ship

Mars flotilla would be assembled near an Earth-orbiting space station. Again, von Braun assumed no robotic

precursors. This time, however, telescopes located on the

space station, high above Earth’s obscuring atmosphere,

2 Monographs in Aerospace History

Chapter 1: On the Grand Scale
would be used to refine knowledge of Mars and select

candidate landing sites before the expedition left Earth.

Mars plans tend to focus on spacecraft, not astronauts.

In the Collier’s Mars article, however, von Braun

explored the psychological problems of the Mars voyage. “At the end of a few months,” he wrote, “someone is

likely to go berserk. Little mannerisms—the way a

man cracks his knuckles, blows his nose, the way he

grins, talks or gestures—create tension and hatred

which could lead to murder . . . [i]f somebody does

crack, you can’t call off the expedition and return to

Earth. You’ll have to take him with you.” He also proposed censoring radio communication to prevent the

crew from hearing dispiriting news about their hometowns.11

The Collier’s articles were expanded into a series of four

classic books. The first four chapters of the 1956 book

The Exploration of Mars12 covered the history of Mars

observation and the then-current state of knowledge.

Wrote von Braun and his collaborator Willy Ley: “This

is the picture of Mars at mid-century: A small planet of

which three-quarters is cold desert, with the rest covered with a sort of plant life that our biological knowledge cannot encompass . . .”13 For von Braun, life on

Mars was a given. In fact, von Braun’s Mars was not too

different from the New Mexico desert where he penned

Das Marsprojekt.

Von Braun and Ley then described the Mars expedition.

They conceded that it was “entirely possible . . . that

within a decade or so successful tests with some sort of

nuclear rocket propulsion system might be accomplished”; however, for the present, it was “exciting as

well as instructive” to show that humans could reach

Mars using available (1950s) technology.14

Their Mars expedition was a cut-price version of the

1952 Das Marsprojekt/1954 Collier’s expedition, with

just 12 crewmembers in two ships. Four hundred

launches would put the parts, propellants, and supplies

needed for the expedition into Earth orbit at the rate of

two launches per day over seven months.

A single-passenger ship would complete the roundtrip voyage. The craft would have an inflatable personnel sphere 26 feet across, with a control room on

deck one and living quarters on decks two and three.

The one-way cargo ship would carry the expedition’s

single 177-ton landing glider in place of a personnel

sphere. The ships together would weigh 3,740 tons

before departing Earth orbit; the passenger ship

would weigh only 38.4 tons when it returned to Earth

orbit alone at the end of the expedition.

Upon reaching Mars, the crew would turn powerful

telescopes toward proposed equatorial landing sites

selected using telescopes on the space station.

Equatorial sites were preferred, von Braun and Ley

wrote, because they would be warmest. Citing the

many kinds of surface features nearby—including

two of the mysterious canals—they proposed as

prime landing site candidate Margaritifer Sinus, a

dark region visible in Earth-based telescopes.15 The

glider would descend to Mars with nine crewmembers on board (leaving three in orbit to mind the passenger ship’s systems) and land on skids at about 120

miles per hour.

After the glider stopped, the intrepid explorers would

walk out onto the wing, leap 18 feet to the ground (the

equivalent of a six-foot drop in Earth gravity), and

immediately prepare the ship for emergency liftoff—

this despite having just spent eight months in weightlessness. They would remove the wings and use the

expedition’s two caterpillar tractors to hoist the bullet-shaped fuselage upright. They would then inflate a

20-foot hemispherical pressurized “tent” to serve as

expedition headquarters.

After a year of Mars surface exploration, they would lift

off, rejoin their compatriots in orbit, and blast for

Earth. The last drops of propellants would place the

ship in a 56,000-mile-high Earth orbit. A relief ship

would ascend from the space station to collect the crew;

they would abandon the Mars ship as a monument to

the early days of planetary exploration.

Mars Beckons

Every 26 months, the orbits of Earth and Mars bring

the two planets relatively close together. At such times

Mars becomes a bright red-orange “star” in Earth’s

skies. Because Mars appears opposite the Sun in the

sky when it is closest to Earth, astronomers call such

events oppositions.

Chapter 1: On the Grand Scale

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 3
Mars has an elliptical orbit, so its distance from Earth

at opposition varies. The best oppositions, when Earth

is closest to Mars while the planet is closest to the Sun,

occur roughly every 15 years. During the best oppositions, Mars’ disk appears about twice as large in telescopes as during the poorest oppositions, when Mars is

farthest from the Sun.

In the 1950s, all knowledge of Mars’ conditions came

from telescopic observations made during the best

oppositions. Since the invention of the telescope in the

early seventeenth century, astronomers eagerly awaited the best oppositions to attempt to pry new secrets

from Mars. For example, the canals were first seen during the excellent 1877 opposition. When the first printing of The Exploration of Mars arrived on bookstore

shelves, astronomers were eagerly awaiting the close

opposition of September 1956.

The year 1956 marked the last “best” Mars opposition

upon which astronomers would entirely depend for

data, because humanity’s relationship with Mars was

about to change. A year after that Mars opposition, on

4 October 1957, the Soviet Union launched Sputnik 1

into Earth orbit. Von Braun’s U.S. Army rocket team

launched the American response, Explorer 1, on 31

January 1958. By 1971, when again Mars shone as

brightly in Earth’s skies as in 1956, spacecraft reconnaissance had revolutionized how we learn about the

solar system. As we will see in the coming chapters,

the 1956 and 1971 “best” oppositions neatly bracketed

the early heyday of NASA Mars exploration planning.

4 Monographs in Aerospace History

Chapter 1: On the Grand Scale
Now it is time to take longer strides—time for

a great new American enterprise—time for this

nation to take a clearly leading role in space

achievement . . . I believe that this nation

should commit itself to achieving the goal,

before this decade is out, of landing a man on

the [M]oon and returning him safely to Earth.

No single space project in this period will be

more impressive to mankind, or more important for the long-range exploration of space . . .

it will not be one man going to the [M]oon—it

will be an entire nation. For all of us must work

to put him there. (John F. Kennedy, 1961)1

NASA’s First Mars Study

As early as November 1957—a month after Sputnik 1

became Earth’s first artificial moon—about 20

researchers at Lewis Research Center, a National

Advisory Committee on Aeronautics (NACA) laboratory in Cleveland, Ohio, commenced research into

nuclear-thermal and electric rocket propulsion for

interplanetary flight.2 (Lewis was renamed Glenn

Research Center at Lewis Field in 1999.) Such

advanced propulsion systems required less propellant

than chemical rockets, thus promising dramatic spacecraft weight savings. This meant fewer costly launches

from Earth’s surface and less Earth-orbital assembly.

Soon after the Lewis researchers began their work,

Congress and the Eisenhower administration began to

work toward the creation of a U.S. national space

agency in response to Soviet space challenges.

President Dwight Eisenhower wanted a civilian agency

to ensure that headline-grabbing space shots would not

interfere with the serious business of testing missiles

and launching reconnaissance satellites. Senator

Clinton Anderson (Democrat-New Mexico) led a faction

that wanted the Atomic Energy Commission (AEC) to

run the space program, citing as justification its

nuclear-thermal rocket experiments. Others supported

expansion of NACA, the federal aeronautics research

organization founded in 1915. On 29 July 1958,

Eisenhower signed into law legislation creating the

National Aeronautics and Space Administration

(NASA) from NACA and various Department of

Defense space organizations.3

When NASA opened its doors on 1 October 1958, Lewis

became a NASA Center. The Lewis researchers sought

to justify and expand their advanced propulsion work.

In April 1959—two years before any human ventured

into Earth orbit—they testified to Congress about their

work and solicited funding for a Mars expedition study

in Fiscal Year (FY) 1960. Congress granted the request,

making the Lewis study the first Mars expedition

study conducted under NASA auspices.4

The Lewis researchers sought to develop weight estimates for Mars ships using their advanced propulsion

systems. For their nuclear-thermal rocket analysis, the

Lewis researchers assumed a Mars mission profile that

would, by the end of 1960s, come to be virtually the

standard NASA model:

The mission begins with the vehicle system

in an orbit about the Earth. Depending on the

weight required for the mission, it can be

inferred that the system has been delivered as

a unit to orbit—or that it has been assembled

in the orbit from its major constituents . . . the

vehicle containing a crew of seven men is

accelerated by a high-thrust nuclear rocket

engine onto the transfer trajectory to Mars.

Upon arrival at Mars, the vehicle is decelerated to establish an orbit about the planet ...a

Mars Landing Vehicle containing two men

descends to the Martian surface . . . . After a

period of exploration these men take off from

Mars using chemical-rocket power and effect a

rendezvous with the orbit party. The . . . vehicle then accelerates onto the return trajectory;

and, upon reaching Earth, an Earth Landing

Vehicle separates and . . . decelerates to return

the entire crew to the surface.5

For analysis purposes, the Lewis researchers targeted

the 1971 launch opportunity, when Mars’ close proximity to Earth minimized the amount of energy (and

thus propellant) needed to reach it. They cautioned,

however, that “[t]his is not meant to imply that actual

trips are contemplated for this period.”6 They opted for

a 420-day round trip with a 40-day stay at Mars, and

found that the optimum launch date was 19 May 1971.

As might be expected, fast Mars trips generally

require more propellant (typically liquid hydrogen in

the case of a nuclear rocket) than slow trips. The

more propellant required, the greater the spacecraft’s

weight at Earth-orbit departure. Thus, longer missions appear preferable if weight minimization is the

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 5

Chapter 2: Earliest NASA Concepts
dominant consideration in a Mars mission plan. The

Lewis team noted, however, that crew risk factors

had to be considered in calculating spacecraft weight.

These were hard to judge because much about conditions in interplanetary space and on Mars remained

unknown. In particular, they cautioned that

“[c]urrent knowledge of radiation hazards is still not

completely satisfactory.”7

Explorer 1 and Explorer 3 (launched 26 March 1958)

detected the Van Allen Radiation Belts surrounding

Earth. Their discovery was the first glimpse of an

unsuspected reef, rock, or shoal menacing navigators in

the new ocean of space. It raised the profile of ionizing

radiation as a possible threat to space travelers.

No longer were the thin-skinned personnel spheres

of von Braun’s 1950s Mars ships judged adequate.

Von Braun had made little provision for limiting

crew radiation exposure, though he had expressed

the hope that “by the time an expedition from earth

is ready to take off for Mars, perhaps in the mid2000s . . . researchers will have perfected a drug

which will enable men to endure radiation for comparatively long periods.”8

The Lewis team did not place its trust in pharmacology. For their study, they assumed the following ionizing radiation sources: the Van Allen belts at Earth

and Mars (in reality, Mars lacks radiation belts), continuous cosmic ray bombardment, solar flares, and, of

course, the ship’s nuclear-thermal rocket engine.

Their spacecraft crew compartment, an unshielded

two-deck cylinder providing 50 square feet of floor

space per crewmember (“between that provided for

chief petty officers and commissioned officers on submarines”), contained a heavily shielded cylindrical

“vault” at its center, into which the crew would retreat

during passage through the Van Allen belts, nuclear

rocket operation, and large solar flares.9

Crewmembers would also sleep in the vault; this

would reduce their cosmic ray exposure during

approximately one-third of each day.

Not surprisingly, the weight of radiation shielding

required depended on how much radiation exposure for

the crew was allowed. If major solar flares could be

avoided during the 420-day voyage and a total radiation dose of 100 Roentgen Equivalent Man (REM) were

permissible, then 23.5 tons of shielding would suffice,

the Lewis researchers found. If, however, one major

flare could not be avoided, shielding weight jumped to

82 tons to keep the total dose below 100 REM. If only

50 REM were considered permissible and one major

flare could not be avoided, shielding weight would

become “enormous”—140 tons.10 “These data,” they

wrote, served “to underscore . . . the importance of

determining more precisely the nature and virulence of

the radiation in space.”11

The Lewis researchers determined that “short trips

are as, or more, economical, in terms of weight, than

long-duration missions,” even though they generally

required more propellant, because long trips

required more heavy shielding to keep the crew

within the radiation dose limit.12 They estimated

that a nuclear-thermal spaceship for a 420-day

round trip in 1971 with a maximum allowable total

radiation dose of 100 REM would weigh 675 tons at

Earth-orbit launch.

Twirling Ion Ships to Mars

Just as the creation of NASA was prompted by the Cold

War clash between the United States and the Soviet

Union, so was the goal that dominated NASA’s first

decade. On 12 April 1961, Soviet cosmonaut Yuri

Gagarin became the first person to orbit Earth. His

Vostok 1 spacecraft completed one circuit of the planet

in about 90 minutes. Gagarin’s flight was a blow to the

new administration of President John F. Kennedy, who

had narrowly defeated Eisenhower’s Vice President,

Richard M. Nixon, in the November 1960 elections.

Gagarin’s flight coincided with the embarrassing failure of a Central Intelligence Agency (CIA)-sponsored

invasion of Cuba at the Bay of Pigs (17-19 April 1961).13

The tide of Kennedy’s political fortunes began to turn

on 5 May 1961, when astronaut Alan Shepard rode the

Freedom 7 Mercury capsule on a suborbital hop into the

Atlantic Ocean. On 25 May 1961, Kennedy capitalized

on this success to seize back the political high ground.

Before a special Joint Session of Congress, he called for

an American to land on Earth’s Moon by the end of the

1960s.

NASA had unveiled a 10-year plan in February 1960

that called for a space station and circumlunar flight

before 1970, and a lunar landing a few years later. The

6 Monographs in Aerospace History

Chapter 2: Earliest NASA Concepts
Agency believed that this constituted a logical program

of experience-building steps.14 Mars planners were torn

over Kennedy’s new timetable. On the one hand, it put

Mars work on the back burner by making the Moon

NASA’s primary, overriding goal. On the other hand, it

promised to make launch vehicles and experience needed for Mars available all the sooner.15

Two contenders led the pack of Apollo lunar mission

modes in mid-1961—Earth-Orbit Rendezvous (EOR)

and Direct Ascent. Both stood to benefit piloted Mars

missions. In EOR, two or three boosters launched Moon

ship modules into Earth orbit. The modules docked;

then the resultant ship flew to the Moon and landed.

Mars planners knew that experience gained through

Moon ship assembly could be applied to Mars ship

assembly. In Direct Ascent, the spacecraft flew directly

from Earth’s surface to the lunar surface and back.

This called for an enormous launch vehicle which could

be used to reduce the number of launches needed to put

Mars ship parts and propellants into orbit.

NASA’s Marshall Space Flight Center in Huntsville,

Alabama, was responsible for developing the rockets

required for lunar flight. Marshall began as the

ABMA’s Guided Missile Development Division. In the

1950s, the von Braun rocket team had developed some

of the first U.S. missiles, including the intermediaterange Redstone, the “Americanized” version of the V-2.

A Redstone variant called Jupiter-C launched the

Explorer 1 satellite.

Just as Saturn was next after Jupiter among the planets, the Saturn series of rockets was next after JupiterC. Saturn I and Saturn IB used a cluster of

Redstone/Jupiter tanks in their first stages. The engineers in Huntsville envisioned yet larger rockets.

NASA’s 1960 master plan called for development of an

enormous “post-Saturn” rocket called Nova. Either

Saturn or Nova could be used to carry out an EOR

Moon mission; Nova was required for Direct Ascent.

Marshall might have performed the first NASA Mars

study, but when the Lewis advanced propulsion engineers testified to Congress in 1959, the Huntsville

organization was still not a part of NASA. Ernst

Stuhlinger’s group within the ABMA Guided Missile

Development Division had commenced work on electric

propulsion in 1953 and considered Mars expeditions in

its design process.

In electric propulsion, a thruster applies electricity to

propellant (for example, cesium), converting its atoms

into positive ions. That is, it knocks an electron off each

cesium atom, giving it an electric charge. The thruster

then electrostatically “grips” the cesium ions and

“throws” them at high speed. Electric propulsion provides constant low-thrust acceleration while expending

much less propellant than chemical or nuclear-thermal

propulsion, consequently reducing spacecraft weight.

Low thrust, however, means low acceleration.

Stuhlinger presented a paper in Austria in 1954

describing a solar-powered electric-propulsion spacecraft with dish-shaped solar concentrators.16 Walt

Disney had contacted von Braun after reading the

Collier’s articles; this contact led to three space flight

television programs from 1955 to 1957. Disney’s Mars

and Beyond, which premiered on 4 December 1957, featured Stuhlinger’s distinctive umbrella-shaped

nuclear-electric Mars ships, not von Braun’s sphereand-girder chemical ships.17

The U.S. Army, eager to retain its foothold in missilery, was loath to release the von Braun team to

NASA as required by President Eisenhower. Army

resistance prevented von Braun, Stuhlinger, and their

colleagues from officially joining the new space

agency until 1 July 1960. However, they had by then

worked directly with NASA for some time—hence

their input to NASA’s February 1960 master plan.18

Wernher von Braun became Marshall’s first director,

and Ernst Stuhlinger became director of Marshall’s

Research Projects Division.

Stuhlinger’s 1962 piloted Mars mission design, targeted for launch in the early 1980s, would include five 150-

meter long Mars ships of two types—“A” and “B”—each

carrying three astronauts.19 As in von Braun’s The

Mars Project, risk to crew was minimized through

redundancy. The expedition could continue if as many

as two ships were lost, provided they were not of the

same type. One ship could return the entire 15-person

expedition to Earth under crowded conditions.

The three “A” ships would carry one 70-ton Mars lander

each. At Mars, an unpiloted cargo lander would detach;

if it landed successfully, the explorers would land in the

second lander. If the cargo lander failed, the second lander would become an unpiloted cargo lander, and the

third lander would deliver the surface team. The lander

Chapter 2: Earliest NASA Concepts

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 7
crew would stay on Mars for 29 days. If the crew lander

ascent stage failed to fire, the explorers could return to

Mars orbit in the cargo lander ascent stage.

Stuhlinger’s ships would each include a nuclear reactor

producing 115 megawatts of heat. The reactor would

heat a working fluid which would drive a turbine; the

turbine in turn would drive a generator to supply 40

megawatts of electricity to two electric-propulsion

thrusters. To reject the heat it retained after leaving

the turbine, the working fluid would circulate through

radiator panels with a total area of 4,300 square

meters before returning to the reactor. The ship would

move through space with its radiator panels edge-on to

the Sun. Radiator tubes would be designed to be individually closed off to prevent a meteoroid puncture

from releasing all of the ship’s working fluid into space.

Each flat, diamond-shaped ship would weigh 360 tons

when it switched on its electric thrusters in Earth orbit

at the start of the Mars voyage—a little more than half

as much as the NASA Lewis nuclear-thermal Mars

ship. Of this, 190 tons (for the “B” ships) or 120 tons (for

the “A” ships) would be cesium propellant. As already

indicated, the price of low spacecraft weight was low

acceleration—Stuhlinger’s fleet would need 56 days to

spiral up and out of Earth orbit; then, after a 146-day

Earth-Mars transfer, it would require 21 days to spiral

down to low-Mars orbit.

Stuhlinger’s ships would rotate 1.3 times per minute to

produce acceleration equal to one-tenth of Earth’s gravity in the crew cabin. The reactor, located at the opposite end of the ship from the crew cabin, would act as

an artificial gravity counterweight. Thus, the separation needed to keep the crew away from the reactor

would also serve to increase spin radius.

Engineers designing artificial gravity systems must

endeavor to make the spin radius as long as possible.

This is because an artificial gravity system with a short

spin radius must rotate more rapidly than one with a

long spin radius to generate the same level of acceleration, which the crew feels as gravity. A short-radius,

fast-spinning rotating system produces pronounced

coriolis effects. For example, water leaving a faucet

curves noticeably. Similarly, a person moving toward or

away from the center of such a rotating system tends to

veer sideways. Turning the head tends to produce nausea. In addition, a troublesome gravity gradient occurs

vertically along the body—the head experiences less

acceleration than the feet.

Stuhlinger’s electric thrusters would be mounted at the

ship’s center of rotation on stalks. These would rotate

against the ship’s spin to remain pointed in the

required direction. In addition to aiding the crew,

Stuhlinger noted, artificial gravity would prevent gas

pockets from forming in the working fluid.20

Stuhlinger’s design included a 50-ton, graphite-clad

radiation shelter (about 15 percent of the entire

weight of the ship) in the ship’s crew compartment.

Drinking water, propellant, oxygen cylinders, and

equipment would be arranged around the shelter to

provide additional shielding. The 2.8-meter-diameter,

1.9-meter-high shelter would hold a three-person

ship’s complement comfortably and would protect the

entire 15-person expedition complement in an emergency. The crew would live in the shelter for 20 days

during the outbound Van Allen belt crossing.

The Moon Intervenes

Stuhlinger wrote that it “is generally accepted that a

manned expedition to . . . Mars will be carried out soon

after such an ambitious project becomes technically

feasible . . . [it is] the natural follow-on project to be

undertaken after the lunar program.”21 Mars planners

took Kennedy at his word when he said that reaching

the Moon was “important for the long-range exploration of space.”

On 11 July 1962, however, NASA announced that it

had selected Lunar Orbit Rendezvous (LOR) over EOR

and Direct Ascent as the Apollo mission mode.

Attention had turned from EOR and Direct Ascent to

LOR early in 1962. LOR, a concept zealously promoted

by NASA Langley Research Center engineer John

Houbolt, promised the lowest lunar spacecraft

weight. This enabled a lunar expedition with only a

single Saturn rocket launch, making LOR the

fastest, cheapest way of meeting Kennedy’s end-ofdecade deadline.22

In LOR, the lunar spacecraft—which consists of a small

lander and a command ship—blasts off directly from

Earth with no Earth-orbital assembly. The lander lands

on the Moon, leaving the large command ship in lunar

8 Monographs in Aerospace History

Chapter 2: Earliest NASA Concepts
orbit. Surface exploration completed, the lander blasts

off from the Moon and returns to the orbiting command

ship. Spacecraft weight is reduced because only the

small, light-weight lander must burn propellant to land

and lift off.

It should be noted that the NASA Lewis and

Stuhlinger Mars plans used the same general

approach for the same reason. Landing the entire

massive ship on Mars and launching it back to Earth

would require impossible amounts of propellant or an

impossibly small interplanetary vehicle. The standard

NASA Mars plan can thus be dubbed Mars Orbit

Rendezvous (MOR).

The LOR decision impacted post-Apollo ambitions.

The reduction in lunar expedition mass promised by

LOR removed the need for a post-Saturn Nova rocket,

as well as the need to learn how to assemble large

modular vehicles in Earth orbit. It thus reduced

Apollo’s utility as a technological stepping stone to

Mars. The need to create a new justification for big

rockets influenced Marshall’s decision to start a new

Mars study in early summer 1962. As will be seen in

the next chapter, this study, known as EMPIRE,

kicked off the most intense period of piloted Mars mission planning in NASA’s history.

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 9

Chapter 2: Earliest NASA Concepts

Manned exploration of Mars is the key mission in interplanetary space flight. Man must

play a key role in the exploration of Mars

because the planet is relatively complex,

remote, and less amenable to exploration by

unmanned probes than is the [M]oon ... serious interest in the Manned Mars Mission is

springing up . . . with many planning studies

being performed by several study teams

within [NASA] and within industry . . . .

Perhaps the most important result emerging

from the present studies is the indication

that the Manned Mars Mission can be performed in the relatively near future with

equipment and techniques that will for the

most part be brought into operation by the

Apollo Project . . . the Manned Mars Mission

is rapidly taking shape as the direct followon to the Apollo Project. (Robert Sohn, 1964)1

EMPIRE

Ernst Stuhlinger’s Research Projects Division was the

smaller of two advanced planning groups in ABMA.

The larger, under Heinz Koelle, became the Marshall

Space Flight Center’s Future Projects Office. Until

1962, Koelle’s group focused primarily on lunar programs—Koelle was, for example, principal author of

the U.S. Army’s 1959 Project Horizon study, which

planned a lunar fort by 1967. Koelle’s deputy, Harry

Ruppe, also supervised a limited number of Mars studies. Ruppe had come from Germany to join the von

Braun team in Huntsville in 1957.

In the 1962-1963 period, however, the Future Projects

Office spearheaded NASA’s Mars planning efforts. As

discussed in the last chapter, Marshall’s primary focus

was on launch vehicles. Advanced planning became

important at Marshall in part because of the long lead

times associated with developing new rockets.

Marshall director von Braun foresaw a time in the mid1960s when his center might become idle if no goals

requiring large boosters were defined for the 1970s. As

T. A. Heppenheimer wrote in his 1999 book The Space

Shuttle Decision,

The development of the Saturn V set the pace

for the entire Apollo program. This Moon

rocket, however, would have to reach an

advanced state of reliability before it could be

used to carry astronauts. The Marshall staff

also was responsible for development of the

smaller Saturn IB that could put a piloted

Apollo spacecraft through its paces in Earth

orbit. Because both rockets would have to

largely complete their development before

Apollo could hit its stride, von Braun knew

that his [C]enter would pass its peak of activity and would shrink in size at a relatively

early date. He would face large layoffs even

while other NASA [C]enters would still be

actively preparing for the first mission to the

Moon.2

Mars was an obvious target for Marshall’s advanced

planning. Von Braun was predisposed toward Mars

exploration, and landing astronauts on Mars provided

ample scope for his Center to build new large boosters.

The timing, however, was not good. The Moon would, if

all went well, be reached by 1970—but NASA would

certainly not be ready to land astronauts on Mars so

soon. For one thing, planners needed more data on the

Martian environment before they could design landers,

space suits, and other surface systems. What Marshall

needed was some kind of short-term interim program

that answered questions about Mars while still providing scope for new rocket development.

A 1956 paper by Italian astronomer Gaetano Crocco,

presented at the Seventh International Astronautical

Federation Congress in Rome, offered a possible way

out of Marshall’s dilemma.3 Crocco demonstrated

that a spacecraft could, in theory, fly from Earth to

Mars, perform a reconnaissance Mars flyby, and

return to Earth. The spacecraft would fire its rocket

only to leave Earth—it would coast for the remainder

of the flight. The Mars flyby mission would require

less than half as much energy—hence propellant—as

a minimum-energy Mars stopover (orbital or landing)

expedition. This meant a correspondingly reduced

spacecraft weight. Total trip time for a Crocco-type

Mars flyby was about one year; for the type of mission

von Braun employed in The Mars Project (1953), trip

time was about three years.

Flyby astronauts would be like tourists on a tour bus,

seeing the sights from a distance in passing but not getting off. Crocco wrote that they would use “a telescope

of moderate aperture . . . to reveal and distinguish natural [features] of the planet . . . .” He found, however,

that Mars’ gravity would deflect the flyby spacecraft’s

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 11

Chapter 3: EMPIRE and After
course so it missed Earth on the return leg if it flew

closer to Mars than about 800,000 miles. Such a distant

flyby would, of course, “frustrate the exploration scope

of the trip.”

To permit a close flyby without using propellant, Crocco

proposed that the close Mars flyby be followed by a

Venus flyby to bend the craft’s course toward Earth.

The Venus flyby would be an exploration bonus, Crocco

wrote, allowing the crew to glimpse “the riddle which is

concealed by her thick atmosphere.” Crocco calculated

that an opportunity to begin an Earth-Mars-VenusEarth flight would occur in June 1971.4

From a vantage point at the start of the twenty-first

century, a piloted planetary flyby seems a strange

notion, yet in the 1960s NASA gave nearly as much

attention to piloted Mars flybys as it did to piloted

Mars landings. Piloted Mars flybys are now viewed

from the perspective of more than three decades of successful automated flyby missions (as well as orbiters

and landers). Of the nine planets in the solar system,

only Pluto has not been subjected to flyby examination

by machines. Robots can do flybys, so why entail the

expense and risk to crew of piloted flybys?

Indeed, there were critics at the time the Future

Projects Office launched its Early Manned PlanetaryInterplanetary Roundtrip Expeditions (EMPIRE) piloted flyby/orbiter study. For example, Maxime Faget,

principal designer of the Mercury capsule, coauthored

an article in February 1963 which pointed out that a

piloted Mars flyby would “demand the least [propulsive] energy . . . but will also have the least scientific

value” because of the short period spent near Mars. He

added that data on Mars gathered through a piloted

flyby would be “in many ways no better than those

which might be obtained with a properly operating,

rather sophisticated unmanned probe.”5

The key phrase in Faget’s criticism is, of course, “properly operating.” When the Future Projects Office

launched EMPIRE in May-June 1962, robot probes did

not yet possess a respectable performance record. The

Mariner 2 probe carried out the first successful flyby

exploration of another planet (Venus) in December

1962, midway through the EMPIRE study, but the

other major U.S. automated effort, the Ranger lunar

program, was off to a shaky start. That series did not

enjoy its first success until Ranger 7 in July 1964. The

first successful Mars flyby did not occur until a year

after that. In fact, one of the early justifications for

piloted flybys was that the astronauts could act as caretakers for a cargo of automated probes to keep them

healthy until just before they had to be released at the

target planet.

Faget also believed that the “overall planning of a total

spaceflight program should be based on a logical series

of steps.” Mercury and Gemini would provide basic experience in living and working in space, paving the way for

Apollo, which would, Faget explained, “have the first real

mission.” After that, NASA should build an Earth-orbiting space station and possibly a lunar base.6

For Faget, a piloted Mars flyby mission in the 1970s

was a deviation from the model von Braun popularized

in the 1950s, which placed the first Mars expedition a

century or more in the future. Faget avoided mentioning, however, that he had already been compelled to

rationalize Kennedy’s politically motivated drive for

the Moon. Going by von Braun’s logical blueprint, piloted lunar flight should have been postponed until after

the Earth-orbiting space station was in place.

For the EMPIRE study, three contractors studied piloted flyby and “capture” (orbiter) expeditions to Mars and

Venus. Aeronutronic studied flybys7; Lockheed looked at

flybys and, briefly, orbiters8; and General Dynamics

focused on orbiter missions.9 Aeronutronic’s study

summed up EMPIRE’s three goals:

• Establish a requirement for the Nova rocket

development program.

• Provide inputs to the joint AEC-NASA nuclear 

rocket program, which had been established in

1960 and included a flight test program over 

which Marshall had technical direction.

• Explore advanced operational concepts necessary for flyby and orbiter missions.10

The first two goals were contradictory as far as spacecraft

weight minimization was concerned. Seeking justification for a new large rocket provided little incentive for

weight minimization, while one of the great attractions of

nuclear-thermal rockets was their increased efficiency

over chemical rockets, which helped minimize weight.

The contractors’ tendency not to tightly control spacecraft

weight assisted them with crew risk minimization. For

example, all three contractors saw fit to include in their

12 Monographs in Aerospace History

Chapter 3: EMPIRE and After
EMPIRE designs heavy spacecraft structures for generating artificial gravity.

Lockheed identified two main Mars flyby trajectory

classes, which it nicknamed “hot” and “cool.” In the former, the piloted flyby spacecraft would drop inside

Earth’s orbit (in some launch windows Venus flyby

occurred), reach its farthest point from the Sun (aphelion) as it flew by Mars, and return to Earth about 18

months after launch. In the latter, the flyby spacecraft

would fly out from Earth’s orbit, pass Mars about 3

months after launch, reach aphelion in the Asteroid

Belt beyond Mars, and return to Earth about 22

months after launch.

The Aeronutronic team opted for a “hot” trajectory.

They assumed a Nova rocket capable of lifting 250 tons

to Earth orbit. For comparison, the largest planned

Saturn rocket, the Saturn C-5 (as the Saturn V was

known at this time) was expected to launch around 100

tons. One Nova rocket would thus be able to launch the

entire 187.5-ton Aeronutronic flyby spacecraft into

Earth orbit.

Aeronutronic’s “design point mission” had the flyby

spacecraft leaving Earth orbit between 19 July 1970

and 16 August 1970, using a two-stage nuclear-thermal

propulsion system. Aeronutronic’s design retained the

empty second-stage hydrogen propellant tanks to help

shield the command center in the ship’s core against

radiation and meteoroids. Two cylindrical crew compartments would deploy from the core on booms; then

the ship would rotate to provide artificial gravity. An

AEC-developed radioisotope power source would

deploy on a boom behind the ship. At the end of the

flight the crew would board a lifting body Earth-return

vehicle and separate from the ship. A two-stage retrorocket package would slow the lifting body to a safe

Earth atmosphere reentry speed while the abandoned

flyby ship sailed by Earth into orbit around the Sun.

Lockheed also emphasized a rotating design for its

EMPIRE spacecraft. In the company’s report, the flyby

crew rode into orbit on a Saturn C-5 in an Apollo

Command and Service Module (CSM) perched atop a

folded, lightweight flyby spacecraft. A nuclear upper

stage would put the CSM and flyby ship on course for

Mars. The CSM would then separate and the flyby

spacecraft would automatically unfold two long booms

from either side of a hub. The CSM would dock at the

end of one boom to act as counterweight for a cylindrical

habitation module at the end of the other boom. When

the ship rotated, the CSM and habitation module would

experience acceleration the crew would feel as gravity.

The weightless hub at the center of rotation would contain chemical rockets for course correction propulsion,

a radiation shelter, automated probes, and a dishshaped solar power system. At Mars, the crew would

stop the spacecraft’s rotation and release the probes. At

journey’s end, the crew would separate from the flyby

craft in the CSM, fire its rocket engine to slow down,

discard its cylindrical Service Module (SM), and reenter Earth’s atmosphere in the conical Command

Module (CM). The abandoned flyby craft would fly past

Earth into solar orbit. Lockheed’s report mentioned

briefly how a Mars orbiter mission might investigate

the Martian moons Phobos and Deimos.11

The General Dynamics report was by far the most

voluminous and detailed of the three EMPIRE entries,

reflecting a real passion for Mars exploration on the

part of Krafft Ehricke, its principal author. Ehricke

commanded tanks in Hitler’s attack on Moscow before

joining von Braun’s rocket team at Peenemünde. He

came to the U.S. in 1945 with the rest of the von Braun

team but left in 1953 to take a job at General Dynamics

in San Diego, California. There he was instrumental in

Atlas missile and Centaur upper-stage development. In

the late 1950s he became involved in General

Dynamics advanced planning.

Ehricke’s team looked at piloted Mars orbiter missions.

These would permit long-term study of the planet from

close at hand, thus answering critics who complained

that piloted flybys would spend too little time near

Mars. General Dynamics’ 450-day Mars orbiter mission

was set to launch in March 1975.

Modularized Mars ships would travel in “convoys”

made up of at least one crew ship and two automated

service ships. Ship systems would be “standardized as

much as practical” so that the crew ship could cannibalize the service ships for replacement parts. If a

meteoroid perforated a propellant tank, for example,

the crew would be able to replace it with an identical

tank from a service ship. The ships would carry small

“tugboat” spacecraft for moving propellant tanks and

other bulky spares.12 This approach—providing many

Chapter 3: EMPIRE and After

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 13
spares—helped minimize risk to crew, but would dramatically boost overall expedition weight.

General Dynamics described many possible ship configurations; what follows was typical. The company

allotted a nuclear propulsion stage for each major

maneuver. After performing its assigned maneuver, the

stage would be cast off. Ehricke’s team estimated that

nuclear engine flight testing would have to occur

between May 1968 and April 1970 to support a March

1975 expedition. The M-1 engine system would perform

Maneuver-1 of the Mars expedition, escape from Earth

orbit (hence its designation). The M-2 engine system

would slow the ship so Mars’ gravity could capture it

into Mars orbit, and M-3 would launch the spacecraft

out of Mars orbit toward Earth. The M-4 engine system

would slow the ship at Earth at the expedition’s end.

Attached to the front of the M-4 stage would be the 10-

foot-diameter, 75-foot-long spine module, or “neck,”

which served two functions: in addition to separating

the astronauts from the nuclear engines to minimize

crew radiation exposure, it would place distance

between the crew and the ship’s center of gravity, making the artificial gravity spin radius longer.

General Dynamics opted arbitrarily for providing artificial gravity equal to 25 percent of Earth’s surface

gravity and estimated that five rotations per minute

was the upper limit for crew comfort. As engine systems were cast off, however, the ship’s center of rotation

would shift forward. For example, before the M-1

maneuver it would be at the aft end of the M-2

engine system, 420 feet from the ship’s nose, and at

the start of the M-2 maneuver it would be at the

front of the M-2 system, 265 feet from the nose. As

the ship grew progressively shorter, the spin radius

would decrease, forcing faster rotation to maintain

the same artificial gravity level. The report proposed

joining the aft end of the crew vehicle to the end of a

service vehicle during return to Earth, after the M-3

engine system was cast off, in order to place the center of rotation at the joint between the two vehicles

and permit an acceptable rotation rate.

The General Dynamics crew ship design included the

Life Support Section (LSS) for the eight-person crew.

The LSS, which would be tested attached to an Earthorbital space station beginning in November 1968,

again illustrated the intense modularity of the

General Dynamics design. The 10-foot-diameter central section would be attached to the front of the spine

module and would house the repair shop, food storage,

and radiation-shielded Command Module (not to be

confused with the Apollo CM). The Command Module

would serve double duty as the ship’s radiation shelter

and “last redoubt” if all other habitable modules were

destroyed. Crewmembers would sleep in the

Command Module’s lower level to reduce their overall

radiation exposure. The top level would serve as the

crew ship’s bridge and the “blockhouse” from which the

service vehicles would be remote-controlled.

Two-level, 10-foot-diameter Mission Modules would

cluster around the central section to provide additional

living space. Individual levels could be sealed off if penetrated by meteoroids, and entire Mission Modules

could be cast off if the crew had to reduce spacecraft

mass to permit return to Earth—for example, if a large

amount of propellant were lost and could not be

replaced from the service vehicles. The LSS would also

include the Earth Entry Module, an Apollo CM-style

conical capsule. In addition to carrying the astronauts

through Earth’s atmosphere at voyage’s end, it would

serve as emergency abort vehicle during the M-1

maneuver. The service vehicles would each carry a

spare Earth Entry Module.

On the service ships, a hangar for robot probes would

replace the LSS. Unlike the Lockheed and

Aeronutronic reports, the General Dynamics report

treated its automated Mars probes in some detail.

They would include the Returner Mars sample collector, a Mars Lander based on technology developed for

NASA’s planned Surveyor lunar soft-landing probes,

Deimos Probe (Deipro) and Phobos Probe (Phopro)

Mars moon hard landers based on technology developed for NASA’s Ranger lunar probes, the Mars

Environmental Satellite (Marens) orbiter, and

Floater balloons.13

General Dynamics’ EMPIRE statement of work

specified that it should study piloted Mars-orbital

missions; however, enthusiastic Ehricke could not

resist inserting an option to carry a small piloted

Mars lander. A piloted Mars orbiter must, after all,

enter and depart Mars orbit, thus performing all the

major maneuvers required of a Mars Orbit

Rendezvous landing mission except the landing itself.

The Mars Excursion Vehicle lander, which would be

14 Monographs in Aerospace History

Chapter 3: EMPIRE and After
based on the automated Returner, would be carried in

a service vehicle probe hangar. It would support two

people for seven days on Mars.14 Ehricke’s team proposed that a crew test it on the Moon in November

1972.

To get its ships into Earth orbit, Ehricke’s team

invoked a very large post-Saturn heavy-lift rocket

capable of launching 500 tons. Two of these giants

would be able to place parts for one ship into orbit so that

only one rendezvous and docking would be required to

complete assembly. By contrast, if the Saturn C-5 were

used, eight launches and seven rendezvous and docking

maneuvers would be needed to launch and assemble

each General Dynamics Mars ship. The Ehricke team

targeted post-Saturn vehicle development to commence

in July 1965; the giant rocket would be declared operational in August 1973.

Mars in Texas

NASA’s Manned Spacecraft Center (MSC) (renamed

the Johnson Space Center in 1973) began as the Space

Task Group (STG) at NASA Langley Research Center

in Hampton, Virginia, where it was formed in late

1958 to develop and manage Project Mercury.

Following Kennedy’s May 1961 Moon speech, the

STG’s responsibilities expanded, so it needed a new

home. The STG became the MSC and moved to

Houston, Texas.

Maxime Faget became MSC’s Assistant Director for

Research and Development. He launched the first MSC

piloted Mars mission study in mid-1961, but it

remained in-house and at a minimal level of effort until

late 1962, after Marshall kicked off EMPIRE. MSC’s

study was supervised by David Hammock, Chief of

MSC’s Spacecraft Technology Division, and Bruce

Jackson, one of his branch chiefs. Chief products of

MSC’s study were a Mars mission profile unlike any

proposed up to that time and the first detailed Mars

Excursion Module (MEM) piloted Mars lander design.

Jackson and Hammock presented MSC’s Mars plan at

the first NASA intercenter meeting focused on interplanetary travel, the Manned Planetary Mission

Technology Conference held at Lewis from 21 to 23

May 1963. The NASA Headquarters Office of Applied

Research and Technology organized the meeting,

which focused mainly on specific technologies, many

with applications to missions other than Mars. The

“Mission Examples” session, chaired by Harry Ruppe,

was relegated to the afternoon session on the last day

of the meeting.

Hammock and Jackson presented MSC’s mission

design publicly for the first time at the American

Astronautical Society (AAS) Symposium on the

Manned Exploration of Mars in Denver, Colorado, the

first non-NASA conference devoted to piloted Mars

travel.15 George Morgenthaler of Martin Marietta

Corporation in Denver organized the symposium. As

many as 800 engineers and scientists heard 26 papers

and a banquet address by Secretary of the Air Force

Eugene Zuckert. It was the first time so many individuals from Mars-related disciplines came together in

one place, and the last Mars conference as large until

the 1980s. Sky & Telescope magazine reported that the

“Denver symposium . . . helped narrow the gaps

between engineer, biologist, and astronomer.”16

Hammock and Jackson called Mars “perhaps the

most exciting target for space exploration following

Apollo . . . because of the possibility of life on its surface and the ease with which men might be supported there.”17 Two of their plans used variations on

the MOR mode, but the third, dubbed the FlybyRendezvous mode, was novel—it would accomplish a

piloted Mars landing while still accruing the

weight-minimization benefits of a Crocco-type flyby.

The Flyby-Rendezvous mode would use two separate

spacecraft, designated Direct and Flyby. They would

reach Earth orbit atop Saturn V rockets. The unpiloted

Flyby craft would depart Earth orbit 50 to 100 days

ahead of the piloted Direct craft on a 200-day trip to

Mars. The Direct craft, which would include the MEM

lander, would reach Mars ahead of the Flyby craft after

a 120-day flight. The astronauts would then board the

MEM and abandon the Direct craft. The MEM would

land while the Direct craft flew past Mars into solar

orbit. Forty days later the Flyby craft would pass Mars

and begin the voyage back to Earth. The crew would lift

off in the MEM ascent vehicle and set out in pursuit,

boarding the Flyby craft about two days after leaving

Mars. Near Earth the astronauts would separate from

the Flyby spacecraft in an Earth-return capsule, enter

Earth’s atmosphere, and land.

Chapter 3: EMPIRE and After

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 15
One of MSC’s MOR plans used aerobraking, while the

other relied on propulsive braking. In aerobraking, the

lifting-body-shaped Mars spacecraft would skim

through Mars’ upper atmosphere to use drag to slow

down and enter orbit. The Mars surface explorers

would separate from the orbiting ship in the MEM and

land for a surface stay of 10 to 40 days. They would

then lift off in the MEM ascent stage, dock with the

orbiting ship, and leave Mars orbit. Earth atmosphere

reentry would occur as in the Flyby-Rendezvous mode.

Hammock and Jackson’s propulsive-braking MOR

mission resembled the aerodynamic-braking mode

design, except that a chemical or nuclear propulsion

stage would place the ship in Mars orbit.

Hammock and Jackson found that the chemical allpropulsive spacecraft design would weigh the most

at Earth-orbit departure (1,250 tons), while the

nuclear aerobraking design would weigh the least

(300 tons). The Flyby-Rendezvous chemical and aerobraking chemical designs would weigh about the

same (1,000 tons).

The MEM design for the Houston Center’s MOR

plans—the first detailed design for a piloted Mars

lander—was presented in June 1964 at the next

major meeting devoted to Mars exploration, the

Symposium on Manned Planetary Missions at

Marshall.18 Philco (formerly Ford) Aeronutronic performed the study between May and December 1963.

Franklin Dixon, the presenter, was Aeronutronic’s

manager for Advanced Space Systems. The design,

which the company believed could land on Mars in

1975, was first described publicly in Houston in

November 1964 at the American Institute of

Astronautics and Aeronautics (AIAA) 3rd Manned

Space Flight Conference.

16 Monographs in Aerospace History

Chapter 3: EMPIRE and After

Figure 1—Landing on Mars. Aeronutronic’s Mars lander, a lifting body glider, relied on aerodynamic lift to minimize required

propellant. The design was based on optimistic estimates of Martian atmospheric density. (“Summary Presentation: Study of

a Manned Mars Excursion Module,” Franklin Dixon, Proceeding of the Symposium on Manned Planetary Missions:

1963/1964 Status, NASA TM X-53049, Future Projects Office, NASA George C. Marshall Spaceflight Center, Huntsville,

Alabama, June 12, 1964, p. 467.)
Dixon pointed out that the chief problem facing Mars

lander designers was the lack of reliable Mars atmosphere data, noting that “two orders of magnitude variations in density at a given altitude were possible

when comparing Mars atmosphere models of responsible investigators.” Aeronutronic settled on a

Martian atmosphere comprising 94 percent nitrogen,

2 percent carbon dioxide, 4 percent argon, and traces

of oxygen and water vapor, with a surface pressure of

85 millibars (about 10 percent of Earth sea-level pressure). For operation in this atmosphere, Aeronutronic

proposed a “modified half-cone” lifting body with two

stubby winglets. The Aeronutronic MEM would measure about 30 feet long and 33 feet wide across its tail.

The 30-ton MEM would ride to Mars on its mothership’s back under a thermal/meteoroid shield which

the crew would eject two hours before the Mars

landing. The three-person landing party, which

would consist of the captain/scientific aide, first officer/geologist, and second officer/biologist, would don

space suits and enter the small flight cabin in the

MEM’s nose. Five minutes before planned deorbit,

the MEM would separate from its mothership and

retreat to a distance of 1,000 feet. There it would

point its tail forward and fire its single descent

engine to begin the fall toward Mars’ surface.

The MEM’s heat-resistant hull would be made

largely from columbium, with nickel-alloy aft surfaces. Aeronutronic calculated that friction heating

would drive nose temperature to 3,050 degrees

Fahrenheit. At Mach 1.5, between 75,000 and

100,000 feet above Mars, a single parachute would

be deployed and the MEM would assume a tail-down

attitude. The engine would then ignite a second time

and the parachute would separate. Aeronutronic’s

design included enough propellant for an estimated

60 seconds of hover before touchdown on four landing legs with crushable pads.

Aeronutronic attempted to select a MEM landing site

using photographs taken by Earth-based telescopes.

Theorizing that living things might follow the retreating edge of the melting polar cap in springtime, they

suggested that NASA target the MEM to Cecropia at

65 degrees north latitude (this corresponds to Vastitas

Borealis north of Antoniadi crater on modern Mars

maps).19 Upon landing, the astronauts would eject

shields covering the MEM windows and look out over

their landing site to evaluate “local hazards,” including

any “unfriendly life forms.”20 Mars surface access would

be through a cylindrical airlock that lowered like an

elevator from the MEM’s tail.

Dixon stated that “biological evaluation of life forms is

essential for the first purely scientific effort to allow

pre-contamination studies before man alters the Mars

environment,”21 implying that little effort would be

made to prevent the astronauts from introducing terrestrial microorganisms. Aeronutronic listed “investigate life forms for possible nutritional value”22 among

the tasks of the Mars biology study program. The crew

would explore Mars for between 10 and 40 days, spending about 16 man-hours outside the MEM each day.

Aeronutronic’s MEM was envisioned as a two-stage

vehicle. For return to Mars orbit, the ascent motor

would fire, blasting the flight cabin free of the descent

stage. Two propellant tanks would be cast off during

ascent. After docking with the orbiting mothership, the

MEM flight cabin would be discarded.

Chapter 3: EMPIRE and After

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 17

Figure 2—Astronauts exploring Mars near Aeronutronic’s

lander would take pains to collect biological specimens before

terrestrial contamination made study impossible. A large

dish antenna (left) would let them share their discoveries

with Earth. (“Summary Presentation: Study of a Manned

Mars Excursion Module,” Franklin Dixon, Proceeding of the

Symposium on Manned Planetary Missions: 1963/1964

Status, NASA TM X-53049, Future Projects Office, NASA

George C. Marshall Spaceflight Center, Huntsville,

Alabama, June 12, 1964, p. 470.)
UMPIRE

Every 26 months, an opportunity occurs for a short (sixmonth) minimum-energy transfer from Earth to Mars.

In some opportunities the planet is farther from Earth

than in others. This means that in some opportunities

the minimum energy necessary to reach Mars is

greater than in others. The most difficult Mars opportunities require about 60 percent more energy than the

best opportunities. The more energy required to reach

Mars, the more propellant a spacecraft must expend.

Because of this, a spacecraft launched in a poor Mars

opportunity will weigh more than twice as much as one

launched in a good Mars opportunity.

The quality of Mars launch opportunities runs

through a continuous cycle lasting about 15 years. Not

surprisingly, this corresponds to the cycle of astronomically favorable oppositions described in Chapter 1.

The EMPIRE studies showed that the best Mars

opportunities since 1956 would occur in 1969 and

1971, just as the Apollo lunar goal was reached.

Opportunities would become steadily worse after that,

hitting a peak in 1975 and 1977, then would gradually improve. The next set of favorable oppositions would

occur in 1984, 1986, and 1988.

The Marshall Future Projects Office contracted with

General Dynamics/Fort Worth and Douglas Aircraft

Company in June 1963 to “survey all the attractive

mission profiles for manned Mars missions during the

1975-1985 time period, and to select the mission profiles of primary interest.” The study, nicknamed

“UMPIRE” (“U” stood for “unfavorable”), was summed

up in a Future Projects Office internal report in

September 1964.23

General Dynamics and Douglas worked independently,

but each found that the “best method of alleviating the

cyclic variation of weight required in Earth orbit is to

18 Monographs in Aerospace History

Chapter 3: EMPIRE and After

Figure 3—Returning to Mars orbit: Like the Apollo Lunar Module, Aeronutronic’s lander design used its descent stage as a

launch pad for its ascent stage. Unlike the Lunar Module, it cast off spent propellant tanks as it climbed to orbit. (“Summary

Presentation: Study of a Manned Mars Excursion Module,” Franklin Dixon, Proceeding of the Symposium on Manned

Planetary Missions: 1963/1964 Status, NASA TM X-53049, Future Projects Office, NASA George C. Marshall Spaceflight

Center, Huntsville, Alabama, June 12, 1964, p. 468.)
plan long (900-1100 days) missions.”24 The companies

advised that “serious consideration . . . be given to the

concept of the first manned landing on Mars being a

long term base” rather than a short visit.25 That is, the

two companies recommended making the first Mars

expedition conjunction class, not opposition class.

The terms “conjunction class” and “opposition class”

refer to the position of Mars relative to Earth during

the Mars expedition. In the former, Mars moves behind

the Sun as seen from Earth (that is, it reaches conjunction) halfway through the expedition; in the latter,

Mars is opposite the Sun in Earth’s skies (that is, at

opposition) at the expedition’s halfway point.

Conjunction-class expeditions are typified by lowenergy transfers to and from Mars, each lasting about

six months, and by long stays at Mars—roughly 500

days. Total expedition duration thus totals about

1,000 days. The long stay gives Mars and Earth time

to reach relative positions that make a minimumenergy transfer from Mars to Earth possible. Von

Braun opted for a conjunction-class expedition in The

Mars Project.

Opposition-class Mars expeditions have one low-energy

transfer and one high-energy transfer separated by a

short stay at Mars—typically less than 30 days. Total

duration is about 600 days. This was the approach

Lewis used in its 1959-1961 study. In the 1960s, most

Mars expedition plans were opposition class.

Because they require more energy, opposition-class

expeditions demand more propellant. All else being

equal, a purely propulsive opposition-class Mars expedition can need more than 10 times as much propellant

as a purely propulsive conjunction-class expedition.

This adds up, of course, to a correspondingly greater

spacecraft weight at Earth-orbit departure.

Therefore, the conjunction-class plan is attractive.

However, the long mission duration is problematical,

for it demands great endurance and reliability from

both machines and astronauts, exposes any crew left in

Mars orbit to risk from meteoroids and radiation for a

longer period, and requires complex Mars surface and

orbital science programs to enable productive use of the

500-day Mars stay.

Mars in California

NASA’s Ames Research Center, a former NACA laboratory in Mountainview, California, also became involved

in piloted Mars planning in the EMPIRE era. In 1963,

Ames contracted with the TRW Space Technology

Laboratory to perform a non-nuclear Mars landing expedition study emphasizing weight reduction. Robert Sohn

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 19

Chapter 3: EMPIRE and After

Figure 4—Conjunction-class Mars missions include a

low-energy transfer from Earth to Mars, a long stay at

Mars, and a low-energy transfer from Mars to Earth. 1 -

Earth departure. 2- Mars arrival. 3 - Mars departure. 4 -

Earth arrival. (Manned Exploration Requirements and

Considerations, Advanced Studies Office, Engineering and

Development Directorate, NASA Manned Spacecraft Center,

Houston, Texas, February 1971, p. 1-7.)

Figure 5—Opposition-class Mars missions offer a short Mars

stay but require one high-energy transfer, so they demand more

propellant than conjunction-class missions. 1 - Earth departure (low-energy transfer). 2 - Mars arrival. 3 - Mars departure

(high-energy transfer). 4 - Earth arrival. (Manned Exploration

Requirements and Considerations, Advanced Studies Office,

Engineering and Development Directorate, NASA Manned

Spacecraft Center, Houston, Texas, February 1971, p. 1-8.)
supervised the study for TRW and presented the study’s

results at the 1964 Huntsville meeting.26 Sohn’s team

targeted 1975 for the first piloted Mars landing.

TRW found that the biggest potential weight-saver was

aerobraking. For its aerobraking calculations, it used

the Rand Corporation’s August 1962 “Conjectural

Model III Mars Atmosphere” model, which posited a

Martian atmosphere consisting of 98.1 percent nitrogen and 1.9 percent carbon dioxide at 10 percent of

Earth sea-level pressure. This atmospheric density and

composition dictated the spacecraft’s proposed shape—

a conical nose with dome-shaped tip, cylindrical center

section, and skirt-shaped aft section. This shape was

based on an Atlas missile nose cone. The TRW team’s

two-stage, 12.5-ton MEM would also use the nose-cone

shape. All else being equal, a version of TRW’s spacecraft for the 1975 Mars launch opportunity that used

braking rockets at Mars and Earth would weigh 3,575

tons, while the company’s aerobraking design would

weigh only 715 tons.

TRW’s Earth aerobraking system was the Earth

Return Module, a slender half-cone lifting body carried

inside the main spacecraft. A few days before Earth

encounter the crew would enter the Earth Return

Module and separate from the main spacecraft. The

Earth Return Module would enter Earth’s atmosphere

as the main spacecraft flew past Earth into solar orbit.

The TRW study proposed a lightweight artificial gravity system—a 500-foot tether linking the main spacecraft to the expended booster stage that pushed it from

Earth orbit—which would, it calculated, add less than

1 percent to overall spacecraft weight. The resultant

assemblage would spin end over end to produce artificial gravity. TRW reported that NASA Langley had

used computer modeling to confirm this design’s longterm rotational stability.27

TRW found that Earth-Mars trajectories designed to

reduce spacecraft weight at Earth departure would

result in high reentry speeds at Earth return. For

example, an Earth Return Module would reenter at

66,500 feet per second at the end of a 1975 Mars voyage, while one returning after a 1980 mission would

reenter at almost 70,000 feet per second. TRW found

that available models for predicting atmospheric friction temperatures broke down at such speeds.28 For

comparison, maximum Apollo lunar-return speed was

“only” 35,000 feet per second.

Reentry speed could be reduced by using rockets. TRW

found, however, that including enough propellant to

slow the entire spacecraft from 66,500 feet per second

to 60,000 feet per second would boost spacecraft weight

from 715 tons to 885 tons. Slowing only the Earth

Return Module by the same amount would increase

overall spacecraft weight to 805 tons.

The study proposed a new alternative—a Venus swingby at the cost of a modest increase in trip time. A ship

returning from Mars in 1975 could, the study found, cut

its Earth reentry speed to 46,000 feet per second by

passing 3,300 kilometers over Venus’s night side. A

Venus swingby during flight to Mars in 1973 would

allow the ship to gain speed without using propellant

and thus arrive at Mars in time to take advantage of a

slower Mars-Earth return trajectory. According to

TRW’s calculations, Venus swingby opportunities

occurred at every Mars launch opportunity.29

20 Monographs in Aerospace History

Chapter 3: EMPIRE and After

Figure 6—TRW’s 1964 Mars ship design, shaped like a

missile warhead, sought to minimize required propellant

by aerobraking in the Martian atmosphere. This cutaway

shows the Mars lander and Earth Return Module inside

the spacecraft. (“Summary of Manned Mars Mission

Study,” Robert Sohn, Proceeding of the Symposium on

Manned Planetary Missions: 1963/1964 Status, NASA

TM X-53049, Future Projects Office, NASA George C.

Marshall Spaceflight Center, Huntsville, Alabama, June

12, 1964, p. 150.)
Building on Apollo

By the end of the June 1964 Marshall Mars symposium, early flyby detractor Maxime Faget had come

to see some merit in the concept. In a panel discussion chaired by Heinz Koelle, Faget declared that

“we should, I think, consider a flyby . . . if we undertake a flyby we really have to face the problems of

man flying out to interplanetary distances . ...I

think we have to undertake a program that will force

the technology, otherwise we will not get [to Mars] in

my lifetime . . . .”30

Von Braun, also a panel member, added, that “I think

[piloted] flyby missions, particularly flybys involving

[automated] landing probes . . . would be invaluable

.... One such flight, giving us more information on

what to expect . . . on the surface of Mars, will be

extremely valuable in helping us in laying out the

equipment for the landing ... that would follow the

first flyby flight.” 31

Von Braun then implicitly announced an impending

shift in NASA advanced planning. “I am also inclined to

believe,” he said, “that our first manned planetary flyby

missions should be based on the Saturn V as the basic

Earth-to-orbit carrier. The reason is that, once the production of this vehicle is established and a certain reliability record has been built up, this will be a vehicle

that will be rather easy to get.” Von Braun’s statement

acknowledged that a post-Saturn rocket appeared

increasingly unlikely.32 In an outline of future plans

submitted to President Lyndon Johnson’s Budget

Bureau in late November 1964, NASA stated that the

post-Saturn rocket should receive low funding priority,

and called for post-Apollo piloted spaceflight to be

focused on Earth-orbital operations using technology

developed for the Apollo lunar landing.33

The 1964 decision to use Apollo technology for missions

after the lunar landing could be seen as a rejection of

post-Apollo piloted Mars missions. Historian Edward

Ezell wrote in 1979 that the “determinism to utilize

Apollo equipment for the near future was very destructive to the dreams of those who wanted to send men to

Mars.”34 As if to emphasize this, the amount of funding

applied to piloted planetary mission studies took a nose

dive after November 1964. In the 17 months preceding

November 1964, $3.5 million was spent on 29 piloted

planetary mission studies. Between November 1964

and May 1966, NASA contracted for only four such

studies at a cost of $465,000.35

Mars planners were not so easily discouraged, however.

After EMPIRE, and concurrent with UMPIRE, a

Marshall Future Projects Office team led by Ruppe commenced an in-house study to look at using Apollo hardware for Mars exploration. Ruppe’s study report, published in February 1965, found that piloted Mars flyby

missions would be technically feasible in the mid- to late1970s using Saturn rockets and other Apollo hardware. 36

The report’s flyby spacecraft design used hardware

already available or in an advanced state of development.

Two RL-10 engines would provide rendezvous and docking propulsion, for example, and an Apollo Lunar Module

descent engine would perform course corrections.

A pressurized hangar would protect a modified Apollo

CSM during the interplanetary voyage. The hangar

would also provide a shirt-sleeve environment so that

the astronauts could act as in-flight caretakers for

five tons of automated probes, including “landers,

atmospheric floaters, skippers, orbiters, and possibly

probes . . . to perform aerodynamic entry tests [of]

designs and materials.”37 The last of these would,

Ruppe wrote, provide data to help engineers design

the piloted Mars landers to follow. His report drew on

the UMPIRE conclusions when it stated that

significant reduction of initial mass in Earth

orbit is possible if we can use aerodynamic

braking at Mars or refueling there, but these

methods assume a knowledge about . . . the

Martian atmosphere, or about Mars surface

resources which just is not available. The first

venture, still assuming that we are not very

knowledgeable . . . would probably transport 2

or 3 men to the surface of Mars for a few days

... [at a cost of] a billion dollars per man-day

on Mars. If the physical properties of Mars

were well known, we could think . . . of the first

landing as a long-duration base, reducing cost

to less than 10 million dollars per man-day.38

The three-person flyby crew would live in a spherical

habitat containing a radiation shelter and a small centrifuge for maintaining crew health (the study rejected

artificial gravity systems that rotated the entire craft as

being too complex and heavy). Twin radioisotope power

units on extendible booms would provide electricity.

Chapter 3: EMPIRE and After

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 21
The mission would require six Saturn V launches and

one Saturn IB launch. Saturn V rocket 1 would launch

the unpiloted flyby spacecraft; then Saturn V rockets 2

through 5 would launch liquid oxygen tankers. The

sixth Saturn V would then launch the Earth-departure

booster, a modified Saturn V second stage called the SIIB, which would reach orbit with a full load of 80 tons

of liquid hydrogen but with an empty liquid oxygen

tank. Ruppe wrote that solar heating would cause the

liquid hydrogen to turn to gas and escape; to ensure

that enough remained to boost the flyby craft toward

Mars, the S-IIB would have to be used within 72 hours

of launch from Earth.

The three astronauts would launch in the modified

Apollo CSM on the Saturn IB rocket and then board

the flyby spacecraft. They would use the RL-10

engines to guide the flyby craft to a docking with the

S-IIB. The oxygen tankers would then dock in turn and

pump their cargoes into the S-IIB’s empty oxygen

tank. Ruppe’s flyby craft and booster would weigh 115

tons at Earth-orbit departure. The S-IIB would then

ignite, burn to depletion, and detach, placing the flyby

craft on course for Mars.

During the flight, the astronauts would regularly

inspect and service the automated probes. As they

approached Mars, the astronauts would release the

probes and observe the planet using 1,000 pounds of

scientific equipment. The flyby spacecraft would relay

radio signals at a high data rate between the Mars

probes and Earth until it passed out of range; then

direct communication between Earth and the probes

would commence at a reduced data rate.

As Earth grew large again outside the viewports, the

flyby astronauts would enter the modified Apollo CSM

and abandon the flyby craft. The CSM’s propulsion

system would slow it to Apollo lunar return speed,

then the CM would separate from the SM, reenter, and

land. Depending on the launch opportunity used, total

mission duration would range from 661 to 691 days.

Even as Ruppe’s report was published, the “robot caretaker” justification for piloted Mars flybys was becoming increasingly untenable. On 31 July 1964, the

Ranger 7 Moon probe snapped 4,316 images of one corner of Mare Nubium before smashing into the lunar

surface as planned. The images showed the Moon to be

sufficiently smooth for Apollo landings, and gave the

credibility of robot explorers a vital boost. As Ruppe

published his report, Mariner 4, launched on 28

November 1964, was making its way toward Mars. Not

long after Ruppe published his report, on 20 February

1965, Ranger 8 returned 7,137 images as it plunged

toward the Sea of Tranquillity. A month later, Ranger 9

returned 5,148 breathtaking images of the complex

112-kilometer crater Alphonsus.

Beyond providing engineering and scientific justifications for the piloted flyby mission, Ruppe’s report tendered a political justification. He wrote:

From the lunar landing in this decade to a

possible planetary landing in the early or

middle 1980s is 10 to 15 years. Without a

major new undertaking, public support will

decline. But by planning a manned planetary

[flyby] mission in this period . . . the United

States will stay in the game.39

That Ruppe felt it necessary in early 1965 to attempt to

justify a piloted Mars flyby mission in terms of probable impact on the U.S. domestic political environment is

telling, as will be seen in the next chapter.

22 Monographs in Aerospace History

Chapter 3: EMPIRE and After
An era ended for the National Aeronautics and

Space Administration last week when Congress

voted a $234-million cut in that agency’s budget

authorization for Fiscal 1968 . . . . The NASA

budget cut is symptomatic of the many currents

of basic change that are flowing through the land

this summer . ... If top NASA officials have not

interpreted their admittedly long and arduous

buffeting on Capitol Hill this spring and summer

correctly, then they are facing a much worse time

in the years ahead . ... (Robert Hotz, 1967)1

Mariner 4

On 15 July 1965, the Mariner 4 probe snapped 21 blurry pictures of Mars’ southern hemisphere as it flew by

at a distance of 9,600 kilometers. The flyby, which

marked the culmination of a seven-and-a-half-month

voyage, was an unprecedented engineering achievement. Mariner 4 had withstood the interplanetary

environment for nearly twice as long as Mariner 2 had

during its 1962 Venus flyby mission.

Mariner 4 revealed Mars to be a disappointingly

Moonlike, cratered world with no obvious signs of

water. Scientists had expected to see a world more like

Earth, where erosion makes obvious craters the exception rather than the rule. That Mariner 4’s images were

black and white accentuated the resemblance to

Earth’s desolate satellite. Canals were conspicuously

absent. They are now believed to have been an optical

illusion or a product of eyestrain.

Mariner 4’s impact on Mars exploration planning is

hard to overestimate. First, it showed that Maxime

Faget had been right in 1962. Robots could perform

Mars flybys—astronauts were not required for this

particular exploration mission. It also showed that

robot probes could reach Mars in reasonably good condition, undermining the “robot caretaker” justification

for piloted Mars flybys.

Mariner 4’s radio-occultation experiment revealed

Mars’ atmosphere to be less than 1 percent as dense as

Earth’s. Based on these new data and on measurements of the Martian atmosphere made from Earth

since the 1940s, planetary scientists calculated that the

majority of Mars’ atmosphere was carbon dioxide, not

nitrogen, as had been widely supposed.2

The new Mars atmosphere data relegated to the recycle

bin aerodynamic landing systems such as von Braun’s

delta-winged gliders and Aeronutronic’s lifting-body.

That meant more rocket propulsion would be required

to accomplish a Mars soft landing, which would in turn

demand more propellant. This would boost minimum

lander weight, which meant more propellant would be

needed to transport the lander from Earth to Mars.

This in turn would boost Mars spacecraft weight at

Earth-orbit departure, which meant, of course, that

more expensive rockets would be required to launch

the Mars ship into Earth orbit.

Most importantly, Mariner 4 dealt a body blow to

hopes for advanced Martian life. Historically,

human perceptions of life on Mars have occurred

along a continuum. At one end stood the romantic

view of nineteenth-century American astronomer

Percival Lowell, whose Mars was a dying Earth

inhabited by a race of civil engineers who had dug a

planet-girdling network of irrigation canals to stave

off the encroaching red desert. By the 1930s,

Lowell’s vision was widely seen as optimistic.

Nonetheless, the romance of Lowell’s Mars inspired

would-be Mars explorers into the 1960s.3 

The Mariner 4 results eradicated any lingering

traces of Lowellian romance, and in fact shifted the

prevailing view of life on Mars all the way down the

continuum to a pessimism with almost as little

basis as Lowell’s optimism. The spacecraft had,

after all, imaged only 1 percent of Mars at resolution so low that, had it photographed Earth, scientists examining its pictures would likely have

missed all signs of terrestrial life.4 NASA took pains

to point out that Mariner 4 had been intended only

as a first, preliminary step toward resolving the

question of life on Mars, and that it had “blazed the

way for later spacecraft to land instruments and,

eventually, men on Mars.”5

On the plus side, Mariner 4 provided the first firm

data on conditions astronauts could expect to

encounter in interplanetary space during the voyage

to Mars. The intrepid robot registered fewer meteoroid

impacts than expected, but also detected a higherthan-expected level of cosmic radiation and between

12 and 20 solar flares during what was expected to be

a quiet Sun period.6

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 23

Chapter 4: A Hostile Environment
Vietnam and Watts

President Lyndon Johnson supported the lunar program launched by his predecessor, which was not surprising, given that he had played a key role in formulating the Moon goal as Kennedy’s Vice President and

National Space Council chair. Like many others, however, he was uncertain what NASA’s scope and direction should be in the years after it put an astronaut on

the Moon. In a letter on 30 January 1964, Johnson

asked NASA Administrator James Webb for a list of

possible future NASA goals.7

As stated in the last chapter, the outline of agency

plans submitted to Johnson’s Budget Bureau in

November 1964 emphasized using Apollo hardware in

Earth orbit. An Apollo-based piloted program in the

early 1970s was seen as an interim step to an Earthorbiting space station in the mid- to late-1970s.8 When

the National Academy of Sciences Space Science Board

called instead for an emphasis on planetary exploration, NASA officials insisted that the Earth-orbital

focus was President Johnson’s preference.9

This philosophy—that the United States would be best

served by using Apollo hardware as an interim step to

a future space station—set the tone for much of NASA’s

post-Apollo planning through the beginning of 1969.

NASA’s program for reapplying Apollo hardware was

the Apollo Applications Program (AAP), an initially

ambitious slate of lunar and Earth-orbital missions

that eventually shrank to become the Skylab program.

As shown in the last chapter, Mars planners in the

Future Projects Office at Marshall sought also to apply

Apollo technology to Mars exploration.

An event on 25 January 1965 also helped set the tone

for NASA’s post-Apollo future. On that date, President

Johnson sent to Congress a $5.26-billion NASA budget

for FY 1966, an increase of only $10 million over the

$5.25-billion FY 1965 budget. This was the smallest

NASA budget increase since the agency was established in 1958. NASA’s eventual FY 1966 appropriation

was $5.18 billion, the Agency’s first budget drop. Most

of the cuts came from AAP and other new starts.

This new frugality in the administration and in

Congress with regards to space reflected growing

unease across the United States. In August 1964, following a naval incident in the Gulf of Tonkin off North

Vietnam, Congress passed the Tonkin Resolution,

which empowered President Johnson to take what

steps he deemed necessary to thwart further communist aggression in Indochina. In February 1965,

Vietcong guerrillas attacked the South Vietnamese military base at Pleiku, killing 8 Americans and wounding

126. In response, Johnson ordered the bombing of

North Vietnam’s base at Dong Hoi. On 8 March, the

first U.S. combat troops—two battalions of marines—

joined the 23,000 American advisors already in South

Vietnam.

As Mariner 4 approached Mars in July, President

Johnson announced that he would increase the number

of soldiers in South Vietnam from 75,000 to 125,000.

On 4 August, while Mariner 4’s images were trickling

back to Earth, Johnson asked Congress for an additional $1.7 billion to support the expanding war.

On 11 August, as Mars planners attempted to reconcile

the thin atmosphere and craters revealed by Mariner 4

with their old plans for Mars, racial violence flared in the

Watts ghetto of Los Angeles, California. Five nights of

anarchy left 34 dead and caused $40 million in damage.

Planetary JAG

Against this backdrop of war, social unrest, and

Mariner 4 results, NASA launched a two-prong assault

on Mars. The first, the Voyager program, aimed at planetary exploration using automated orbiters and landers. The second was an internal piloted Mars flyby

study involving several NASA centers.

As already indicated, planetary scientists had rejected

the AAP space station emphasis in favor of planetary

exploration, which, they felt, was being neglected in

NASA’s headlong rush to reach the Moon. In its report

Space Research: Directions for the Future, released in

January 1966, the National Academy of Sciences Space

Science Board designated “the exploration of the near

planets as the most rewarding goal on which to focus

national attention for the 10 to 15 years following

manned lunar landing.”10 In May 1966, the American

Astronomical Society Symposium “The Search for

Extraterrestrial Life” re-emphasized the importance of

seeking life on Mars despite the Mariner 4 results.11

These inputs helped build both Voyager and piloted

flyby mission rationales.

24 Monographs in Aerospace History

Chapter 4: A Hostile Environment
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 25

Voyager, first proposed in 1960 at the Jet Propulsion

Laboratory (JPL) in Pasadena, California, was envisioned as a follow-on program to the Mariner flyby

series. The 1960s Voyager should not be confused with

the twin Voyager flyby probes launched to the outer

planets in 1977 and 1978. In the FY 1967 budget cycle,

NASA had postponed proposing Voyager as a new start

following assurances that it could get off to an aggressive start in FY 1968. The delay was partly a result of

the Mariner 4 findings. New atmosphere data forced a

re-design that drove the program’s estimated cost

beyond $2 billion.12 Voyager was initially targeted for

first launch in 1971, with a second mission in 1973, and

other missions to follow.

The NASA Headquarters Office of Manned Space

Flight (OMSF) under George E. Mueller, Associate

Administrator for Manned Space Flight, managed

the piloted flyby study. Mueller had taken charge of

the OMSF in September 1963 and had set up the

Advanced Manned Missions Office under Edward

Gray in November 1963 to direct NASA’s piloted

planetary mission planning activities. At a meeting

on 15 April 1965, Mueller had received authority

from NASA Deputy Administrator Robert Seamans

to put together a NASA-wide group to plan piloted

planetary missions. A preliminary meeting of the

group occurred on 23 April 1965. This prepared the

ground for development of the Planetary Joint Action

Group (JAG), which was formally established later in

the year. The Planetary JAG was headed by Gray and

drew members from NASA Headquarters, Marshall,

MSC, and Kennedy Space Center (KSC), as well as

from the Apollo planning contractor, Bellcomm.13

Initially the Planetary JAG’s focus was on piloted

Mars missions using nuclear rockets. In April 1966,

however, Mueller launched a piloted Mars flyby

study within the Planetary JAG at the request of

Nobel Laureate Charles Townes, chair of the NASA

Science and Technology Advisory Committee.

Townes had asked Mueller in January 1966 to carry

out a study comparing the unpiloted Voyager project

with a piloted flyby with robot probes (what he

called a “manned Voyager”).14 In the second half of

1966, NASA spent $2.32 million on 12 piloted planChapter 4: A Hostile Environment

Figure 7—The 1966 Planetary Joint Action Group study used existing and near-term technology for its piloted Mars flyby

spacecraft design. Note the Earth Entry Module (left) based on the Apollo Command Module. (NASA Photo S-66-11230)
etary mission studies supporting the Planetary

JAG.15

Later that year, Mueller testified to the House Space

Committee on the benefits of a piloted flyby. He

explained that it afforded 

the best opportunity for performing manned

planetary exploration with minimal cost and at

an early date . . . . The attractiveness of this

type of mission . . . stems from the relatively

light burden which it imposes on the propulsion system, although the short interval of

direct contact with the target planet detracts

from its desirability. The usefulness of the flyby

mission becomes clearly established when

viewed as an in-situ test-bed for evaluating the

performance of various subsystems such as

navigation, life support, and communications

to be used in later landing missions; [and]

when also viewed as a platform for launching

instrumented probes toward the target planet

during the close passage.16

On 3 October 1966, the Planetary JAG published its

Phase 1 report, Planetary Exploration Utilizing a

Manned Flight System.17 The report placed piloted flybys within an evolutionary “integrated program” of

new and Apollo-based technology with “balanced” use

of humans and robots, the objective of which was

“maximum return at minimum cost, assuming intensive investigation of the planets is a goal.” By this

time the integrated program concept had been discussed for more than a year outside NASA.18 The

Planetary JAG’s integrated program proceeded

through the following steps:

• Apollo Applications Program (1968-73):

Astronauts would remain aloft in space stations

based on Apollo hardware for progressively

longer periods to collect data on human reactions to weightlessness. Some would live in

Earth orbit for more than a year approximately

the duration of a piloted Mars flyby mission.

• Mariner (1969-73) and Voyager (1973): The

Planetary JAG report cast Mariner and

Voyager as lead-ins to piloted expeditions by

stating that data they collected would aid engineers designing piloted flyby hardware. A

Mariner probe would fly by Mars in 1969; in

1971 another Mariner would drop a probe into

Mars’ atmosphere. The first Voyager probe

would land on Mars in 1973 bearing a suite of

life-detection experiments.

• Piloted Mars/Venus Flybys (1975-80): The first

piloted Mars flyby mission would leave Earthorbit in September 1975. Mars flyby launch

opportunities would also occur in October 1977

and November 1979. Multiple flyby missions

were possible—a Venus/Mars mission could

start in December 1978, and a Venus/Mars/

Venus mission could launch in February 1977.

These would dispense automated probes based

on Mariner and Voyager technology.

• Piloted Mars Landing and piloted Venus

Capture (orbiter) missions (post-1980) would

see introduction of AEC-NASA nuclear-thermal rockets. The Planetary JAG deemed

nuclear propulsion “essential for a flexible

Mars landing program” capable of reaching

Mars in any launch opportunity regardless of

the energy required. (The nuclear rocket program is described in more detail in Chapter 5.)

The Planetary JAG’s piloted Mars flyby spacecraft

would reach Earth orbit on an Improved Saturn V

rocket with a modified S-IVB (MS-IVB) third stage.

The MS-IVB would feature stretched tanks to

increase propellant capacity and internal foam insulation to permit a 60-hour wait in Earth orbit before

solar heating caused its liquid hydrogen fuel to turn

to gas and escape.

The four-person flyby crew would ride into Earth orbit

on a two-stage Improved Saturn V in an Apollo CSM

stacked on top of the flyby craft. Upon reaching orbit,

the CSM/flyby craft combination would detach from the

spent Saturn V S-II second stage; then the astronauts

would detach the CSM, turn it around, and dock with a

temporary docking structure on the flyby craft’s forward end.

The Planetary JAG’s flyby spacecraft would consist of

the Mid-Course Propulsion Module with four main

engines; the Earth Entry Module, a modified Apollo

CM for Earth atmosphere reentry at mission’s end;

and the Mission Module, the crew’s living and working

26 Monographs in Aerospace History

Chapter 4: A Hostile Environment
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 27

space. The Earth Entry Module would serve double

duty as a radiation shelter during solar flares. MidCourse Propulsion Module propellant tanks would be

clustered around it to provide additional radiation

shielding. The Mission Module’s forward level (for “rest

and privacy”) would be lined with lockers containing

freeze-dried foods; the aft level would contain the flyby

craft’s control console, science equipment, and wardroom table. The Planetary JAG report proposed that

the Mission Module structure and subsystems, such as

life support, be based on Earth-orbital space station

module designs.

The automated probes would be housed in the

Experiment Module forming the aft end of the flyby

spacecraft, along with a probe deployment manipulator

arm, a biology laboratory, a 40-inch telescope, and an

airlock for spacewalks with an Apollo-type docking

unit. A 19-foot-diameter radio dish antenna for highdata-rate communications with Earth unfolded from

the back of the Experiment Module, as did a 2,000-

square-foot solar array capable of generating 22 kilowatts of electricity at Earth, 8.5 kilowatts at Mars, and

4.5 kilowatts in the Asteroid Belt.

With the crew and flyby craft in Earth orbit, three

Improved Saturn V rockets would launch 12 hours

apart to place the three MS-IVB rocket stages in orbit.

Chapter 4: A Hostile Environment

Figure 9—Three modified Apollo S-IVB stages burn one

after the other to launch the 1967 Planetary Joint Action

Group Mars flyby spacecraft out of Earth orbit. (NASA

Photo S-67-5998)

Figure 8—Typical piloted Mars flyby mission. 1—depart Earth orbit. 2, 4, 10—course corrections. 3, 5, 6, 7—eject automated

Mars probes. 8—automated probe collects Mars surface sample and launches it off the planet. 9—piloted flyby craft retrieves

Mars surface sample. 11—crew leaves Mars flyby craft in Earth return capsule. The abandoned flyby spacecraft sails past

Earth into solar orbit. 12—Earth atmosphere reentry and landing. (Planetary Exploration Utilizing a Manned Flight

System, Office of Manned Space Flight, NASA Headquarters, Washington, DC, October 3, 1966, p. 16.)
28 Monographs in Aerospace History

This rapid launch rate, a veritable salvo of 3,000-ton

rockets, each nearly 400 feet tall, would demand construction of a third Saturn V launch pad at KSC. The

Planetary JAG determined, however, that Pad 39C

would be the only major new ground facility needed to

accomplish its flyby program.

Using the CSM’s propulsion system, the astronauts

would perform a series of rendezvous and docking

maneuvers to bring together the flyby craft and three

MS-IVBs. The flyby crew would then undock the CSM

from the temporary docking structure, re-dock it to the

airlock docking unit on the flyby craft’s side, and enter

the flyby craft for the first time. They would discard the

CSM and eject the temporary docking structure.

Launch from Earth orbit would occur between 5

September and 3 October 1975. The MS-IVB stages

would in turn ignite, deplete their propellants, and be

discarded. As Earth and Moon shrank in the distance,

the crew would deploy the radio antenna and rectangular solar array.

The astronauts would perform a wide range of scientific experiments during the 130-day flight to Mars.

These included solar studies, monitoring themselves to

collect data on the physiological effects of weightlessness, planetary and stellar observations, and radio

astronomy far from terrestrial radio interference.

Mars flyby would occur between 23 January and 4

February 1976, the precise date being dependent on the

date of Earth departure. Beginning several weeks before

flyby, the crew would turn the craft’s telescope toward

Mars and its moons. The pace would quicken 10 days

before flyby, when the flyby craft was 2 million kilometers from Mars. At that time the astronauts would use

the probe deployment arm to unstow and release the

automated probes. At closest approach, the flyby spacecraft would fly within 200 kilometers of the Martian

dawn terminator (the line between day and night).

For the 1975 mission, the flyby craft would carry in its

Experiment Module three 100-pound Mars impactors,

one five-ton Mars polar orbiter, one 1,290-pound Mars

lander, and one six-ton Mars Surface Sample Return

(MSSR) lander. The MSSR was designed to leave the

flyby craft, land on Mars, gather a two-pound sample of

dirt and rock, and then blast it back to the passing flyby

craft using a three-stage liquid-fueled ascent vehicle.

This last concept, an effort to improve the piloted flyby

mission’s scientific productivity, was proposed by

Chapter 4: A Hostile Environment

Figure 11—The 1967 Planetary Joint Action Group’s Mars

flyby spacecraft releases automated probes and deploys

instruments. Close Mars flyby would last mere hours, but the

astronauts would study themselves throughout the mission,

helping to pave the way for future Mars landing expeditions.

(NASA Photo S-67-5999)

Figure 10—Following final S-IVB stage separation, the 1967

Planetary Joint Action Group’s Mars flyby spacecraft deploys

solar arrays and a dish-shaped radio antenna. (NASA Photo

S-67-5991)
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 29

Bellcomm at the Planetary JAG’s meeting at KSC on

29-30 June 1966.19 The concept originated in a paper by

R. R. Titus presented in January 1966.20 Titus, a United

Aircraft Research Laboratories engineer with a talent

for unfortunate acronyms, dubbed his concept FLEM,

for “Flyby-Landing Excursion Mode.” He had been part

of the Lockheed EMPIRE team.

Titus’ mission plan had a piloted MEM lander separating from the flyby spacecraft during the Mars voyage and changing course to intersect the planet. Titus

calculated that MEM separation 60 days before Mars

flyby would permit it to stay for 16 days at Mars, while

separation 30 days out yielded a 9-day stay time. At

Mars the MEM would fire its rocket engine to enter

orbit, then land. As the flyby spacecraft passed Mars,

the excursion module would blast off in pursuit. The

amount of propellant required for FLEM was much

less than for an MOR landing mission because only

the MEM would enter and depart Mars orbit. Titus

calculated that a FLEM mission boosted to Mars in

1971 using a nuclear-thermal rocket might weigh as

little as 130 tons—light enough, perhaps, to permit a

piloted Mars landing with a single Saturn V launch.

In the 1966 JAG piloted flyby plan, the automated

MSSR would land on Mars about two hours before the

flyby craft flew past the planet and would immediately

set to work gathering rock and soil samples using

scoop, brush, sticky tape, drill, and suction collection

devices. Less than two hours after MSSR touchdown,

its ascent vehicle first stage would ignite. If all went

well, the ascent vehicle’s small third stage would deliver the samples to a point in space a few miles ahead of

the flyby craft about 17 minutes later, 5 minutes after

the flyby craft’s closest Mars approach. As their craft

overtook the sample package, the astronauts would

snatch it in passing using a boom-mounted docking

ring. They would then deposit it inside the Experiment

Module’s biology lab.

The Planetary JAG pointed out that the MSSR/piloted

flyby approach improved the chances for studying living Martian organisms because the Mars samples

would reach a trained biologist within minutes of collection. Living organisms collected using a purely automated sample-return lander would likely perish during

the months-long flight to a lab on Earth.

The trip back to Earth would last 537 days, during

which the astronauts would study the Mars samples

and repeat many of the same experiments performed during the Earth-Mars voyage. The flyby

craft would penetrate the Asteroid Belt before

falling back to Earth, making piloted asteroid flybys

a possibility. When farthest from the Sun the flyby

craft would be on the opposite side of the Sun from

Earth, making possible simultaneous observations

of both solar hemispheres.

A few days before reaching Earth, the crew would

board the Earth Entry Module and abandon the flyby

craft. On 18 July 1977, the Earth Entry Module would

reenter Earth’s atmosphere, deploy parachutes, and

lower to a land touchdown, while the flyby craft would

fly past Earth into solar orbit. Just before the landing,

solid-propellant rocket motors would fire to cushion

impact, ending the 667-day Martian odyssey.

The Fire

NASA’s FY 1967 funding request was $5.6 billion. The

White House Budget Bureau trimmed this to $5.01 billion out of a $112 billion Federal budget before sending

the budget on to Capitol Hill. By the time President

Johnson signed it into law, NASA’s FY 1967 appropriation was $4.97 billion, more than $200 million less than

FY 1966. Programs aimed at giving NASA a postApollo future were hardest hit. Of the $270 million

NASA requested for AAP, for example, only $83 million

was appropriated. Voyager funding start-up was

bumped to FY 1968. Apollo Moon program funding, by

contrast, barely suffered. In part this was because the

agency was flying frequent Gemini missions—10 in 20

months—which kept the Moon goal in the public eye.

Kennedy’s goal seemed very close, with the first piloted

lunar landing expected in just over a year.

In Gemini’s last year, however, America’s attention was

increasingly drawn away from space. In March 1966,

protesters marched against the Vietnam War in

Boston, San Francisco, Chicago, Philadelphia, and

Washington. The summer of 1966 saw race riots in

Chicago and Atlanta and racist mob violence in

Grenada, Mississippi. In June 1966, President Johnson

ordered bombing raids against the North Vietnamese

cities of Haiphong and Hanoi. By then, 285,000

Americans were serving in Vietnam. As Gemini 12, the

Chapter 4: A Hostile Environment
last in the series, splashed down in November 1966, the

number of American soldiers on the ground in Vietnam

was well on its way to its 1 January 1967 total of

380,000.

Against this backdrop, in January 1967, the Planetary

JAG resumed piloted flyby planning, this time with the

purpose of developing “a clear statement of the activities required in FY 69 for budget discussions”21 to place

NASA “in a position to initiate a flyby project in FY

1969.”22 Planetary JAG participants had some reason to

be hopeful. As they reconvened, President Johnson

announced a $5.1-billion FY 1968 NASA budget that

included $71.5 million for Voyager and $8 million for

advanced planning. He also backed $455 million for a

substantial AAP. In presenting his budget, the

President explained that “we have no alternative unless

we wish to abandon the manned space capability we

have created.”23

On 26 January the OMSF presented its ambitious AAP

plans to Congress. Barely more than a day later,

NASA’s plans received a harsh blow as fire erupted

inside the AS-204 Apollo spacecraft on the launch pad

at KSC, killing Apollo 1 astronauts Gus Grissom, Ed

White, and Roger Chaffee. They had been scheduled to

test the Apollo CSM for 14 days in Earth orbit beginning in mid-February. NASA suspended piloted Apollo

flights pending the outcome of an investigation. The

AS-204 investigation report, issued in April, found

shortcomings in Apollo management, design, construction, and quality control. Apollo redesign kept

American astronauts grounded until September 1968.

After the fire, NASA could no longer count on a friendly reception on Capitol Hill. The fire, plus growing

pressure on the federal budget, meant that all NASA

programs were subjected to increased oversight. In

March, Aviation Week & Space Technology reported a

“growing antipathy from Congress” toward NASA’s

programs, adding that “[d]elays in the manned program, resulting from the Apollo 204 crew loss . . . will

hamper the agency’s arguments before Congress since

public interest will dwindle without spectacular

results.”24 The magazine predicted, however, that

Project Gemini’s conclusion would free up funds in FY

1968, permitting “a modest start on Apollo

Applications and . . . Voyager.” 25

As NASA in general came under increased scrutiny, the

piloted flyby concept suffered high-level criticism for

the first time. The President’s Science Advisory

Committee (PSAC) report The Space Program in the

Post-Apollo Period (February 1967) was generally positive, calling for continued Apollo missions to the Moon

after the first piloted lunar landing, as well as planetary exploration using robots such as Voyager.26 The

PSAC reiterated Faget’s 1962 criticism of the piloted

flyby mission, however, stating that 

the manned Mars flyby proposal, among its

other weaknesses, does not appear to utilize

man in a unique role . . . it appears to us that

NASA must address itself more fully to the

question, “What is the optimum mix of manned

and unmanned components for planetary

exploration?”27

The PSAC also complained that Voyager and the

Planetary JAG’s piloted flyby plans were “distinct and

apparently independent plans for planetary exploration,” and criticized NASA for “absence of integrated planning in this area.”28 As has been seen, this criticism reached the Planetary JAG early enough for an

integrated plan to be included in its report. NASA

officials denied, however, that the PSAC’s criticisms

had prompted its effort to integrate Voyager and the

piloted flyby.29

The PSAC’s critique stung the Planetary JAG. One

response was to distance itself from the term “flyby”—a

word identified increasingly with automated explorers

since Mariner 4’s success—by dubbing its mission an

“encounter.”30 Planetary JAG members also sought to

reemphasize that the encounter mission astronauts

would accomplish productive observations and experiments throughout their two-year voyage, not just during the hours of Mars encounter.

OMSF advanced planner Edward Gray and his deputy

Franklin Dixon first publicly proposed the Planetary

JAG’s Apollo-based piloted Mars flyby as an FY 1969

new start the next month (March 1967) at the AAS

Fifth Goddard Memorial Symposium, where they presented a paper called “Manned Expeditions to Mars

and Venus.”31 That same month, NASA forecast a stable

annual budget of about $5 billion per year through

1970, after which the budget would decline to $4.5 billion annually for the rest of the 1970s. New programs

30 Monographs in Aerospace History

Chapter 4: A Hostile Environment
such as Voyager and the piloted flyby would be phased

in as the share of NASA’s budget allotted to Apollo

lunar missions decreased.32 In May, Aviation Week &

Space Technology reported that the $71.5-million newstart funding approved for Voyager by the House Space

Committee “does not face serious problems.”33

A New Era for NASA

By the beginning of 1967, 25,000 United States servicemen had died in Vietnam. The summer of 1967 saw

racial violence wrack Newark, New Jersey, and Detroit,

Michigan. Large sections of Detroit burned to the

ground. At least 5,000 people lost their homes, and

more than 70 lost their lives. Violence also swept more

than 100 other American cities. Detroit alone suffered

up to $400 million in damage. Needless to say, most

Americans focused more on Earth than on space.

The cost of the Vietnam War soared to $25 billion a

year—the entire FY 1966 NASA budget every 10

weeks. This, plus the cost of President Johnson’s Great

Society social welfare programs, led to spiraling

Federal budget deficits. Congress approached the

Johnson Administration’s 1968 Federal Budget with its

scissors out, and NASA was an easy target.

In early July, Aviation Week & Space Technology

reported that the House and Senate had “sustained

the pace of spending in the Apollo program but seriously cut into NASA’s plans for both manned and

unmanned space programs of the future.”34 The

Senate voted down all Voyager funding, while the

House cut the program to $50 million. House and

Senate conferees settled on $42 million for the automated Mars program. In response, NASA announced

that a 1971 Voyager mission was out of the question.

A 1973 landing was, however, still feasible if the program was funded adequately in FY 1969.35

In early July, the Senate report on its FY 1968 NASA

authorization bill specifically advised against piloted

planetary missions, stating that “all near-term [piloted]

missions should be limited to earth orbital activity or

further lunar exploration.”36 Later that month, in testimony to the Senate Appropriations Committee, James

Webb refused to “give aid and comfort to those who

would cut our program” when asked by Spessard

Holland (Democrat-Florida) to choose between $45

million for AAP and $50 million for Voyager. Holland

chided Webb for “failing to see that Congress is faced

with dilemmas in applying all its economies.”37

That some in the aerospace world were sympathetic to

Holland’s plight is telling. In an editorial titled “New

Era for NASA,” for example, Aviation Week & Space

Technology editor Robert Hotz wrote,

We have no quarrel with reductions imposed so

far by Congress . . . . They reflect a judicious and

necessary pruning of NASA’s budget . . . . [Space

exploration] cannot hope to occupy such a large

share of the national spotlight in the future as

it did during the pioneering days of Mercury

and Gemini when the war in Vietnam was only

a tiny cloud on a distant horizon; when no

American city cores had yet glowed red at night,

and when a tax cut was the order of the day

instead of the tidal wave of tax rises that now

threatens to engulf the nation.38

Though none of this augured well for piloted planetary

missions, the Planetary JAG continued planning its

piloted encounter mission with the aim of seeing it

included as an FY 1969 new start. The revised

Planetary JAG plan called for just two MS-IVBs.39 This

meant that only two Saturn V rockets would need to be

launched in rapid succession, so the costly new Pad 39C

was no longer required.

The encounter spacecraft would again include an

Experiment Module with an automated probe suite

based on Voyager technology. This time, however, the

probes, including at least one large MSSR lander,

would be sealed in the Experiment Module before

launch from Earth and sterilized to avoid biological

contamination of Mars. Previous piloted flyby studies

had justified the presence of astronauts in part by their

ability to service the probes during flight. This would

now be impossible because servicing would introduce

contamination.

The Planetary JAG realized that the MSSR was the

most challenging element of its encounter mission

plan—the one demanding the earliest development

start if the first piloted encounter mission was to be

ready for flight in 1975. On 3 August 1967, therefore,

MSC issued a Request for Proposals for a “9-month

engineering study . . . to perform a detailed analysis

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 31

Chapter 4: A Hostile Environment
32 Monographs in Aerospace History

and preliminary design study of unmanned probes that

would be launched from a manned spacecraft on a

Mars encounter or a Mars capture mission, [and] would

retrieve samples of the Mars surface and atmosphere

and rendezvous with the manned spacecraft.” MSC

added, “The results of this study” would “aid in selecting experiment payload combinations of these and

other probes and in configuring the Experiment

Module section of the manned spacecraft used in the

Mars . . . Reconnaissance/Retrieval missions in the

1975-1982 time period.” Cost and technical proposals

were to be submitted to MSC by 4 September.40 At the

same time, MSC released an RFP calling for a piloted

flyby spacecraft design study.

The Planetary JAG knew of the de facto congressional

“no new starts” injunction but apparently assumed

that it did not apply to studies with implications

beyond the next fiscal year.41 Congressman Joseph

Karth (Democrat-Minnesota), chair of the House

Subcommittee on Space Science and Applications, saw

it differently. Normally a strong NASA supporter, he

lashed out at the “ostrich-like, head-in-the-sand

approach of some NASA planning,” and added, “Very

bluntly, a manned mission to Mars or Venus by 1975 or

1977 is now and always has been out of the question—

and anyone who persists in this kind of misallocation of

resources is going to be stopped.”42

By August, the expected 1967 Federal budget deficit

was $30 billion. Goaded by MSC’s Request for

Proposals, on 16 August 1967 the House zeroed out

funding for both Voyager and advanced piloted mission

planning. AAP funding fell to $122 million. On 22

August, the House approved a $4.59 billion FY 1968

NASA budget—a cut of more than $500 million from

the January 1967 White House request.

Faced by a spiraling budget deficit, war and anti-war

dissent, and urban riots, President Johnson reduced his

support for NASA, saying, “Under other circumstances

I would have opposed such a cut. However, conditions

have greatly changed since I submitted my January

budget request.”43 He added, “Some hard choices must

be made between the necessary and the desirable . . . .

We . . . dare not eliminate the necessary. Our task is to

pare the desirable.”44

Denouement

The Voyager program died in part because NASA cast

it as a lead-in to piloted flybys. The scientific community viewed Voyager’s loss as a slap in the face. In

September, in an unusual move, NASA officials went

before the Senate Appropriations Committee to negotiate a Mariner mission in 1971 and a Mars landing

mission in 1973, both designed “to conform to sharply

reduced funding in FY 1969.”45 The 1971 Mariner

mission became Mariner 9. In March 1968, NASA

unveiled Project Viking—a cut-price version of the

Voyager program. Viking, managed by NASA’s

Langley Research Center, emerged as one of the few

FY 1969 NASA new starts.

MSC received and reviewed MSSR study proposals

from industry, although, of course, no contract for such

a study was ever issued. The piloted flyby mission, the

object of so much study from mid-1962 to late 1967,

was defunct. Despite the obvious congressional hostility toward advanced planning, however, NASA’s

piloted Mars mission studies were not. As will be

seen in the next chapter, the focus shifted to the

other area of Planetary JAG emphasis—piloted

Mars landing missions using nuclear rockets.

Chapter 4: A Hostile Environment
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 33

Thus, Mr. Vice President—[the s]olar system is

opening up before us. With landing on the

Moon we know that man can lay claim to the

planets for his use. We know further that man

will do this. The question is when? We know

that [the] U.S. will take part. The question is

how soon will we follow up on what we have

begun with Apollo? It could be the early 1980s.

(Thomas Paine, 1969)1

The Big Shot

In a November 1965 article on the next 20 years of

space flight, Wernher von Braun sought to convey the

Saturn V rocket’s immense potential. “One Saturn V

alone,” he wrote, “will carry twice as much payload as

the entire NASA space program up to this point in

time. In fact, all the orbiters, all the deep space

probes, and all the Mercurys and Geminis that have

ever flown would only load the cargo compartment of

one Saturn V to 50% of capacity.”2 With Saturn V

available, the Moon, Mars, and indeed the entire solar

system seemed within reach.

The first of fifteen Saturn V’s ordered by NASA to support Project Apollo rolled out to Launch Pad 39A at

Kennedy Space Center on 26 August 1967. Designated

AS-501, the mighty rocket would launch Apollo 4, the

first unmanned test of an Apollo CSM spacecraft. The

24-hour countdown commenced early on 8 November

and reached T-0 at 7 a.m. Eastern Standard Time on 9

November. Seen from the KSC press site, three and

one-half miles from the pad, the white and black

rocket rose slowly at the summit of an expanding

mountain of red flame and gray smoke. Thunder from

“the Big Shot,” as the news media nicknamed AS-501,

drowned out television and radio reporters giving live

commentary and threatened to collapse their temporary

studios.

AS-501 stood 111 meters tall and weighed about 2,830

metric tons at liftoff. Its 10-meter-diameter S-IC first

stage carried 2,090 metric tons of kerosene fuel and

liquid oxygen oxidizer for its five F-1 rocket engines.

They gulped 13.6 metric tons of propellants each second to develop a total of 3.4 million kilograms of thrust

at liftoff. AS-501’s first stage depleted its propellants in

two and one-half minutes at an altitude of 56 kilometers, detached, and crashed into the Atlantic about 72

kilometers from Pad 39A.

The 10-meter-diameter S-II second stage carried 423

metric tons of liquid hydrogen and liquid oxygen for

its five J-2 engines, which developed a total of 1 million pounds of thrust. The S-II depleted its propellants after six and one-half minutes at an altitude of

161 kilometers.

The 6.7-meter-diameter S-IVB third stage carried 105

metric tons of liquid hydrogen and liquid oxygen for its

single restartable J-2 engine, which fired for two minutes to place the Apollo 4 CSM in a 185-kilometer parking orbit. For an Apollo lunar mission, the J-2 engine

would ignite again after one orbit to place the Apollo

spacecraft on course for the Moon. For Apollo 4, the

third stage restarted after two Earth orbits, 3 hours and

11 minutes after liftoff, putting the stage and spacecraft

into an Earth-intersecting ellipse with a 17,335-kilometer apogee (highest point above the Earth).

The Apollo 4 CSM separated from the S-IVB stage,

then fired its engine for 16 seconds to nudge its apogee

to 18,204 kilometers. The CSM engine ignited a second

time 8 hours and 10 minutes into the flight to throw

the CM at Earth’s atmosphere at a lunar-return speed

of about 40,000 kilometers per hour. The CM separated

and positioned itself with its bowl-shaped heat shield

forward. Heat shield temperature soared to 2,760

degrees Celsius, and CM deceleration reached eight

times the pull of Earth’s gravity. Three parachutes

opened, and the Apollo 4 CM splashed into the Pacific

Ocean 10 kilometers from the planned spot, 8 hours

and 38 minutes after liftoff.

The success of AS-501/Apollo 4 helped rebuild confidence in NASA’s ability to fulfill Kennedy’s mandate

following the January 1967 fire. President Johnson told

reporters that the “successful completion of today’s

flight has shown that we can launch and bring back

safely to Earth the space ship that will take men to the

[M]oon.” Von Braun told reporters that he regarded

“this happy day as one of the three or four highlights of

my professional life—to be surpassed only by the

manned lunar landing.”3

“To the Very Ends of the Solar System”

Apollo 4 also cheered Mars planners, for Saturn V had

become their launch vehicle of choice following the end

of post-Saturn rocket planning in 1964. NASA and AEC

engineers developing the NERVA nuclear-thermal

Chapter 5: Apogee
rocket engine saw special cause for celebration, for

Saturn V was their brainchild’s ride into space. The

encouragement was well timed. NERVA, which stood

for Nuclear Engine for Rocket Vehicle Application, still

had no approved mission and had just survived a narrow scrape in a Congress ill-disposed toward funding

technology for future space missions.

NERVA was a solid-core nuclear-thermal rocket

engine. Hydrogen propellant passed through and was

heated by a uranium nuclear reactor, which caused the

propellant to turn to plasma, expand rapidly, and vent

out of a nozzle, producing thrust. Unlike chemical

rockets, no oxygen was required to burn the hydrogen

in the vacuum of space. Nuclear-thermal rockets

promised greater efficiency than chemical rockets,

meaning less propellant was required to do the same

work as an equivalent chemical system. This would

reduce spacecraft weight at Earth-orbit departure,

opening the door to a broad range of advanced missions.

Initial theoretical work on nuclear-thermal rockets

began at Los Alamos National Laboratory (LANL) in

1946. The New Mexico laboratory operated under the

aegis of the AEC. The joint AEC-U.S. Air Force ROVER

nuclear rocket program began in 1955, initially to

investigate whether a nuclear rocket could provide

propulsion for a massive intercontinental missile. In

1957, the solid-core reactor engine design was selected

for ground testing. The test series engine was appropriately named Kiwi, for it was intended only for

ground testing, not for flight.

Citing LANL’s nuclear rocket work, AEC supporters in

the U.S. Senate, led by New Mexico Democrat Clinton

Anderson, pushed unsuccessfully in 1958 for the commission to be given control of the U.S. space program.

Anderson was a close friend of Senate Majority Leader

Lyndon Johnson, who led the Senate Space Committee

formed after Sputnik 1’s launch on 4 October 1957.4 In

October 1958, the Air Force transferred its ROVER

responsibilities to the newly created NASA, and

ROVER became a joint AEC-NASA program. AEC and

NASA set up a joint Space Nuclear Propulsion Office

(SNPO). NASA Lewis—which at this time was performing the first NASA Mars study, an examination of

the weight-minimizing benefits of advanced propulsion, including nuclear rockets (see chapter 2)—became

responsible within NASA for technical direction of the

ROVER program.

In July 1959, the first Kiwi-A test was carried out successfully using hydrogen gas as propellant at the

Nuclear Rocket Development Station (NRDS) at

Jackass Flats, Nevada, 90 miles from Las Vegas.

Senator Anderson arranged for delegates to the

Democratic National Convention to be on hand for the

second Kiwi-A test in July 1960. At the Convention,

Anderson arranged for a plank on nuclear rocket

development to be inserted into the Democratic Party

platform.5 In October 1960, the third Kiwi-A test using

hydrogen gas showed promising results, building support for a contract to be issued for development of a

flight-worthy nuclear rocket engine.

The Democratic ticket of John Kennedy and Lyndon

Johnson narrowly defeated Dwight Eisenhower’s Vice

President, Richard Nixon, in the November 1960 election. Anderson took over as head of the Senate Space

Committee. President Kennedy embraced space after

the Soviet Union helped end his White House honeymoon by launching the first human into space on 12

April 1961. He charged Johnson with formulating a

visible, dramatic space goal the United States might

reach before the Soviets. Johnson suggested landing

an American on the Moon.

Before a special joint session of Congress on 25 May

1961, Kennedy called for an American astronaut on the

Moon by the end of the 1960s. Then he asked for “an

additional $23 million, together with $7 million already

available, [to] accelerate development of the ROVER

nuclear rocket. This gives promise of some day providing a means for even more exciting and ambitious

exploration of space, perhaps beyond the Moon, perhaps to the very ends of the solar system . . . .”6 

Because of Kennedy’s speech, FY 1962 saw the real

start of U.S. nuclear rocket funding. NASA and the

AEC together were authorized to spend $77.8 million

in FY 1962. Funding in the preceding 15 years had

totaled about $155 million.

In July 1961, Aerojet-General Corporation won the contract to develop a 200,000-pound-thrust NERVA flight

engine. NERVA Phase 1 occurred between July 1961

and January 1962, when a preliminary design was

developed and a 22.5-foot NERVA engine mockup was 

34 Monographs in Aerospace History

Chapter 5: Apogee
assembled. At the same time, NASA Marshall set up

the Nuclear Vehicle Projects Office to provide technical

direction for the Reactor-In-Flight-Test (RIFT), a

Saturn V-launched NERVA flight demonstration

planned for 1967.

The first Kiwi-B nuclear-thermal engine ground test

using liquid hydrogen (December 1961) ended early

after the engine began to blast sparkling, melting bits

of uranium fuel rods from its reactor core out of its nozzle. Though the cause of this alarming failure remained

unknown, Lockheed Missiles and Space Company was

made RIFT contractor in May 1962. In early summer

1962 the Marshall Future Projects Office launched the

EMPIRE study, motivated in part by a desire to develop missions suitable for nuclear propulsion. Hence,

early on NERVA became closely identified with Mars.

The second and third Kiwi-B ground tests (September

1962 and November 1962) failed in the same manner as

the first. Failure cause remained uncertain, but vibration produced as the liquid hydrogen propellant flowed

through the reactor fuel elements was suspected.

The PSAC and the White House Budget Bureau allied

against the nuclear rocket program following the third

Kiwi-B failure. They opposed funding for an early RIFT

flight test because they saw it as a foot in the door leading to a costly piloted Mars mission, and because they

believed the technology to be insufficiently developed,

something the Kiwi-B failures seemed to prove.

Kennedy himself intervened in the AEC-NASA/Budget

Bureau-PSAC deadlock, visiting Los Alamos and the

NRDS in December 1962.

On 12 December 1962, Kennedy decided to postpone

RIFT until after additional Kiwi-B ground tests had

occurred, explaining that “the nuclear rocket . . . would

be useful for further trips to the [M]oon or trips to

Mars. But we have a good many areas competing for

our available space dollars, and we have to channel it

into those programs which will bring a result—first,

our [M]oon landing, and then consider Mars.”

Kennedy’s decision marked the beginning of annual

battles to secure continued nuclear rocket funding.7

At the May 1963 AAS Mars symposium in Denver,

SNPO director Harold Finger pessimistically reported

that nuclear rockets were not likely to fly until the mid1970s.8 However, the fourth Kiwi-B test, in August

1963, revealed that vibration had indeed produced the

earlier core failures. The problem had a relatively easy

solution, so NASA, AEC, and nuclear engine supporters

in Congress became emboldened. They pressed

Kennedy to reverse his December 1962 decision.

William House, Aerojet-General’s Vice President for

Nuclear Rocket Engine Operations, felt sufficiently

optimistic in October 1963 to tell the British

Interplanetary Society’s Symposium on Advanced

Propulsion Systems that a Saturn V would launch a 33-

foot-diameter RIFT test vehicle to orbit in 1967. He

predicted that one NERVA stage would eventually be

able to inject 15 tons on direct course to Mars, or 3 tons

on a three-year flight to distant Pluto.9

Kennedy never had the opportunity to reconsider his

RIFT decision. Following the young President’s

November 1963 assassination, President Johnson

took up the question. With an eye to containing government expenditures, he canceled RIFT in December

1963 and made NERVA a ground-based research and

technology effort.

The year 1964 saw the successful first ground test of

the redesigned Kiwi-B engine and the first NERVA

start-up tests. It also marked the nuclear rocket program’s peak funding year, with a joint AEC-NASA

budget of $181.1 million. Though NERVA was grounded, work proceeded under the assumption that success

would eventually lead to clearance for flight.

The nuclear rocket program budget gradually declined,

dropping to $140.3 million in FY 1967. NERVA did not

come under concerted attack, however, until the bitter

battle over the FY 1968 NASA budget. In August 1967,

Congress deleted all advanced planning and Mars

Voyager funds from NASA’s FY 1968 budget because it

saw them as lead-ins to a costly piloted Mars program,

and Johnson refused to save them (see chapter 4).

NERVA funding was eliminated at the same time.

Voyager had to wait until FY 1969 to be resurrected

as Viking. Through Anderson’s influence, however,

NERVA did better—the nuclear rocket program was

restored with a combined AEC-NASA budget of

$127.2 million for FY 1968. As if to celebrate

Anderson’s intervention, the NRX-A6 ground test in

December 1967 saw a NERVA engine operate for 60

minutes without a hitch.

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 35

Chapter 5: Apogee
36 Monographs in Aerospace History

Boeing’s Behemoth

In January 1968, the Boeing Company published the

final report of a 14-month nuclear spacecraft study conducted under contract to NASA Langley. The study was

the most detailed description of an interplanetary ship

ever undertaken.10 As shown by the EMPIRE studies,

the propellant weight minimization promised by

nuclear rockets tended to encourage big spacecraft

designs. In fact, Boeing’s 582-foot long Mars cruiser

marked the apogee of Mars ship design grandiosity.

At Earth-orbital departure, Boeing’s behemoth would

include a 108-foot-long, 140.5-ton piloted spacecraft

and a 474-foot-long propulsion section made up of five

Primary Propulsion Modules (PPMs). The entire spacecraft would weigh between 1,000 and 2,000 tons, the

exact weight being dependent upon the launch opportunity used. Each 33-foot-diameter, 158-foot-long PPM

would hold 192.5 tons of liquid hydrogen. A 195,000-

pound-thrust NERVA engine with an engine bell 13.5

feet in diameter would form the aft 40 feet of each

PPM. The six-person piloted spacecraft would consist of

a MEM lander, a four-deck Mission Module, and an

Earth Entry Module.

Three PPMs would constitute Propulsion Module-1

(PM-1); two would constitute PM-2 and PM-3, respectively. PM-1 would push the ship out of Earth orbit

toward Mars, then detach; PM-2 would slow the ship so

that Mars’ gravity could capture it into orbit, then it

would detach; and PM-3 would push the ship out of

Mars orbit toward Earth. At Earth, the crew would separate in the Apollo CM-based Earth Entry Module,

reenter Earth’s atmosphere, and splash down at sea.

Six uprated Saturn V rockets would place parts for

Boeing’s Mars ship in Earth orbit for assembly.

Assembly crews and the flight crew would reach the

spacecraft in Apollo CSMs launched on Saturn IB

rockets. The 470-foot-tall uprated Saturn V, which

would include four solid-fueled strap-on rockets, would

Chapter 5: Apogee

Figure 12—In January 1968, Boeing proposed this complex Mars expedition plan using nuclear rockets and an opposition-class

trajectory. The company’s Mars ship would measure nearly 200 meters long and support a crew of six. (Integrated Manned

Interplanetary Spacecraft Concept Definition, Vol. 1, Summary, D2-113544-1, Boeing Company, Aerospace Group, Space

Division, Seattle, Washington, p. 7.)
be capable of delivering 274 tons to a 262-mile circular

Earth orbit. Boeing envisioned modifying KSC Saturn

V launch pads 39A and 39B to launch the uprated

Saturn V, and building a new Pad 39C north of the

existing pads.

The company’s report listed opportunities for nine

Venus-swingby, one conjunction-class, and five opposition-class Mars expeditions between November 1978

and January 1998. The conjunction-class mission would

last 900 days, while the Venus-swingby and oppositionclass missions would last from 460 to 680 days.

Boeing envisioned using the MOR mission plan NASA

Lewis used in its 1959-1961 studies. The MEM for

descending to Mars from Boeing’s orbiting Mars ship

was designed for MSC between October 1966 and

August 1967 by North American Rockwell (NAR), the

Apollo CSM prime contractor.11 NAR’s MEM report,

published the same month as the Boeing report, was

the first detailed MEM study to incorporate the

Mariner 4 results. Cost minimization was a factor in

NAR’s MEM design. The company proposed a 30-footdiameter lander shaped like the conical Apollo CM.

The Apollo shape, it argued, was well understood and

thus would require less costly development than a

novel design.

The lightest NAR MEM (33 tons) would carry only

enough life support consumables to support two people

on Mars for four days, while the heaviest (54.5 tons)

was a four-person, 30-day lander. Like the Apollo Lunar

Module (and many previous MEM designs), NAR’s

MEM design included a descent stage and an ascent

stage. The MEM would contain two habitable areas—

the ascent capsule and the descent stage lab compartHumans to Mars: Fifty Years of Mission Planning, 1950–2000 37

Chapter 5: Apogee

Figure 13—Cutaway of North American Rockwell’s 1968 Mars lander. Based on the Apollo Command Module shape, its design

incorporated new Mars atmosphere data gathered during the 1965 Mariner 4 automated Mars flyby. (Manned Exploration

Requirements and Considerations, Advanced Studies Office, Engineering and Development Directorate, NASA Manned

Spacecraft Center, Houston, Texas, February 1971, p. 5-3.)
38 Monographs in Aerospace History

ment. The ascent capsule would include an Apollo docking unit for linking the MEM to the mothership, and

the lab compartment would include an airlock for

reaching the Martian surface.

The MEM’s Apollo-style bowl-shaped heat shield

would protect it from friction heating during Mars

atmosphere entry. To reduce cost, NAR proposed to

develop a single heat shield design for both flight

tests in Earth’s atmosphere and Mars atmosphere

entry. This meant, of course, that the shield would be

more robust, and thus heavier, than one designed

specifically for Mars atmosphere entry. During Mars

atmosphere entry the crew would feel seven Earth

gravities of deceleration.

After atmospheric entry, the MEM would slow its

descent using a drogue parachute followed by a larger

ballute (balloon-parachute). At an altitude of 10,000

feet the ballute would detach. The MEM’s descent

engine would fire; then two of the astronauts would

climb from their couches to stand at controls and pilot

the MEM to touchdown. The company proposed using

liquid methane/liquid oxygen propellants that would

Chapter 5: Apogee

Figure 14—North American Rockwell’s plan for landing on Mars and returning to Mars orbit. The company’s lander, a two-stage

design, would support up to four astronauts on Mars for up to 30 days and return to the orbiting mothership with up to 300

pounds of rocks. (Integrated Manned Interplanetary Spacecraft Concept Definition, Vol. 4, System Definition, D2-113544-4,

Boeing Company, Aerospace Group, Space Division, Seattle, Washington, January 1968, p. 145.)
offer high performance but not readily boil off or

decompose. The MEM would carry enough propellants

for two minutes of hover. Its six landing legs would

enable it to set down safely on a 15-degree slope.

For return to the mothership in Mars orbit, the crew

would strap into the ascent capsule with their Mars

samples and data. The ascent stage engine would

ignite, burning methane/oxygen propellants from eight

strap-on tanks. The ascent stage would blast away

from the descent stage, climb vertically for five seconds, then pitch over to steer toward orbit. Once

empty, the strap-on tanks would fall away; the ascent

engine would then draw on internal tanks to complete

Mars orbit insertion and rendezvous and docking with

the mothership.

NAR had MEM development commencing in 1971 to

support a 1982 Mars landing. The company envisioned

a MEM flight test program using six MEM test articles

and a range of rockets, including three two-stage

Saturn Vs. The 1979 piloted MEM entry and landing

test, for example, would have a fully configured MEM

launched into Earth orbit on a two-stage Saturn V with

a piloted CSM on top. In orbit the CSM would detach,

turn, and dock with the MEM for crew transfer. The

crew would then cast off the CSM and fly the MEM to

landing on Earth.

Boeing scheduled the first Mars expedition for 1985-

1986, with Mars expedition contract awards in 1976,

and Mars hardware tests in low-Earth orbit beginning

in 1978. NAR estimated development cost of its MEM

at $4.1 billion, while Boeing’s study placed total Mars

program cost at $29 billion.

End of an Era

As Aerospace Technology magazine put it in May 1968,

“If the political climate in Washington for manned

planetary missions is as bleak as the initial congressional budget hearings indicate, the [NAR MEM]

study is . . . likely to be the last of its type for at least

a year.”12 In fact, it was the last until the late 1980s. As

the battle over the FY 1968 budget during the summer

of 1967 made abundantly clear, a $29-billion Mars program enjoyed support in neither the Johnson White

House nor the Congress. Events in 1968 made even

more remote the possibility that the U.S. might take on

a new Apollo-scale space commitment.

On 30 January 1968, immediately after Boeing and

NAR published their reports, North Vietnam invaded

South Vietnam on the eve of Tet, the lunar new year.

Though repulsed by U. S. and South Vietnamese forces,

the large-scale offensive drove home to Americans and

the Johnson White House that American involvement

in Indochina would likely grow before it shrank.

At the end of May, the Defense Department asked for

a $3.9-billion supplemental appropriation. Of this,

$2.9 billion was earmarked to pay for the Tet

Offensive—the Defense Department needed, for

example, to replace 700 destroyed helicopters—while

$1 billion would beef up U.S. defenses in South Korea

following the Pueblo incident, in which North Korea

seized a U.S. ship.13 A total of 14,592 American soldiers had been killed in Vietnam by the close of 1968,

by which time the total U.S. forces in Indochina stood

at more than half a million.

There was also trouble at home. Johnson was a political casualty of Tet and other troubles shaking the

nation. On 31 March 1968, he announced that he

would not stand for reelection. On 4 April 1968, civil

rights leader Martin Luther King Jr. was gunned down

in Memphis, Tennessee; his death triggered racial violence across the country. That same month students at

Columbia University in New York seized buildings to

protest the Vietnam War in one of more than 200

major demonstrations at some 100 universities during

the year. On 6 June 1968, Democratic Party front-runner Robert Kennedy was shot in Los Angeles. In

August, antiwar protesters disrupted the Democratic

National Convention.

Near the start of the FY 1969 budget cycle in early

February 1968, as American and South Vietnamese

forces pushed back the North Vietnamese, James Webb

testified to the House Space Committee, where a $4 billion FY 1969 NASA budget was, according to one committee staffer, a “fait accompli.” He reminded the

Committee that 

NASA’s 1969 authorization request, at the

$4.37-billion level, is $700 million below the

amount requested last year. NASA expenditures for Fiscal 1969 will be down $230 million

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 39

Chapter 5: Apogee
from this year, $850 million from last year, and

$1.3 billion less than in Fiscal 1966. The NASA

program has been cut. I hope you will decide it

has been cut enough . . . .14

In testimony to the Senate Appropriations Committee

in May, after the House approved a $4-billion NASA

budget, Webb told the Senators that President Johnson

had directed him to acquiesce to the cut, then

expressed concern over NERVA’s future.15 The nuclear

rocket stayed alive in early June 1968 only after a

lengthy Senate floor battle waged by Howard Cannon

(Democrat-Nevada), whose state included the NRDS.

Webb told the Senate Appropriations Committee later

that month that the $4-billion NASA budget would

require halting Saturn V production for a year and canceling NERVA. In an attempt to rally NERVA supporters to approve their engine’s ride into space, he added

that “to proceed with NERVA while terminating

Saturn V cannot be justified.”16

On 1 August 1968, Webb turned down George Mueller’s

request to make long lead-time purchases for manufacture of two more Saturn V’s, the sixteenth and seventeenth in the series. He informed the OMSF chief that

production would halt with the fifteen already allotted

for the Apollo lunar program.17 A week later Webb told

Congress that “the future is not bright” for the Saturn

rockets.18

At a White House press conference on 16 September

1968, Webb announced that he would step down after

nearly 8 years as NASA Administrator. He told journalists that he left the Agency “well prepared . . . to carry out

the missions that have been approved . . . . What we have

not been able to do under the pressures on the budget

has been to fund new missions for the 1970s . . . .”19

Thomas Paine Takes Charge

The final FY 1969 NASA budget was $3.995 billion,

making it the first below $4 billion since 1963. This was

more than $370 million below NASA’s request, but

almost exactly what Johnson had told Webb to accept

in May. The Saturn V production line went on standby.

The nuclear rocket program received $91.1 million, of

which $33.1 million came from NASA funds.

NASA Deputy Administrator Thomas Paine became

Acting NASA Administrator upon Webb’s departure on

7 October. Webb, a 25-year veteran of Federal government service, had described Paine as one of a “new

breed of scientist-administrators making their way into

government.”20 Formerly director of General Electric’s

TEMPO think tank, he had entered government service through a program for recruiting managers from

industry. Paine had become Webb’s Deputy

Administrator in March 1968, replacing Robert

Seamans. When he took over NASA from Webb, Paine

had seven months of Federal government experience.

Immediately after taking NASA’s reins, Paine told the

Senate Space Committee that he would seek a $4.5 billion NASA budget in FY 1970, followed by annual

increases leading to a $5.5-billion budget in FY 1975.

Paine said that he wanted a six- to nine-man space station serviced by Apollo CSMs in the mid-1970s. George

Mueller also testified, calling for a $4.5-billion NASA

budget in FY 1970. He said that this was necessary to

avoid a gap in piloted flights after the Apollo lunar

landings.21

On 30 October 1968, the Budget Bureau completed a

“highlights” paper on “major aspects of National

Aeronautics and Space operations which warrant

attention at an early point in 1969” for President

Johnson’s successor. The paper noted that “pressure is

mounting to budget significant sums for follow-on

manned space flight activities.” It stated that “the

advantages of nuclear propulsion do not begin to

approximate the costs for missions short of a manned

Mars landing. No national commitment has been made

to undertake this mission[,] which would cost $40-

$100B[illion] . . . nevertheless, pressures are strong in

NASA, industry, and Congress to undertake the development of the nuclear rocket.”22

Republican Richard Nixon defeated Hubert Humphrey,

Johnson’s Vice President, for the White House in

November. Though Apollo 7 had triumphantly returned

NASA astronauts to orbit in October, space had been

overshadowed as a campaign issue by the war, the

economy, student revolt, and many other “down-toEarth” issues. Nixon had promised a tax cut, which

promised to place yet more pressure on Federal agencies to cut spending.

40 Monographs in Aerospace History

Chapter 5: Apogee
Six weeks after the election, in the Johnson

Administration’s twilight days, space flight won back

the front page. On 21 December 1968, Apollo 8 astronauts Frank Borman, James Lovell, and William

Anders became the first people to launch into space on

a Saturn V rocket and the first humans to orbit a world

other than Earth. The Apollo 8 CSM dropped behind

the Moon early on 24 December and fired its engine for

four minutes to slow down and allow the Moon’s gravity to capture it into lunar orbit.

Thirty-five minutes after the spacecraft passed beyond

the Moon’s limb, it emerged from the other side. As it

did, Earth rose into view over the hilly lunar horizon,

and the crew snapped their planet’s picture. Lovell

described the Moon to people on Earth as “essentially

gray, no color; looks like plaster of Paris or sort of grayish deep sand.”23 Later, in one of the most memorable

moments of the space age, the crew took turns reading

to the world from the biblical book of Genesis. Early on

Christmas Day 1968, after 10 lunar orbits, the Apollo 8

crew fired their CSM’s engine to escape the Moon’s

gravitational pull and fall back to Earth.

Originally Apollo 8 was intended as an Earth-orbital test

of the Saturn V and the Lunar Module Moon lander, but

the Lunar Module was not ready. Sending Apollo 8 to

orbit the Moon was first proposed in August 1968 by

George Low, director of the Apollo Spacecraft Program

Office at MSC, and was eagerly promoted by Tom Paine

despite initial skepticism from NASA Administrator

Webb.24 Because the crew lacked a Lunar Module, they

lacked the backup propulsion and life support systems it

could provide. These would come in handy during

James Lovell’s next flight to the Moon on Apollo 13 in

April 1970.

The image of Earth rising into view over the pitted gray

Moon featured prominently on end-of-year magazines

and newspapers. It formed a counterpoint of fragile

beauty and bold human achievement that accentuated

the war, dissent, and assassinations of 1968. This was

reflected in Nixon’s first inaugural speech on 20

January 1969:

We have found ourselves rich in goods, but

ragged in spirit; reaching with magnificent

precision for the Moon, but falling into raucous discord on Earth. We are caught in war,

wanting peace. We are torn by divisions,

wanting unity.25

Democrat Paine submitted his resignation pro forma

when Republican Nixon took office. Surprisingly, Nixon

did not accept it. Though Aviation Week & Space

Technology reported that Nixon was impressed by the

job Paine had done since coming to NASA, the real reasons were apparently less meritorious.26 Nixon had

never shown much interest in space and could find no

ideologically suitable replacement who wanted to head

NASA. He may also have desired to have a Democrat in

place to blame if the Kennedy/Johnson Apollo program

failed.27 Paine was confirmed as NASA Administrator

in March 1969.

Being a Democrat in a Republican administration was

enough to leave Paine in a weak position. On top of

that, however, Paine was a Washington neophyte.

Webb had been wily, a Washington insider given to

deal-making; Paine was an idealist given to emotive

arguments. Paine was, according to NASA Historian

Roger Launius, “every bit as zealous for his cause as

had been his namesake.” Furthermore, he was “unwilling to compromise and . . . publicly critical of the

[Nixon] administration’s lack of strong action” with

regards to space.28 He excoriated his Center directors

for lacking boldness. He considered this disloyal to his

view of America, the expansive country, ready to tackle

any challenge.29

To Paine, the late 1960s was not a time to try men’s souls.

He complained to the Washington Evening Star of “what

I would call almost a national hypochondria . . . in many

ways crippling some of the forward-looking things we’re

able to do . . . I feel that one of the very highest priority

matters is the war on poverty and the problems of the

cities. But in the meantime we’re making . . . a lot of

progress in the civil rights area and really, this

nation is a good deal healthier than we’re giving it

credit for today.”30

Paine tried to use the excitement generated by Apollo

8 as a lever to gain Nixon’s commitment to an expansive post-Apollo future for NASA. His efforts were

countered by voices counseling caution. Nixon had

appointed “transition committees” to help chart a

course for his new Administration. On 8 January 1969,

the Task Force on Space transition committee, chaired

by Charles Townes, handed in its report. The Task

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 41

Chapter 5: Apogee
Force, made up of 13 technologists and scientists, recommended against new starts and proposed a steady

NASA budget of $4 billion per year “a rather frugal

amount” equivalent to “three-quarters of one percent

of GNP [Gross National Product].”31

The Task Force counseled continued lunar exploration

after the initial Apollo Moon landings and advised

Nixon to postpone a decision on a large space station

and the reusable shuttle vehicle needed to resupply it

economically. The primary purpose of the station was, it

said, “to test man’s ability for an extended spaceflight

over times of a year or more, so that the practicality of

a manned planetary mission could be examined.

However, the desirability of such a mission is not yet

clear . . . .”32

The Task Force recommendations resembled those in

the February 1967 PSAC report, and with good reason—the membership lists of the two groups were

almost identical. One new addition was Robert

Seamans, Secretary of the Air Force, who had been

NASA Deputy Administrator when the PSAC had submitted its 1967 report.

Even as the Task Force presented its recommendations

to Nixon, Paine’s optimistic plans for NASA’s FY 1970

budget foundered. President Johnson’s FY 1970 budget

request for NASA, released 15 January 1969, was $3.88

billion—$800 million less than the $4.7 billion “optimum” figure Paine had given the Budget Bureau in

November and more than $100 million less than what

Paine had said was the “minimum acceptable.” When

Nixon’s Budget Bureau chief, Robert Mayo, asked

agency heads a week later to further trim the Johnson

budget, Paine pushed for a $198-million increase. Mayo

quickly rebuffed Paine’s request.33 Nixon’s FY 1970

budget went to Congress on 15 April. NASA’s share was

$3.82 billion, of which Congress eventually appropriated $3.75 billion.

Space Task Group

Paine pointed to the Task Force on Space report as an

example of what he did not want for NASA’s future.34 At

a NASA meeting on space stations held in February at

Langley, Paine invoked instead von Braun’s Collier’s

articles.35 Following the meeting, Aviation Week &

Space Technology magazine reported that NASA

planned a 100-person space station by 1980, with first

12-person module to be launched on a modified Saturn

V in 1975.36

Nixon’s science advisor, Lee Dubridge, tried to get

authority to set NASA’s future course, in part because

he sensed Paine’s aims were too expansive, but Paine

protested. On 13 February 1969, President Nixon sent

a memorandum to Dubridge, Paine, Defense Secretary

Melvin Laird, and Vice President Spiro Agnew, asking

them to set up a Space Task Group (STG) to provide

advice on NASA’s future.37 On 17 February, Nixon

solicited Paine’s advice on the agency’s direction.

Paine’s long, detailed letter of 26 February sought to

step around the STG process and secure from Nixon

early endorsement of a space station.38 In his

response, Nixon politely reminded Paine of the newly

formed STG.39

STG meetings began on 7 March 1969. In addition to

the four voting members, the group included

observers: Glenn Seaborg of the AEC; U. Alexis

Johnson, Under Secretary of State for Political Affairs;

and, most influential, the Budget Bureau’s Mayo.

Robert Seamans stood in for Melvin Laird. The STG

chair was Agnew, another Washington neophyte.

Misreading the Vice President’s importance within the

Nixon Administration, Paine focused his efforts on

wooing Agnew to his cause. Much of the STG’s work

was conducted outside formal STG meetings, which

occurred infrequently.

NASA’s STG position became based on the Integrated

Program Plan (IPP) developed by Mueller’s OMSF,

which was first formally described to Paine in a report

dated 12 May.40 Mueller attributed many of its concepts

to a NASA Science and Technical Advisory Council

meeting held in La Jolla, California, in December 1968.

Though concerned mostly with Earth-orbital and cislunar missions, the report proposed that “the subsystems, procedures and even vehicles” for such missions

“be developed with a view towards their possible use in

a future planetary program . . . .”41

The IPP schedule was aggressive even by 1960s Moon

race standards. Between 1970 and 1975, NASA would

conduct a dozen Apollo lunar expeditions and launch

and operate three AAP space stations—two in Earth

orbit and one in lunar polar orbit. The year 1975 would

see the debut of the reusable Earth-orbital Space

42 Monographs in Aerospace History

Chapter 5: Apogee
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 43

Shuttle, which could carry a 25-ton, 40-foot-long, 22-

foot-wide payload in its cargo bay.

Shuttle payloads would include a standardized space

station module housing up to 12 astronauts, a propulsion module usable as a piloted Moon lander or Space

Tug, and tanks containing liquid hydrogen propellant

for the NERVA-equipped Nuclear Shuttle, which would

first reach Earth orbit on an uprated Saturn V in 1977.

Significantly, Mueller’s IPP gave NERVA a non-Mars

mission as part of a larger reusable transportation system in cislunar space. Up to 12 astronauts would conduct a Mars flight simulation aboard the Space Station

in Earth orbit from 1975 to 1978, and 1978 would see

establishment of a Lunar Base.

By 1980, 30 astronauts would live and work in cislunar space at any one time. Four Nuclear Shuttle

flights and 42 Space Shuttle flights per year would

support the Space Station Program. Six Nuclear

Shuttle flights, 48 Space Shuttle flights, and eight

Space Tug Moon lander flights per year would support

the Lunar Base Program.

NASA’s Big Gun

Paine liked Mueller’s ambitious IPP. He asked Wernher

von Braun to make it even more expansive by building

a Mars mission concept onto it in time for a 4 August

presentation to the STG. The presentation was timed to

capitalize on the enthusiasm and excitement generated

by the first Apollo Moon landing mission, which was set

to lift off on 16 July 1969.

Paine saw von Braun as “NASA’s big gun.” He believed

that the space flight salesmanship for which the

German-born rocketeer was famous could still help

shape the future of American space flight as it had in

the previous two decades. According to Von Braun, “it

was an effort of a very few weeks to put a very consistent and good and plausible story together.”42 

Meanwhile, Paine’s efforts to woo Agnew were, it

appeared, beginning to pay off. At the Apollo 11 launch,

the Vice President spoke of his “individual feeling” that

the United States should set “the simple, ambitious,

optimistic goal of a manned flight to Mars by the end of

the century.”43

On 20 July, Apollo 11 Commander Neil Armstrong and

Lunar Module Pilot Edwin “Buzz” Aldrin landed the

spider-like Lunar Module Eagle on the Moon’s Sea of

Tranquillity. At the start of humanity’s first two-hour

Moon walk, Aldrin described the landscape as a “magnificent desolation.” The astronauts remained at

Tranquillity Base for 21 hours before rejoining

Command Module Pilot Michael Collins aboard the

CSM Columbia in lunar orbit. On 24 July 1969, they

splashed down safely in the Pacific Ocean, achieving

the goal Kennedy had set eight years before.

In reporting the Apollo 11 landing, the Los Angeles

Herald-Examiner pointed to space-age spin-offs, such

as “new paints and plastics,” then predicted that “the

Mars goal should bring benefits to all mankind even

greater than the . . . [M]oon program.”44 The

Philadelphia Inquirer anticipated opposition to a Mars

program; it asked, “will the inspiration be abandoned

before the veiled censure of those who seem to suggest

the solution of all human dilemmas lies in turning

away from space to other priorities?”45

Aviation Week & Space Technology reported that “[s]pace

officials sense that public interest is near an all-time

high . . . .”46 Yet polls taken at the time did not indicate

strong public support for Mars exploration. A Gallup poll

showed that the majority of people polled aged under 30

years favored going on to Mars; however, a larger majority of those over 30 opposed. Taken together, 53 percent

of Americans opposed a Mars mission, 39 percent

favored it, and 8 percent had no opinion.47

In addition to the polls, new automated probe data supplied Mars mission detractors with ammunition. The

Mariner 6 spacecraft had left Earth on 24 February,

just before STG meetings began. On 31 July 1969, as

Paine and von Braun put the finishing touches on their

4 August pitch, it flew over the southern hemisphere of

Mars, snapping 74 grainy images of a forbidding landscape pocked by craters. A feature known to Earthbased telescopic observers as Nix Olympica (“the

Olympian Snows”) appeared as a 300-mile crater with

a bright central patch.

The spacecraft’s twin, Mariner 7, had left Earth on 26

March. It flew over Mars’ southern hemisphere on 5

August 1969, snapping 126 images of the smoothfloored Hellas basin, the heavily cratered Hellespontus

region, and the south pole ice cap. The probes seemed

Chapter 5: Apogee
to confirm the pessimistic picture painted by Mariner 4

in 1965. The New York Times noted that NASA had

“begun drumming up pressure to spend huge sums

required to send men to Mars in the early 1980s . . . .

But the latest Mariner information makes the possibility of life on Mars much less than it seemed even a

week ago, thus removing much of the original motivation for such a project.”48

NASA’s 4 August STG presentation had three parts,

lasted 55 minutes, and took into account neither the

opinion polls nor the new Mars data. In the first part,

Paine spent 20 minutes describing the “mystery, challenge, rich potential, and importance to man of the

solar system” and “how the United States can move

from [the] start represented by Apollo to exploration of

the entire solar system with a program requiring only

a modest investment of our national resources.”49

Von Braun followed Paine and spent 30 minutes

describing a piloted Mars expedition in 1982. His presentation formed the heart and soul of NASA’s STG

pitch.50 In retrospect, it also marked the apogee of von

Braun’s career.

Von Braun drew on a sizable library of conceptual Mars

spacecraft art generated in the Marshall Future

Projects Office to show Mayo, Dubridge, Seamans,

Johnson, Seaborg, and Agnew vehicles similar to the

Boeing Mars cruiser and the NAR MEM. In his IPPbased plan, the MEM was the only piece of hardware

applicable only to Mars flight. All other vehicle elements would, he explained, be developed for cislunar

roles. MEM go-ahead in 1974 would mark de facto commitment to a 1982 Mars expedition. The first space station module, the design of which would provide the

basis for the Mars ship Mission Module, would fly in

1975, as would the first Earth-orbital Space Shuttle.

The year 1978 would see the MEM test flight; then, in

1981, the first Mars mission would depart Earth orbit

for a Mars landing in 1982.

The Mars mission would employ two Mars spacecraft

consisting of three Nuclear Shuttles arranged side by

side and a Mission Module. The complete spacecraft

would measure 100 feet across the Nuclear Shuttles

and 270 feet long. All modules would reach orbit on

upgraded Saturn V rockets. After the twin expedition

ships were assembled, reusable Space Shuttles would

launch water, food, some propellant, and two six-person

crews to the waiting Mars ships. At Earth-orbit launch,

each ship would mass 800 tons, of which 75 percent was

hydrogen propellant.

Von Braun targeted Mars expedition departure for 12

November 1981. The port and starboard Nuclear

Shuttles would then fire their NERVA engines, achieve

44 Monographs in Aerospace History

Chapter 5: Apogee

Figure 15—Twin Mars ships blast their all-male crews from

Earth orbit using NERVA nuclear rocket stages. In August

1969, Wernher von Braun used images such as this to present NASA’s vision of a Mars expedition in the 1980s to the

Space Task Group and to Congress. (NASA Photo MSFC69-PD-SA-176)

Figure 16—Compared with cramped Apollo spacecraft, the

lodgings proposed for NASA’s 1980s Mars ships were palatial. In this cutaway, note the four-deck Mission Module

(center) and large conical Mars lander (right). (NASA

Photo S-69-56295)
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 45

Trans-Mars Injection, and shut down and separate from

the center Nuclear Shuttle and Mission Module. They

would turn around and fire their engines again to slow

down and enter elliptical Earth orbit. A few days later

they would reach perigee (lowest point above the Earth)

at the original assembly orbit altitude, fire their engines

to circularize their orbits, and rendezvous with the

Space Station for refurbishment and re-use. The ships

would weigh 337.5 tons each after port and starboard

Nuclear Shuttle separation.

As in the Planetary JAG piloted flyby missions, the

nine-month coast to Mars would be “by no means an

idle phase.” The ships each would serve as “a manned

laboratory in space, free of the disturbing influences of

the Earth.” According to von Braun, “[t]he fact that

there will be two observation points, Earth and spacecraft, permits several possible experiments.” In addition, “as yet unidentified comets might be observed for

the first time.”51

Von Braun had the twin Mars ships reaching Mars on

9 August 1982. Each would fire the NERVA engine on

its remaining Nuclear Shuttle to slow down and enter

Mars orbit. At Mars Orbit Insertion each spacecraft

would weigh 325 tons. The crews would then spend

two days selecting landing sites for the expedition’s 12

automated Sample Return Probes. The probes would

land, retrieve samples uncontaminated by human

contact, and lift off, then deliver the samples automatically to sterilized bio-labs on the ships for study.

If the samples contained no hazards, a three-man landing party would descend to the surface in one of the

47.5-ton MEMs. The other would be held in reserve—

von Braun explained that “capability is provided for

one man to land a MEM and bring a stranded crew

back to the ship.” He promised that “Man’s first step on

Mars will be no less exciting than Neil Armstrong’s

first step on the Moon.”52

The astronauts would then spend between 30 and 60

days on Mars. Von Braun listed objectives for Martian

exploration, including the following:

• Understand Martian geology “because Mars

probably closely paralleled the earth in origin

and . . . development.”

• Search for life—von Braun stated that “preliminary data indicate that some lower forms of life

can survive in the Martian environment . . . in

isolated areas higher forms . . . may exist. Man

on Mars will [also] be able to study . . . the

behavior of terrestrial life forms transplanted to

the Martian environment.”

• “Drilling for . . . water will be an early objective . . . and its discovery would open many

possibilities . . . . For example, it might

become possible to produce rocket fuel for the

return trip on later missions.”53

The landing party would lift off in the MEM ascent

stage using the descent stage as a launch pad. The

ascent stage would dock with the orbiting ship and the

crew would transfer 900 pounds of samples and equipment, then would discard the expended ascent stage.

The ships would ignite their center Nuclear Shuttles to

leave Mars on 28 October 1982, after 80 days near the

planet. The ships would weigh 190 tons each prior to

Mars orbit departure.

Von Braun told the STG that the twin Mars ships

would fly by Venus on 28 February 1983, to use the

planet’s gravity to slow their approach to Earth, thereby reducing the amount of braking propellant needed

to enter Earth orbit. During swingby the astronauts

would map Venus’ cloud-shrouded surface with radar

and deploy four automated probes.

Von Braun scheduled return to Earth for 14 August

1983. He noted that an Apollo-style direct reentry was

possible; however, until “a better assessment can be

made of the back contamination hazard (the return by

man of pathogens that might prove harmful to earth

inhabitants), a more conservative approach has been

planned, i.e., the return of the crew to earth orbit for a

quarantine period.”54 The center Nuclear Shuttles

would place the Mission Modules in Earth orbit and

perform rendezvous with the Space Station, where doctors would examine the astronauts. The Mars ships

would weigh 80 tons each at mission’s end, one-tenth of

their Earth-departure weight. Following their quarantine period, the crew would return to Earth aboard a

Space Shuttle. The center Nuclear Shuttles, meanwhile, would be refurbished and reused.

He then looked beyond the first expedition, stating that

additional flights to Mars could occur during the periods 1983-84, 1986-87, and 1988-89. The 50-person Mars

Base might be established in 1989, in time for the 20th

Chapter 5: Apogee
46 Monographs in Aerospace History

anniversary of von Braun’s presentation. Von Braun

told the STG that NASA’s budget would peak at $7 billion per year in 1975, or about 0.6 percent of GNP, and

that it would level out at $5 billion in 1989, at which

time its share of GNP would be 0.3 percent.55 This

assumed steady 4 percent annual growth in the U.S.

economy. In his closing remarks, Paine put the cost a

little higher than had von Braun; he told the other STG

members that “[t]his kind of program would be possible

for the United States with a budget rising to about $9

billion [per year] in the last half of the decade.”56

“Now Is Not the Time . . .”

NASA’s vision was breathtaking, but stood little

chance of acceptance in 1969 America. Robert

Seamans appears to have been generally sympathetic

to Paine’s vision, yet cognizant of political and economic realities. He arrived at the 4 August meeting

with a letter for Agnew laying out a less expansive

view of America’s future in space—one similar to the

recommendations made by the transition Task Force

in January. Seamans wrote, “I don’t believe we should

commit this Nation to a manned planetary mission, at

least until the feasibility and need are more firmly

established. Experience must be gained in an orbiting

space station before manned planetary missions can

be planned.” Then he recommended against early commitment to a space station.

Seamans advised instead that NASA should expand

AAP and continue lunar exploration “on a careful stepby-step basis reviewing scientific data from one flight

before going to the next.” He differed from the transition Task Force by recommending “a program to study

by experimental means including orbital tests the possibility of a Space Transportation System that would

permit the cost per pound in orbit to be reduced by a

substantial factor (ten times or more).”57 Aviation Week

& Space Technology had by this time already predicted that the STG would recommend a reusable

Space Shuttle as NASA’s post-Apollo focus.58

On 5 August, the day Mariner 7 flew past Mars, Paine

and von Braun presented their pitch to the Senate

Space Committee. Clinton Anderson, its chair, had in

effect already responded to the presentation; on 29 July

1969, he said that “now is not the time to commit ourselves to the goal of a manned mission to Mars.”59

Coming from Anderson, this was ominous and somewhat puzzling. The New Mexico Senator had backed

NASA since its birth, in large part because the Agency

gave the nuclear rocket program he supported funding

and a raison d’être. His rejection of Mars placed him in

a dilemma—how could he back nuclear propulsion yet

not support what was widely seen as its chief mission?

Other Space Committee members had similar reactions to NASA’s presentation. Senator Mark Hatfield

(Republican-Oregon) told Paine and von Braun that he

supported the space program, but was “not really

ready, at this point . . . to make commitments . . . to

meet a deadline to get a man to Mars.” Senator

Margaret Chase Smith (Republican-Maine) named

Paine’s game, saying that the government “should

avoid making long-range plans during this emotional

period [following Apollo 11] . . . otherwise we may

become involved in a crash program without the justification we had for Apollo—and therefore without the

full support of Congress.”60

Despite the clear signals from Congress, the STG

remained split between Washington neophytes and old

hands, with the former stubbornly preaching Mars and

the latter counseling something less expansive. Robert

Mayo broke the deadlock when he proposed that the

group offer the President several pacing options contingent on available funds.61

Paine and Mueller then took their case to the public

with a presentation to the National Press Club. Mueller

painted a picture of NASA’s space activities in 1979,

when, he said, more than 200 people would work in

space at one time. Most would be scattered in facilities

between Earth orbit and the lunar surface; however, 12

would be en route to Mars in two ships.62 Aviation Week

& Space Technology editor Robert Hotz attended the

Press Club talks and became swept up in NASA’s vision.

In his editorial following the talks he took a page from

Paine’s book, writing that

the Apollo 11 mission has opened an endless

frontier which mankind must explore. Man is

extending his domain from the 8,000-milediameter of his home planet earth to the 8-

billion-mile diameter of the solar system . . . .

Hopefully [the President] will note that only

by setting extremely high goals have extraordinary results been achieved . . . . We think

Dr. Paine made a telling point when he

warned against establishing future goals too

low.63

Chapter 5: Apogee
Congress, meanwhile, voiced more reservations.

George Miller (Democrat-California), chair of the

House Committee on Science and Astronautics, did

not want “to commit to a specific time period for setting sail to Mars.” Miller was not opposed to going to

Mars on principle; in fact, he believed it “highly probable that five, perhaps 10 years from now we may

decide that it would be in the national interest to

begin a carefully planned program extending over

several years to send men to Mars.”64

J. W. Fulbright (Democrat-Arkansas), Committee on

Foreign Relations chair, sought to put Apollo in proper

perspective as an element of 1960s realpolitik: “The

[Apollo 11] landing called forth a great deal of poetizing

about the human spirit bursting earthly bounds . . . . In

all this I perceive not humbug . . . but rather more sententiousness than plain hard truth. Americans went to

the Moon for a number of reasons of which, I am convinced, the most important by far was to beat the

Russians.”65 Sending American astronauts on to Mars

had nothing to do with beating the Russians. Therefore,

Fulbright saw little cause to support such a mission.

America’s Next Decades in Space

NASA released its report America’s Next Decades in

Space: A Report to the Space Task Group on 15

September 1969.66 Paine was the principal author of

the report, which aimed to promote NASA’s STG position. In retrospect the report marked the apogee of

NASA Mars expedition planning. With a note of pride

it pointed out that, in NASA’s first decade,

the American space program progressed from

the 31-pound Explorer 1 in earth orbit to

Apollo spacecraft weighing 50 tons sent out to

the moon [and] from manned flights of a few

thousand miles and 15-minute duration to

the 500,000 mile round-trip 8-day [Apollo 11]

mission which landed men on the [M]oon and

returned them safely to [E]arth.67

The NASA report then appealed to President Nixon to

think of his place in history, and to see his decision as

an unprecedented opportunity:

At the moment of its greatest triumph, the

space program of the United States faces a crucial situation. Decisions made this year will

affect the course of space activity for decades to

come . . . . This Administration has a unique

opportunity to determine the long-term future

of the Nation’s space progress. We recommended that the United States adopt as a continuing

goal the exploration of the solar system . . . . To

focus our developments and integrate our programs, we recommend that the United States

prepare for manned planetary expeditions in

the 1980s.68

Not surprisingly, the NASA report’s program closely

resembled the one Paine and von Braun described in

their 4 August STG presentation. Continued piloted

lunar exploration after Apollo would, the NASA report

proclaimed, “expand man’s domain to include the

[M]oon” by establishing a lunar base. This would lay

groundwork for a piloted Mars expedition in the 1980s.

As Mayo had proposed, the NASA report described

different program rates, each with a different date for

reaching Mars, the ultimate goal of all the programs.

The “maximum rate,” in which money was no object

and only the pace of technology could slow NASA’s

rush to Mars, scheduled the first Mars expedition for

1981. Program I launched the first expedition in

1983, while Program II, the pacing option favored by

Agnew, put it in 1986. Program III was identical to

Program II, except that no date was specified for the

first Mars expedition.

The STG report proper, The Post-Apollo Space Program:

Directions for the Future, was also published on 15

September 1969. It had a split personality.69 The main

body closely followed NASA’s America’s Next Decades in

Space report—not surprisingly, since Paine was again

the principal author. The introductory “Conclusions and

Recommendations” section, however, differed markedly

in tone and emphasis from the NASA-authored section.

This was because it was added in early September at

the insistence of senior White House staffers who did

not want to provide President Nixon with only ambitious objectives from which to choose.70

The “Conclusions and Recommendations” section

acknowledged that NASA had “the demonstrated

organizational competence and technology base . . . to

carry out a successful program to land man on Mars

within 15 years”; however, it failed to advocate an

aggressive Mars program, recommending instead

sending humans to Mars “before the end of this century.” At the same time, it cautioned that “in a balHumans to Mars: Fifty Years of Mission Planning, 1950–2000 47

Chapter 5: Apogee
anced program containing other goals and activities,

this focus should not assume over-riding priority and

cause sacrifice of other important activity in times of

severe budget constraints.”71

New space capabilities would be developed in a threephase program, to which the introductory section

attached no firm schedule. Phase 1 would see “exploitation of existing capability and development of new

capability, maintaining program balance within available resources.” This would include continued “Apollotype” lunar missions. New development would be based

on the principles of “commonality, reusability, and economy.” Phase 2 was an “operational phase” using new

systems in cislunar space with emphasis on “exploitation of science and applications” aboard space stations.

In Phase 3, “manned exploration missions out of

[E]arth-[M]oon space” would occur, “building upon the

experience of the earlier two phases.”72 The

“Conclusions and Recommendations” section cautioned,

Schedule and budgetary implications within

these three phases are subject to Presidential

choice and decision . . . with detailed program

elements to be determined in a normal annual

budget and program review process. 73

Nixon’s Response

Shortly after the Apollo 11 lunar landing, von Braun

told space policy analyst John Logsdon that 

the legacy of Apollo has spoiled the people at

NASA . . . . I believe that there may be too many

people in NASA who at the moment are waiting

for a miracle, just waiting for another man on a

white horse to come and offer us another planet,

like President Kennedy.74

Von Braun might have placed his boss in that category.

Paine placed great stock in the effect the NASA section

of the STG report would have on President Nixon.

Another document—a lengthy memorandum by Mayo

dated 25 September 1969—apparently had greater

effect, however. Mayo told the President that NASA

had requested $4.5 billion for FY 1971 despite a $3.5-

billion cap imposed by his office. He then recommended

that Nixon “hold an announcement of your space decision until after you have reviewed the [STG] report recommendations specifically in the context of the total

1971 budget problem . . . .” Mayo added that he believed

the NASA sections of the STG report “significantly

underestimated” the costs of future programs.75

In late September, Aviation Week & Space Technology

reported that NASA was hopeful that it might receive

a supplemental appropriation in FY 1970 to begin work

toward Mars.76 In October this optimism led Mueller to

establish the Planetary Missions Requirements Group

(PMRG), which included representatives from NASA

Headquarters and several NASA field centers. The

PMRG, the successor to the Planetary JAG, first met

formally in December 1969. Its purpose was to blueprint Mars mission concepts in the context of the STG

integrated plan.77

By the time the PMRG met for the first time, however,

NASA had received bad news. On 13 November 1969,

Mayo’s Office of Management and Budget (OMB) (formerly the Budget Bureau) had informed Paine that

NASA’s FY 1971 request would be $1 billion shy of his

request—just $3.5 billion. Paine called the figure “unacceptable” and told Mayo that “the proposed rationale”

for this budget figure “ignores and runs counter to the

conclusions reached by the Space Task Group . . . the

OMB staff proposals would force the President to reject

the Space Program as an important continuing element

of his Administration’s total program.”78

Paine was compelled to acquiesce, however. On 13

January 1970, he briefed newsmen on NASA’s budget

ahead of Nixon’s FY 1971 budget speech. He termed

the $3.5 billion budget “solid,” and announced that the

Saturn V rocket production line, already dormant,

would close down permanently.79 This was a serious

blow to the nuclear rocket program. It meant that, in

addition to having no approved mission, it now had no

way to get into space. NASA subsequently began study

of using the Earth-orbital Space Shuttle to place

NERVA-equipped rocket stages into Earth orbit.

Paine also canceled the planned tenth lunar landing

mission, Apollo 20, so that its Saturn V could launch

the Skylab space station, and announced that the

Viking Mars probe would slip to a 1975 launch with a

1976 Mars landing. In an apparent effort to raise alarm

and fend off further cuts, Paine released a list of NASA

Center closures in order of priority. First to go would be

48 Monographs in Aerospace History

Chapter 5: Apogee
Ames, in Nixon’s California stronghold, and the last

three in order would be MSC, Marshall, and KSC.80

In late January, just before Nixon unveiled his Federal

budget for FY 1971, NASA took another cut. When sent

to Capitol Hill on 2 February 1970, NASA’s portion of

the budget had fallen to $3.38 billion. In announcing

NASA’s budget, Nixon said that “[o]ur actions make it

possible to begin plans for a manned mission to Mars.”81

In fact, the 1970-71 period would see NASA’s last formal piloted Mars plan until the 1980s.

Nixon did not use his 22 January 1970 State of the

Union address to plot the way forward in space as

some in NASA had hoped that he might. His first priority, he said, was to “bring an end to the war in

Vietnam.” He also proposed to “begin to make reparations for the damage we have done to our air, to our

land, and to our waters.”82 Apollo 8 pictures of blue

Earth rising over the barren Moon had become a rallying point for the environmental movement—not, as

Paine had hoped, for space exploration. Paine was

unimpressed by Nixon’s environmentalist slant. He

told an industry group that “[w]e applaud the increase

in sewage disposal plants. But we certainly hope this

doesn’t mean the nation has taken its eyes off the

stars and put them in the sewers.”83

Nixon finally issued his policy on the post-Apollo

space program on 7 March 1970. Unlike Kennedy’s

1961 Moon speech, Nixon’s statement was broad and

vague, with no specifics about NASA funding. Rather

than endorse a specific target date for a piloted Mars

mission, he said that “we will eventually send men to

explore the planet Mars.” The British weekly The

Economist reported that people at NASA “looked like

children who got the jigsaw puzzle they were expecting

rather than the bicycle they were dreaming of.”84

PSAC Recommends Shuttle

At the same time Nixon issued his space policy, his

PSAC issued The Next Decade in Space, a report

extolling the possibilities of a Space Shuttle-based space

program. The presidential advisory body acknowledged

that “[e]normous technological capabilities have been

built up in the Apollo Program,” but recommended “a

civilian space effort about half the magnitude of the

present level.”85 The PSAC emphasized the military and

direct economic benefits of piloted space travel, which it

said could only be accrued by replacing virtually all

expendable rockets with a reusable Space

Transportation System (STS). This would include the

Space Shuttle and a reusable orbital tug.

The STS would allow “orbital assembly and ultimately

radical reduction in unit cost of space transportation,”

the PSAC stated, quoting a NASA/Defense Department

study that placed the cost per flight of the STS at $5

million, or 1 percent of the Saturn V cost.86 At the time

the PSAC released its report, the U.S. could launch four

Saturn V rockets per year, each with a payload of about

100 tons. The PSAC reasoned that “[s]ince only ten

flights of the STS can in principle fulfill the role of two

Saturn V launches/year, this capability might be

reached soon after initial operation of the STS.”87

The PSAC then addressed piloted Mars exploration,

writing that “[p]rudence suggests that the possibility of

undertaking a manned voyage to Mars be kept in mind

but that a national commitment to this project be

deferred at this time.”88 The STS, it expected,“could place

the equipment needed for the Mars mission in orbit with

one or two dozen launches and at a cost substantially

below that of a single Saturn V.” It also recommended

that the permanent space station it said should precede

a piloted Mars mission be deferred until after the STS

could be used to assemble it.89 Despite the heavy reliance

it placed on the STS, the PSAC recommended deferring

a decision to build it until FY 1972.

In July 1970, Paine submitted his resignation. On 15

September the first anniversary of the release of the

STG and NASA reports, George Low took over as

Acting NASA Administrator. In February 1971,

Presidential Assistant Peter Flanigan was ordered to

find a NASA Administrator who would “turn down

NASA’s empire-building fervor and turn his attention

to . . . work[ing] with the OMB and White House.”90

The Last Mars Study

The PMRG, meanwhile, continued low-level Mars expedition planning. NASA’s post-Apollo Mars aspirations

died with a whimper—a call to NASA Centers participating in the PMRG for reports summing up their work.

PMRG work at MSC resided in the Engineering and

Development Directorate’s Advanced Studies Office

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 49

Chapter 5: Apogee
50 Monographs in Aerospace History

under Morris Jenkins. MSC Associate Director of

Engineering Maxime Faget reviewed Jenkins’ February

1971 report. In his introduction, Jenkins explained,

Official statements regarding the manned

Mars mission have always been conditioned by

an emphasis that there was no set time frame

for it. This together with problems of budget

constraints on the more immediate future programs and the overall posture of the space program, influenced formal support for this study.

Justifiably, the formal support was always very

small and . . . non-continuous . . . .91

The guiding principle of MSC’s PMRG study was

austerity. In general configuration its Mars ship

resembled Boeing’s 1968 behemoth, but chemical

propulsion stood in for nuclear. According to

Jenkins, “everything [was] done to make [this study]

a useful point of departure when national priorities

and economic considerations encourage the mounting of a manned Mars expedition.”92 MSC targeted

its 570-day Mars expedition for the 1987-88 launch

opportunity, following an 11-year development and

test period beginning in the mid-1970s.

MSC assumed availability of a fully reusable Space

Shuttle based on Max Faget’s “flyback” design. The flyback shuttle would include a winged orbiter launched

on a winged booster. Both booster and orbiter would

carry astronauts. MSC envisioned a booster the size of

a 747 and an orbiter on the scale of a DC-9.

The study rejected launching Mars spacecraft components in the 15-foot-diameter payload bay of the

orbiter because as many as 30 modules would have to

be launched separately and brought together in orbit,

necessitating a “complex and lengthy assembly and

checkout process.”93 Instead, MSC proposed launching the Mars ship’s three 24-foot-diameter modules

on the back of the Shuttle booster with the aid of

Chemical Propulsion System (CPS) stages. Three

CPS stages would be launched into orbit without

attached modules.

The Shuttle booster would carry the CPS and attached

module (if any) partway to orbit, then separate to

Chapter 5: Apogee

Figure 17—Last gasp (for a while): NASA’s 1971 Mars spaceship design, the last until the 1980s, proposed to reduce cost

by using projected Space Shuttle technology and rejecting nuclear engines in favor of cheaper chemical propulsion.

(Manned Exploration Requirements and Considerations, Advanced Studies Office, Engineering and Development

Directorate, NASA Manned Spacecraft Center, Houston, Texas, February 1971, p. 5-2.)
return to the launch site. The CPS would then ignite to

achieve Earth orbit. Each CPS would weigh 30 tons

empty and hold up to 270 tons of liquid hydrogen/liquid

oxygen propellants. In keeping with the principle of

austerity, the CPS stages would use the same rocket

engine and propellant tank designs as the Shuttle

booster and orbiter, and do double duty as Mars ship

propulsion stages. Assembling the expedition’s single

ship would need 71 Shuttle booster launches. Six would

launch the ship (three modules and six CPS stages),

and the remainder would carry Shuttle orbiters serving

as tankers for loading the CPS stages with propellants.

The assembled Mars ship would include a hangar for

automated probes and a MEM based on the 1968 NAR

design. For redundancy, its 55-ton, four-deck Mission

Module would be split into two independent pressurized volumes, each containing a duplicate spacecraft

control station. Deck four would be the ship’s solar flare

radiation shelter. The 65-foot-long Electrical Power

System module would contain pressurized gas storage

tanks and twin solar arrays. The crew would rotate the

Mars ship end over end about twice per minute to produce artificial gravity in the Mission Module equal to

one-sixth Earth’s gravity (one lunar gravity).

Earth departure would require a series of maneuvers.

Maneuver 1 would expend two CPS stages to place the

Mars ship in elliptical “intermediate orbit.” Maneuver 2

and Maneuver 3 would use one CPS stage—the first

would place the ship in elliptical “waiting orbit,” and

the second would adjust the plane of the departure

path. Space tugs would later recover the three discarded CPS stages for reuse. Maneuver 4 would place the

ship on a 6-month trajectory to Mars. The fourth CPS

would enter solar orbit after detaching from the Mars

ship and would not be recovered.

Slowing the ship so that Mars’ gravity could capture

it into a 200-mile by 10,000-mile orbit would expend

the fifth CPS. The elliptical orbit would require less

propellant to enter and depart than a circular one.

The five-person crew would spend 15 days in orbit

studying Mars and preparing the MEM for landing;

then three crewmembers would separate in the MEM,

leaving behind two to watch over the mothership.

The MEM crew would explore their landing site using

a pair of unpressurized electric rovers resembling the

Apollo Lunar Roving Vehicle, which was slated to be

driven on the Moon for the first time on Apollo 15 in

July 1971. During Mars surface excursions, one

crewmember would remain in the MEM while the

other two took out one rover each. This “tandem convoy” arrangement would allow the Mars explorers to

avoid the “walk back” limit imposed on single-rover

traverses in the Apollo program. Walk back distance

was limited less by astronaut stamina than by the

amount of water and air the space suit backpacks could

hold. If one Mars rover failed, the functional rover

would return both astronauts to the MEM. Each rover

would include a hook for towing the failed rover back to

the MEM for repairs.

Rover maximum speed would be 10 miles per hour, and

total area available to two rovers would amount to

8,000 square miles, compared to only 80 square miles

for a single rover. Once every 15 days, a 36-hour traverse of up to 152 miles would occur, with the astronauts sleeping through the frigid Martian night on the

parked rovers in their hard-shelled aluminum space

suits. Jenkins did not attempt to estimate the amount

of sleep the astronauts might actually be able to

achieve during their overnight camping trips.

The astronauts would collect samples of rock and soil

with emphasis on finding possible life. According to the

MSC report, “[t]he potential for even elementary life to

exist on another planet in the solar system may . . . be

the keystone to the implementation of a manned planetary exploration program . . . man’s unique capabilities in exploration could . . . have a direct qualitative

impact on life science yield.”94

After 45 days of surface exploration, the crew would

blast off in the MEM ascent stage and dock with the

mothership. Any specimens of Mars life collected would

be transferred to a Mars environment simulator. The

crew would discard the ascent stage; then the sixth

and final CPS would ignite to push the ship back

toward Earth. The MEM astronauts would remain

quarantined in one pressurized volume until the danger of spreading Martian contagion to the other astronauts was judged to be past.

The MSC PMRG report received only limited distribution within NASA and virtually none outside the

Agency. Formal studies within NASA aimed at sending

humans to Mars would not occur again until the

Manned Mars Missions exercise in 1984 and 1985.

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 51

Chapter 5: Apogee
52 Monographs in Aerospace History

Chapter 5: Apogee

NERVA Falls, Shuttle Rises

The OMB’s FY 1972 request for NASA was $3.31 billion. The budget slashed NERVA funding in favor of

continued Space Shuttle studies. Combined AECNASA nuclear rocket funding plummeted to $30 million split evenly between the two agencies. NASA and

the AEC had together requested $110 million. The

allotted budget threatened to place the NRDS on

standby and was considered by many sufficient only to

shut down the program.

In February 1971, Clinton Anderson held a hearing on

the cut in NASA’s NERVA funding. In his introductory

remarks, he lauded the nuclear rocket program as “one

of the most successful space technology programs ever

undertaken” and pointed to the $1.4-billion investment

in nuclear propulsion technology since 1955.95 Senator

Alan Bible (Democrat-Nevada) then pointed out that

the STG report called for nuclear rockets.96

Acting NASA Administrator George Low took his

marching orders from the highest levels of the Nixon

White House. The Earth-orbital Shuttle had to come

first, he said—without it NERVA had no ride to space.

He told the Senators that, “NERVA needs the Shuttle,

but the Shuttle does not need NERVA.”97

Low denied that the funding cut would kill the program, explaining that “useful work on long lead-time

items” could be accomplished.98 There would, however,

be no technical progress during FY 1972, and possibly

none in FY 1973. “We have not, as yet, been able to look

forward beyond that,” Low added.99

Two months later, in May 1971, 21 members of

Congress wrote to President Nixon requesting more

funds for NERVA in FY 1972. When the White House

failed to respond, Congress of its own accord budgeted

$81 million for nuclear rockets, of which NASA’s portion was $38 million. In October, however, the OMB

refused to release more than the $30 million the

Administration had requested. In November the OMB

stood by its FY 1972 nuclear propulsion request despite

protests from the Senate floor.100

On 5 January 1972, President Nixon met with James

Fletcher, Tom Paine’s successor as NASA

Administrator, at the “Western White House” in San

Clemente, California. Afterward, Fletcher read out

Nixon’s statement calling for an FY 1973 new start on

the Shuttle. The announcement’s venue was significant—California, a state of many aerospace firms, was

vital to Nixon’s 1972 reelection bid.101 Nixon pointed out

that “this major new national enterprise will engage

the best efforts of thousands of highly skilled workers

and hundreds of contractor firms over the next several

years.” Fletcher added that it was “the only meaningful

new manned program that can be accomplished on a

modest budget.”102 First flight was scheduled for 1978.

Nixon sent his FY 1973 budget to Capitol Hill on 24

January 1972. As its supporters had feared, the budget

contained no funds for NERVA. Anderson, nuclear

propulsion’s greatest champion, was ill and could not

defend it. The last NERVA tests occurred in June and

July of 1972. Anderson retired from the Senate at the

end of 1972. The FY 1974 budget terminated what

remained of the U.S. nuclear rocket program.103

With both NERVA and Saturn V gone—the last Saturn

V flew in May 1973—NASA’s piloted space flight ambitions collapsed back to low-Earth orbit. Yet the Agency

did not cease to strive toward Mars. As we will see in

the next chapter, NASA’s robot explorers conducted the

first in-depth Mars exploration in the 1970s, holding

open the door for renewed piloted Mars planning.
Additional automated missions will most certainly occur, but the ultimate scientific study of

Mars will be realized only with the coming of

man—man who can conduct seismic and electromagnetic sounding surveys; who can launch

balloons, drive rovers, establish geologic field

relations, select rock samples and dissect them

under the microscope; who can track clouds and

witness other meteorological transients; who

can drill for permafrost, examine core tubes,

and insert heat-flow probes; and who, with his

inimitable capacity for application of scientific

insight and methodology, can pursue the quest

for indigenous life forms and perhaps discover

the fossilized remains of an earlier biosphere.

(Benton Clark, 1978)1

The New Mars

In the 1960s, most automated missions beyond lowEarth orbit—the Rangers, Surveyors, and Lunar

Orbiters—supported the piloted Apollo program. In the

1970s, as NASA’s piloted program contracted to lowEarth orbit, its automated program expanded beyond

the Moon. Sophisticated robots flew by Mercury,

Jupiter, and Saturn, and orbited and landed on Venus

and Mars.

Though they were not tailored to serve as precursors to

human expeditions in the manner of the Rangers,

Surveyors, and Lunar Orbiters, the automated missions

to Mars in the 1970s shaped the second period of piloted

Mars mission planning, which began in about 1981. The

first of these missions, Mariner 9, took advantage of the

favorable Earth-Mars transfer opportunity associated

with the August 1971 opposition to carry enough propellant to enter Mars orbit. It was launched from Cape

Kennedy on 30 May 1971.

In September, as Mariner 9 made its way toward Mars,

Earth-based astronomers observing the planet through

telescopes saw a bright cloud denoting the onset of a

dust storm. By mid-October it had become the largest

on record. Wind-blown dust obscured the entire surface, raising fears that Mariner 9 might not be able to

map the planet from orbit as planned.2

On 14 November 1971, after a 167-day Earth-Mars

transfer, Mariner 9 fired its engine for just over 15 minutes to slow down and become Mars’ first artificial

satellite. Dust still veiled the planet, so mission controllers pointed the spacecraft’s cameras at the small

Martian moons Phobos and Deimos. In Earth-based

telescopes they were mere dots nearly lost in Mars’ red

glare. In Mariner 9 images, Phobos was marked by parallel cracks extending from a large crater. Apparently

the impact that gouged the crater had nearly smashed

the little moon. Deimos, Mars’ more distant satellite,

had a less dramatic, dustier landscape.

The giant dust storm subsided during December,

theatrically unveiling a surprising world. Mars was

neither the dying red Earth espoused by Percival

Lowell nor the dead red moon glimpsed by the flyby

Mariners.3 From its long-term orbital vantage point,

Mariner 9 found Mars to be two-faced, with smooth

northern lowlands and cratered southern highlands.

The missions to the Moon confirmed that a relationship exists between crater density and age—the

more densely cratered a region, the older it is. Hence,

Mars has an ancient hemisphere and a relatively

young hemisphere.

Mars is a small world—half Earth’s diameter—with

large features. The Valles Marineris canyons, for

example, span more than 4,000 kilometers along

Mars’ equator. Nix Olympica, imaged by Mariner 6

and Mariner 7 from afar and widely interpreted as a

bright crater, turned out to be a shield volcano 25 kilometers tall and 600 kilometers wide at its base.

Renamed Olympus Mons (“Mount Olympus”), it

stands at one edge of the Tharsis Plateau, a continentsized tectonic bulge dominating half the planet. Three

other shield volcanoes on the scale of Olympus Mons

form a line across Tharsis’ center.

Most exciting for those interested in Martian life were

signs of water. Mariner 9 charted channels tens of kilometers wide. Some contain streamlined “islands”

apparently carved by enormous rushing floods. Many of

the giant channels originate in the southern highlands

and open out onto the smooth northern plains. The

northern plains preserve rampart craters—also called

“splosh” craters—which scientists believe were formed

by asteroid impacts in permafrost. The heat of impact

apparently melted subsurface ice, which flowed outward from the impact as a slurry of red mud, then

refroze.4

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 53

Chapter 6: Viking and the Resources of Mars
Mariner 9 depleted its nitrogen attitude-control propellant on 27 October 1972, after returning more than

7,200 images to Earth. Controllers quickly lost radio

contact as it tumbled out of control. A week later, on 6

November 1972, mission planners using Mariner 9

images announced five candidate Viking landing sites.5

Viking 1 left Earth on 20 August 1975 and arrived in

Mars orbit on 19 June 1976. Its twin, Viking 2, left

Earth on 9 September 1975 and arrived at Mars on 7

August 1976. The spacecraft consisted of a nuclearpowered lander and a solar-powered orbiter. The Viking

1 lander separated from its orbiter and touched down

successfully in eastern Chryse Planitia on 20 July

1976. Viking 2 alighted near the crater Mie in Utopia

Planitia on 3 September 1976.

The first color images from the Viking 1 lander showed

cinnamon-red dirt, gray rocks, and a blue sky. The sky

color turned out to be a processing error based on preconceived notions of what a sky should look like. When

the images were corrected, Mars’ sky turned dusky

pink with wind-borne dust.6

The Vikings confirmed the old notion that Mars is the

solar system planet most like Earth, but only because

the other planets are even more alien and hostile. A

human dropped unprotected on Mars’ red sands would

gasp painfully in the thin carbon dioxide atmosphere,

lose consciousness in seconds, and perish within two

minutes. Unattenuated solar ultraviolet radiation

would blacken the corpse, for Mars has no ozone layer.

The body would freeze rapidly, then mummify as the

thin, parched atmosphere leeched away its moisture.

By the time the Vikings landed, almost no one believed

any longer that multicellular living things could exist

on Mars. They held out hope, however, for hardy singlecelled bacteria. On 28 July 1976, the Viking 1 lander

scooped dirt from the top few centimeters of Mars’ surface and distributed it among three exobiology detectors and two spectrometers. The instruments returned

identical equivocal readings—strong positive responses

that tailed off, weak positive responses that could not

be duplicated in the same sample, and, most puzzling,

an absence of any organic compounds the instruments

were designed to detect.

Viking 1 and Viking 2 each scooped additional samples—

even pushing aside a rock to sample underneath—and

repeated the tests several times with similar equivocal

results. Most scientists interpreted the Viking results

as indicative of reactive soil chemistry produced by

ultraviolet radiation interactions with Martian dirt,

not of life. The reactive chemistry probably destroys any

organic molecules.7

Improved cameras on the Viking orbiters, meanwhile,

added detail to Mariner 9’s Mars map. They imaged

polygonal patterns on the smooth northern plains

resembling those formed by permafrost in Earth’s

Arctic regions. Some craters—Gusev, for example—

looked to be filled in by sediments and had walls

breached by sinuous channels. Perhaps they once held

ice-clad lakes.

The Viking images also revealed hundreds of river-size

branching channels—called “valley networks”—in

addition to the large outflow channels seen in Mariner

9 images. Though some were probably shaped by slowly melting subsurface ice, others appeared too finely

branched to be the result of anything other than surface runoff from rain or melting snow. Ironically, most

of the finely branched channels occurred in the southern hemisphere, the area that reminded people in the

1960s of Earth’s dead Moon. The flyby Mariners might

have glimpsed channels among the Moonlike craters

had their cameras had better resolution.

Low pressure and temperature make free-standing

water impossible on Mars today. The channels in the

oldest part of Mars, the cratered southern highlands,

seem to point to a time long ago when Mars had a

dense, warm atmosphere. Perhaps Mars was clement

enough for a sufficiently long period of time for life to

form and leave fossils.8

The Viking landers and orbiters were gratifyingly longlived. The Viking 1 orbiter functioned until 7 August

1980. Together with the Viking 2 orbiter, it returned

more than 51,500 images, mapping 97 percent of the

surface at 300-meter resolution. Though required to

operate for only 90 days, the Viking 1 lander, the last

survivor of the four vehicles, returned data for more

than six years. The durable robot explorer finally broke

contact with Earth on 13 November 1982.9

Viking was a tremendous success, but it had been widely billed as a mission to seek Martian life. The inconclusive Viking exobiology results and negative inter54 Monographs in Aerospace History

Chapter 6: Viking and the Resources of Mars
pretation placed on them helped dampen public enthusiasm for Mars exploration for a decade. Yet Viking

showed Mars to be eminently worth exploring.

Moreover, Viking revealed abundant resources that

might be used to explore it.

Living off the Land

During the period that Mariner 9 and the Vikings

revealed Mars to be a rich destination for explorers,

almost no Mars expedition planning occurred inside

or outside NASA. The Agency was preoccupied with

developing the Space Shuttle, and Mars planners

independent of NASA—who would make many contributions during the 1980s—were not yet active in

significant numbers.

Papers on In-Situ Resource Utilization (ISRU) were

among the first signs of re-awakening interest in piloted Mars mission planning. ISRU is an old concept, dating on Earth to prehistory. ISRU can be defined as

using the resources of a place to assist in its exploration—the phrase “living off the land” is essentially

synonymous. In the context of space exploration, ISRU

enables spacecraft weight minimization. If a spacecraft

can, for example, collect propellants at its destination,

those propellants need not be transported at great

expense from Earth’s surface. In the 1960s, ISRU was

studied largely in hopes of providing life-support consumables. By the 1980s, the propellant production

potential of ISRU predominated.

NASA first formally considered ISRU in 1962, when it

set up the Working Group on Extraterrestrial

Resources (WGER). The WGER, which met throughout

the 1960s, focused on lunar resources, not Martian.

This was because more data were available on lunar

resource potential, and because lunar resource use

was, in the Apollo era, potentially more relevant to

NASA’s activities.10

The UMPIRE study (1963-1964) recommended applying ISRU to establish and maintain a Mars base during long conjunction-class surface stays. Doing this

would, of course, demand more data on what resources

were available on Mars. NASA Marshall’s UMPIRE

summary report stated that “[t]his information,

whether it is obtained by unmanned probes or by

manned [flyby or orbiter] reconnaissance missions, would

make such a base possible,” making the “ ‘cost effectiveness’ of Mars exploration . . . much more reasonable

than [for] the short excursions.”11

Fifteen years after UMPIRE, the Vikings at last produced the in-situ data set required for serious consideration of Mars ISRU. The first effort to assess the

potential of Martian propellant production based on

Viking data spun off a 1977-78 NASA JPL study of an

automated Mars sample-return mission proposed as a

follow-on to the Viking program. Louis Friedman

headed the study, which was initially inspired by

President Gerald Ford’s apparently casual mention of

a possible “Viking 3” mission soon after the successful

Viking 1 landing.12 Robert Ash, an Old Dominion

University professor working at JPL, and JPL staffers

William Dowler and Giulio Varsi published their

results in the July-August 1978 issue of the refereed

journal Acta Astronautica.13

They examined three propellant combinations. Liquid

carbon monoxide and liquid oxygen, they found, were

easy to produce from Martian atmospheric carbon

dioxide, but they rejected this combination because it

produced only 30 percent as much thrust as liquid

hydrogen/liquid oxygen. Electrolysis (splitting) of

Martian water could produce hydrogen/oxygen, but

they rejected this combination because heavy, energyhungry cooling systems were necessary to keep the

hydrogen liquid, thus negating the weight-reduction

advantage of in-situ propellant manufacture.

Liquid methane/liquid oxygen constituted a good compromise, they found, because it yields 80 percent of

hydrogen/oxygen’s thrust, yet methane remains liquid

at higher temperatures, and thus is easier to store. The

Martian propellant factory would manufacture

methane using a chemical reaction discovered in 1897

by French chemist Paul Sabatier. In the Sabatier reaction, carbon dioxide is combined with hydrogen in the

presence of a nickel or ruthenium catalyst to produce

water and methane. The manufacture of methane and

oxygen on Mars would begin with electrolysis of

Martian water. The resultant oxygen would be stored

and the hydrogen reacted with carbon dioxide from

Mars’ atmosphere using the Sabatier process. The

methane would be stored and the water electrolyzed to

continue the propellant production process.

Chapter 6: Viking and the Resources of Mars

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 55
56 Monographs in Aerospace History

Chapter 6: Viking and the Resources of Mars

Ash, Dowler, and Varsi estimated that launching a onekilogram sample of Martian soil direct to Earth would

need 3.8 metric tons of methane/oxygen, while launching a piloted ascent vehicle into Mars orbit would need

13.9 metric tons. These are large quantities of propellant, so conjunction-class trajectories with Mars surface stay-times of at least 400 days would be necessary

to provide enough time for propellant manufacture.

Benton Clark, with Martin Marietta (Viking’s prime

contractor) in Denver, published the first papers

exploring the life-support implications of the Viking

results. His 1978 paper entitled “The Viking Results—

The Case for Man on Mars” pointed out that every kilogram of food, water, or oxygen that had to be shipped

from Earth meant that a kilogram of science equipment, shelter structure, or ascent rocket propellant

could not be sent.14 Clark estimated that supplies for a

10-person, 1,000-day conjunction-class Mars expedition

would weigh 58 metric tons, or about “one hundred

times the mass of the crew-members themselves.” The

expedition could, however, reduce supply weight, thereby either reducing spacecraft weight or increasing

weight available for other items, by extracting water

from Martian dirt and splitting oxygen from Martian

atmospheric carbon dioxide during its 400-day Mars

surface stay.

Clark wrote that Mars offered many other ISRU possibilities, but that they probably could not be exploited

until a long-term Mars base was established. This was

because they required structures, processing equipment, or quantities of power unlikely to be available to

early expeditions. Crop growth using the “extremely

salty” Martian soil, for example, would probably have to

await availability of equipment for “pre-processing . . . to

eliminate toxic components.”15

The Vikings’ robotic scoops barely scratched the

Martian surface, yet they found useful materials such

as silicon, calcium, chlorine, iron, and titanium. Clark

pointed out that these could supply a Mars base with

cement, glass, metals, halides, and sulfuric acid.

Carbon from atmospheric carbon dioxide could serve

clever Martians as a foundation for building organic

compounds, the basis of plastics, paper, and elastomers.

Hydrogen peroxide made from water could serve as

powerful fuel for rockets, rovers, and powered equipment such as drills.

During the 1980s, the Mars ISRU concept generated

papers by many authors, as well as initial experimentation.16 Robert Ash, for example, developed experimental Mars ISRU hardware at Old Dominion University

with modest funding support from NASA Langley17 and

from a non-government space advocacy group, The

Planetary Society.18 That a private organization would

fund such work was significant.

Before ISRU could make a major impact, piloted Mars

mission planning had to awaken more fully from its

decade-long post-Apollo slumber. Post-Apollo Mars

planning occurred initially outside official NASA auspices. This constituted a sea-change in Mars planning—up to the 1970s, virtually all Mars planning was

government-originated. In the 1980s, as will be seen in

the coming chapters, individuals and organizations

outside the government took on a central, shaping role.
We didn’t know all of the people who finally did

speak . . . until they called us! Somehow they

heard about the conference, through the flyers

we sent around and from word of mouth, and

they volunteered. It really was a Mars

Underground! (Christopher McKay, 1981)1

Columbia

Columbia, the first Space Shuttle, lifted off from Pad

39A at Kennedy Space Center on 12 April 1981, with

Commander John Young and Pilot Robert Crippen on

board for a two-day test flight. Nearly 12 years before,

the Apollo 11 CSM Columbia had left the same pad

atop a Saturn V at the start of the first Moon landing

mission. For Shuttle flights, the twin Complex 39 pads

were trimmed back and heavily modified. Designated

STS-1, it was the first U.S. piloted space flight since the

joint United States-Soviet Apollo-Soyuz mission in July

1975.

At launch, the 2,050-metric-ton Shuttle “stack” consisted of the delta-winged orbiter Columbia and twin

45.4-meter-long Solid Rocket Boosters (SRBs)

attached to a 47.4-meter-long expendable External

Tank (ET). Columbia measured 37.2 meters long with

a wingspan of 23.8 meters. Seconds before planned

liftoff, the three Space Shuttle Main Engines (SSMEs)

in the orbiter’s tail ignited in rapid sequence, drawing

liquid hydrogen and liquid oxygen propellants from

the ET. Then, at T-0, the two SRBs lit up. Unlike the

Saturn V, which climbed slowly during first-stage

operation, Columbia leapt from the launch pad. Also

unlike the Saturn V engines, the SRBs could not be

turned off once they ignited, making abort impossible

until they exhausted their propellants and separated.

This was not considered a major risk—SRBs, used

since the 1950s, were considered a mature technology.

Two minutes into STS-1, the SRBs separated and fell

into the Atlantic for recovery and reuse. Columbia’s

SSMEs, the world’s first reusable large rocket engines,

continued pushing the orbiter and ET toward space.

Eight and one-half minutes after launch, the SSMEs

shut down and the ET separated. Young and Crippen

fired Columbia’s twin Orbiter Maneuvering System

(OMS) engines to complete orbital insertion while the ET

tumbled and reentered, then opened the long doors covering Columbia’s 18.3-meter by 4.6-meter payload bay.

The payload bay was the orbiter’s raison d’être.

Maximum payload to low-Earth orbit was about 30

metric tons, though center of gravity and landing

weight constraints restricted this to some degree. The

payload bay could carry satellites for release into orbit

or a European-built pressurized laboratory module

called Spacelab. The Space Shuttle orbiter was also the

only space vehicle that could rendezvous with a satellite and capture it for repair or return to Earth—it

could return about 15 metric tons to Earth in its payload bay. NASA hoped to use the Space Shuttle to

launch components for an Earth-orbiting space station

and other vehicles, such as aerobraking Orbital

Transfer Vehicles (OTVs) based at the station.

On 14 April Young and Crippen fired Columbia’s OMS

engines for about two minutes to begin reentry. The

STS-1 reentry had almost nothing in common with previous piloted reentries. Columbia’s heat shield did not

ablate—that is, burn away—to protect it from the friction heat of reentry. Instead, in the interest of reusability, Columbia relied on more than 24,000 individually

milled spun-glass tiles to shield its aluminum skin.

After a pair of close-timed sonic booms—they would

become a Space Shuttle trademark—Columbia glided

to a touchdown on the wide dry lake bed at Edwards

Air Force Base, California. Future landings would

occur on a runway seven kilometers from the Complex

39 Shuttle pads at KSC.2

NASA heralded the flight as the start of a new era of

routine, inexpensive space access that might spawn

industry off Earth. An ebullient Young told reporters,

“We’re not really too far—the human race isn’t—from

going to the stars.”3

The Case for Mars

The Mars buffs who were gathered in Boulder,

Colorado, for the first Case for Mars conference, just

two weeks after the first Shuttle flight, would have settled for NASA’s setting its sights on Mars—never mind

the stars. Fueled by the Viking discoveries, would-be

Mars explorers dared look beyond the Space Shuttle.

They hoped that Mars ship propellants and components

might soon be manifested as Shuttle payloads. They

also saw in the Shuttle and in the Space Station

Program (expected soon to follow) sources of hardware

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 57

Chapter 7: The Case for Mars
for Mars ship parts, much as planners in the 1960s envisioned using Apollo hardware for piloted Mars flybys.

The 1981 Case for Mars conference provided the first

public forum for Mars planning since the 1960s. The

conference crystallized around an informal seminar

based on NASA’s 1976 study The Habitability of Mars,

organized by Christopher McKay, a University of

Colorado at Boulder astro-geophysics Ph.D. candidate.

The seminar brought together Mars enthusiasts from

Boulder and around the country. The “Mars

Underground,” as they light-heartedly called themselves, decided in the spring of 1980 that the time was

ripe for a conference on Mars exploration.4 

The Case for Mars conference drew its name from the

title of Benton Clark’s 1978 Mars ISRU paper (see

chapter 6). Clark took part in the conference, along

with about 300 other engineers, scientists, and enthusiasts.5 It was the largest gathering of would-be Mars

explorers since the 1963 Symposium on the Manned

Exploration of Mars.

The conference was in part a brain-storming session—

an opportunity to take stock of ideas on how to explore

Mars. Among the concepts presented was S. Fred

Singer’s “PH-D Proposal,” which drew upon Shuttlerelated technology expected to exist in 1990.6 Singer’s

scenario had staying power—he was still writing about

it in the spring of 2000.7

Singer’s $10-billion expedition would use Deimos, Mars’

outer moon, as a base of operations for exploring the

Martian system. It was similar to the 1960s piloted

flyby and orbiter missions in how it minimized spacecraft weight. None of the six to eight astronauts would

land on Mars, though a sample-return lander would

bring up a “grab sample” from the planet and two astronauts would visit Phobos, Mars’ inner moon. The astronauts would remote-control between 10 and 20 Mars

surface rovers during their two-to-six-month stay in the

Martian system. At Deimos’ orbital distance, round-trip

radio travel time would be only one-fifth of a second.

Two astronauts would be “medical scientists” who

would study human reactions to weightlessness, radiation, and isolation throughout the expedition. They

would minimize risk to the crew from these longduration space flight hazards by continually monitoring

their health; data they gathered would also minimize risk

for future Mars landing expeditions.

Singer’s expedition would rely on solar-electric

thrusters, using electricity from a large solar array to

ionize and electrostatically expel argon gas. As

described in chapter 2, electric propulsion thrusters

produce constant low-thrust acceleration while using

very little propellant. Singer assumed that the solar

array would be available in high-Earth orbit in 1990 as

part of a pre-existing Shuttle-launched cislunar infrastructure. The cost of the solar array was thus not

included in Singer’s expedition cost estimate.

At the start of the PH-D Proposal expedition, the

unpiloted solar-electric propulsion system would spiral

out from Earth, slowly gaining speed. Several weeks

later, as it was about to escape Earth orbit, the piloted

Phobos-Deimos craft would catch up, using chemical

rockets, and dock. This technique minimized risk to

crew by reducing the amount of time they had to spend

in weightlessness and by speeding them through the

Van Allen Radiation Belts. The solar-electric propulsion

system would accelerate the spacecraft until expedition

mid-point; then its thrusters would be turned to point in

the direction of travel. The spacecraft would then decelerate until it was captured into orbit by Mars’ gravity.

The 1990-91 target launch date would allow Singer’s

expedition to take advantage of a Venus flyby opportunity to gain speed and change course without using

propellant. Total expedition duration would be “something less than two years.” Electric propulsion plus

Venus flyby plus postponing the piloted Mars landing

until a later expedition would reduce spacecraft weight

at Earth-orbit departure to about 300 tons.

The Planetary Society

In 1983, The Planetary Society, a non-profit space

advocacy organization with about 100,000 members,

commissioned the most detailed piloted Mars mission

study since 1971. The organization did this because,

as Society president Carl Sagan and executive director Louis Friedman wrote in their foreword to the

study report, “since Apollo, there have been, in the

United States at least, almost no serious studies of

manned (or womanned) voyages to other worlds,

despite the fact that enormous technological advances

58 Monographs in Aerospace History

Chapter 7: The Case for Mars
have been made since those early lunar landings.”8

Writing in the Society’s member magazine, The

Planetary Report, Friedman explained that “we funded [the study] because it is important to have solid

technical evidence to back us in our advocacy of new

goals . . . .”9 The nine-month study, “a labor of love”

performed at a “bargain basement price” by Science

Applications International Corporation (SAIC), was

completed in September 1984.10 

SAIC’s Mars mission design resembled MSC’s 1963

Flyby-Rendezvous mode. Eighteen Space Shuttle

launches would deliver more than 160 metric tons of

spacecraft components to Earth orbit. The four-person

crew would travel to Mars in a 121-metric-ton

Outbound Vehicle consisting of four “sub-vehicles.”

These were the 38-metric-ton Interplanetary Vehicle,

the 19-metric-ton Mars Orbiter, the 54-metric-ton Mars

Lander, and the 10-metric-ton Mars Departure Vehicle.

The Interplanetary Vehicle, which would provide onequarter of Earth’s gravity by spinning three times each

minute, would include pressurized crew modules based

on Spacelab modules. The Mars Orbiter, the Mars

Departure Vehicle, and the conical, two-stage Mars

Lander were together designated the Mars Exploration

Vehicle (MEV). The MEV would include a 54-meterdiameter aerobrake. The crew would return from Mars

in the 43-metric-ton Earth Return Vehicle (ERV),

which resembled the Interplanetary Vehicle except in

that it would include a conical 4.4-metric-ton Earthreturn capsule nested in a 13-meter-diameter aerobrake. Of these vehicles, only the MEV would have to

slow down and enter Mars orbit. This, plus extensive

use of aerobraking, would reduce the amount of propellant required to carry out SAIC’s Mars expedition,

which in turn would reduce spacecraft weight.

The unpiloted ERV would depart Earth orbit on 5 June

2003, using three large OTVs stacked together, each

carrying over 27 metric tons of propellants. The SAIC

team assumed that reusable space-based OTVs would

be available in Earth orbit as part of NASA’s Space

Station Program. The expense of developing, launching,

and operating the OTVs was thus not counted in the

cost of the expedition. OTV 1 would fire its engines at

perigee, increasing its apogee distance, then separate.

OTV 2 would repeat this procedure. OTV 3’s perigee

burn would place the ERV on course for Mars. This

series of maneuvers would require about six hours.

The crew would depart Earth in the Outbound Vehicle

ten days later, on 15 June 2003. Because it was nearly

three times heavier than the ERV, the Outbound

Vehicle would need perigee burns by seven OTVs over

about two days to achieve a Mars-bound trajectory.

On 24 December 2003, the crew would near Mars in

the Outbound Vehicle, board and undock the MEV, and

aerobrake into Mars orbit. The abandoned

Interplanetary Vehicle would fly past Mars into solar

orbit. Three of the four crew would enter the Mars

Lander and descend to the surface, which they would

explore using a pressurized rover. On 23 January

2004, after a month on Mars, the surface crew would

lift off in the Mars Lander ascent stage with 400 kilograms of rock samples to rejoin their colleague aboard

the Mars Orbiter.

The ERV, meanwhile, would approach Mars on a flyby

trajectory. The crew would board the Mars Departure

Vehicle, abandon the Mars Lander ascent stage and

Mars Orbiter, and leave Mars orbit in pursuit of the

ERV. Rendezvous and docking would occur while the

ERV was outbound from Mars. Friedman noted that

“[b]ecause the orbit doesn’t close around Mars, the crew

has only a chance at one precise time, to rendezvous

with the return vehicle. Although this is risky, SAIC

analysis found it acceptable compared to other mission

risks. (However, some of us at The Planetary Society

wonder if the crew will feel the same way!)”11

Eighteen months later, on 5 June 2006, the crew

would board the Earth-return capsule and separate

from the ERV. They would aerobrake in Earth’s

atmosphere while the abandoned ERV flew past

Earth into solar orbit.

The SAIC team estimated the cost of their Mars expedition at $38.5 billion in 1984 dollars, of which $14.3

billion would be spent on Mars spacecraft hardware,

$2 billion would pay for Shuttle launches, and $18.5

billion would be spent on operations. Friedman pointed out that, over a decade, this cost averaged about $4

billion annually, or about 60 percent of NASA’s

approximately $7-billion FY 1984 budget.12

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 59

Chapter 7: The Case for Mars
Space Station

Traditionally, space stations have been envisioned as

having multiple functions, not least of which was as an

assembly and servicing base—a spaceport—for spacecraft, including those bound for Mars. In 1978, as Space

Shuttle development moved into its final stages,

NASA’s Johnson Space Center (JSC) (as MSC was

renamed in 1973) began planning a Shuttle-launched

modular space station called the Space Operations

Center (SOC). A space shipyard, the SOC was the most

important station concept in the years 1978 through

1982—the period immediately before gaining approval

for a station became a realistic goal for NASA.13

An internal NASA presentation in May 1981—one

month after STS-1—described the SOC as the central element of a “space operations system” that

would include the Space Shuttle, OTVs for moving

objects assembled at the SOC to orbits beyond the

Shuttle’s altitude limit, and Manned OTVs for

transporting astronauts on satellite service calls.14 A

JSC press release in early 1982 referred to the SOC

as a “space base and marshaling yard for large and

complex payloads” providing “garage space for

reusable cryogenic stages.”15

After his first year in office, during which NASA took

deep cuts, President Ronald Reagan came to see the

political benefits of being identified with a successful

space program. On 4 July 1982, Columbia returned

from space at the end of mission STS-4. Reagan was on

hand amid fluttering American flags to declare the

Shuttle operational. He spoke of establishing a more

permanent presence in space, but withheld a clear

mandate to build a space station until his 25 January

1984 State of the Union address. When he did, he

emphasized its laboratory function:

We can follow our dreams to distant stars, living and working in space for peaceful economic

and scientific gain. Tonight I am directing

NASA to develop a permanently manned Space

Station and to do it within a decade. The Space

Station would permit quantum leaps in our

research in science, communications, in metals

and in life-saving medicines which can only be

manufactured in space . . . .16

The lab function was emphasized partly to keep the

Station’s estimated cost as close to $8 billion as possible.17 As we have seen, Mars planners early in the

1980s assumed that OTVs and other Earth-orbit infrastructure applicable to Mars exploration would soon

become available. With the spaceport role de-emphasized and the lab role moved to the fore, the justification for OTVs was largely removed, and the ability to

assemble other Earth-orbit infrastructure, such as

Singer’s solar array, was made forfeit. Assembling the

Space Station itself would provide some experience

with application to Mars ship assembly. However, it

would provide little experience with handling tankage

and propellants in space, both crucial to building a

Mars ship.

Soviets to Mars

In the early 1980s, such NASA advanced planning as

existed focused more on the Moon than on Mars. The

revival in NASA Mars interest owes much to geologist

and Apollo 17 Moonwalker Harrison Schmitt, and to

the Agency’s lunar base studies, which had never

receded to the same degree as its Mars studies.

Schmitt was concerned about an on-going Soviet space

buildup, which saw long stays by cosmonauts aboard

Salyut space stations and development of a Soviet

shuttle and heavy-lift rocket, as well as plans for ambitious robotic Mars missions.18 Schmitt also concentrated on Mars because he had asked children, the future

space explorers, about returning to the Moon and

found that they were not interested because people

had already been there.19

Schmitt had attempted to promote Mars exploration in

the late 1970s while serving as Republican U.S.

Senator from New Mexico. Following Viking’s success,

he had put forward a bill calling for the U.S. to develop

the capability to establish a settlement on Mars by

2010. His “Chronicles Plan” excited momentary interest in President Jimmy Carter’s White House, inducing

NASA Administrator Robert Frosch to activate a small

NASA study team. The team’s July 1978 workshop at

Wallops Island, Virginia, produced nothing new. In fact,

the consensus was that “past work [from the 1960s]

should not be updated unless serious consideration is

being given to conducting a manned Mars mission prior

to the year 2000.”20 In short, NASA was too busy working on the Space Shuttle in 1978 to think about Mars.

60 Monographs in Aerospace History

Chapter 7: The Case for Mars
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 61

Schmitt renewed his Mars efforts in 1983 by contacting

Paul Keaton of LANL during a meeting held in the runup to the 1984 Lunar Bases and Space Activities of the

21st Century conference, held at the National Academy

of Sciences in Washington, DC.21 As seen in Chapter 5,

LANL was involved in space flight before NASA was

created through its work on nuclear rockets. At the

lunar base conference, Schmitt presented a paper on

his “Mars 2000 Millennium Project,” which he hoped

would “mobilize the energies and imaginations of

young people who are already looking beyond Earth

orbit and the [M]oon.”22 He also made contact with

NASA engineers and scientists interested in exploring

Mars as well as the Moon.23

Schmitt then pressed for a study to give the President

the option to send humans to Mars should he desire to

respond to the Soviet buildup. LANL partnered with

NASA to conduct the Manned Mars Mission (MMM)

study during 1984 and 1985. The effort culminated in

the joint NASA-LANL MMM workshop at NASA

Marshall (10-14 June 1985).24 The workshop published

three volumes of proceedings in 1986.25

Especially noteworthy, given Schmitt’s primary rationale for the MMM workshop, was a JSC plan for a piloted Mars flyby based on technology expected to exist in

the 1990s as part of the Space Station Program. This

aimed at countering a possible Soviet piloted Mars

flyby mission.

In April 1985, at Schmitt’s request, the CIA prepared

an analysis of possible Soviet space moves. The analysis cited “[p]ublic comments in 1982 by the Soviet

S[cience] & T[echnology] Attaché assigned to

Washington and in 1984 by the President of the Soviet

Academy of Science,” which suggested that “the

Soviets have confidence in their ability to conduct such

a mission.” The CIA then predicted that “ . . . they will

choose a one-year flyby as their first step.”26

The analysis cited current and future indicators pointing to Soviet piloted Mars exploration. These included

continuing work on a heavy-lift rocket “capable of

placing into low-earth orbit about five times the

payload of the present largest Soviet space launch

vehicle, thereby significantly reducing the number

of launch vehicles required.”27 The “strongest current

indicator,” however, was “the long-duration stays in

space by cosmonauts” aboard Salyut space stations.

Potential future indicators included “a cosmonaut stay

in low-earth orbit of one year duration . . . [and] space

tests of a nuclear propulsion system . . . .”28 The CIA

guessed that the first Soviet Mars flyby might occur as

early as 1992, in time for the 500th anniversary of

Columbus’s arrival in the Americas.29

The JSC flyby plan for countering this possible Soviet

move was prepared by Barney Roberts, who performed

lunar base studies in the JSC Engineering Directorate.30

Roberts’ year-long Mars flyby mission would begin with

orbital assembly at the Space Station. Shuttles would

deliver two expendable strap-on propellant tanks and

an 18-ton Mission Module to the Station. The latter

would dock with a 6-ton Command Module (not to be

confused with the Apollo CM) and two 5.75-ton OTVs

assumed to be in space already as part of the Space

Station Program. Shuttle-derived heavy-lift rockets

would then deliver 221 tons of liquid hydrogen/liquid

oxygen propellants. The propellants would be loaded

into the strap-on and OTV tanks just prior to departure

for Mars. Spacecraft weight at Earth-orbit departure

would come to 358 tons.

Chapter 7: The Case for Mars

Figure 18—In 1985, NASA’s Johnson Space Center

responded to suspected Soviet Mars plans by proposing a

U.S. Mars flyby using Space Station and lunar base hardware then planned for the 1990s. Here the flyby spacecraft

orbits Earth before setting out for Mars. (“Concept for a

Manned Mars Flyby,” Barney Roberts, Manned Mars

Missions: Working Group Papers, NASA M002, NASA/Los

Alamos National Laboratories, Huntsville, Alabama/Los

Alamos, New Mexico, June 1986, Vol. 1, p. 210.)
62 Monographs in Aerospace History

At the proper time, the OTV engines would ignite and

burn for about one hour to put the flyby craft on course

for Mars. This would empty the strap-on tanks, but

Roberts advised retaining them to provide additional

meteoroid and radiation shielding for the crew modules. After a six-month Earth-Mars transfer, the flyby

spacecraft would spend two and one-half hours within

about 20,000 miles of Mars. Closest approach would

occur 160 nautical miles above the Martian surface

with the flyby craft moving at 5 miles per second.

As Earth grew from a bright star to a distant disk, the

astronauts would discard the strap-on tanks, then

undock one OTV and redock it to the Command Module.

They would enter the Command Module and discard

the Mission Module and the second OTV. The OTV/

Command Module combination would slow to a manageable reentry speed using the OTV’s engines, aerobrake to

Earth-orbital speed, then dock at the Space Station.

Roberts found (as had planners in the 1960s) that

Earth return was the most problematical phase of the

flyby mission because the OTV would hit Earth’s

atmosphere at 55,000 feet per second, producing friction heating beyond the planned limits of the OTV heat

shields. In addition, the crew would experience “exorbitant” deceleration levels after spending a year in

weightlessness.

In the 1960s, planners proposed a Venus flyby to reduce

reentry speed without using propellant, but Roberts

did not mention this possibility. He proposed instead to

slow the OTV and Command Module to 35,000 feet per

second using the former’s engines. Adding this burn

would nearly double spacecraft weight at Earth-orbit

departure. Roberts calculated that, assuming the Space

Shuttle-derived heavy-lift rocket could deliver cargo to

Earth orbit at a cost of $500 per pound, Earth-braking

propellant would add $250 million to mission costs.31

Interplanetary Infrastructure

Some Mars planners envisioned the NASA Space

Station in low-Earth orbit as merely the first in a series

of stations in logical places serving as Mars transportation infrastructure, much like trails, canals, railChapter 7: The Case for Mars

Figure 19—During return to Earth the flyby spacecraft

discards empty propellant tanks, revealing cylindrical

Command and Mission Modules between twin almondshaped Orbital Transfer Vehicles. (“Concept for a Manned

Mars Flyby,” Barney Roberts, Manned Mars Missions:

Working Group Papers, NASA M002, NASA/Los Alamos

National Laboratories, Huntsville, Alabama/Los Alamos,

New Mexico, June 1986, Vol. 1, p. 210.)

Figure 20—The flyby crew prepares to aerobrake in Earth’s

atmosphere. As Earth grows from a bright star to a disk, they

undock the Command Module and one Orbital Transfer

Vehicle, abandoning the second Orbital Transfer Vehicle and

their home for the previous year, the Mission Module.

(“Concept for a Manned Mars Flyby,” Barney Roberts,

Manned Mars Missions: Working Group Papers, NASA

M002, NASA/Los Alamos National Laboratories, Huntsville,

Alabama/Los Alamos, New Mexico, June 1986, Vol. 1, p. 213.)
ways, and coaling stations formed transportation infrastructure in bygone days. They looked ahead to solarorbiting space stations, known as cyclers, traveling a

regular path between Earth and Mars, and to spaceports at the Lagrange gravitational equilibrium points.

Apollo 11 Lunar Module Pilot Buzz Aldrin, the second

man on the Moon, described cyclers in a popular-audience

article in Air & Space Smithsonian magazine in 1989:

Like an oceanliner on a regular trade route, the

Cycler would glide perpetually along its beautifully predictable orbit, arriving and departing

with clock-like regularity. By plying the solar

system’s gravitational “trade winds” it will carry

mankind on the next great age of exploration

. . . . For roughly the same cost as getting

humans safely to Mars via conventional expendable rocketry (because the problems to be solved

would be largely the same), the Cycler system

would provide a reusable infrastructure for travel between Earth and Mars far into the future.32 

In the 1960s, Massachusetts Institute of Technology professor Walter Hollister and others studied “periodic”

orbits related to Crocco flyby orbits but indefinitely

repeating. A space station in such an orbit would cycle

“forever” between Earth and the target planet. In

January 1971, Hollister and his student, Charles Rall,

described an Earth-Mars transport system in which at

least four cycling periodic-orbit stations would operate

simultaneously, permitting opportunities every 26

months for 6-month transfers between Earth and Mars.33

As the large periodic-orbit station flew past Earth or

Mars, small “rendezvous shuttle vehicles” would race

out to meet it and drop off crews and supplies for the

interplanetary transfer. After several Mars voyages,

the cycler approach would yield a dramatic reduction in

spacecraft mass over the MOR mission mode because

the cycler would only need to burn propellants to leave

Earth orbit once; after that, only the small shuttles

would need to burn propellants to speed up and slow

down at Earth and Mars.

The Case for Mars II conference (10-14 July 1984)

included a workshop that planned “a permanent Mars

research base using year 2000 technology” as a “precursor to eventual colonization.” The Case for Mars II

workshop took advantage of the long-term weightminimization inherent in cyclers and Mars ISRU. The

Boulder Center for Science and Policy published a JPLfunded report on the workshop results in April 1986.34

The Case for Mars had begun to gather steam.

Participants in the second conference included

Harrison Schmitt with a paper on his Mars 2000 project, Benton Clark, and Christopher McKay, who had

earned his Ph.D. and gone to work at NASA Ames.

Former NASA Administrator Tom Paine presented a

timeline of Mars exploration spanning 1985 to 2085. It

predicted, among other things, a lunar population in

the thousands in the 2025-2035 decade and a Martian

population of 50,000 in the 2055-2065 decade.35 Barney

Roberts, Michael Duke, and lunar scientist Wendell

Mendell presented a paper called “Lunar Base: A

Stepping Stone to Mars,”36 while NASA Space Station

manager Humboldt Mandell presented a paper called

“Space Station: The First Step.”37

In the Case for Mars II plan, the cycler’s Earth-Mars leg

lasted six months, followed by a Mars-Earth leg lasting

20 to 30 months. Each crew would spend two years on

Mars, and new crews would leave Earth every two years.

The first crew would leave Earth in 2007 and return in

2012; the second crew would depart in 2009 and return

in 2014; and so on. This schedule would require at least

two cyclers. As Hollister and Rall proposed, small Crew

Shuttle vehicles would transfer crews to and from the

passing cycler. The Crew Shuttles were envisioned as

two-stage biconic vehicles designed for aerobraking at

Earth and Mars. Their proposed shape was derived

from ballistic missile warhead research.

A heavy-lift rocket capable of launching at least 75

metric tons, possibly based on Shuttle hardware, would

place cycler components, some based on Shuttle and

Space Station hardware, into Earth orbit for assembly.

The 1984 Case for Mars plan called for cycler assembly

at the low-Earth orbit Space Station; in a subsequent

version, a dedicated assembly facility was proposed.

The first Mars expedition would require 24 heavy-lift

rocket launches and 20 Shuttle launches.

ISRU would supply the Case for Mars II base with

many consumables, including propellant. “Mars is

abundantly endowed with all the resources necessary

to sustain life,” the report stated, adding that “propellant production on the surface of Mars is critical to

reducing the cost of the program” because it “reduces

the Earth launch weight by almost an order of magniHumans to Mars: Fifty Years of Mission Planning, 1950–2000 63

Chapter 7: The Case for Mars
64 Monographs in Aerospace History

tude.”38 Each Crew Shuttle would require 150 tons of

Mars ISRU-manufactured carbon monoxide/oxygen

propellant to catch up with the passing Earth-bound

cycler. The Case for Mars II workshop proposed that an

automated probe should test ISRU propellant production on Mars before the Mars base program began.

Lagrangia

Like the cycler concepts, the notion of siting infrastructure at the Lagrange points dates to the 1960s. Its theoretical roots, however, date to 1772. In that year, French

mathematician Joseph Lagrange noted that gravitational equilibrium points exist in isolated two-body systems.

Lagrange points exist in space—for example, in the

two-body Earth-Moon system. In theory, an object

placed at one of these points will remain as if nesting

in a little cup of space-time. In practice, Lagrange

points in space are unstable or quasi-stable because

planets and moons do not exist as isolated two-body

systems. In the case of the Earth-Moon system, the

Sun’s gravitational pull introduces instability.

Objects placed at the Earth-Moon Lagrange points

thus tend to move in “halo orbits” around the

Lagrange point and require modest station keeping

to avoid eventual ejection.

Robert Farquhar, an engineer at NASA’s Goddard

Space Flight Center in Greenbelt, Maryland, first

wrote about using the Lagrange equilibrium points of

the Earth-Moon system in the late 1960s.39 For the

NASA MMM workshop in June 1985, Farquhar teamed

up with David Dunham of Computer Sciences

Corporation to propose using Lagrange points as “stepping stones” for Mars exploration.40

Farquhar and Dunham envisioned a large, reusable

Interplanetary Shuttle Vehicle (ISV) in halo orbit about

the quasi-stable Earth-Sun Lagrange 1 point, 1.5 million kilometers in toward the Sun. A Mars transport

spacecraft parked there would be gravitationally bound

to Earth much more weakly than if parked in low-Earth

orbit. A mere propulsive burp would suffice to nudge the

ISV out of halo orbit; then gravity-assist swingbys of the

Moon and Earth would place it on course for Mars with

little additional propellant expenditure. This meant, of

course, that the amount of propellant that would need

to be launched from Earth was minimized. To save even

more propellant, the ISV might park at the Mars-Sun

Lagrange 1 point, about 1 million kilometers Sunward

from Mars, and send the crew to the Martian surface

using small shuttle vehicles.

Farquhar and Dunham pointed out that an automated spacecraft had already left Earth-Sun Lagrange 1

on an interplanetary trajectory. The International

Sun-Earth Explorer-3 spacecraft had entered EarthSun Lagrange 1 halo orbit on 20 November 1978.

After completing its primary mission it was maneuvered during 1984 through a series of Earth and

Moon swingbys to place it on course for Comet

Giacobinni-Zinner. Farquhar supervised the effort.

The maneuvers consumed less than 75 kilograms of

propellant. Renamed the International Comet

Explorer, the spacecraft successfully flew past

Giacobinni-Zinner, 73 million kilometers from Earth,

on 11 September 1985.

Paul Keaton elaborated on Farquhar and Dunham’s

MMM paper in a “tutorial” paper published in August

1985. He wrote that “[a]n evolutionary manned space

program will put outposts along routes with economic,

scientific, and political importance” to serve as “‘filling

stations’ for [making and] storing rocket fuel” and

“transportation depots for connecting with flights to

other destinations.”41

The first outpost would, of course, be NASA’s planned

Space Station in low-Earth orbit, where Earth’s magnetic field would help protect travelers from galactic

cosmic rays and solar flare radiation, and medical

researchers would learn about the effects of long-term

weightlessness on the human body. Keaton then looked

beyond Earth orbit for the next outpost site. He proposed placing it in halo orbit around the Earth-Moon

Lagrange 2 point, 64,500 kilometers behind the Moon,

or at Farquhar’s Earth-Sun Lagrange 1 site. He wrote,

[f]or the settlement of space, a Lagrange equilibrium point between the Sun and Earth has

the nearly ideal physical characteristics of a

transportation depot . ... Lagrange point halo

orbits are the present standard by which any

alternative concept for a transportation depot

must be gauged.42

Cyclers and Lagrange point spaceports—infrastructure spanning worlds—imply large-scale permanent

Chapter 7: The Case for Mars
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 65

Chapter 7: The Case for Mars

space operations and long-term commitment to building space civilization. Such grandiose visions are not

widely shared outside of a subset of the small community of would-be Mars explorers, as will be seen in

the next chapter.
Mars is the world next door, the nearest planet

on which human explorers could safely land.

Although it is sometimes as warm as a New

England October, Mars is a chilly place, so cold

that some of its thin carbon dioxide atmosphere

freezes out at the winter pole. There are pink

skies, fields of boulders, sand dunes, vast

extinct volcanoes that dwarf anything on

Earth, a great canyon that would cross most of

the United States, sandstorms that sometimes

reach half the speed of sound . . . hundreds of

ancient river valleys . . . and many other mysteries. (The Mars Declaration, 1987)1

National Commission on Space

Late 1984, when the Space Shuttle was operational

and Space Station development was underway, seemed

an auspicious time to begin charting a course for NASA

to follow after Space Station completion in the early

1990s. Congress mandated that President Reagan create an independent commission to sort through the

possibilities and provide recommendations. The

National Commission on Space (NCOS) was launched

officially on 29 March 1985 with the goal of blueprinting the next 20 years of the civilian space program. The

NCOS was to present results to the White House and

Congress following a one-year study.

Reagan tapped Tom Paine, NASA Administrator

from 1968 to 1970, to head the NCOS. Fourteen commissioners joined Paine. They included such luminaries as Neil Armstrong, the first human to walk on

the Moon; Chuck Yeager, the first human to break

the sound barrier; former United Nations

Ambassador Jeane Kirkpatrick; Space Shuttle astronaut Kathy Sullivan; and retired Air Force General

Bernard Schriever. Laurel Wilkening, a planetary

scientist and Vice Provost of the University of

Arizona, was Vice Chair.

Non-voting NCOS members included representatives

from both parties of Congress and the Departments of

State, Commerce, Agriculture, and Transportation, as

well as the National Science Foundation and the White

House Office of Science and Technology Policy. In addition to the inputs provided by its members, the NCOS

held public forums and solicited written contributions

from academe, business, and the general public.

The result was Pioneering the Space Frontier, a glossy

report billed as “an exciting vision of our next fifty

years in space.”2 It was the first in a series of high-profile space reports produced in the Reagan/Bush years.

Paine’s attitude had not changed much since his time

as NASA Administrator. He still saw it as his job to

challenge Americans to take on the solar system. The

NCOS report’s expansive vision bore Paine’s unmistakable stamp; in fact, it bore a resemblance to Paine’s

timeline from the Case for Mars II. Paine looked to an

expanding 21st-century economy with “free societies

on new worlds” and “American leadership on the new

frontier.”

Events caught up with the NCOS exercise, however. On

the chilly Florida morning of 28 January 1986, with

much of the Commission’s work complete, Space

Shuttle Challenger exploded 73 seconds into mission

STS-51L, killing seven astronauts and grounding the

remaining three Shuttle orbiters. The immediate cause

of the accident was failure of a seal in one of the

Shuttle’s twin SRBs.

The Challenger accident threw the giddy optimism of

Paine’s NCOS report into sharp relief. It was a wake-up

call. The Space Shuttle would not, could not, provide the

kind of low-cost, routine space access envisioned during

the 1970s. “The myth of an economic Shuttle” was laid

bare.3 The basic tool for establishing space infrastructure was found wanting, forcing many of the infrastructure elements envisioned by Mars planners in the early

1980s into some indefinite post-Shuttle future.

The accident contributed to NASA’s decision to redesign

the Space Station in mid-1986.After more than two years

of studies, NASA had unveiled its station design in early

1986. Called the Dual Keel, it was primarily a space laboratory, but included a large rectangular truss which

might eventually hold hangars, assembly equipment, and

a propellant depot for Moon and Mars spacecraft. The

rectangular truss was, however, adopted primarily to provide attachment points for anticipated user payloads,

with space-facing payloads on the top and Earth-facing

payloads on the bottom.4

Following Challenger, the Dual Keel design came to be

seen as too ambitious. The rectangular truss was

deferred to a future Phase II of station assembly. Phase

I would consist of a single straight truss holding solar

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 67

Chapter 8: Challengers
arrays and a cluster of pressurized modules. Designers

sought, however, to include software “scars” and hardware “hooks” in the Phase I design to permit eventual

expansion to the full Dual Keel configuration.5

From the Mars explorers’ point of view, the accident

demonstrated that the Space Shuttle could not be used

to launch Mars ships. It had been felt by many before

Challenger that the Shuttle would have to be supplemented by a heavy-lift rocket if piloted flight beyond

low-Earth orbit was to be a credible NASA goal, but it

became patently obvious to most everyone on that cold

day in January 1986.

Paine’s report was crammed full of new vehicles and

interplanetary infrastructure based largely on SAIC

and Eagle Engineering studies. The NCOS called for

new cargo and passenger launch vehicles to replace the

Space Shuttle by 1999 and 2000, respectively. These

were components of a “Highway to Space” that would

include the initial Earth-orbital Space Station (1992), a

space-based OTV (1998), and an initial Earth-orbital

spaceport (1998). This segued into a “Bridge Between

Worlds” that would include a single-stage-to-orbit

space plane, a Moon base with facilities for mining

lunar oxygen, cyclers and Lagrange point stations,

nuclear-electric space freighters, and, by 2026, a Mars

base resembling the one put forward at the Case for

Mars II workshop (1984).

The NCOS program would cost about $700 billion

between 1995 and 2020. This cost would, Paine wrote,

be paid through increases in NASA funding keeping

pace with projected increases in U.S. GNP of 2.4 percent per year. NASA funding in 1986 was about $10 billion, or less than 1 percent of GNP. According to the

report, if NASA funding remained near 1 percent of

GNP, it would increase to $20 billion in 2000 and to $35

billion in 2020. For the near-term, the report urged that

the new technology development share of NASA’s budget be raised from 2 percent to 6 percent.

The NCOS turned over its report to the Reagan White

House in March 1986, two months after the Challenger

accident. Paine went public with the report even before

presenting it to the White House by giving a draft to

Aviation Week & Space Technology magazine.6

Unusually, the report was also published as a trade

paperback and sold in bookshops.

Paine presented the NCOS report formally to President

Reagan and the Senate and House Space Committees

on 22 July 1986. It urged the White House to direct the

NASA Administrator to respond by 31 December 1986

with general long-range and specific short-range implementation plans. Paine summed up the NCOS report

the next day at the NASA Mars Conference, underway

at the National Academy of Sciences to commemorate

the tenth anniversary of Viking 1’s landing. He told the

assembled scientists and engineers that Reagan had

assured him that the Commission’s recommendations

would be accepted.7

The report’s conclusion assumed—correctly—that

Paine’s vision would be seen as grandiose, and took

pains to defend it. As he had done in the 1969 Space

Task Group report, Paine described the technological

progress made in the past in an effort to demonstrate

the progress that could be made in coming decades.

Is our expansive view of America’s future

realistic? Are the technical advances we

project achievable? Will people accept the

risks and discomforts to work on other

worlds? We believe that the answer to all

three questions is “Yes!” Few Americans in

the early days of the Air Age ever expected to

fly the Atlantic... yet nearly 75,000 people

now fly the Atlantic daily . ... It is equally

difficult for Americans this early in the

Space Age to visualize the 21st-century technologies that will enable the average citizen

to soar into orbit at low cost, to fly to new

worlds beyond Earth, and to work and live on

the space frontier in closed-ecology biospheres using robotically-processed local

resources . . . . We should . . . emphasize that:

The Commission is not prophesying; it is

describing what the United States can make

happen through vigorous leadership in pioneering the space frontier.8

The NCOS plan was not so much a plan for guiding

NASA’s future as an evocation of the pioneering spirit

which Paine felt was flagging in 20th-century

Americans. The romantic attraction to pioneering has

in fact always been a rare thing. Those afflicted by it

frequently feel great zeal, which blinds them to the fact

that they are rarities—that others, while frequently

68 Monographs in Aerospace History

Chapter 8: Challengers
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 69

sympathetic to their vision, do not place as high a priority as they do upon making it real.

The NCOS report was not well received, primarily

because the Challenger accident had made clear that

NASA was in no position to tackle such an expansive, allencompassing plan. But it was also seen as too general,

with too many proposals. In late August 1986, former

Presidential Science Advisor George Keyworth, who

had been a non-voting NCOS member, said the report

had forfeited impact by putting forward proposals

“that stretch all the way from China to New York.”9 At

a time when NASA was grounded and struggling to

adapt its programs to the Shuttle’s revealed shortcomings, the NCOS discussed topics as wide-ranging as

self-replicating space factories, the International

Space Year, and the Big Bang. Arguably, all were

important to NASA’s future missions, but presenting

them in a single report merely made the view forward

seem more clouded.

The Reagan White House quietly shelved the NCOS

report; as Paine complained in an Aviation Week &

Space Technology opinion piece in September 1987,

“[T]he mandated presidential response to the commission has been delayed.”10 It is hard to fault the spirit of

Paine’s report. But the Agency’s challenge in 1986 was

to recover from the Challenger accident. If a plan for

NASA’s future in space was to be drawn up, it would

have to attempt to take into account the realities of U.S.

space flight in the mid-1980s. Such a plan was not long

in coming, thanks to heightened public interest in

NASA’s activities following the Challenger accident,

widespread concern that NASA had no long-term direction, and on-going efforts by Mars advocates.

The Ride Report

Sally Ride was a member of the 1978 astronaut class,

the first selected for Space Shuttle flights; in 1983 she

became the first American woman in space. She flew on

the Shuttle twice and sat on the Rogers Commission

investigating the Challenger accident before James

Fletcher, in his second stint as NASA Administrator,

appointed her as his Special Assistant for Strategic

Planning (18 August 1986) and charged her with

preparing a new blueprint for NASA’s future. She was

assisted by a 10-member panel and a small staff. The

result of her 11-month study was a slim report entitled

Leadership and America’s Future in Space.

Aviation Week & Space Technology reported initial

resistance inside NASA to releasing Ride’s report. The

magazine quoted an unnamed NASA manager who

said the agency was “afraid of being criticized by the

Office of Management and Budget.” The report’s frank

tone may also have contributed to NASA’s reluctance.

In the end, Agency managers relented and published

2,000 copies in August 1987.11

On 22 July 1987, Ride testified to the House

Subcommittee on Space Science and Applications. She

told the Subcommittee that the “civilian space program

faces a dilemma, aspiring toward the visions of the

National Commission on Space, but faced with the realities of the Rogers Commission report.”12 Ride explained

that she had attempted to reconcile “two fundamental,

potentially inconsistent views.” “Many people,” she said,

believed that “NASA should adopt a major visionary

goal.They argue that this would galvanize support, focus

NASA programs, and generate excitement.” Others, Ride

stated, maintained that NASA was “already overcommitted for the 1990s”—that it would be “struggling to

operate the Space Shuttle and build the Space Station,

and could not handle another major program.”13

While Paine’s NCOS report urged rapid implementation of an expansive vision, Ride’s report outlined four

more limited leadership initiatives “as a basis for discussion.” She explained that her report was “not

intended to culminate in a selection of one initiative

and elimination of the other three, but rather to provide concrete examples which could catalyze and focus

the discussion of the goals and objectives of the civil

space program, and of NASA efforts required to pursue

them.”14

Ride thus deviated from the pattern Paine had established in the STG report and continued in the NCOS

report; she did not propose a single “master plan.” In

her congressional testimony she explained her guiding

principle: “goals must be carefully chosen to be consistent with the national interest and . . . NASA capabilities. It is not appropriate for NASA to set the goals of

the civilian space program. But NASA should lead the

discussion . .., present options, and be prepared to

make recommendations.”15 Ride’s four Leadership

Initiatives were as follows:

• Mission to Planet Earth: “a program that

would use the perspective afforded from space

to study . . . our home planet on a global scale.”

Chapter 8: Challengers
• Solar system exploration using robots.

• Outpost on the Moon: an “. . . evolutionary, not

revolutionary . . . program that would build on.

. . the legacy of the Apollo Program . . . to continue exploration, to establish a permanent scientific outpost, and to begin prospecting the

Moon’s resources.”

• Humans to Mars: “a series of round trips to

land on the surface of Mars, leading to the

eventual establishment of a permanent base.”

The Mars mission, Ride asserted, should “not

be another Apollo—a one-shot foray or a political stunt.”16

None of Ride’s four initiatives necessarily depended on

the others. Her “attempt to crystallize our vision of the

space program in the year 2000” in fact represented a

partial break from the space station-Moon-Mars progression that had typified most NASA advanced planning.17 Ride’s approach caused confusion. For example,

Aviation Week & Space Technology magazine and many

newspapers incorrectly reported that she had called for

a Moon base as a precursor to a piloted Mars mission.

In fact, her report stated that the Moon was “not

absolutely necessary” as a “stepping stone” to Mars.18, 19

This reflected the influence of a NASA Advisory

Council Task Force led by Apollo 11 astronaut Michael

Collins. “I think it is a mistake to consider the [M]oon

as a necessary stepping stone to Mars,” Collins told

Aviation Week & Space Technology in July. “It will not

get support politically, or from the U.S. public, which

thinks we’ve ‘already done the [M]oon.’”20 Ride personally favored the Moon-Mars progression, however; she

wrote that it “certainly makes sense to gain experience,

expertise, and confidence near Earth first.”21

In common with the station-Moon-Mars progression,

Ride’s initiatives all included NASA’s Space Station.

This was a ground rule established by Fletcher—not

surprisingly, since the Space Station Program had

begun only three years before and was fiercely defended by NASA.22 As explained earlier, in Challenger’s

aftermath, Space Station had become a two-phase program. Ride pointed out that a decision on NASA’s

future course would impact the Phase II configuration.

She wrote that a “key question for the not-too-distant

future is ‘how should the Space Station evolve?’” and

noted that Space Station evolution workshops in 1985

and 1986 had found that “a laboratory in space featuring long-term access to the microgravity environment

might not be compatible with an operational assembly

and checkout facility [of the type envisioned to support

Moon and Mars exploration], as construction operations could disturb the scientific environment.”23

Like the NCOS report, Ride’s report called for NASA to

increase its efforts to develop advanced space technology

for exploration missions. She told the House

Subcommittee that “the future of our space program lies

in careful selection and dedicated pursuit of a coherent

civil space strategy, and the health of our current space

program lies in determined development of technologies

required to implement that strategy.”24 Ride’s report recommended Project Pathfinder, a program to develop

technologies that had been identified by a panel of NASA

engineers as crucial to future space programs. These

included aerobraking, automated rendezvous and docking, and advanced chemical propulsion. “Until advanced

technology programs like Pathfinder are initiated” wrote

Ride, “the exciting goals of human exploration will

always remain 10 to 20 years in the future.”25

On 1 June 1987, Fletcher had created the NASA

Headquarters Office of Exploration, with Ride as

Acting Assistant Administrator for Exploration,

responsible for coordinating missions to “expand the

human presence beyond Earth.” In explaining this

move, Fletcher said that “[t]here are considerable—

even urgent—demands for a major initiative to reenergize America’s space program . . . this office is a step in

responding to that demand.”26 In her report, Ride wrote

that “[e]stablishment of the Office of Exploration was

an important first step. Adequate support of the Office

will be equally important.” She noted that there was

“some concern that the office was created only to placate critics, not to provide a serious focus for exploration. Studies relating to human exploration of the

Moon or Mars currently command only about 0.03 percent of NASA’s budget . . . this is not enough . . . .”27

Ride targeted the first Mars landing for 2005. Her

report pointed out, however, that “NASA’s available

resources were strained to the limit flying nine Shuttle

flights in one year.” “This suggests,” it concluded, “that

we should . . . proceed at a more deliberate (but still

aggressive) pace, and allow the first human landing to

70 Monographs in Aerospace History

Chapter 8: Challengers
occur in 2010. This spreads the investment over a

longer period.”28

SAIC began designing the Mars mission in Ride’s

report in January 1987 and completed its study for the

NASA Headquarters Office of Exploration in

November 1987.29 John Niehoff, the study’s Principal 

Investigator, was the “Humans to Mars Initiative

Advocate” for the Ride Report. He had also worked on

The Planetary Society’s 1984 Mars study (see Chapter

7). Niehoff’s team proposed a three-part Mars exploration strategy:

• 1990s: Robotic missions, including a global

mapper and a sample-return mission, would

“address key questions about exobiology and

obtain ground-truth engineering data.” This

period would also see research aboard the

Space Station into the effects of prolonged

weightlessness on astronaut health, and development of “heavy-lift launch vehicles, high

energy orbital transfer stages, and large-scale

aerobrakes.”

• 2000s: Piloted missions with round-trip times

of about one year, stay-times near Mars of 30 to

45 days, and Mars surface excursions of 10 to

20 days were the primary emphasis of the

SAIC study. These missions would explore

potential outpost sites and build up interplanetary flight experience. The one-year trip-time

was designed to reduce crew exposure to

weightlessness and radiation.

• After 2010: “A piloted base on Mars . . . a great

national adventure which would require our

commitment to an enduring goal and its supporting science, technology, and infrastructure

for many decades.”30

A large amount of energy would be required to get the

ship to Mars and back in about a year, which in turn

would demand a prohibitively large amount of propellant. With an intent to reduce the number of heavy-lift

rocket launches needed to mount the expedition, SAIC

adopted a split/sprint mission mode based on a design

developed by students from the University of Texas and

Texas A&M University. This had a one-way, automated

cargo vehicle leaving Earth ahead of the piloted sprint

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 71

Chapter 8: Challengers

Figure 21—Science Applications International Corporation developed its Mars mission plan for NASA during 1987. The piloted spacecraft (shown here in cutaway) would reach Mars with empty propellant tanks and dock with a waiting automated

cargo ship to fill up for the trip home—a controversial departure from past Mars plans. (Piloted Sprint Missions to Mars,

Report No. SAIC-87/1908, Study No. 1-120-449-M26, Science Applications International Corporation, Schaumburg, Illinois,

November 1987, p. 9.)
vehicle on a low-energy trajectory. The cargo vehicle

would carry Earth-return propellants for the piloted

ship. To some this was worrisome—if the sprint spacecraft could not rendezvous and dock with the cargo

vehicle, the crew would become stranded at Mars with

no propellants for return to Earth.31

In phase 1 of SAIC’s four-phase Mars mission, seven

heavy-lift rockets would launch parts for the cargo

vehicle and a reusable OTV, propellants, and cargo into

orbit near the Space Station. The OTV and cargo vehicle together would measure 30.5 meters long and weigh

58.8 metric tons fully fueled. In addition to Earthreturn propellants for the piloted sprint vehicle, the

23.9-metric-ton cargo vehicle would carry the Mars lander and scientific equipment.

According to SAIC’s timetable, on 9 June 2003 the OTV

would push the cargo ship onto a minimum-energy

Mars trajectory, then separate and aerobrake in

Earth’s atmosphere to return to the Space Station for

reuse. The cargo ship would aerobrake into Mars orbit

on 29 December 2003.

Phase 2 would start one year after phase 1. Eight

heavy-lift launch vehicles would place propellants and

components for the piloted sprint vehicle and a second

OTV into Earth orbit near the space station. The OTV

used to launch the cargo vehicle would be combined

with the new OTV and the sprint vehicle to create a

73.9-metric-ton, 47.5-meter-long stack. The sprint vehicle alone would weigh 19.4 metric tons fully fueled.

SAIC’s sprint vehicle design was based on a 24.4-meterdiameter saucer-shaped aerobrake. Four pressurized

living modules housing six explorers nestled within the

saucer. Twin restartable rocket engines drew propellant

from spherical liquid hydrogen and liquid oxygen tanks

mounted on top of the living modules. A docking tunnel

started at the conical ERV mounted on the aerobrake’s

inner surface, passed through a “bridge” tunnel linking

the modules, and protruded beyond the twin engine

bells. The thick-walled ERV doubled as the ship’s radiation shelter.

The sprint vehicle would leave Earth on 21 November

2004. The first OTV would accelerate the sprint ship

and second OTV, separate, and aerobrake in Earth’s

atmosphere for return to the Space Station. The second

OTV would also accelerate the sprint ship and return

to the station. The OTVs could be reused for future

sprint/split Mars expeditions. The sprint vehicle would

then fire its own rockets briefly to complete insertion

onto a low-energy trans-Mars trajectory. A six-month

trip to Mars would be possible, but Niehoff’s team

advocated an eight-month trajectory that would allow

a Mars flyby and abort to Earth if the cargo ship waiting in Mars orbit with the piloted ship’s Earth-return

propellant failed during the crew’s flight to Mars. An

abort would have the Mars crew back on Earth on 5

January 2006. Assuming no abort became necessary,

the sprint ship would aerobrake into Mars orbit on 3

July 2005.32

In phase 3, the sprint spacecraft would dock with the

cargo ship in Mars orbit. Three astronauts would board

the two-stage lander, undock, and land on Mars for 10

to 20 days. The crew in orbit, meanwhile, would perform scientific research, eject the sprint ship’s Mars

72 Monographs in Aerospace History

Chapter 8: Challengers

Figure 22—Two Orbital Transfer Vehicles would push the

Science Applications International Corporation piloted

Mars ship out of Earth orbit. The company assumed that

Orbital Transfer Vehicles would be built for non-Mars programs in time to support its expedition, slated to reach Mars

in 2005. (Piloted Sprint Missions to Mars, Report No. SAIC87/1908, Study No. 1-120-449-M26, Science Applications

International Corporation, Schaumburg, Illinois, November

1987, p. 27.)
aerobrake, and transfer Earth-return propellant from

the cargo vehicle. The lander crew would then return to

Mars orbit in the ascent stage. On 2 August 2005, the

sprint vehicle would fire its engines for a high-energy

five-month sprint return to Earth.

Phase 4 would begin a few days before Earth arrival

(15 January 2006 for a nominal mission). The astronauts would enter the ERV and separate from the

sprint spacecraft. The ERV would aerobrake into Earth

orbit while the abandoned sprint ship entered solar

orbit. A station-based OTV would recover the ERV;

then a Space Shuttle would return the crew to Earth.

On 26 May 1987, NASA had announced that, after finishing her study, Ride would leave NASA to become

Science Fellow in the Stanford University Center for

International Security and Arms Control.33 In August,

John Aaron took over the Office of Exploration. Studies

begun in January 1987 to support the Ride report

became the basis for piloted exploration “case studies”

in FY 1988. These examined a mission to Phobos, a

Mars landing mission, a lunar observatory, and a lunar

outpost-to-Mars evolutionary program. All commenced

with assembly of the Phase I Space Station.34

Martin Marietta became the Office of Exploration’s de

facto exploration study contractor. On 15 May 1987,

NASA Marshall had awarded the $1.4-million Mars

Transportation and Facility Infrastructure Study contract to the company, with SAIC in “an important teaming role,” and Life Systems and Eagle Engineering as

subcontractors.35 The initial contract focus was in keeping with Marshall’s propulsion emphasis; as in the

EMPIRE days, the Huntsville Center anticipated

developing new rockets for Mars.

However, because it was the only Mars-related NASA

contract when the Office of Exploration was established, it became a mechanism for funding more general Mars-related studies. The contract, which lasted

until 30 April 1990, underwent 500 percent growth as

new study areas were grafted on. By the time it ended,

Martin Marietta had generated nearly 3,000 pages of

reports. Though Martin Marietta lost the contract to

Boeing when it was recompeted in late 1989, it served

to create an institutional expertise base for Martin

Marietta studies during the Space Exploration

Initiative (1989–93).36

Opposition

NASA started as an instrument of Cold War competition with the Soviet Union. In the 1970s, having won

the race to the Moon, NASA was partly reapplied as an

instrument of international détente. The 1972 Space

Cooperation Agreement called for the Apollo-Soyuz

Test Project and other cooperative space activities. A

Soviet Soyuz spacecraft docked in Earth orbit with

America’s last Apollo spacecraft in July 1975. When the

agreement was renewed in 1977, it included plans for a

U. S. Shuttle docking with a Soviet Salyut space station. By 1980, however, the Soviet invasion of

Afghanistan had undermined détente, ending virtually

all talks on piloted space cooperation.37

In 1982, the Reagan White House let the Space

Cooperation Agreement lapse to protest continued

Soviet involvement in Afghanistan and martial law in

Poland. In the first major step toward renewed cooperation, Senator Spark Matsunaga (Democrat-Hawaii)

sponsored legislation calling for renewal of the Space

Cooperation Agreement. Congress passed the

Matsunaga resolution, and President Reagan signed it

into law in October 1984.38

On 11 March 1985, Mikhail Gorbachev became the

Soviet Union’s new leader. He set about implementing

a raft of new reform policies. Making them work meant

diverting resources from Cold War confrontation to

domestic production. A charismatic leader representing

a new generation of Soviet politicians, he encouraged

many in the West by working to thaw relations with the

United States.

Against this background, The Planetary Society partnered with the influential AIAA to hold the Steps to Mars

conference in Washington, DC, on the tenth anniversary

of Apollo-Soyuz. NASA Administrator James Beggs was

on hand to hear Carl Sagan and others promote a joint

United States-Soviet Mars expedition.

Sally Ride had written of the difficulty of reconciling

visionary and conservative space goals. The Planetary

Society Mars proposal fell into the former category.

Unlike some visionary goals, however, it proposed giving Mars exploration a political purpose, just as Apollo

lunar exploration had a political function in the 1960s.

Beggs endorsed U.S.-Soviet space cooperation, but cauHumans to Mars: Fifty Years of Mission Planning, 1950–2000 73

Chapter 8: Challengers
tioned that “when you get down to the nitty-gritty of

working out details, it’s not so easy.”39

The U.S. and the Soviet Union renegotiated a new

Space Cooperation Agreement in November 1986.

Unlike its predecessors in 1972 and 1977, it contained

no provision for cooperative piloted missions. A month

later, Sagan published a prescient editorial in Aviation

Week & Space Technology. The Cornell University

astronomer asked, “What if sometime in the next few

years a general strategic settlement with the Soviet

Union is achieved . . . ? What if the level of military procurement . . . began to decline?” Sagan believed that

“[I]t [was] now feasible to initiate a systematic program

of exploration and discovery on the planet Mars . . .

culminating in the first human footfalls on another

planet” at a cost “no greater than a major strategic

weapons system, and if shared by two or more nations,

still less.” He added that Mars was “a human adventure

of high order, able to excite and inspire the most promising young people.”40

The U.S. and the Soviet Union renewed the Space

Cooperation Agreement in April 1987. Emboldened,

The Planetary Society circulated The Mars Declaration

widely in late 1987. Declaration signatories included

former NASA Administrators and Apollo-era officials,

astronauts, Nobel laureates, actors, authors, politicians, university presidents and chancellors, professors, pundits, composers, artists, and others. It called

for a joint U.S.-Soviet expedition to serve as a model for

superpower cooperation in tackling problems on Earth,

and it called Mars a “scientific bonanza” that could provide “a coherent focus and sense of purpose to a dispirited NASA” in the wake of the Challenger accident.41

Mars, the Declaration continued, would give the U.S.

Space Station a “crisp and unambiguous purpose” as an

assembly point for Mars ships and as a laboratory for

research into long-duration space flight. Planetary

Society vice president and former JPL director Bruce

Murray was outspoken on this point. Reiterating what

George Low and Nixon’s PSAC had stated in the early

1970s, he told the AIAA in January 1988 that “the principal logic for the [S]tation is in the context of a Mars

goal.”42

Meanwhile, the “future indicators” the CIA had listed

for Harrison Schmitt in 1985 had begun to occur. On 15

May 1987, the Soviet Union launched the first Energia

rocket, the most powerful to leave Earth since the U.S.

scrapped the Saturn V. Energia functioned perfectly,

though its 80-metric-ton Polyus payload failed to

achieve orbit. On 21 December 1988, cosmonauts

Vladimir Titov and Musa Manarov returned to Earth

after a record 365-day stay aboard the Mir space station—long enough to have performed a one-year piloted Mars flyby.

Mikhail Gorbachev first publicly called for a joint U.S.-

Soviet Mars mission as Titov and Manarov boarded

Mir in December 1987. He told the Washington Post

and Newsweek before the May 1988 Moscow summit

that he would “offer to President Reagan cooperation in

the organization of a joint flight to Mars. That would be

worthy of the Soviet and American people.”43 On 24

May 1988, Pravda carried an article by Soviet space

flight leaders Yuri Semyonov, Leonid Gorshkov, and

Vladimir Glushko calling for a joint Mars mission.44

Little progress was made toward Mars at the Moscow

Summit, but major strides were taken toward ending

the Cold War. Time magazine’s cover for 18 July 1988

showed a Viking photo of Mars with U.S. and Soviet

flags and the legend “Onward to Mars.”

Halfway through Titov and Manarov’s year-long stay

on Mir (7 July 1988), the Soviet Phobos 1 Mars probe

lifted off from Baikonur Cosmodrome on a Proton

rocket. Phobos 2 lifted off on 12 July. The twin probes

featured involvement by more than a dozen countries,

including the United States. They were designed to

orbit Mars and explore their namesake moon Phobos.

After rendezvous with the pockmarked little moon,

they would drop a “hopper” rover and a small lander.

In retrospect, however, the probes were the Soviet Mars

program in miniature—they got off to a triumphant

start, then sputtered. On 31 August 1988, operators at

the Flight Control Center in Kaliningrad, near Moscow,

sent the Phobos 1 Mars spacecraft an erroneous radio

command that caused it to lose attitude control and

turn its solar arrays away from the Sun. Starved for

power, Phobos 1 failed just two months into its 200-day

flight to Mars. Phobos 2 reached Mars orbit on 29

January 1989. The spacecraft returned useful data on

Mars and Phobos; however, it failed in late March as it

neared the long-anticipated Phobos rendezvous.

At 6.5 metric tons each, the Phobos probes were the

heaviest Mars probes ever to leave Earth orbit. They

74 Monographs in Aerospace History

Chapter 8: Challengers
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 75

took advantage of the minimum-energy launch opportunity associated with the September 1988 Mars opposition, the best since 1971.

Mars glowed bright orange-red in Earth’s skies as the

Space Shuttle Discovery was rolled to its Florida

launch pad for the first Shuttle flight since Challenger.

On 29 September 1988, as Earth overtook Mars in its

orbit and pulled ahead, Discovery lifted off on the 26th

flight of the Space Shuttle Program. The four-day, fivecrew STS-26 flight ended a 33-month hiatus in U.S.

piloted space flight—the longest since the 1975-1981

Shuttle development period. By the time STS-27

launched in December, Mars was fading fast and the

U.S. Space Shuttle was no longer the world’s only

reusable piloted spacecraft. The second Energia rocket

had launched on 15 November 1988 with a Buran

shuttle on its back for an unpiloted test flight.

The Mars planning community, though still small

and with few resources, was in ferment. New leadership in the Soviet Union, the expanding Soviet space

program, and the thawing of U.S.-Soviet relations,

coupled with America’s return to piloted space flight

and growing public awareness of Mars, seemed to create an opportunity. As will be seen in the next chapter, newly elected President George Bush would take

up the mantle of President Kennedy and declare for

Mars. Though a failure, his initiative would not be

without significant results.

Chapter 8: Challengers
The study and programmatic assessment

described . . . have shown that the [Space]

Exploration Initiative is indeed a feasible

approach to achieving the President’s goal . . . .

The last half of the 20th century and the first

half of the 21st century will almost certainly be

remembered as the era when humans broke the

bonds that bound them to Earth and set forth

on a journey into space . ... Historians will further note that the journey to expand the human

presence into the solar system began in earnest

on July 20, 1989, the 20th anniversary of the

Apollo 11 landing. (The 90-Day Study, 1989)1

Space Wraith

Viewed as a space program, as it was intended to be,

the Space Exploration Initiative (SEI) was a failure.

Viewed as an “idea generator” for Mars exploration

planning, however, SEI was a success—some concepts

it fostered dramatically reshaped subsequent planning

efforts.2 It was also successful as a painful but necessary growth process. SEI relieved NASA of weighty historical baggage. It weaned large segments of the

Agency from its faith in the efficacy of Kennedyesque

Presidential proclamations, and it further weakened

the pull the station-Moon-Mars progression exerted on

senior NASA managers, a process that had first seen

high-level expression at NASA in the 1987 Ride report.

Like Apollo before it, the decision to launch SEI had

more to do with non-space policy than with its stated

space flight aims. SEI and Apollo were, however, diametrical opposites in most other respects. Apollo

occurred at the Cold War’s height, while SEI occurred

at its end. Apollo aimed at displaying American technological prowess to counter Soviet space successes,

while SEI aimed in part to provide new tasks for

defense-oriented government agencies and contractors

as the Soviet threat receded. Apollo was greeted with

public enthusiasm, while SEI was forgotten even as it

began. Finally, Apollo accomplished both its political

and space flight goals, while SEI accomplished neither.

The concept of a big Apollo-style space initiative was in

the air in the late 1980s. In late 1987 and early 1988,

the Reagan Administration considered and rejected a

“Kennedy-style declaration” calling for a Moon base or

a man on Mars. White House staffers explained that

they had lacked information adequate to make a “technically and fiscally responsible decision.”3 The White

House opted instead for its National Space Policy

(February 1988) and for giving NASA’s Space Station a

name—Freedom (July 1988). More importantly, it

requested $100 million in FY 1989 to start NASA’s

Pathfinder technology development program. The

Agency had asked for $120 million. In December 1987,

a National Research Council report estimated that

NASA would have to spend $1 billion a year on technology development for several years to make up for

past neglect. Despite this finding, the funding request

was poorly received in Congress—not a propitious sign

for big new initiatives.4

Early in his Administration, President George Bush reestablished the National Space Council and put his

Vice President, Dan Quayle, in charge. On 31 May

1989, Bush directed NASA to prepare for a Presidential

decision on America’s future in space by proposing a

space goal with visible milestones achievable early in

the 21st century. The directive was said to have originated with OMB director Richard Darman and

Quayle’s advisors.5 NASA Administrator Richard Truly,

Assistant Administrator for Exploration Franklin

Martin, and JSC director Aaron Cohen briefed Quayle

in June.

Bush revealed what they had told Quayle and launched

the SEI on the steps of the National Air and Space

Museum on 20 July 1989, the 20th anniversary of the

Apollo 11 Moon landing. Bush told his audience,

Space is the inescapable challenge . . . . We

must commit ourselves to a future where

Americans and citizens of all nations will

live and work in space . ... In 1961 it took a

crisis—the space race—to speed things up.

Today we don’t have a crisis. We have an

opportunity. To seize this opportunity, I’m

not proposing a 10-year plan like Apollo. I’m

proposing a long-range, continuing commitment. First, for the coming decade—for the

1990s—Space Station Freedom, our critical

next step in all our space endeavors. And

next—for the new century—back to the

Moon. Back to the future. And this time,

back to stay. And then, a journey into tomorrow, a journey to another planet—a manned

mission to Mars . . . today I’m asking . . . our

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 77

Chapter 9: Space Exploration Initiative
able Vice President, Dan Quayle, to lead the

National Space Council in determining

specifically what’s needed . . . . The space

council will report back to me as soon as possible with concrete recommendations to

chart a new and continuing course to the

Moon and Mars and beyond.6

Aviation Week & Space Technology greeted the initiative

with skepticism and a pun, calling it a “space wraith.”

“President Bush,” the magazine reported, “set forth a

long-term space plan without a budget and with no more

than a skeletal timetable. He then called for more

study.”7 The initiative was, moreover, “sprung” on

Congress with little “spadework” by either the

Administration or by NASA.8 This helped ensure opposition. Congress sent the Bush White House a clear message by eliminating funds for the Pathfinder technology

development program from the FY 1990 NASA budget.

On 26 July, Truly and Martin briefed NASA employees on the President’s call. They outlined a “building

block approach to progressively more difficult human

missions.”9 The proposal, a retread of the 1960s

Integrated Program Plan, ignored the less expansive

alternative program approach laid out by Sally Ride in

1987. Ride’s report was based on conservative projections

of NASA’s future resources, but the Truly and Martin

plan took it for granted that resources for a large, Apollostyle program would automatically follow the President’s

Kennedyesque proclamation.10

Truly and Martin laid out the following timetable:

• 1995-2000: Space Station Freedom operational;

robotic precursor spacecraft explore the Moon 

• 2001-2010: Lunar outpost; robotic precursors 

explore Mars 

• Post-2010: Mars expedition 

The Moon and Mars goals would give “direction and

focus” to Space Station Freedom, Truly and Martin

stated, while the lunar outpost would give American

astronauts experience in living and working on

another world before confronting Mars’ greater

demands. The Moon’s proximity to Earth (“a three-day

trip”) and scientific value made it an attractive way

station on the road to Mars. For its part, Mars was

SEI’s ultimate goal because it had “intrigued humans

for centuries,” was “scientifically exciting” and “the

most Earth-like planet,” and because it had resources

to support human life. Striving for Mars would “cement

long-term U.S. leadership in space” by providing a

“challenging focus for [the] space program.”

Truly and Martin told NASA civil servants that Bush’s

call was “a major institutional challenge for NASA”

that would “require restructure of [the] [A]gency.”

NASA would seek to add staff and facilities and would

streamline its procurement system.

The 90-Day Study

The task of turning NASA’s SEI plan into a report for

Quayle’s National Space Council fell to an internal

NASA team led by Aaron Cohen. He had 90 days to

complete his study, which started on 4 August 1989.

The schedule was said to have been driven in part by

Bush’s desire to have an SEI implementation plan in

hand for his State of the Union speech in early 1990. In

September, Truly said that Cohen’s study involved 160

managers from across the Agency, of whom 100 were

based at JSC. Mark Craig, JSC Lunar-Mars

Exploration Program Office manager, headed the JSC

study team.11 On 2 November 1989, Truly passed

Cohen’s report to President Bush.

Cohen’s report contained five “reference approaches”

that followed “the President’s strategy: First, Space

Station Freedom, and next back to the Moon, and then

a journey to Mars.” There was, of course, nothing new to

this approach. In common with the 1969 Space Task

Group report, the reference approaches were in fact one

approach with multiple timetables for carrying it out,

not a range of alternate plans. NASA seemed to be saying that there was only one way to explore the Moon

and Mars.

Approach A emphasized “balance and speed.” Space

Station Freedom assembly would be completed in

1997, two to three years ahead of the completion date

planned at the time Cohen’s report was released.

Astronauts would return to the Moon in 2001 and permanently staff a lunar outpost the following year. By

2010 the outpost would produce 60 tons of oxygen per

year. In 2016, four astronauts would travel to Mars in

a transfer vehicle using lunar oxygen propellant and

78 Monographs in Aerospace History

Chapter 9: Space Exploration Initiative
would spend 30 days on the surface. The year 2018

would see the first 600-day tour-of-duty in a permanent Mars outpost.

Cohen’s Approach B aimed for the “earliest possible

landing on Mars.” The lunar and Mars activities outlined in Approach A would occur simultaneously,

requiring more spending in the 2000-2010 decade. The

first Mars expedition would occur in 2011.

Approach C strove for “reduced logistic support from

Earth”—that is, increased reliance on ISRU. Lunar

oxygen production would thus begin in 2005, earlier

than in Approach A.

Approach D was to pick Approach A, B, or C, then slip

all dates two to three years to allow Space Station

Freedom completion in 1999 or 2000. Americans would

return to the Moon in 2004.

Approach E assumed that the U.S. would undertake

Bush’s initiative, but on a “reduced scale.” Freedom

would be completed as scheduled in 1999 or 2000,

and Americans would return to the Moon in 2004.

The lunar outpost would be completed in 2012, and

astronauts would spend 30 days on Mars in 2016. A

60-day Mars stay would occur in 2018, followed by a

90-day stay in 2022. The Mars outpost would be activated in 2027.

Cohen’s report called for new heavy-lift rockets based

on Space Shuttle hardware or on the Pentagon’s

Advanced Launch System. The largest would place up

to 140 metric tons into orbit and have a launch shroud

up to 15 meters wide—large enough to cover reusable

aerobrake heat shields.

To support the Bush initiative, Space Station

Freedom would evolve from lab to spaceport through

four configurations. First, the baseline single truss

would be expanded to include the vertical lower keel

trusses and lower boom truss of the Dual Keel

design. The second configuration saw the addition of

a lunar spacecraft hangar and a second habitation

module to house four-person crews en route to the

Moon. The crew roster would rise to 12 in the third

configuration to support lunar spacecraft servicing

and increased life sciences research and Freedom

maintenance. The fourth configuration would see the

addition of the Dual Keel upper trusses and installation of a Mars spacecraft assembly facility.

The report called for increased civil service hiring

and new budget processes within NASA, but it

included no cost estimates. A JSC team led by

Humboldt Mandell performed a cost analysis and

prepared a cost section, but it was stricken and most

copies shredded by Truly’s order because the costs

arrived at were deemed politically unacceptable.12

Cost information was leaked from the National

Space Council, however, so suppressing the cost

data merely stymied informed discussion.13 SEI’s

critics seized on the highest leaked cost estimates

without consideration of the cushion they contained

because they lacked complete information—or, if

they had access to the details of the cost estimate,

they could safely ignore them because they were not

publicly available.

According to Mandell, The 90-Day Study plan “was

over-costed by a considerable amount.”14 The stricken

cost estimates included a 55 percent reserve—”an

allowance incorporating both the cost estimating

uncertainties for individual developments (i.e., projectlevel reserves) and allowances for changes in scope

(i.e., program-level reserves).”15 The initial cost of a

permanent Moon base using Approach A and including

the 55 percent “cushion” would be $100 billion in constant 1991 dollars between 1991 and 2001. The Mars

expedition would cost an additional $158 billion

between 1991 and 2016 based on the same stipulations. Thus, achieving the letter of Bush’s speech—a

return to the Moon to stay and a mission to Mars—

would cost a total of $258 billion, of which 55 percent

($141 billion) was cushion.16

Continuing operations would, of course, add to SEI’s

cost. In Approach A, operating the lunar base from

2001 to 2025 would cost $208 billion, while operating

a Mars outpost from 2017 to 2025 would cost $75 billion. Thus the SEI program cost for Approach A for 34

years, from 1991 to 2025, including operations and a

55 percent cushion, would come to $541 billion.17

The cost summary had NASA’s annual budget climbing

from about $13 billion in 1990 to about $35 billion in

2007 for Approach A. At its peak, about half would be

allotted to Moon and Mars programs, meaning that the

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 79

Chapter 9: Space Exploration Initiative
average annual cost for Moon and Mars would be about

$15 billion per year.18

A Quick Study

The 90-Day Study plan was NASA’s official proposal for

accomplishing SEI, but it was not the only SEI plan put

forward by the Agency. In the summer of 1989, an

Office of Exploration task force under Ivan Bekey performed a “quick study . . . with analysis support by

Martin Marietta” which, it claimed, “defined a much

more practical Mars program . . . by virtue of reducing

the scale of operations through judicious choices and

invention of a new launch vehicle concept.”19 Focused on

Mars and relying heavily on Mars ISRU for propellant

production, it appears in retrospect as a premonition of

piloted Mars planning in the 1990s.

The study was based on Martin Marietta work performed

under the Marshall Transportation Infrastructure contract, as well as on the Phobos and Mars Case Studies.

Bekey’s task force briefed Truly on its proposal in the

summer of 1989, but it had little obvious influence on The

90-Day Study.20 Bekey presented the concept at the 40th

International Astronautical Federation Congress in

Malaga, Spain, in October 1989, just before Truly sent

Cohen’s report to President Bush.

The Bekey task force proposed that astronauts go first

to Phobos. There they would set up an ISRU propellant

plant for making propellants from Phobos materials,

which are believed to be water-rich. Bekey’s group also

proposed to minimize impact on Space Station Freedom

by using heavy-lift launch vehicles to launch a few

large components rather than resorting to on-orbit

assembly of many small components. Mission rate

would be kept low to reduce spending rate. The piloted

Mars expedition would be preceded in the 1990s by a

“preparatory program” including automated precursors, technology development, and biomedical research.

The Moon played no mandatory role in Bekey’s proposed Mars program.

Bekey’s task force found that, assuming an opposition-class trajectory with a Venus flyby for the initial

Phobos expedition and a conjunction-class trajectory

for the Mars landing expeditions, the maximum

spacecraft mass at Earth-orbit departure for a Phobos

expedition was similar to the minimum mass for a

Mars landing expedition—about 700 tons. Therefore,

the short Phobos mission in 2004 could act as a

“shakedown cruise” for the Mars landing mission

spacecraft design, helping to minimize risk to the

crew during the longer landing missions.

Three astronauts would travel to Phobos with a

piloted Mars lander, which would touch down

unpiloted on Mars to act as a backup habitat for the

2007 Mars landing expedition crew. The 2004 crew

would spend a month at Phobos, during which they

would demonstrate an automated ISRU pilot plant.

Three expeditions would then travel to Mars’ surface to

set up infrastructure for a Mars outpost. Five astronauts would launch to Mars in 2007, land near the

backup habitat from the 2004 mission, and spend a

year on the surface. On the next expedition, five astronauts would set up the first half of a propellant production facility on Phobos and land on Mars.

Expedition 4 would set up the remainder of the propellant plant, “readying the Mars infrastructure for a sustained series of visits” that would establish a permanent outpost on Mars.

The task force Phobos/Mars spacecraft design consisted of a large dish-shaped aerobrake with twin Space

Station Freedom-derived cylindrical habitats. The

spacecraft would rely on tethers to create artificial

gravity; the astronauts would reel out the habitat

modules from the aerobrake, then rotate the assemblage end over end to produce artificial gravity.

Bekey proposed launching Mars ship components and

propellant on Shuttle-derived Shuttle-Z rockets, which

would include three or four Space Shuttle Main

Engines (SSMEs), a strengthened External Tank, and

two Solid Rocket Boosters. Shuttle-Z would use existing

Kennedy Space Center Shuttle facilities and cost about

the same per launch as the Shuttle, “but with 4-6 times

the payload.”28

By using the Mars transfer stage as the Shuttle-Z

third stage, up to 164 tons could be placed in lowEarth orbit. This would permit the Phobos/Mars

spacecraft to be fully assembled with “at most” two

Shuttle-Z launches. Three Shuttle-Z launches would

refuel the Mars transfer stage in orbit. A similar concept was proposed in the 1971 MSC PMRG study. The

crew would then board the ship from a Space Shuttle

80 Monographs in Aerospace History

Chapter 9: Space Exploration Initiative
orbiter and fire the refueled transfer stage to leave

Earth orbit for Mars.

The Bekey task force estimated that the total weight

launched per year to carry out its Mars program would

be about half that needed to carry out the split-sprint

mission plan defined by SAIC for the 1987 Ride Report.

Bekey’s admittedly optimistic preliminary cost estimate was $40 billion for two landings on Mars.20

The Great Exploration

Alternatives to The 90-Day Study also surfaced outside

NASA. In mid-September, at about the time Cohen presented his initial briefing on his study to the National

Space Council, Lawrence Livermore National

Laboratory (LLNL) engineers, led by Lowell Wood,

briefed Quayle on their Great Exploration plan for

SEI.21 LLNL, which was operated by the University of

California under contract to the U.S. Department of

Energy, was associated with design and test of nuclear

weapons, as well as research into advanced particle

beam and laser weapon systems.

The Livermore plan was not well received by NASA,

which saw it as an effort to invade its territory.22 The

meaning of the “opportunity” Bush mentioned in his 20

July speech thus seemed clear—SEI was to be an

opportunity for the national laboratories to expand

their bailiwick. According to some participants, one

purpose of SEI was to provide work for Federal government agencies and contractors suffering cut-backs

because the Cold War was ending. Cohen’s study had,

in fact, taken into account the need to provide tasks for

organizations such as the Army Corps of Engineers and

the Department of Energy labs.23 NASA’s understanding was, however, that NASA would be in charge.24

LLNL’s Great Exploration plan drew on its 1985

Columbus lunar and 1988 Olympia Mars studies.25, 26

Wood and his colleagues explained that their plan

respected “contemporary politico-economic realities,”

which would not tolerate a $400-billion space program

lasting three decades. Their plan, they claimed, would

require a decade and cost only $40 billion.27

The Livermore team called for “manned space exploration as though it were a profit-seeking enterprise”

with “swift exploration, settlement and infrastructure

creation.” “Each step,” they explained, would leave

“major operational legacies—and commitments” so

that “Lunar and Martian Bases, once manned, never

need be unmanned thereafter.” They also called for

extensive use of off-the-shelf technology to launch and

outfit inflatable structures (“community-sized space

suits”), including an Earth-orbital station, “Gas

Station” propellant depots, and Moon and Mars surface

bases.28

The Great Exploration program would commence in

mid-1992, when a single Titan VI or HL Delta rocket

would launch a 50-metric-ton folded Earth Station and

Gas Station payload with an Apollo CM on top. The

stations would deploy and inflate automatically in

orbit under the crew’s supervision. The Earth Station

would consist of seven 15-meter-long sausage-shaped

modules arranged end to end. It would rotate end over

end four times each minute to create artificial gravity

that would vary from deck to deck over the length of

the station, thus providing crews with lunar and

Martian gravity experience. The Gas Station would

use solar power to electrolyze water into liquid hydrogen/liquid oxygen spacecraft propellants. Water would

be launched by competing companies and purchased

by the government from the lowest bidder.

In late 1994, a single rocket would launch a 70-metricton folded Lunar Base with an Apollo CM-based Earth

Return Module on top. The Lunar Base would refuel at

the Gas Station, fly to the Moon, and inflate on the surface. The astronauts would live in Spartan conditions,

with crew rotation every 18 months. A lunar surface

fuel factory and lunar-orbit Gas Station would be

established when the second crew arrived in late 1996.

The 70-metric-ton Mars Expedition ship would be

launched in late 1996, inflated in Earth orbit, and refueled at the Gas Station. It would then fly to Mars orbit

and visit Phobos or Deimos before landing on Mars.

The Mars Base would inflate on the surface, and the

first crew would move in for a 399-day stay. They would

mine Martian water to manufacture propellants for a

rocket-powered hopper.

The plan was innovative, but could it work? NASA

managers and engineers thought not. The national laboratories, however, had supporters in the White House

and on the National Space Council, among them Vice

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 81

Chapter 9: Space Exploration Initiative
82 Monographs in Aerospace History

President Quayle. They held up the LLNL proposal as

a good example of “innovative thinking.”29

Faced with two rival plans for carrying out his initiative, in December Bush asked the National Research

Council (NRC) to examine the studies. H. Guyford

Stever, science advisor to Presidents Nixon and Ford

and a former Director of the National Science

Foundation, chaired the NRC’s Committee on Human

Exploration of Space. Among its 14 members were

Apollo 10 astronaut Thomas Stafford and (until his

death on 31 January 1990) Apollo program manager

Samuel Phillips.

The Stever Committee report, unveiled on 7 March

1990, stated that the LLNL approach entailed “relatively high risk” and underestimated “the many

practical and difficult engineering and operational

challenges” of exploring space.30 The report threw

cold water on the push to give SEI over to the

national laboratories by stating that “NASA has the

organizational expertise and demonstrated capability to conduct human space exploration . . . . To

attempt to replicate such expertise elsewhere would

be costly and time-consuming.”31

The Stever Committee also pointed out a basic truth

applicable to all large space projects: that the “pace at

which the initiative should proceed, while clearly

influenced by scientific and technical considerations, is

inherently determined by social and political decisionmaking processes in which non-technical constraints,

such as the sustainable level of resource commitment

and acceptable level of risk[,] are paramount.”32 In

other words, policy makers bore as much responsibility for setting SEI’s pace, price tag, and chances

for eventual success as the engineers, and they

would have to make firm decisions before the engineers could plan effectively and proceed.

The Stever Committee then called for more studies,

stating that “the [N]ation is at a very early stage in

the development” of its Moon and Mars plans (this

despite the many studies performed inside and outside NASA over the decades). “None of the analyses

to date—The 90-Day Study, The Great Exploration,

or, indeed, this report—should be regarded as providing more than a framework for further discussion,

innovation, and debate,”33 it stated, then added that

“ . . . the eventual choice of mission architecture will

incorporate the ideas from a variety of concepts, some

that now exist and others that will arise in the future

.... The variety of concepts should be regarded as a

‘menu’ of opportunities.”34

In late February, a week before the Stever Committee

report was publicly released, President Bush directed

that NASA should be the “principal implementary

agency” for SEI, with the Departments of Defense and

Energy in “major roles.”35 Within a week of the report’s

release, President Bush followed its advice and called

for more study. He asked that at least two substantially different reference architectures for SEI be produced

over the next several years.

Idea collection for the Stever Committee’s “menu” had

begun in mid-January 1990, when the Aerospace

Industries Association, an organization representing

aerospace contractors, had met to start a process of

gathering ideas to turn over to NASA. The Agency’s

Office of Aeronautics and Space Technology served as

ad hoc coordinator for this effort.36 NASA also enlisted

Rand Corporation to manage a campaign to solicit

ideas from industry, universities, national labs, and the

general public. NASA Administrator Truly led a U.S.

Government interagency effort. This broad gathering of

ideas became known as the SEI Outreach Program.

Ideas collected through the Outreach Program were to

be reviewed by an independent SEI Synthesis Group,

which would then issue a report. The Synthesis Group

approach had been recommended by the Aerospace

Industries Association in April. On 16 May 1990,

Congress agreed to provide $4.55 million for the

Outreach Program, but not without a price. NASA had

to agree that it would release no SEI-related contracts

to industry until 1991. As one congressional staffer

explained, this deferment was designed “to avoid raising expectations in the private sector, given the incredible [Federal] budget restraints.” The Agency also

agreed to defer $5 million in internal NASA study work

until 5 August 1990.37 On 31 May, Truly introduced Tom

Stafford as Synthesis Group chair.

Paul Bialla, NASA Programs Manager for General

Dynamics, expressed well the skepticism many in

industry felt toward the SEI Outreach Program. “For

the most part, our ideas have already been shared with

NASA,” he told Space News. “Throwing the door open to

everyone is simply going to delay the process.”38

Chapter 9: Space Exploration Initiative
A Political Liability

The Outreach Program was SEI’s most far-reaching

contribution to Mars expedition planning, for it

compiled a large body of ideas for how to send

humans to Mars. In terms of implementing SEI,

however, the Outreach Program amounted to a

means of allowing the abortive initiative to fade quietly after it had become an obvious political liability for the Bush Administration.

Even as the Outreach Program began, SEI was mortally wounded. The Bush Administration’s NASA

budget request for FY 1991 was $15.1 billion, a 23

percent increase over FY 1990. This included $216

million to start SEI. Two days of NASA budget hearings in mid-March 1990 showed, however, that the

Moon and Mars initiative enjoyed almost no support

in Congress. By the summer of 1990, it was writ

large—no matter what good ideas the Outreach

Program might produce, SEI stood almost no chance

of gaining congressional support.

It was a two-part problem. On the one hand, the

Democrat-controlled Congress was not eager to hand

the Republican Bush Administration any victories,

especially after it had cast its 1988 Presidential candidate, Michael Dukakis, as a spend-thrift Democrat.39

More importantly, however, the late 1980s and early

1990s were marked by an enormous Federal debt—$3

trillion in 1990—and annual budget deficits. Budget

problems alone made it unlikely that a new space initiative would be well received, even if it didn’t have a

rumored price tag of half a trillion dollars.

On fiscal grounds, SEI opposition was bipartisan. Bill

Green (Republican-New York), a member of the House

Appropriations Committee, said, “[G]iven the current

budget situation, I would not anticipate a significant

start on Mars in the near future.”40 Robert Traxler

(Democrat-Michigan), chair of the House

Subcommittee on Housing and Urban Development

and Independent Agencies, summed it up succinctly:

“Basically, we don’t have the money.”41

On 1 May 1990, President Bush called congressional

leaders to the White House to lobby for SEI. Richard

Darman sought to declare NASA’s proposed budget

increase exempt from mandatory cuts imposed by

Gramm-Rudman deficit reduction legislation, and

Bush proposed that aerospace technology cuts should

come from the Defense budget, not from NASA.42 The

congressional response was quick in coming. On 3 May

1990, Senator Albert Gore (Democrat-Tennessee), chair

of the NASA Authorization Panel, told his fellow legislators that “before discussing a mission to Mars, the

Administration needs a mission to reality.”43

Bush used his 11 May commencement address at Texas

A&M University to signal SEI’s importance to his

administration. His speech was historic—in it he

became the first U.S. President to set a target date for

an American expedition to Mars. “I am pleased to

announce a new age of exploration,” he told the crowd,

“with not only a goal but also a timetable: I believe that

before America celebrates the 50th anniversary of its

landing on the Moon [in 2019], the American flag

should be planted on Mars.”44

Congress, however, handed Bush his first clear defeat

in mid-June, when a House panel eliminated all funds

for SEI from the FY 1991 NASA budget. On 20 June

Bush declared that he would fight for his Moon and

Mars program. His Administration had, he said,

“matched rhetoric with resources.” The full House eliminated all SEI funds at the end of June.45

On top of issues of party and finance were badly timed

NASA problems not directly related to SEI. These

raised inevitable questions about the desirability of

committing the Agency to a major new initiative when

it appeared it could not handle what it already had. In

late June, NASA announced that the $1.5-billion

Hubble Space Telescope, launched into orbit on 24 April

1990, was rendered myopic by an improperly manufactured mirror. At the same time, the Shuttle fleet was

grounded by persistent hydrogen fuel leaks. The three

orbiters sat on the ground for five months while NASA

engineers struggled with the problem.

On the first anniversary of Bush’s SEI speech, a NASA

panel headed by former astronaut and spacewalker

William Fisher announced that Space Station Freedom

would need 6,200 hours of maintenance spacewalks

before it was permanently staffed and 3,700 hours of

maintenance spacewalks each year thereafter. This

would cut deeply into time available for research

aboard the orbiting space laboratory.46 The Fisher

Panel’s findings helped lead to a new round of station

redesign in 1990 and 1991. In an effort to reduce cost

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 83

Chapter 9: Space Exploration Initiative
and complexity, the potential for Phase II expansion to

the Dual Keel design was eliminated, along with the

option for hangars, fueling facilities, and other Moonand Mars-related systems.47

Space Station Freedom thus lost virtually all hope of

being useful for Mars transportation. It remained

important, however, as a place to gather data on the

biomedical effects of long-duration space flight as part

of efforts to minimize risk to future Mars crews. Not

coincidentally, Mars plans that ignored the Station,

except to say that they did not intend to use it, began

to proliferate. NASA internal planning, however, continued to place Space Station Freedom—or some future

station—squarely on the path to Mars.

In October, House and Senate conferees agreed to an

FY 1991 NASA budget of $13.9 billion. While this constituted an increase of $1.8 billion over NASA’s FY

1990 budget, it included no funds for SEI. Bush bowed

to the inevitable and signed the appropriation into law.

A New Initiative

By the fall of 1990, the course of piloted space flight

over the next decade was taking shape. Bush had mentioned international space cooperation in his speech of

20 July 1989. SEI, however, stressed U.S. space leadership, which implied competition with the Soviet Union.

The Soviets had built up an impressive space infrastructure in the 1970s and 1980s. By 1990, however,

with economic and political reforms underway in their

country, they could no longer afford to use it.

As early as March 1990, Bush had directed the

National Space Council to pursue space cooperation

with the Soviets in an effort to encourage and support

Mikhail Gorbachev’s on-going reforms. On 8 July 1990,

Bush agreed to let U. S. commercial satellites fly on

Soviet rockets. On 25 July 1990, the United States and

Soviet Union agreed to fly a NASA Mission to Planet

Earth instrument on a Soviet satellite scheduled for

launch in 1991. In October 1990, Quayle told reporters

that “we are in serious discussions with the Soviet

Union” on flying an American astronaut on Mir and a

Soviet cosmonaut on the Shuttle.48

Yuri Semyonov, director of NPO Energia, the leading

Soviet astronautics design bureau, promoted joint U.S.-

Soviet piloted Mars exploration at space conferences in

Montreal in 1990 and Houston in 1991.49 Would-be Mars

explorers saw in this an opportunity. At the Case for

Mars IV conference in June 1990, for example, Benton

Clark suggested using the Energia heavy-lift rocket to

transport Mars spacecraft propellants to orbit. “Use of

the Soviet booster would,” he declared, “make the

dependency between the cooperating countries simple

and straightforward.”50 This represented a dramatic shift

from the early 1980s, when Harrison Schmitt pushed for

the LANL/NASA Manned Mars Missions study to help

counter Soviet Mars moves.

In July 1990, Semyonov and Leonid Gorshkov, head of

Energia’s orbital stations department, published an

article on Energia’s Mars plans in the Soviet popularaudience publication Science in the USSR.51 The configuration of the Mars spacecraft depended, they

wrote, on the choice of “powerplant.” They rejected

chemical propulsion, saying that an all-chemical Mars

ship would weigh upwards of 2,000 metric tons at

Earth-orbit departure. A nuclear-thermal rocket Mars

ship would weigh about 800 metric tons. More promising, however, were solar-electric or nuclear-electric

propulsion systems which could reduce ship mass to

between 350 and 400 metric tons.

Semyonov and Gorshkov wrote that Soviet “aerospace

technology is advanced enough to make a mission to

Mars a reality,” then summarized existing Soviet capabilities. In addition to the Energia rocket (“capable of

lofting into Earth orbit whole sections of a spacecraft

for final assembly”), the Soviet Union had “perfected

the automatic docking procedures for putting together

a spacecraft from sections in orbit” through more than

50 flights of automated Progress freighters to space

stations. Semyonov and Gorshkov claimed that “[m]ost

of the problems that would be faced by a crew on a long

voyage to Mars in zero-gravity have been resolved”

through 20 years of Soviet space station flights “in an

environment very similar, if not identical, to that of a

Mars mission.” Finally, they reported that “electric . . .

engines of the required parameters have been flawlessly performing on Earth.”52

In 1991, Energia released a Mars expedition report

reflecting “the expediency to take into account . . .

world public opinion, which [is] against the launch of

nuclear power”—an aversion reinforced by the Soviet

Union’s own April 1986 Chernobyl nuclear reactor

84 Monographs in Aerospace History

Chapter 9: Space Exploration Initiative
meltdown.53 NPO Energia’s 355-metric-ton solarelectric Mars spacecraft would reach Earth orbit in

sections strapped to the sides of five Energia heavylift rockets. The designers envisioned a pair of 40,000-

square-meter solar panels supplying 7.6 megawatts of

electricity at Earth’s distance from the Sun and 3.5

megawatts at Mars.

The crew section of Energia’s Mars ship design included two cylindrical modules linked end to end. The large

living module would contain a “vitamin greenhouse”

and individual cabins for four cosmonauts. Water tanks

would surround the cabins to shield them from radiation. Over the course of the expedition the water would

be gradually consumed and replaced by “waste bricks.”

An airlock for spacewalks and electric motors for pointing the solar arrays would separate the living module

from a smaller control/laboratory module. The spacecraft’s lithium-propellant electric propulsion system

would be housed in twin modules attached to the sides

of the control/lab module.

According to the report, Soviet designers had studied

conical piloted Mars landers outwardly similar to the

NAR MEM from 1969 to 1971.54 Their 1991 Mars

Landing Vehicle was, however, a cylinder with a conical forward section, a shape selected in part because it

fit within the Energia rocket’s payload envelope. The

two-person lander’s cylindrical section would house

an ascent stage with a docking unit on top. The 60-

metric-ton Mars Landing Vehicle would land horizontally. The cosmonauts would live in the lander’s forward cone while on the Martian surface. After a week

on Mars, the cosmonauts would blast off in the ascent

stage to rejoin their comrades aboard the orbiting

Mars ship.

At journey’s end, the crew would separate from the

Mars ship in the 10-metric-ton Earth Return Vehicle,

a conical reentry module resembling the Apollo CM.

The Earth Return Vehicle was designed for land landing—like the Soyuz space station transport, it would

include solid-fueled soft-landing rockets under its

ablative heat shield.

Bush and Gorbachev formally agreed at their July

1991 summit meeting to fly an American astronaut to

Mir and a Soviet cosmonaut on the Space Shuttle.

Less than two weeks later, in August 1991, communist

hardliners launched an abortive coup d’etat against

Gorbachev, triggering the collapse of the Soviet

Union. The following summer, Bush confirmed the

July 1991 cooperation agreements with Russian

President Boris Yeltsin. The first Russian cosmonauts

arrived in Houston for Space Shuttle flight training in

November 1992.

Space cooperation expanded dramatically under

President William Clinton beginning in 1993. Space

Station Freedom was redesigned as the International

Space Station, which incorporated Russian hardware

originally built for the Soviet Mir-2 space station.

Mars-related cooperation, however, remained small in

scale. For example, NASA Lewis researchers worked

with Russian engineers on electric thrusters.

America at the Threshold

The SEI Synthesis Group released its report America

at the Threshold in May 1991.55 The report, though

written at a time when U. S.-Soviet space cooperation

was becoming increasingly important to NASA’s future,

contained little on cooperation. The Synthesis Group

report was the last in the series of high-profile documents proposing future directions for NASA that had

begun with the National Commission on Space report

in 1986.

Stafford headed a group of 22 experts from NASA and

the Departments of Energy, Defense, and

Transportation. They included retired JSC director

Christopher Kraft and retired JSC engineering director

Maxime Faget. Robert Seamans, retired from top

NASA, Air Force, and Department of Energy posts, was

Stafford’s co-chair. They set up shop with a staff of 40

in Crystal City, Virginia, just outside Washington, DC.

The SEI Outreach Program provided the Synthesis

Group with about 500 inputs from the 44,000-member

AIAA. The Aerospace Industries Association, meanwhile, organized corporate briefings. These included a

presentation by Martin Marietta featuring the Mars

Direct plan. NASA took out newspaper advertisements

around the country and set up toll-free telephone numbers to receive ideas from the public. About 900 concepts

were submitted to Rand Corporation by early

September. The national laboratories turned over their

ideas during September. All told, the Synthesis Group

had about 2,000 inputs in hand in late September.56

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 85

Chapter 9: Space Exploration Initiative
The Synthesis Group was to submit at least two concepts

based on these inputs to Truly, who would forward them

to the National Space Council. A two-year NASA study

would follow, during which the Agency would attempt to

identify critical technologies needed to carry out the concepts proposed by the Synthesis Group.

In June 1991, the Group distributed 40,000 copies of its

colorful report, emblazoned with the U. S. Presidential

Seal, to industry, educators, government agencies, and

international organizations. The report outlined four

SEI architectures. In all of them, the ultimate goal was

landing Americans on Mars. The Moon would serve as a

rehearsal stage; nuclear systems would push spacecraft

and power bases; and heavy-lift rockets would blast

everything into orbit. Including nuclear propulsion was,

as in the 1960s, in part a concession to Los Alamos,

which had begun stumping for SEI nuclear systems as

early as February 1990.57

In none of the architectures was Space Station Freedom

an element of Mars transportation infrastructure. In

September, Aviation Week & Space Technology quoted

Stafford as saying, “I know when I went to the Moon . . .

on Apollo 10, I did not have to stop at a space station.”58

This was a radical departure from SEI’s ground rules. It

was, in fact, a deviation from ground rules that had

guided Mars planning since the time of the Apollo

Moon missions, when NASA had first began to push for

a space station.

Stafford’s Architecture I emphasized Mars exploration

but would spend five years on the Moon first. In 2005, a

heavy-lift rocket would launch an automated cargo lander/habitat to the Moon. A second heavy-lift rocket

would launch a crew of six to lunar orbit. Five astronauts

would land on the Moon near the cargo lander; the sixth

astronaut would mind the mothership in lunar orbit,

just as the CM Pilot had minded his craft during Apollo

Moon landing missions. The surface crew would stay on

the Moon for 14 Earth days (one lunar daylight period).

In 2009-10, after four more heavy-lift rocket launches

and two more lunar expeditions, a six-person Mars

rehearsal crew would carry out a 300-day Mars expedition simulation in lunar orbit and on the Moon. After

that, the Moon would not be visited again.

In 2012, the ninth heavy-lift rocket of Synthesis Group

Architecture I would launch the first nuclear rocket of

the program. It would push an automated cargo lander

to Mars. The cargo lander would include a habitat identical to that landed on the Moon. The first six-person

Mars crew would leave Earth in 2014 on the tenth

heavy-lift rocket. After a flight lasting approximately

120 days, they would decelerate into Mars orbit using

their nuclear-thermal rocket, separate from the Mars

transfer habitat, and land near the 2012 cargo lander.

The crew would spend 30 days testing systems and

exploring before returning to the transfer spacecraft

and firing the nuclear rocket for return to Earth. In the

same launch opportunity, the eleventh heavy-lift rocket

of the program would launch a cargo lander for the 2016

Mars expedition, which would spend 600 days on Mars.

The report stated that Architecture I was conducive to

more rapid execution (first Mars landing in 2008) if provided with “robust” funding.

The other architectures were generally similar.

Architecture II, “science emphasis for the Moon and

Mars,” was designed to characterize the Moon and

Mars scientifically through wide-ranging exploration

and visits to multiple scientifically interesting landing

sites. Architecture III, “Moon to stay and Mars exploration,” emphasized a permanent lunar base. The base

would achieve 18-person permanent staffing in 2007. A

total of 47 six-person piloted expeditions would reach

the Moon between 2004 and 2020, and the first piloted

Mars landing would occur as in Architecture I.

The Stafford Group noted that “space is a unique store

of resources: solar energy in unlimited amounts, materials in vast quantities from the Moon and Mars, gases

from the [M]artian atmosphere, and the vacuum and

zero gravity of space itself”—hence Architecture IV,

which emphasized “space resource utilization.”59 Lunar

ISRU would aim first for self-sufficiency; then it would

export to Earth electricity and Helium-3 for fusion

reactors. Mars ISRU would aim solely to provide selfsufficiency—the planet’s greater distance would make

exports to Earth impractical, the report stated. The

Mars rehearsal on the Moon would take place as

described in Architecture I, and Mars expeditions

would occur in 2016 and 2018. The second expedition

would establish an experimental greenhouse. Both

expeditions would manufacture propellants for their

rovers from Martian air.

The report made organizational recommendations for

carrying out its program. It called upon NASA to

86 Monographs in Aerospace History

Chapter 9: Space Exploration Initiative
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 87

establish “a long range strategic plan for the [N]ation’s

civil space program with the Space Exploration

Initiative as its centerpiece,” and asked President

Bush to “establish a National Program Office by

Executive order.” In addition, it advocated advanced

technology development programs.60

The SEI Synthesis Group had produced a cut-price version of The 90-Day Study—a disappointing outcome,

given the magnitude of the Outreach Program. Few

Americans took notice of America at the Threshold, and

few of its recommendations were implemented. SEI

funding fared no better in FY 1992 and FY 1993 than

in the previous two years. The planned two-year followup study of critical technologies did not take place.

NASA disbanded the Headquarters Exploration Office

in late 1992. The JSC Exploration Directorate closed

down a few months later.61 The poorly attended Case for

Mars V conference in May 1993 became SEI’s wake. By

the beginning of 1994, Mars planning across NASA

threatened to slip back into its post-Apollo slumber.

Chapter 9: Space Exploration Initiative
Recent developments in the exploration of

Mars have served to focus attention once

again on the possibilities for human exploration of that planet. The unprecedented

interest shown in the recently published evidence pointing to past life on Mars and in the

Mars Pathfinder mission indicates that

exploration of our solar system has not

become so commonplace that the public cannot become surprised and fascinated by the

discoveries being made. And these events

have also rekindled the questions not of

whether, but when will humans join the

robots in exploring Mars. (Kent Joosten,

Ryan Schaefer, and Stephen Hoffman, 1997)1

Mars Direct

Like the STG, NCOS, and The 90-Day Study teams

before it, the SEI Synthesis Group opted for a “bruteforce” approach to piloted Mars exploration requiring

such big-ticket items as heavy-lift rockets that dwarfed

the old Saturn V, nuclear-thermal propulsion, and a

lunar outpost. As has been seen, this approach has

never gained much support. Proposing it repeatedly

over the past 30 years has succeeded mainly in ingraining the belief that Mars exploration must be exorbitantly expensive (more expensive than a small war, for

example) and needs decades to achieve its goal.

Subsequent NASA Mars plans have sought to apply

technologies new and old to reduce cost and tighten the

schedule. They have begun the slow process of expunging the perception that a Mars mission must be conducted in a costly way.

Since 1992, NASA has based most of its Mars plans on

the Mars Direct concept developed in 1990 by Martin

Marietta. Mars Direct originated in Martin Mariettasponsored efforts to develop SEI concepts. The plan

has had staying power in part because it is an appealingly clever synthesis of concepts with respectable

pedigrees. Mars Direct employs ISRU, aerobraking, a

split mission architecture, a tether for artificial gravity,

and a conjunction-class mission plan—all concepts that

date from the 1960s or earlier. Mars Direct was influenced by the Case for Mars conferences, the Ride

Report, and the NASA Exploration Office Studies, as

well as ISRU research conducted by Robert Ash,

Benton Clark, and others.2

Mars Direct has also had staying power since 1990

because one of its authors, engineer Robert Zubrin, has

remained its zealous champion. On April 20, 1990,

Zubrin and co-author David Baker unveiled their plan

to NASA engineers gathered at NASA Marshall.3 Mars

Direct went public at a National Space Society conference in Anaheim, California, in June 1990. It first

received widespread attention a week later, after

Zubrin presented it at the Case for Mars IV conference

in Boulder, Colorado.4

In August 1990 the AIAA magazine Aerospace America

carried a non-technical description of Mars Direct capturing Zubrin’s promotional style.5 It asked,

Can the United States send humans to Mars

during the present decade? Absolutely. We

have developed vehicle designs and a mission

architecture that can make this possible.

Moreover, the plan we propose is not merely a

“flags and footprints” one-shot expedition, but

would put into place immediately an economical method of Earth-to-Mars transportation,

vehicles for long-range surface exploration,

and functional bases that could evolve into a

mostly self-sufficient Mars settlement.6

Zubrin and Baker had the first Mars Direct expedition beginning in December 1996 with the launch of

a Shuttle-derived heavy-lift rocket from the Kennedy

Space Center. The rocket, which Zubrin and Baker

dubbed Ares, would consist of a modified Shuttle

External Tank, two Advanced Solid Rocket Boosters,

and four Space Shuttle Main Engines mounted on the

External Tank’s underside. A liquid hydrogen/liquid

oxygen upper stage and an unpiloted Mars cargo lander covered by a streamlined shroud sat on top of the

External Tank. The 40-ton cargo lander included an

aerobraking heat shield, descent stage, Earth-Return

Vehicle, In-Situ Resource Utilization propellant factory, 5.8 tons of liquid hydrogen feedstock for propellant manufacture, and a 100-kilowatt nuclear reactor

on a robot truck. The lander was, they wrote, “light

enough for the booster upper stage to project it

directly onto a six-month transfer orbit to Mars without any refueling or assembly in Earth orbit”—hence

the name Mars Direct.7

The cargo lander would aerobrake in Mars’ atmosphere

and land. After touchdown, the robot truck bearing the

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 89

Chapter 10: Design Reference Mission
reactor would trundle away to a natural depression or

one created using explosives. It would lower the reactor

into the crater—the crater rim would shield the landing

site from radiation—then would run cables back to the

lander.The reactor would activate, powering compressors

which would draw in Martian air to manufacture propellant. Manufacturing propellants on Mars would help

minimize the weight of propellants that had to be

shipped from Earth.

The propellant factory would use the Sabatier process

first proposed for use on Mars in 1978 by Robert Ash,

William Dowler, and Giulio Varsi. Liquid hydrogen

feedstock would be exposed to Martian carbon dioxide

in the presence of a catalyst, producing 37.7 tons of

methane and water. The methane would be stored and

the water electrolyzed to yield oxygen and more hydrogen. The oxygen would then be stored and the hydrogen recycled to manufacture more water and methane.

Additional oxygen would be manufactured by decomposing carbon dioxide into carbon monoxide and oxygen and venting the carbon monoxide. In a year, the

propellant factory would manufacture 107 tons of

methane and oxygen propellants. The piloted Mars

spacecraft would not be launched until the automated

cargo ship finished manufacturing the required propellants, thereby reducing risk to crew.

In January 1999—the next minimum-energy Mars

transfer opportunity—two more Ares rockets would

lift off. One would carry a cargo lander identical to

the one already on Mars. The other would carry a

“manned spacecraft looking somewhat like a giant

hockey puck 27.5 f[ee]t in diameter and 16 f[ee]t tall”

based on Martin Marietta designs developed for the

NASA Office of Exploration.8 The top floor would

comprise living quarters for the four-person crew,

while the bottom floor would be stuffed with cargo

and equipment, including a pressurized rover.

Zubrin and Baker estimated the piloted spacecraft’s

weight at 38 tons.

The upper stage would launch the “hockey puck”

spacecraft on course for Mars and separate, but the

two would remain attached by a 1,500-meter tether.

This assemblage would rotate once per minute to produce acceleration equal to Martian surface gravity in

the piloted spacecraft. A similar lightweight artificial

gravity concept was proposed by Robert Sohn in

1964. Near Mars the upper stage and tether would be

discarded.

The piloted spacecraft would aerobrake into Mars

orbit, then land near the 1996 cargo lander. No part of

the ship would remain in orbit. Landing the entire crew

on the surface would help minimize risk. Once on Mars,

the Martian atmosphere would provide some radiation

protection, and the crew could use Martian dirt as additional shielding. They would also experience Martian

gravity. Though only a third as strong as Earth’s gravity, it seemed likely that even that small amount would

be preferable to a long weightless stay in Mars orbit.

As in the SAIC split-sprint plan, the crew would have

to rendezvous at Mars with propellants for their trip

home. This was seen by some as increasing risk. Unlike

the SAIC crew, however, the Mars Direct astronauts

would have options if they could not reach their Earthreturn propellants.

Baker and Zubrin pointed out that the crew had their

rover to drive to the 1996 cargo lander, though ideally

they would land within walking distance. If some gross

error meant they landed more than 600 miles from the

1996 cargo lander—beyond the range of their rover—

they could command the cargo lander launched with

them in 1999 to land nearby. It would then manufacture propellant for their return to Earth. If the 1999

cargo lander failed, the Mars Direct astronauts would

have sufficient supplies to hold out until a relief expedition arrived in two years. Assuming that the crew

landed near the 1996 cargo lander as planned, the 1999

cargo lander would set down 500 miles from the first

Mars landing site and begin to make propellants for

the second Mars expedition, which would leave Earth

in 2001.

Eleven of the 107 tons of propellants manufactured by

the 1996 cargo lander would be set aside to power the

pressurized rover. During their 500-day stay on Mars,

the explorers would conduct long traverses—up to 600

miles round-trip—thoroughly characterizing the region

around their landing site. This impressive capability

would maximize science return by allowing the crew to

survey large areas, though with some increased risk. If

the rover broke down, the crew could become stranded

beyond hope of rescue, hundreds of kilometers from base.

90 Monographs in Aerospace History

Chapter 10: Design Reference Mission
At the end of the 500-day Mars stay, the ERV engine

would ignite, burning methane and oxygen propellants

manufactured using the Martian atmosphere. The

small ERV spacecraft would use the cargo lander as a

launch pad to perform ascent and direct insertion onto

a trajectory to Earth. After six weightless months in

the cramped ERV, the crew would reenter Earth’s

atmosphere and perform a parachute landing. The

small ERV was considered by many to be a weak link

in the Mars Direct plan.

The 2001 expedition crew would land near the 1999

cargo lander. If all went as planned, the 2001 cargo lander would land 500 miles away. The 2003 crew would

land next to the 2001 cargo lander, while the 2003

cargo lander would touch down 500 miles away for the

2005 expedition, and so on. After several expeditions, a

network of bases would be established. “Just as towns

in the western U.S. grew up around forts and outposts,”

wrote Baker and Zubrin, “future [M]artian towns

would spread out from some of these bases. As information returns about each site, future missions might

return to the more hospitable ones and larger bases

would begin to form.”9

SEI’s Last Gasp

In SEI’s last days, the Stafford Synthesis Group report

formed the basis of NASA’s Mars planning. From 1991

to 1993, the Agency performed the First Lunar Outpost

(FLO) study, which took as a point of departure the

lunar elements of the Synthesis Group’s four architectures. In the summer of 1992, the NASA Headquarters

Exploration Office under Michael Griffin, the successor

to the Office of Exploration first headed by Sally Ride,

launched a NASA-wide study to determine how FLO

might find hardware commonality with a follow-on

Mars expedition, thereby reducing the costs of both

programs.10

The Mars Exploration Study Team workshop held in

August 1992 produced a plan containing elements of

both Mars Direct and the Synthesis Group Mars plan.

It was briefed to Griffin in September.11 The May 1993

Mars Exploration Study Team workshop produced a

Mars expedition Design Reference Mission (DRM)

with little overt FLO commonality beyond a common

heavy-lift rocket and outwardly similar vehicles for

lunar and Mars ascent. In fact, the DRM was modeled

on Mars Direct. Robert Zubrin was an advisor to the

Mars Exploration Study Team in late 1992 and 1993.

He briefed Griffin on Mars Direct in June 1992, then

briefed the JSC Exploration Program Office in

October 1992.12

The Mars Exploration Study Team DRM was reported in a workshop summary and in technical papers

in September and November 1993.13, 14 It included

the following:

• no low-Earth orbit operations or assembly—

that is, no reliance on a space station as a Mars

transportation element,

• no reliance on a lunar outpost or other lunar

operations,

• heavy-lift rocket capable of launching 240 tons

to low-Earth orbit, 100 tons to Mars orbit, and

60 tons to the Martian surface (more than

twice the capability of the Saturn V),

• short transit times to and from Mars and long

Mars surface stay times beginning with the

first expedition (conjunction-class missions),

• six crewmembers to ensure adequate manpower and skills mix,

• early reliance on Mars ISRU to minimize

weight launched to Mars, and

• common design for surface and transit habitats to reduce development cost.

The most significant difference between Mars Direct

and the Mars Exploration Study Team’s DRM was the

division of the Mars Direct ERV functions between two

vehicles. In the Mars Direct plan, the ERV lifted off

from Mars at the end of the surface mission and flew

directly to Earth. In the judgment of many, however,

the Mars Direct ERV was too small to house four astronauts during a six-month return from Mars, let alone

the DRM’s six astronauts.15 In the DRM, therefore, only

a small Mars Ascent Vehicle (MAV) would rely on

ISRU. The crew would use it to reach Mars orbit at the

end of their surface stay and dock with the orbiting

ERV. The addition of a rendezvous and docking in Mars

orbit was seen by some as increasing risk to crew, but

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 91

Chapter 10: Design Reference Mission
there seemed to be little alternative if a realistically

large ERV was to be provided.

The September 2007 Mars transfer opportunity was

used for the study because it would be challenging in

terms of time and energy required for Mars transfer,

not necessarily because an expedition was planned for

that time. The first expedition would begin with launch

of three heavy-lift rockets, each bearing one unmanned

spacecraft and one nuclear propulsion upper stage. The

three spacecraft were the cargo lander, the ERV orbiter,

and an unmanned Habitat lander. They would weigh

between 60 and 75 tons each, a weight estimate considered more realistic than the 30 to 40 tons quoted in

Mars Direct.

The ERV and Habitat designs were based on a common

crew module design resembling the Mars Direct “hockey puck.” The cargo lander would carry the MAV, ISRU

propellant factory, and hydrogen feedstock, along with

40 tons of cargo, including the pressurized rover. All

would reach Mars during August and September 2008.

The ERV would aerobrake into Mars orbit, while the

cargo lander and Habitat would land on Mars. The

cargo lander would then set about manufacturing 5.7

tons of methane and 20.8 tons of oxygen for the MAV

and a 600-day cache of life-support consumables.

As in Mars Direct, the crew would follow during the next

Mars launch opportunity 26 months later (OctoberNovember 2009), accompanied by unmanned vehicles

supporting the next expedition or providing backup for

those already on Mars.The explorers would land near the

2007 cargo lander and Habitat. The Habitats would

92 Monographs in Aerospace History

Chapter 10: Design Reference Mission

Figure 23—NASA’s 1993 Mars mission plan: after landing on

Mars, the automated propellant factory manufactures liquid

methane and liquid oxygen propellants for the conical Mars

Ascent Vehicle it carries on top. (NASA Photo S93-50643)

Figure 24—The crew Habitat lands near the propellant

factory with empty propellant tanks. Note wheels for moving the Habitat on the martian surface. (NASA Photo S93-

050645)

Figure 25—Mars Base 1: the crew docks its Habitat on the

surface with a second Habitat and begins a 600-day stay.

They use a pressurized rover (left) to explore up to 500 kilometers from base. (NASA Photo S93-45582)
include wheels to allow the explorers to move them

together so they could be linked using a pressurized tunnel. The 2007 Habitat would also provide a backup pressurized volume if the 2009 Habitat was damaged during

landing and rendered uninhabitable.

The first Mars outpost thus established, the crew

would unpack the pressurized rover from the 2007

cargo lander. During their 600-day stay on Mars, the

crew would carry out several 10-day rover traverses

ranging up to 500 kilometers from the outpost.

In October 2011, the 2009 crew would lift off from Mars

in the 2007 MAV. They would dock in Mars orbit with

the 2007 ERV and fire its twin liquid methane/liquid

oxygen rocket engines to leave Mars orbit for Earth,

retaining the MAV capsule. Near Earth the explorers

would enter the MAV capsule and detach from the

ERV, which would sail past Earth into solar orbit. They

would then reenter Earth’s atmosphere and perform a

parachute landing.

The Mars Exploration Study Team effort was SEI’s last

gasp. Before it was completed, NASA had begun to dismantle its formal Mars exploration planning organization. The Headquarters Exploration Office was abolished in late 1992. The JSC Exploration Directorate,

created soon after The 90-Day Study’s release, was

trimmed back and re-created as the JSC Planetary

Projects Office.16

As the apparatus for piloted Mars planning within

NASA shrank, automated Mars exploration also suffered a cruel blow. Mars Observer, the first U.S. automated Mars mission since the Vikings, had left Earth on

25 September 1992. On 21 August 1993, three days

before planned Mars orbit arrival, the spacecraft’s transmitter was switched off as planned to protect it from

shocks during propellant system pressurization. Contact

was never restored. An independent investigation report

released in January 1994 pointed to a propulsion system

rupture as the most probable cause of Mars Observer’s

loss, the first post-launch failure of a U.S. planetary

exploration mission since Surveyor 4 in 1967.17

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 93

Chapter 10: Design Reference Mission

Figure 26—Using the propellant factory as a launch pad,

the Mars Ascent Vehicle blasts off burning propellants made

from terrestrial hydrogen and Martian atmospheric carbon

dioxide. (NASA Photo S93-050644)

Figure 27—Mars Orbit Rendezvous: The Mars Ascent

Vehicle docks with the Earth Return Vehicle in Mars orbit.

The Earth Return Vehicle’s rocket engines would place the

crew on a six-month low-energy trajectory homeward. (NASA

Photo S93-27626)
NASA almost immediately announced plans to fly Mars

Observer’s science instruments on an inexpensive Mars

orbiter as soon as possible. This marked the genesis of

the Mars Surveyor Program, which aimed to launch

low-cost automated spacecraft to Mars every 26 months,

at each minimum-energy launch opportunity.18

Refreshed Dreams

In 1994, the JSC Planetary Projects Office, NASA’s de

facto focus for piloted Mars planning following abolition of the Headquarters Exploration Office, was downsized, then abolished. In February it became a branch

of the JSC Solar System Exploration Division, and in

June its remaining personnel were assigned to the

JSC Office of the Curator, where they explored lowcost options for sending people to the Moon.19 The

Curator’s Office managed disposition of Apollo lunar

samples and meteorites, including one meteorite designated ALH 84001. Even as the Planetary Projects

Office was abolished, ALH 84001 was determined to

have originated on Mars.

On 7 August 1996, NASA, Stanford University, and

McGill University scientists led by NASA scientist

David McKay announced that they had discovered possible fossil microorganisms in Martian meteorite ALH

84001. In a NASA Headquarters press conference, the

McKay team cited the evidence for past Martian life.

This included the presence of complex carbon compounds resembling those produced when Earth bacteria die, magnetite particles similar to those in some

Earth bacteria, and segmented features on the scale of

some Earth nanobacteria. McKay told journalists,

There is not any one finding that leads us to

believe that this is evidence of past life on Mars.

Rather, it is a combination of many things that

we have found. They include Stanford’s detection of an apparently unique pattern of organic

molecules, carbon compounds that are the basis

of life. We also found several unusual mineral

phases that are known products of primitive

microorganisms on Earth. Structures that could

be microscopic fossils seem to support all of this.

The relationship of these things in terms of

location—within a few hundred-thousandths of

an inch of each other—is the most compelling

evidence.20

According to their analysis, the 1.9-kilogram rock

soaked in carbonate-rich water containing the possible

microorganisms 3.6 billion years ago. It lay in the

Martian crust, shocked by the occasional local

upheaval, until an asteroid impact blasted it off Mars

16 million years ago. After orbiting the Sun several million times, ALH 84001 landed in Antarctica 13,000

years ago, where it was collected on 27 December 1984

in the Allan Hills ice field.21

The McKay team’s discovery generated unprecedented

public enthusiasm for Mars, which in turn provided the

catalyst for reestablishment of the JSC Exploration

Office in November 1996. The new office, managed by

Doug Cooke, was reconstituted as part of the Advanced

Development Office in the JSC Engineering

Directorate.22 Mars planners dusted off the 1993 DRM

to serve as the point of departure for new planning.

At the same time, NASA Headquarters took an important step toward eventual piloted Mars exploration. On

7 November 1996, Associate Administrator for Space

Flight Wilbur Trafton,Associate Administrator for Space

Science Wesley Huntress, and Associate Administrator

for Life and Microgravity Sciences and Applications

Arnauld Nicogossian signed a joint memorandum calling for NASA’s Human Exploration and Development of

Space (HEDS) Enterprise and Space Science Enterprise

to work together toward landing humans on Mars.

They told Jet Propulsion Laboratory director Edward

Stone and JSC director George Abbey that “[r]ecent

developments regarding Mars and the growing maturity of related programs lead us to believe that this is the

right time to fully integrate several areas of robotic and

human Mars exploration study and planning.”23 The

Associate Administrators then gave Stone and Abbey

until 1 February 1997, to produce “a proposal that

NASA can bring forward, after successful deployment

of the International Space Station, for human exploration missions beginning sometime in the second

decade of the next [21st] century.”24

Trafton, Huntress, and Nicogossian also asked for “a

credible approach to achieving affordable human Mars

exploration missions.” They defined “a credible cost” as

“the amount currently spent by NASA on the

International Space Station”—that is, less than $2 billion annually. This was a dramatic reduction over the

$15 billion per year proposed in the excised cost section

94 Monographs in Aerospace History

Chapter 10: Design Reference Mission
of The 90-Day Study. They asked that Stone and Abbey

identify “technology investments and developments

that could dramatically decrease the cost of human and

robotic missions.”25

In March 1997, the HEDS and Space Science

Enterprises agreed that the 2001 Mars Surveyor lander

should include instruments and technology experiments

supporting piloted Mars exploration.Among the planned

experiments was a compact system for testing ISRU

propellant manufacture on Mars. In a press conference,

Huntress called it “the first time since the 1960s” that

“NASA’s space science and human space flight programs

are cooperating directly on the exploration of another

planetary body.” Trafton called the joint effort “a sign

that NASA is acquiring the information that will be

needed for a national decision, perhaps in a decade or so,

on whether or not to send humans to Mars.”26

In addition to stating that NASA’s robotic program

would complement its piloted Mars flight planning

efforts, the joint memorandum showed that, at a high

managerial level, NASA had not abandoned its plans to

eventually send people to Mars despite SEI’s collapse.

There was no firm timetable for accomplishing the

piloted Mars mission and no Presidential declaration.

Instead, there was a new philosophy—continuing lowlevel, low-cost planning, much of it in-house, and lowlevel Earth-based technology research accompanied by

efforts to use the existing low-cost robotic exploration

program to answer questions relevant to piloted exploration. In short, the Agency accepted publicly for the

first time that it might eventually send people to Mars

without recourse to a new large program—without a

new Space Exploration Initiative or Apollo program.

This philosophy continues to guide NASA Mars planning at the time of this writing (mid-2000).

Success or failure in the automated Mars program thus

became success or failure for piloted Mars planners.

The joint human-robotic Mars effort received a boost on 4

July 1997, when Mars Pathfinder successfully landed at

Ares Vallis, one of the large outwash channels first spotted by Mariner 9 in 1971 and 1972. Pathfinder, the first

U.S. Mars lander since the Vikings, dropped to the rockstrewn surface and bounced to a stop on airbags, then

opened petals to right itself and expose instruments and

solar cells. The technique was similar to the one the

Soviets employed to land robots on the Moon in the 1960s

and on Mars in the 1970s. The Sojourner rover—the first

automated rover to operate on another world since the

Soviet Union’s Lunokhod 2 explored the Moon in 1972—

crawled off its perch on one of Pathfinder’s petals and

crept about the landing area analyzing rock and dirt composition. Sojourner and Pathfinder—the latter renamed

the Sagan Memorial Station—successfully completed

their primary mission on 3 August.

As Mars Pathfinder bounced to a successful landing in

Ares Vallis, the glossy report Human Exploration of

Mars: The Reference Mission of the NASA Mars

Exploration Study Team rolled off the presses.27 In addition to a detailed description of the 1993 DRM, the July

1997 document contained general recommendations on

the conduct of a piloted Mars program based on experience gained through SEI and the Space Station program.

The report recommended that NASA set up “a Mars

Program Office . . . early in the process.” It also proposed to avoid Space Station’s redesigns and delays by

establishing “a formal philosophical and budgetary

agreement . . . as to the objectives and requirements

imposed on the mission before development is initiated,

and to agree to fund the project through to completion.”

Finally, taking into account the McKay team’s discovery, it called for “adequate and acceptable human quarantine and sample handling protocols early in the Mars

exploration program” to protect Earth and Mars from

possible biological contamination.28

The JSC Exploration Office called its report “another

chapter in the ongoing process of melding new and

existing technologies, practical operations, fiscal reality, and common sense into a feasible and viable human

mission to Mars,” adding that “this is not the last chapter in the process, but [it] marks a snapshot that will

be added to and improved upon by others in the

future.”29 In fact, by the time the report saw print, the

next chapter was nearly complete.

Scrubbing the DRM

Subsequent DRM evolution focused on minimizing

spacecraft weight in an effort to reduce estimated

mission cost. The slang term engineers used to

describe this process was “scrubbing.” The 1997

“scrubbed” DRM went public in August 1997.30 It minimized mass by reducing common Habitat diameter;

combining the functions of the pressure hull, aeroHumans to Mars: Fifty Years of Mission Planning, 1950–2000 95

Chapter 10: Design Reference Mission
96 Monographs in Aerospace History

brake heat shield, and Earth launch shroud; and

employing lightweight composite structures. The

nuclear stages for injecting the spacecraft toward

Mars would be launched into Earth orbit without

spacecraft attached, then docked with the spacecraft

in Earth orbit. These steps and others allowed planners to eliminate the 1993 DRM’s large heavy-lift

rocket, potentially the costliest mission element.

To place the first crew on Mars, the 1997 DRM would

require eight launches of a Shuttle-derived rocket capable of boosting 85 tons into Earth orbit. In the first

launch opportunity, six of these rockets would launch

payloads—three nuclear propulsion stages and three

Mars spacecraft (cargo lander, ERV, and unpiloted

Habitat). Each spacecraft would dock with its nuclear

stage in Earth orbit, then launch toward Mars. In the

second launch opportunity, 26 months later, six more

Shuttle-derived rockets would launch three nuclear

stages and three spacecraft, including a Habitat lander

containing the crew.The spacecraft would dock with their

nuclear stages and launch toward Mars. The rest of the

mission plan closely resembled the 1993 DRM. To accomplish the first expedition, the 1997 DRM would launch

303 tons to Mars—75 tons less than the 1993 DRM.

The new DRM was on the street, and a few weeks later,

a new automated spacecraft was orbiting Mars. On 11

September 1997, the Mars Global Surveyor orbiter, the

first spacecraft in the Mars Surveyor Program, arrived

in an elliptical Mars orbit after a 10-month flight. Mars

Global Surveyor carried backups of instruments lost

with Mars Observer in 1993. It commenced a series of

passes through Mars’ upper atmosphere to reach a

lower, more circular Mars orbit without using propellants. A damaged solar array threatened to collapse

under the pressure of atmospheric drag, however, so

the aerocapture maneuvers had to be extended over a

year. Nevertheless, the spacecraft turned its instruments toward Mars and began initial observations.

Defining the Surface Mission

As Mars planners sought to minimize spacecraft

weight, it became clear that they would require more

data on the mission’s Mars surface payload. Planners

historically have spent little time detailing what astronauts would do once they landed on Mars. To begin the

process of better defining the 500-to-600-day Mars surface mission, veteran Moon and Mars planner Michael

Chapter 10: Design Reference Mission

Figure 29—Nuclear stages in NASA’s 1997 Mars plan

included engines (left) based on revived 1960s NERVA

technology. (NASA Photo S97-07843)

Figure 28—NASA’s 1997 Mars plan proposed to reduce

weight by using an aerobrake integrated with the spacecraft

hull and nuclear rockets. These steps would help eliminate

need for a heavy-lift rocket, permitting a cheaper Shuttlederived launch system. (NASA Photo S97-07844)
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 97

Duke chaired a workshop held at the Lunar and

Planetary Institute in Houston on 4-5 October 1997.31

Workshop participants divided into two working

groups. The Science and Resources group based its discussions on a “three-pronged approach” to Mars exploration. Mars explorers would seek evidence of life or its

precursors and attempt to understand Mars climate

history. They would also act as prospectors, seeking

water, minerals, energy, and other resources for supporting future Mars settlements. This three-pronged

science approach also guided the automated Mars

Surveyor program.32

The Living and Working on Mars group looked at

chores the crew would need to perform during their

Mars stay. These included initial base setup, such as

deploying an inflatable greenhouse, and base maintenance, such as ridding air filters of ever-present

ultra-fine Martian dust. Astronauts on Mars would

also harvest crops, service their space suits, and

perform less mundane tasks such as exploring the

surface in the pressurized rover and drilling deep in

search of Martian microorganisms that might hide

far beneath the surface.

The workshop recommended that “a process and program be put into place whereby a wide range of people

could contribute to the thought process.” The report

urged that students in particular be involved, because

“their representatives will be the ones who are actually to do this exploration.”33

A New Concept

Meanwhile, engineers at NASA Lewis studied using

solar-electric propulsion in the DRM to further reduce

the amount of weight that would have to be launched

into orbit. In January 1999, they proposed a novel concept using a Solar-Electric Transfer Vehicle (SETV)

which never left Earth orbit, but which provided most

of the energy needed to launch the Mars vehicles from

Earth orbit toward Mars.34 

The 1997 DRM required eight Shuttle-derived rockets

for the first Mars expedition. By contrast, the Lewis

solar-electric DRM required only five rockets. Removal

of the backup Habitat lander—a decision taken by

Mars planners in the JSC Exploration Program

Office—eliminated two heavy-lift rockets. Replacing

the four nuclear stages used to leave Earth in the 1993

and 1997 DRMs with the SETV and three small

expendable chemical stages eliminated one more. This

substitution also eliminated the cost of developing a

nuclear rocket engine and the potential political

headaches of launching nuclear payloads.

The Lewis team envisioned a self-erecting SETV

weighing 123 tons and measuring 194.6 meters across

its thin-film solar arrays. The arrays would provide

electricity to two sets of Stationary Plasma Thrusters

(SPTs), also known as TAL (Thruster with Anode

Layer) or Hall thrusters, an electric propulsion technology pioneered by the Russians.

The SETV would need months to complete large orbit

changes. Because of this, it would spend considerable

time crossing through Earth’s Van Allen Radiation

Belts. This meant that the Lewis DRM vehicles would

require radiation-hardened systems. The authors

assumed that the SETV would be good for two missions

beyond the Van Allen belts before radiation, temperature extremes, meteoroid impacts, and ultraviolet light

seriously degraded its solar arrays.

Chapter 10: Design Reference Mission

Figure 30—In 1998, NASA Lewis Research Center proposed

a reusable Solar-Electric Transfer Vehicle (SETV) and clever

use of orbital mechanics to reduce Mars expedition mass.

SETV’s solar panel spars would inflate in orbit, spreading

“wings” of solar cell fabric. (NASA Photo S99-03585)
The SETV’s first mission would place one unpiloted

cargo vehicle and one unpiloted ERV, each with a small

chemical rocket stage, into High-Energy Elliptical

Parking Orbit (HEEPO) around the Earth. The SETV

would start in a nearly circular low-Earth orbit and

raise its apogee by operating its SPT thrusters only at

perigee. It would need from six to twelve months to

raise its apogee to the proper HEEPO for Earth-Mars

transfer. The final HEEPO apogee would be more than

40,000 kilometers, making it very lightly bound by

Earth’s gravity.

When Earth, Mars, and the plane of the HEEPO were

properly aligned for Earth-Mars crossing, the SETV

would release the cargo lander, ERV, and small chemical stages. At next perigee the chemical stages would

ignite, pushing the spacecraft out of the HEEPO on a

path that would intersect Mars six months later. After

releasing the chemical stages and spacecraft, the SETV

would point its SPTs in its direction of motion and

operate them at perigee to return to a circular lowEarth orbit.

The SETV’s second mission would place one Habitat

lander with a small chemical stage into HEEPO.

Because the climb to HEEPO again would require up to

twelve months and long periods inside the Van Allen

Radiation Belts, the Habitat lander would remain

unpiloted until just before Earth orbit departure. As

the SETV climbed toward planned final HEEPO

apogee, a small, chemical-propellant “taxi” carrying the

Mars crew would set out in pursuit. The crew would

transfer to the Habitat lander, cast off the taxi, then

separate the Habitat lander and chemical stage from

the SETV. At the next perigee, the chemical stage

would ignite to place the first expedition crew on course

for Mars. The remainder of the first Mars expedition

would occur as described in the 1997 scrubbed DRM,

except for the absence of a backup Habitat lander.

In February 1999, soon after the Lewis team made

public their variation on the 1997 DRM, Mars Global

Surveyor achieved its nominal mapping orbit. At this

writing, exploration and data interpretation are ongoing, but it is already clear that the spacecraft is revolutionizing our understanding of Mars. By mid-2000,

its instruments had detected evidence that Mars once

had a strong planetary magnetic field, a finding

potentially important for the early development of

Martian life; that Mars’ polar regions once knew

extensive glaciers; and that water flowed on Mars’

surface recently, and perhaps flows occasionally today,

carving gullies in cliffs and crater walls.

Not the Last Chapter

In May 1998, a small team of NASA and contractor

space suit engineers traveled to sites in northern

Arizona where Apollo Moonwalkers had trained three

decades before. They observed and assisted as a veteran geologist wearing a space suit performed geological

field work and set out simulated scientific instruments

in Mars-type settings—for example, on the rim of

Meteor Crater. The team contained cost by traveling

from Houston to Arizona overland and by reusing a

space suit originally designed for Space Station

Freedom. In addition to gathering data on space suit

mobility to enable design of future Mars space suits,

the exercise permitted veteran space suit engineers

who had participated in the development of the Apollo

lunar space suits to pass on their experience to young

engineers who had been children, or not yet born, when

Americans last walked on an alien world.35

Michael Duke and the other organizers of the Human

Exploration and Development of Space-University

Partners (HEDS-UP) program had a similar motive.

They sought to involve and inspire the next generation

of Mars planners, who might become the first generation of Mars explorers. In May 1998, the first HEDSUP Annual Forum saw undergraduate and graduate

design teams from seven universities across the United

States present Mars design studies.36 Twice as many

universities sent enthusiastic students to the 1999

HEDS-UP Annual Forum.37

In the nearly half-century since von Braun wowed

Americans with visions of Mars flight in Collier’s magazine, our understanding of Mars has steadily

improved. We have progressed from hazy telescopic

views of Mars to pictures on the Internet of Sojourner

rearing up on a flood-tossed Martian boulder. Plans for

piloted Mars exploration have matured in step with our

improved vision. For example, no longer do planners

seek to bring all necessities from Earth, for now it is

known that Mars has useful resources.

98 Monographs in Aerospace History

Chapter 10: Design Reference Mission
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 99

The Mars planning concepts developed in the twilight

years of the second millennium form a launch pad for

Mars planners—and perhaps Mars explorers—at the

dawn of the third. Current technological trends—for

example, increasingly capable miniaturized robots and

direct public engagement in Mars exploration through

the Internet—promise to reshape Mars planning.

Yet it should be remembered that ISRU, the concept

that dominated Mars planning in the 1990s, dates from

the 1960s and 1970s. This suggests that, in addition to

whatever new revolutions future technological development brings, other revolutions might lie buried in the

historical archives awaiting the careful and imaginative researcher. Further, this suggests that Mars planners should carefully preserve their work lest they

deprive future planners of useful concepts.

Young people now looking to Mars, such as the student

participants in the HEDS-UP program, should not have

to waste their time reinventing old concepts. They

should instead be able to study the old concepts and

build new ones upon them. They should also be able to

study the political and social settings of the old concepts, so that they might better navigate the “illogical”

pitfalls that can bring down a technically logical Mars

plan. Providing the next generation with the history of

Mars planning helps hasten the day when humans will

leave bootprints on the dusty red dunes of Mars.

Chapter 10: Design Reference Mission
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 101

AAP Apollo Applications Program

AAS American Astronautical Society

ABMA Army Ballistic Missile Agency

AEC Atomic Energy Commission

AIAA American Institute of Astronautics and Aeronautics

CIA Central Intelligence Agency

CM Command Module

CPS Chemical Propulsion Stage

CSM Command and Service Module

DRM Design Reference Mission

EMPIRE Early Manned Planetary-Interplanetary Roundtrip Expeditions

EOR Earth-Orbit Rendezvous

ERV Earth-Return Vehicle

ET External Tank

FLEM Flyby-Landing Excursion Mode

FLO First Lunar Outpost

FY Fiscal Year

GNP Gross National Product

HEDS Human Exploration and Development Space

HEDS-UP Human Exploration and Development Space—University Partners

HEEPO High-Energy Elliptical Parking Orbit

IPP Integrated Program Plan

ISRU In-Situ Resource Utilization

ISV Interplanetary Shuttle Vehicle

JAG Joint Action Group

JPL Jet Propulsion Laboratory

JSC Johnson Space Center

KSC Kennedy Space Center

LANL Los Alamos National Laboratory

LLNL Lawrence Livermore National Laboratory

LOR Lunar-Orbit Rendezvous

LSS Life Support Section

M Maneuver

MAV Mars Ascent Vehicle

MEM Mars Excursion Module

MEV Mars Exploration Vehicle, Mars Excursion Vehicle

MMM Manned Mars Mission

MOR Mars-Orbit Rendezvous

MSC Manned Spacecraft Center

MSSR Mars Surface Sample Return

NACA National Advisory Committee for Aeronautics

NAR North American Rockwell

NASA National Aeronautics and Space Administration

NCOS National Commission on Space

NERVA Nuclear Engine for Rocket Vehicle Application

NRC National Research Council

NRDS Nuclear Rocket Development Station

OMB Office of Management and Budget

OMS Orbiter Maneuvering System

Acronyms
102 Monographs in Aerospace History

OMSF Office of Manned Space Flight

OTV Orbital Transfer Vehicle

PH-D Phobos-Deimos

PM Propulsion Module

PMRG Planetary Missions Requirements Group

PPM Primary Propulsion Module

PSAC President’s Science Advisory Committee

REM Roentgen Equivalent Man

RIFT Reactor-In-Flight Test

SAIC Science Applications International Corporation

SEI Space Exploration Initiative

SETV Solar-Electric Transfer Vehicle

SM Service Module

SNPO Space Nuclear Propulsion Office

SOC Space Operations Center

SPT Stationary Plasma Thrusters

SRB Solid Rocket Booster

SSME Space Shuttle Main Engine

STG Space Task Group

STS Space Transportation System

TAL Thruster with Anode Layer

UMPIRE Unfavorable Manned Planetary-Interplanetary Roundtrip Expeditions

WGER Working Group on Extraterrestrial Resources

Acronyms
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 103

Preface

1. Edward Ezell, “Man on Mars: The Mission That NASA Did Not Fly” (paper presented at the American

Association for the Advancement of Science Annual Meeting, Houston, Texas, 3-8 January 1979), p. 24.

2. Readers seeking additional information on Mars planning are directed to the author’s Web site Romance to

Reality (http://members.aol.com/dsfportree/explore.htm), which contains over 250 annotations of Moon and

Mars planning documents, with more added regularly.

Chapter 1

1. Wernher von Braun with Cornelius Ryan, “Can We Get to Mars?” Collier’s (30 April 1954), p. 23.

2. Frederick Ordway and Mitchell Sharpe, The Rocket Team (New York: Thomas Y. Crowell, 1979), p. 408.

3. Wernher von Braun, The Mars Project (Urbana, IL: University of Illinois Press, 1962).

4. Ibid., p. 3.

5. Ibid., p. 75.

6. Louise Crossley, Explore Antarctica (Cambridge, England: Cambridge University Press, 1995), p. 40.

7. Fred Whipple and Wernher von Braun, “Man on the Moon: The Exploration,” Collier’s (25 October 1952),

p. 44.

8. Wernher von Braun, “Crossing the Last Frontier,” Collier’s (22 March 1952): 24-29, 72.

9. Wernher von Braun, “Man on the Moon: The Journey,” Collier’s (18 October 1952): 52-60; Whipple and von

Braun, “Man on the Moon: The Exploration,” pp. 38-48.

10. Von Braun with Ryan, “Can We Get to Mars?” pp. 22-28.

11. Ibid., pp. 26-27.

12. Willy Ley and Wernher von Braun, The Exploration of Mars (New York: Viking Press, 1956).

13. Ibid., p. 85.

14. Ibid., p. 98.

15. Ibid., p. 157.

Chapter 2

1. John F. Kennedy, “Excerpts from ‘Urgent National Needs,’ ” Speech to a Joint Session of Congress, 25 May

1961, in John Logsdon, gen. ed., with Linda Lear, Janelle Warren-Findlay, Ray Williamson, and Dwayne

Day, Exploring the Unknown: Selected Documents in the History of the U.S. Civil Space Program, Volume I:

Organizing for Exploration (Washington, DC: NASA SP-4407, 1995), pp. 453-54.

Endnotes
Endnotes

104 Monographs in Aerospace History

2. Robert Merrifield, “A Historical Note on the Genesis of Manned Interplanetary Flight,” AAS Preprint 69-

501 (paper presented at the AAS 15th Annual Meeting, 17-20 June 1969), p. 7.

3. David S. F. Portree, NASA’s Origins and the Dawn of the Space Age (Washington, DC: NASA Monographs

in Aerospace History #10, 1998), pp. 8-11.

4. Ezell, “Man on Mars,” pp. 5-6; see also Merrifield, “A Historical Note,” p. 8.

5. S. C. Himmel, J. F. Dugan, R. W. Luidens, and R. J. Weber, “A Study of Manned Nuclear-Rocket Missions to

Mars,” IAS Paper No. 61-49 (paper presented at the 29th Annual Meeting of the Institute of Aerospace

Sciences, 23-25 January 1961), p. 2.

6. Ibid., p. 5.

7. Ibid., p. 18.

8. Von Braun with Ryan, “Can We Get to Mars?” p. 24.

9. Himmel, et al., “A Study of Manned Nuclear-Rocket Missions to Mars,” p. 35.

10. Ibid., p. 24.

11. Ibid., p. 30.

12. Ibid., p. 33-34.

13. John Logsdon, The Decision to Go to the Moon: Project Apollo and the National Interest (Cambridge, MA:

MIT Press, 1970), pp. 111-12.

14. Office of Program Planning and Evaluation, “The Long Range Plan of the National Aeronautics and

Space Administration,” 16 December 1959, Logsdon, gen. ed., Exploring the Unknown, Vol. I, p. 404.

15. Ezell, “Man on Mars,” p. 8.

16. Ernst Stuhlinger, “Possibilities of Electrical Space Ship Propulsion,” Friedrich Hecht, editor, Bericht über

de V Internationalen Astronautischen Kongress (Osterreichen Gesellschaft für Weltraumforschung, Vienna,

Austria, 1955).

17. “Mars and Beyond,” The Wonderful World of Disney television program, 4 December 1957.

18. Portree, NASA’s Origins, p. 12.

19. Ernst Stuhlinger and Joseph King, “Concept for a Manned Mars Expedition with Electrically Propelled

Vehicles,” Progress in Astronautics, Vol. 9 (San Diego: Univelt, Inc., 1963), pp. 647-64.

20. Ibid., p. 658.

21. Ibid., p. 648.
Endnotes

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 105

22. James Hansen, Enchanted Rendezvous: John C. Houbolt and the Genesis of the Lunar-Orbit Rendezvous

Concept (Washington, DC: NASA Monographs in Aerospace History #4, 1995).

Chapter 3

1. Robert Sohn, “Summary of Manned Mars Mission Study,” Proceeding of the Symposium on Manned

Planetary Missions: 1963/1964 Status (Mountain View, CA: NASA TM X-53049, 1964), p. 151.

2. T. A. Heppenheimer, The Space Shuttle Decision: NASA’s Search for a Reusable Space Vehicle (Washington,

DC: NASA, 1999), pp. 60-61.

3. “One-Year Exploration-Trip Earth-Mars-Venus-Earth,” Gaetano A. Crocco, Rendiconti del VII Congresso

Internanzionale Astronautico, Associazione Italiana Razzi (paper presented at the Seventh Congress of

the International Astronautical Federation, Rome, Italy, 1956), pp. 227-252.

4. Ibid., p. 239.

5. Maxime Faget and Paul Purser, “From Mercury to Mars,” Aeronautics & Aerospace Engineering (February

1963): 27.

6. Ibid., p. 24.

7. Aeronutronic Division, Ford Motor Company, EMPIRE, A Study of Early Manned Interplanetary

Expeditions (Huntsville, AL: NASA CR-51709, 21 December 1962).

8. Lockheed Missiles & Space Company, Manned Interplanetary Mission Study (Lockheed Missiles and

Space Company, March 1963).

9. General Dynamics Astronautics, A Study of Early Manned Interplanetary Missions Final Summary Report

(San Diego, CA, General Dynamics Astronautics, 31 January 1963).

10. Aeronutronic, p. 1-2.

11. Lockheed, p. xx.

12. General Dynamics, p. 8-2.

13. Ibid., pp. 8-92 - 8-122.

14. Ibid., pp. 8-119 - 8-122.

15. David Hammock and Bruce Jackson, “Vehicle Design for Mars Landing and Return to Mars Orbit,”

George Morgenthaler, editor, Exploration of Mars (San Diego, CA: Univelt, Inc., 1964), pp. 174-95.

16. Raymond Watts, “Manned Exploration of Mars?” Sky & Telescope (August 1963): 63-67, 84.

17. Hammock and Jackson, “Vehicle Design for Mars Landing,” p. 175.
Endnotes

106 Monographs in Aerospace History

18. Franklin Dixon, “Summary Presentation: Study of a Manned Mars Excursion Module,” Proceeding of the

Symposium on Manned Planetary Missions: 1963/1964 Status (Huntsville, AL: NASA TM X-53140, 1964),

pp. 443-523.

19. Ibid., p. 449.

20. Ibid., p. 479.

21. Ibid., p. 449.

22. Ibid., p. 479.

23. J. N. Smith, Manned Mars Missions in the Unfavorable (1975-1985) Time Period: Executive Summary

Report (Huntsville, AL: NASA TM X-53140, 1964).

24. Ibid., p. 7.

25. Ibid., pp. 11-12.

26. Sohn, “Summary of Manned Mars Mission Study,” pp. 149-219.

27. Ibid., p. 156.

28. Ibid., p. 170.

29. Ibid., p. 165-166.

30. “Part 17: Panel Discussion,” Proceeding of the Symposium on Manned Planetary Missions: 1963/1964

Status (Huntsville, AL: NASA TM X-53140, 1964), pp. 748-749.

31. Ibid., p. 751.

32. Ibid.

33. “Future Efforts to Stress Apollo Hardware,” Aviation Week & Space Technology (16 November 1964): 48.

34. Ezell, “Man on Mars,” p. 13.

35. Ibid., p. 12.

36. Harry Ruppe, Manned Planetary Reconnaissance Mission Study: Venus/Mars Flyby (Huntsville, AL:

NASA TM X-53205, 1965).

37. Ibid., p. 53.

38. Ibid., p. 7.

39. Ibid., p. 8.
Endnotes

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 107

Chapter 4

1. Robert Hotz, “New Era for NASA,” Aviation Week & Space Technology (7 August 1967): 17.

2. Samuel Glasstone, The Book of Mars (Washington, DC: NASA SP-179, 1968), pp. 76-91.

3. William Hartmann and Odell Raper, The New Mars: The Discoveries of Mariner 9 (Washington, DC: NASA

SP-337, 1974), pp. 6-11.

4. Edward Clinton Ezell and Linda Neumann Ezell, On Mars: Exploration of the Red Planet, 1958-1978

(Washington, DC: NASA 1984), pp. 74-82.

5. NASA, “A Report from Mariner IV,” NASA Facts 3 (1966): 1.

6. Ibid., pp. 5-6; Oran Nicks, Summary of Mariner 4 Results (Washington, DC: NASA SP-130), p. 35.

7. Hal Taylor, “LBJ Wants Post-Apollo Plans,” Missiles and Rockets (4 May 1964); NASA, Summary Report:

Future Programs Task Group, January 1965, Logsdon, gen. ed., Exploring the Unknown, Vol. I, p. 473.

8. “Future Effort to Stress Apollo Hardware,” Aviation Week & Space Technology (16 November 1964): 48-51.

9. “Scientists Urge Priority for Mars Missions,” Aviation Week & Space Technology (23 November 1964): 26.

10. Merrifield, “A Historical Note,” p. 12; Astronautics and Aeronautics 1966 (Washington, DC: NASA SP4007), p. 17.

11. Willard Wilks and Rex Pay, “Quest for Martian Life Re-Emphasized,” Technology Week (6 June 1966): 26-

28.

12. Ezell and Ezell, On Mars, pp. 102-05.

13. Associate Administrator, Office of Space Science and Applications to Director, Office of Space Science and

Applications, “Manned Planetary Missions Planning Group,” 30 April 1965.

14. Franklin Dixon, “Manned Planetary Mission Studies from 1962 to 1968,” IAA-89-729 (paper presented at

the 40th Congress of the International Astronautical Federation, Malaga, Spain, 7-12 October 1989), p. 9.

15. Ezell, “Man on Mars,” p. 12.

16. Merrifield, “A Historical Note,” p. 13.

17. Planetary JAG, Planetary Exploration Utilizing a Manned Flight System (Washington, DC: NASA, 1966).

18. For example, see Robert Sohn, “A Chance for an Early Manned Mars Mission,” Astronautics & Aeronautics

(May 1965): 28-33.

19. Chief, NASA Kennedy Space Center Advanced Programs Office to Distribution, “Minutes of Joint Action

Group Meeting of June 29-30, 1966,” 8 July 1966.
Endnotes

108 Monographs in Aerospace History

20. R. R. Titus, “FLEM—Flyby-Landing Excursion Mode,” AIAA Paper No. 66-36 (paper presented at the 3rd

AIAA Aerospace Sciences Meeting, New York, New York, 24-26 January 1966).

21. Edward Gray to H. K. Weidner, F. L. Williams, M. Faget, W. E. Stoney, J. West, J. P. Claybourne, and R.

Hock, TWX, “Meeting to Establish Follow-on Activities Covering the Advanced Manned Planetary, Earth

Orbital, and Lunar Exploration Programs,” 17 November 1966.

22. Edward Gray to H. K. Weidner, F. L. Williams, J. W. Carter, R. J. Harris, J. P. Claybourne, R. Hock, and R.

J. Cerrato, TWX, “Follow-on Activity for Manned Planetary Program,” 2 December 1966.

23. John Logsdon, “From Apollo to the Space Shuttle: U.S. Space Policy, 1969-1972,” unpublished manuscript,

p. I-43.

24. “U.S. Space Funding to Grow Moderately,” Aviation Week & Space Technology (6 March 1967): 126.

25. William Normyle, “Post-Apollo Program Potential Emerging,” Aviation Week & Space Technology (6 March

1967): 126.

26. President’s Science Advisory Committee, The Space Program in the Post-Apollo Period (Washington, DC:

The White House, February 1967).

27. Ibid., p. 18.

28. “Science Advisors Urge Balanced Program,” Aviation Week & Space Technology (6 March 1967): 135.

29. William Normyle, “Manned Mars Flights Studied for the 1970s,” Aviation Week & Space Technology (27

March 1967): 63.

30. Merrifield, “A Historical Note,” p. 13.

31. Normyle, “Manned Mars Flights Studied,” p. 62-63; Edward Gray and Franklin Dixon, “Manned

Expeditions to Mars and Venus,” Eric Burgess, editor, Voyage to the Planets (San Diego, CA: Univelt, Inc.,

1967), pp. 107-35.

32. “U.S. Space Funding Set to Grow Moderately,” pp. 123-24.

33. “House Unit Trims NASA Budget, Fight Pledged for Further Slashes,” Aviation Week & Space Technology

(22 May 1967): 24.

34. “Space Funds Cut Deeply by House, Senate,” Aviation Week & Space Technology (3 July 1967): 28.

35. “Conferees Vote Space Cut,” Aviation Week & Space Technology (7 August 1967): 24.

36. William Normyle, “Small Hope Seen to Restore Space Funds,” Aviation Week & Space Technology (10 July

1967): 38.

37. Katherine Johnsen, “Webb Refuses to Choose Program for Cuts,” Aviation Week & Space Technology (31

July 1967): 20.
Endnotes

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 109

38. Hotz, “New Era for NASA,” p. 17.

39. Spacecraft Engineering Branch, Apollo-based Venus/Mars Flybys (Houston: NASA MSC, September 1967).

40. Contracting Officer to Prospective Contractors, “Planetary Surface Sample Return Probe Study for

Manned Mars/Venus Reconnaissance/Retrieval Missions,” Request for Proposal No. BG721-28-7-528P, 3

August 1967.

41. Irving Stone, “Manned Planetary Vehicle Study Proposed,” Aviation Week & Space Technology (2 October

1967): 87.

42. William Normyle, “Priority Shift Blocks Space Plans,” Aviation Week & Space Technology (11 September

1967): 27.

43. Ezell and Ezell, On Mars, p. 118.

44. “White House Stand Blocks NASA Budget Restoration,” Aviation Week & Space Technology (28 August

1967): 32.

45. Ezell and Ezell, On Mars, p. 142.

Chapter 5

1. NASA, “Outline of NASA Presentation to Space Task Group, August 4, 1969” (28 July 1969), p. 20.

2. Wernher von Braun, “The Next 20 Years of Interplanetary Exploration,” Astronautics & Aeronautics

(November 1965): 24.

3. NASA, Astronautics and Aeronautics 1967 (Washington, DC: NASA SP-4008), pp. 339-41.

4. James Dewar, “Atomic Energy: The Rosetta Stone of Space Flight,” Journal of the British Interplanetary

Society (May 1994): 200.

5. Ibid., p. 202.

6. John Kennedy, “Excerpts from ‘Urgent National Needs,’” Logsdon, gen. ed., Exploring the Unknown, Vol. I,

p. 454.

7. Dewar, “Atomic Energy,” p. 203-04.

8. Raymond Watts, “Manned Exploration of Mars?” Sky & Telescope (August 1963): 64.

9. William House, “The Development of Nuclear Rocket Propulsion in the United States,” Journal of the

British Interplanetary Society 19, No. 8 (March-April 1964): 317-18.

10. Boeing Aerospace Group, Integrated Manned Interplanetary Spacecraft Concept Definition, Vol. 1,

Summary (Seattle, Washington: NASA CR-66558, January 1968).
Endnotes

110 Monographs in Aerospace History

11. North American Rockwell Corporation Space Division, Definition of Experimental Tests for a Manned

Mars Excursion Module: Final Report, Vol. 1, Summary (SD 67-755-1, 12 January 1968).

12. Arthur Hill, “Apollo Shape Dominates NAR Manned Mars Study,” Aerospace Technology (6 May 1968): pp.

26.

13. “Cost of Tet,” Aviation Week & Space Technology (27 May 1968): 25.

14. “Congressional Critics Aim to Cut NASA Budget to $4-Billion Level,” Aviation Week & Space Technology

(12 February 1968): 22.

15. Katherine Johnsen, “NASA Gears for $4-Billion Fund Limit,” Aviation Week & Space Technology (27 May

1968): 30.

16. “Webb Urges Full $4-Billion NASA Fund,” Aviation Week & Space Technology (1 July 1968): 22.

17. Administrator to Associate Administrator for Manned Space Flight, “Termination of the Contract for

Procurement of Long Lead Time Items for Vehicles 516 and 517,” Logsdon, gen. ed., Exploring the

Unknown, Vol. I, pp. 494-95.

18. “Work on Future Saturn Launchers Halted,” Aviation Week & Space Technology (12 August 1968): 30.

19. NASA, Astronautics and Aeronautics 1968 (Washington, DC: NASA SP-4010), pp. 212-13.

20. NASA, Astronautics and Aeronautics 1968 (Washington, DC: NASA SP-4010), p. 215.

21. William Normyle, “NASA Plans Five-Year Fund Rise,” Aviation Week & Space Technology (14 October

1968): 16.

22. Bureau of the Budget, “National Aeronautics and Space Administration: Highlight Summary,” 30 October

1968, Logsdon, gen. ed., Exploring the Unknown, Vol. I, pp. 497-98.

23. Courtney Brooks, James Grimwood, and Loyd Swenson, Jr., Chariots for Apollo, A History of Manned

Lunar Spacecraft (Washington, DC: NASA SP-4205, 1979), p. 279.

24. Ibid., pp. 256-60.

25. Arthur Schlesinger, Jr., The Almanac of American History (Greenwich, CT: Brompton Books, 1993), p. 581.

26. “Against the Tide,” Aviation Week & Space Technology (17 March 1969): 15.

27. Heppenheimer, The Space Shuttle Decision, pp. 115-16.

28. Roger Launius, “The Waning of the Technocratic Faith: NASA and the Politics of the Space Shuttle

Decision,” Philippe Jung, editor, History of Rocketry and Astronautics, AAS History Series, Volume 21 (San

Diego, CA: Univelt, Inc., 1997), p. 190.

29. Heppenheimer, The Space Shuttle Decision, p. 127.
Endnotes

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 111

30. NASA, Astronautics and Aeronautics 1968 (Washington, DC: NASA SP-4010), pp. 215.

31. Charles Townes, et al., “Report of the Task Force on Space,” 8 January 1969, Logsdon, gen. ed., Exploring

the Unknown, Vol. I, p. 502.

32. Ibid., p. 505.

33. Heppenheimer, The Space Shuttle Decision, pp. 121-22.

34. Dwayne Day, “Viewpoint: Paradigm Lost,” Space Policy (August 1995): 156.

35. Heppenheimer, The Space Shuttle Decision, pp. 127-28.

36. William Normyle, “NASA Aims at 100-man Station,” Aviation Week & Space Technology (24 February

1969): 16.

37. Richard Nixon, “Memorandum for the Vice President, the Secretary of Defense, the Acting Administrator,

NASA, and the Science Advisor,” 13 February 1969, Logsdon, gen. ed., Exploring the Unknown, Vol. I, p. 513.

38. Thomas Paine, “Problems and Opportunities in Manned Space Flight,” Logsdon, gen. ed., Exploring the

Unknown, Vol. I, pp. 513-19.

39. Logsdon, “From Apollo to the Space Shuttle,” pp. III-7 - III-8; Heppenheimer, The Space Shuttle Decision,

pp. 130-31.

40. NASA, “Integrated Manned Space Flight Program, 1970-1980” (12 May 1969).

41. Ibid., p. 2.

42. Logsdon, “From Apollo to the Space Shuttle,” p. IV-50.

43. Logsdon, “From Apollo to the Space Shuttle,” p. IV-40.

44. NASA, Astronautics and Aeronautics 1969 (Washington, DC: NASA SP-4014), pp. 235-36.

45. NASA, Astronautics and Aeronautics 1969 (Washington, DC: NASA SP-4014), p. 239.

46. “Washington Roundup,” Aviation Week & Space Technology (21 July 1969): 15.

47. NASA, Astronautics and Aeronautics 1969 (Washington, DC: NASA SP-4014), p. 270.

48. NASA, Astronautics and Aeronautics 1969 (Washington, DC: NASA SP-4014), p. 271.

49. NASA, “Outline of NASA Presentation to Space Task Group, August 4, 1969” (28 July 1969), p. 20.

50. Wernher von Braun, “Manned Mars Landing Presentation to the Space Task Group,” presentation materials 

(4 August 1969).

51. Ibid., p. 4.
Endnotes

112 Monographs in Aerospace History

52. Ibid., pp. 22-24.

53. Ibid., p. 26.

54. Ibid., p. 35.

55. Ibid., pp. 41-43.

56. NASA, “Outline of NASA Presentation,” p. 23.

57. Robert Seamans, Jr., Secretary of the Air Force, to Spiro Agnew, Vice President, letter, 4 August 1969,

Logsdon, gen. ed., Exploring the Unknown, Vol. I, p. 521-22.

58. “Washington Roundup,” p. 15.

59. Logsdon, “From Apollo to the Space Shuttle,” p. IV-53.

60. Ibid.

61. Ibid., pp. 57-63.

62. “Space Manpower,” Aviation Week & Space Technology (11 August 1969): 25.

63. Robert Hotz, “The Endless Frontier,” Aviation Week & Space Technology (11 August 1969): 17.

64. William Normyle, “Manned Mission to Mars Opposed,” Aviation Week & Space Technology (18 August

1969): 16.

65. Ibid., p. 17.

66. NASA, America’s Next Decades in Space: A Report to the Space Task Group (Washington, DC: NASA,

September 1969).

67. Ibid., p. 7.

68. Ibid., p. 1.

69. Space Task Group, The Post-Apollo Space Program: Directions for the Future (Washington, DC: NASA,

September 1969).

70. Logsdon, gen. ed., Exploring the Unknown, Vol. I, pp. 522-23.

71. Space Task Group, The Post-Apollo Space Program, pp. ii-iii.

72. Ibid., p. iv.

73. Ibid.

74. Wernher von Braun interview by John Logsdon, referenced in T. A. Heppenheimer, The Space Shuttle

Decision, p. 152.
Endnotes

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 113

75. Robert Mayo, Director, Bureau of the Budget, “Memorandum for the President, ‘Space Task Group

Report,’” 25 September 1969, Logsdon, gen. ed., Exploring the Unknown, Vol. I, pp. 545-46.

76. “NASA Budget Faces House-Senate Parley,” Aviation Week & Space Technology (29 September 1969): 19.

77. George Mueller to John Naugle, 6 October 1969; Morris Jenkins, Manned Exploration Requirements and

Considerations (Houston: NASA, February 1971), pp. iii-iv.

78. Logsdon, “From Apollo to the Space Shuttle,” p. V-22.

79. “Bill of Fare,” Aviation Week & Space Technology (2 February 1970): 11; NASA, Astronautics and

Aeronautics 1970 (Washington, DC: NASA SP-40), pp. 11-12.

80. “Centers Reviewed,” Aviation Week & Space Technology (19 January 1970): 16.

81. “Space in the 1970s,” Aviation Week & Space Technology (9 February 1970): 11.

82. Schlesinger, p. 586.

83. “Ad Astra per Aspera,” Aviation Week & Space Technology (9 February 1970): 10.

84. Logsdon, “From Apollo to the Space Shuttle,” p. V-40.

85. Space Science and Technology Panel of the President’s Science Advisory Committee, The Next Decade in

Space (Washington, DC: Executive Office of the President, Office of Science and Technology, March 1970),

pp. 3, 22.

86. Ibid., p. i.

87. Ibid., p. 45.

88. Ibid., p. 4.

89. Ibid., p. 52.

90. Launius, “The Waning of the Technocratic Faith,” p. 185.

91. Morris Jenkins, Manned Mars Exploration Requirements and Considerations (Houston: NASA, February

1971), p. iv.

92. Ibid., p. iii.

93. Ibid., p. 4–14.

94. Ibid., p. 2–15.

95. U.S. Congress, Nuclear Rocket Development Program, Joint Hearings before the Committee on

Aeronautical and Space Sciences, United States Senate and the Joint Committee on Atomic Energy, 92nd

Congress of the United States, First Session, 23-24 February 1971, p. 1.
Endnotes

114 Monographs in Aerospace History

96. Ibid., pp. 13-15.

97. Ibid., p. 21.

98. Ibid., p. 34.

99. Ibid., p. 40.

100. “OMB Limits NASA to $15 Million for NERVA,” Aviation Week & Space Technology (4 October 1971): 20.

101. Launius, “The Waning of the Technocratic Faith,” pp. 188-89.

102. NASA, Astronautics and Aeronautics 1972, (Washington, DC: NASA SP-4017), pp. 4-5

103. Dewar, “Atomic Energy,” p. 205.

Chapter 6

1. Benton Clark, “The Viking Results—The Case for Man on Mars,” AAS 78-156, Richard Johnston, Albert

Naumann, and Clay Fulcher, editors, The Future U.S. Space Program (San Diego: Univelt, Inc., 1978), p. 263.

2. Hartmann and Raper, The New Mars, pp. 32.

3. Ray Bradbury, Arthur C. Clarke, Bruce Murray, Carl Sagan, and Walter Sullivan, Mars and the Mind of Man

(New York: Harper and Row, 1973) is an informative and entertaining exploration of changing human perceptions of the planet Mars.

4. Hartmann and Raper, The New Mars, pp. 94-107.

5. Andrew Wilson, Solar System Log (New York: Jane’s, 1987), p. 69.

6. Richard Lewis, “On the Golden Plains of Mars,” Spaceflight (October 1976): 364.

7. Richard Lewis, “The Puzzle of Martian Soil,” Spaceflight (November 1976): 391-95. See also Bevan

French, Mars: The Viking Discoveries (Washington, DC: NASA, 1977), pp. 20-22; Andrew Chaikin, “The

Case for Life on Mars,” Air & Space Smithsonian (February/March 1991): 63-71; Harold Klein, Norman

Horowitz, and Klaus Biemann, “The Search for Extant Life on Mars,” Hugh Kieffer, Bruce Jakosky,

Conway Snyder, and Mildred Mathews, editors, Mars, (Tucson: University of Arizona Press, 1992), pp.

1221-33.

8. Cary Spitzer, editor, Viking Orbiter Views of Mars (Washington, DC: NASA, 1980), pp. 31-32. See also Victor

Baker, Michael Carr, Virginia Gullick, Cameron Williams, and Mark Marley, “Channels and Valley

Networks”; and Christopher McKay, R. L. Mancinelli, Carol Stoker, and R. A. Wharton, “The Possibility of Life

on Mars During a Water-Rich Past,” both in Hugh Kieffer, et al., editors, Mars, pp. 493-522 and 1234-45.

9. Ezell and Ezell, On Mars, pp. 422-23.

10. NASA, Proceedings of the Seventh Annual Working Group on Extraterrestrial Resources (Washington, DC:

NASA SP-229, 1970), p. iii.
Endnotes

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 115

11. J. N. Smith, Manned Mars Missions in the Unfavorable (1975-1985) Time Period, pp. 11-12.

12. Louis Friedman interview by David S. F. Portree, 15 August 1999.

13. R. L. Ash, W. L. Dowler, and G. Varsi, “Feasibility of Rocket Propellant Production on Mars,” Acta

Astronautica (July-August 1978): 705-24.

14. Clark, “The Viking Results,” p. 273.

15. Ibid., p. 274.

16. Other examples of Mars ISRU papers in the 1980s include the following: Benton Clark, “The Chemistry of

the Martian Surface: Resources for the Manned Exploration of Mars,” AAS 81-243, Penelope Boston, editor, The Case for Mars, (San Diego, CA: Univelt, Inc., 1984), pp. 197-208; G. R. Babb and W. R. Stump, “The

Effect of Mars Surface and Phobos Propellant Production on Earth Launch Mass,” Michael Duke and Paul

Keaton, editors, Manned Mars Missions: Working Group Papers, Vol. 1 (Huntsville, AL, and Los Alamos, NM:

NASA M002, NASA/LANL, June 1986), pp. 162-175; R. H. Frisbee, “Mass and Power Estimates for Mars InSitu Propellant Production Systems,” AIAA-87-1900 (papers presented at the AIAA/SAE/ASME/ASEE 23rd

Joint Propulsion Conference, 29 June-2 July 1987); Benton Clark and Donald Pettit, “The Hydrogen

Peroxide Economy on Mars,” AAS 87-214, Carol Stoker, editor, The Case for Mars III: Strategies for

Exploration—General Interest and Overview (San Diego, CA: Univelt, Inc.,1989), pp. 551-57; Robert Ash,

Joseph Werne, and Merry Beth Haywood, “Design of a Mars Oxygen Processor,” AAS 87-263, Carol Stoker,

editor, The Case for Mars III: Strategies for Exploration—Technical (San Diego, CA: Univelt, Inc.,1989), pp.

479-87; Diane L. Galecki, “In-Situ Propellant Advantages for Fast Transfer to Mars,” AIAA-88-2901 (paper

presented at the AIAA/ASME/SAE/ASEE 24th Joint Propulsion Conference, 11-13 July 1988); Thomas

Meyer and Christopher McKay, “The Resources of Mars for Human Settlement,” Journal of the British

Interplanetary Society (April 1989): 147-60; J. R. French, “Rocket Propellants from Martian Resources,”

Journal of the British Interplanetary Society (April 1989): 167-70.

17. Louis Friedman interview, 15 August 1999. Friedman founded The Planetary Society with Carl Sagan and

Bruce Murray in 1980.

18. Robert Ash interview by David S. F. Portree, 29 July 1999. Ash called Friedman “ISRU’s godparent.”

Chapter 7

1. Alcestis Oberg, “The Grass Roots of the Mars Conference,” AAS 81-225, Penelope Boston, editor, The Case

for Mars (San Diego, CA: Univelt, Inc., 1984), p. ix.

2. Tim Furniss, Space Shuttle Log (New York: Jane’s, 1986), pp. 15-18, 34-36.

3. William Stockton and John Noble Wilford, Spaceliner (New York: Times Books, 1981), p. 159.

4. Oberg, “The Grass Roots,” p. ix.

5. Benton Clark interview by David S. F. Portree, 27 August 1999.

6. S. Fred Singer, “The PH-D Proposal: A Manned Mission to Phobos and Deimos,” AAS 81-231, Penelope

Boston, editor, The Case for Mars (San Diego, CA: Univelt, Inc., 1984), pp. 39-65.
Endnotes

116 Monographs in Aerospace History

7. S. Fred Singer, “To Mars By Way of Its Moons,” Scientific American (March 2000): 56-57.

8. Space Sciences Department, Manned Lunar, Asteroid and Mars Missions, Visions of Space Flight: Circa 2001

(Schaumburg, IL: Science Applications International Corporation, September 1984).

9. Louis Friedman, “Visions of 2010,” The Planetary Report (March/April 1985): 5.

10. Louis Friedman interview by David S. F. Portree, 15 August 1999.

11. Friedman, “Visions,” pp. 6, 22.

12. Ibid., p. 22.

13. “Beggs Calls for Start on Space Station,” Space News Roundup (25 June 1982): 1, 3-4.

14. Clarke Covington, “The Role of the Space Operations Center,” presentation materials (28 May 1981).

15. Dave Alter, “Space Operations Center” (Houston, TX: NASA Johnson Space Center Press Release 82-008, 19

February 1982).

16. Presidential Papers of the President: Administration of Ronald Reagan, 1985 (Washington, DC: U.S.

Government Printing Office, 1985), p. 90.

17. Humboldt Mandell, personal communication.

18. Michael Duke interview by David S. F. Portree, 26 August 1999.

19. Paul Keaton interview by David. S. F. Portree, 30 August 1999.

20. R. F. Baillie to R. W. Johnson, “Manned Planetary Exploration Action Item from the Wallops Workshop”

(August 1, 1978); Joseph Loftus, Jr., interview by David S. F. Portree, 15 August 1999.

21. Keaton interview, 30 August 1999.

22. Harrison Schmitt, “A Millennium Project—Mars 2000,” Wendell Mendell, editor, Lunar Bases and Space

Activities of the 21st Century (Houston, TX: Lunar and Planetary Science Institute, 1985), p. 787.

23. Duke interview, 30 August 1999; Keaton interview, 30 August 1999.

24. Ibid.

25. Michael Duke and Paul Keaton, editors, Manned Mars Missions, Working Group Summary Report

(Huntsville, AL, and Los Alamos, NM: NASA M001, NASA/LANL, May 1986); Michael Duke and Paul

Keaton, editors, Manned Mars Missions, Working Group Papers, Vol. 1 and Vol. 2 (Huntsville, AL, and Los

Alamos, NM: NASA M002, NASA/LANL, June 1986).

26. Charles Cravotta and Melanie DeForth, “Soviet Plans for a Manned Flight to Mars” (Office of Scientific and

Weapons Research, U.S. Central Intelligence Agency, 2 April 1985), p. 2.
Endnotes

Humans to Mars: Fifty Years of Mission Planning, 1959–2000 117

27. Ibid.

28. Ibid., p. 7.

29. Ibid., p. 8.

30. Barney Roberts, “Concept for a Manned Mars Flyby,” Manned Mars Missions: Working Group Papers, Vol.

1 (Huntsville, AL, and Los Alamos, NM: NASA M002, NASA/LANL, June 1986), pp. 203-18.

31. Ibid., pp. 213-15.

32. Buzz Aldrin, “The Mars Transit System,” Air & Space Smithsonian (October/November 1990): 47.

33. Charles Rall and Walter Hollister, “Free-fall Periodic Orbits Connecting Earth and Mars,” AIAA No. 71-92

(paper presented at the American Institute of Aeronautics and Astronautics 9th Aerospace Sciences

Meeting, New York, New York, 25-27 January 1971). Cycler proponent Buzz Aldrin was one of Hollister’s

students at MIT before he became a NASA astronaut.

34. S. M. Welch and C. R. Stoker, editors, The Case for Mars: Concept Development for a Mars Research Station

(Boulder, CO: Boulder Center for Science Policy, 10 April 1986).

35. Thomas Paine, “A Timeline for Martian Pioneers,” AAS 84-150, Christopher McKay, editor, The Case for

Mars II (San Diego, CA: Univelt, Inc., 1985), pp. 18-19.

36. Michael Duke, Wendell Mendell, and Barney Roberts, “Lunar Base: A Stepping Stone to Mars,” AAS 84-162,

Christopher McKay, editor, The Case for Mars II (San Diego, CA: Univelt, Inc., 1985), pp. 207-20.

37. Humboldt Mandell, “Space Station—The First Step,” AAS 84-160, Christopher McKay, editor, The Case for

Mars II (San Diego, CA: Univelt, Inc.,1985), pp. 157-70.

38. Welch and Stoker, The Case for Mars: Concept Development, p. 53.

39. For examples, see Robert Farquhar, “Lunar Communications with Libration-Point Satellites,” Journal of

Spacecraft and Rockets (October 1967): 1383, and Robert Farquhar, “A Halo-Orbit Lunar Station,”

Astronautics & Aeronautics (June 1972): 59-63. In 1971, Farquhar became involved in Harrison Schmitt’s

effort to target Apollo 17 to the lunar farside crater Tsiolkovskii. He studied the possibility of placing communication relay satellites in Lagrange point halo orbits to permit continuous communication between the

Apollo 17 moonwalkers at Tsiolkovskii and Mission Control on Earth (“Lunar Backside Landing for Apollo

17,” presentation materials, 2 September 1971).

40. Robert Farquhar and David Dunham, “Libration-Point Staging Concepts for Earth-Mars Transportation,”

Manned Mars Missions: Working Group Papers, Vol. 1 (Huntsville, AL, and Los Alamos, NM: NASA M002,

NASA/LANL, June 1986), pp. 66-77.

41. Paul Keaton, A Moon Base/Mars Base Transportation Depot (Los Alamos, NM: LA-10552-MS, UC-34B, Los

Alamos National Laboratory, September 1985).

42. Ibid., p. 10.
Endnotes

118 Monographs in Aerospace History

Chapter 8

1. [Carl Sagan, Louis Friedman, and Bruce Murray], The Mars Declaration, special supplement to The

Planetary Report (November/December 1987). Author names revealed in Louis Friedman interview, 15

August 1999.

2. National Commission on Space (NCOS), Pioneering the Space Frontier: The Report of the National

Commission on Space (New York: Bantam Books, May 1986).

3. Lyn Ragsdale, “Politics Not Science: The U.S. Space Program in the Reagan and Bush Years,” Spaceflight

and the Myth of Presidential Leadership, Roger Launius and Howard McCurdy, editors (Urbana, IL:

University of Illinois Press, 1997), p. 151.

4. Carole Shifrin, “NASA Nears Final Decisions on Station Configuration,” Aviation Week & Space Technology

(10 March 1986): 107-109; NASA, “NASA Facts: Space Station” (Kennedy Space Center Press Release No.

16-86, January 1986).

5. “NASA Managers Divided on Station,” Aviation Week & Space Technology (28 July 1986): 24-25; Craig

Covault, “Launch Capacity, EVA Concerns Force Space Station Re-Design,” Aviation Week & Space

Technology (21 July 1986): 20; NASA, Space Station Freedom Media Handbook (Washington, DC: NASA,

April 1989), p. 7; Mark Hess, “NASA Proceeding Toward Space Station Development” (Johnson Space

Center Press Release 87-50, 3 April 1987), p. 2.

6. Paul Mann, “Commission Sets Goals for Moon, Mars Settlement in 21st Century,” Aviation Week & Space

Technology (24 March 1986): 18-21.

7. Thomas Paine, “Overview: Report of the National Commission on Space,” Duke Reiber, editor, The NASA

Mars Conference (San Diego: Univelt, Inc., 1988), p. 533.

8. NCOS, Pioneering, p. 191.

9. “Spaced Out,” Aviation Week & Space Technology (15 September 1986): 11.

10. Thomas Paine, “Who Will Lead the World’s Next Age of Discovery?” Aviation Week & Space Technology (21

September 1987): 43.

11. Craig Covault, “Ride Panel Calls for Aggressive Action to Assert U.S. Leadership in Space,” Aviation Week

& Space Technology (24 August 1987): 26.

12. NASA, “Statement by Dr. Sally K. Ride, Associate Administrator for Exploration (Acting) before the

Subcommittee on Space Science and Applications, Committee on Science, Space, and Technology, House of

Representatives” (22 July 1987), p. 1.

13. Sally Ride, Leadership and America’s Future in Space (Washington, DC: NASA, August 1987), p. 5.

14. Ride, Leadership, p. 21.

15. NASA, “Statement by Dr. Sally K. Ride,” p. 2.
Endnotes

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 119

16. Ride, Leadership, p. 53.

17. Ibid., p. 6.

18. Craig Covault, “Ride Panel Calls for Aggressive Action,” p. 26; NASA, Astronautics and Aeronautics 1986-

1990 (Washington, DC: NASA SP-4027), p. 126.

19. Ride, Leadership, p. 55.

20. Craig Covault, “Ride Panel Will Urge Lunar Base, Earth Science as New Space Goals,” Aviation Week &

Space Technology (13 July 1987): 17; see also Michael Collins, Mission to Mars (New York: Grove Weidenfeld,

1990), pp. xii, 197.

21. Ride, Leadership, p. 55.

22. Ibid., p. 22.

23. Ibid., p. 43.

24. NASA, “Statement by Dr. Sally K. Ride,” p. 4.

25. Ride, Leadership, p. 40.

26. “NASA Forms Office to Study Manned Lunar Base, Mars Missions,” Aviation Week & Space Technology (8

June 1987): 22.

27. Ride, Leadership, p. 53.

28. Ibid., p. 47.

29. Science Applications International Corporation, Piloted Sprint Missions to Mars (Schaumberg, IL: Report

No. SAIC-87/1908, Study No. 1-120-449-M26, November 1987).

30. Ibid., p. 2.

31. Ibid., p. 13; University of Texas and Texas A&M University Design Team, “To Mars—A Manned Mars

Mission Study,” Summer Project Report (NASA Universities Advanced Space Design Program, Advanced

Programs Office, Johnson Space Center, August 1985).

32. Ibid., p. 17.

33. NASA, Astronautics and Aeronautics 1986-1990, p. 115.

34. Office of Exploration, Exploration Studies Technical Report, FY 1988 Status, Volume 1: Technical Summary

(Washington, DC: NASA TM-4075, December 1988); Office of Exploration, “FY88 Exploration Studies

Technical Presentation to the Administrator,” presentation materials (25 July 1988).

35. Martin Marietta, Manned Mars System Study (MMSS) Executive Summary (Denver, CO: Martin Marietta,

July 1990).
Endnotes

120 Monographs in Aerospace History

36. Clark interview, 27 August 1999.

37. David S. F. Portree, Thirty Years Together: A Chronology of U.S.-Soviet Space Cooperation (Houston: NASA

CR-185707, February 1993), pp. 26-27.

38. Harvey Meyerson, “Spark Matsunaga 1916-1990,” The Planetary Report (July/August 1990): 26.

39. Philip Klass, “Commission Considers Joint Mars Exploration, Lunar Base Options,” Aviation Week & Space

Technology (29 July 1985): 47.

40. Carl Sagan, “To Mars,” Aviation Week & Space Technology (8 December 1986): 10.

41. The Mars Declaration.

42. Richard O’Lone, “Scientist Sees Space Station Useful Only If Linked to Manned Mars Mission,” Aviation

Week & Space Technology (25 January 1988): 55, 57.

43. Portree, Thirty Years Together, p. 30.

44. V. Glushko, Y. Semyonov, and L. Gorshkov, “The Way to Mars,” The Planetary Report (November-December

1988): 4-8. Translation of Pravda article dated 24 May 1988.

Chapter 9

1. NASA, Report of the 90-Day Study on Human Exploration of the Moon and Mars (Washington, DC: NASA,

November 1989), pp. 9-12 - 9-13.

2. Aaron Cohen interview by David S. F. Portree, 27 August 1999.

3. Craig Covault, “Space Policy Outlines Program to Regain U.S. Leadership,” Aviation Week & Space

Technology (22 February 1988): 20.

4. “NASA Funds $100-Million Pathfinder Program for Mars, Lunar Technology,” Aviation Week & Space

Technology (18 January 1988): 17.

5. Dwayne Day, “Doomed to Fail,” Spaceflight (March 1995): 80.

6. Office of the White House Press Secretary, “Remarks of the President at the 20th Anniversary of Apollo

Moon Landing” (Washington, DC: White House, 20 July 1989).

7. “Space Wraith,” Aviation Week & Space Technology (24 July 1989): 21.

8. Mark Craig interview by David S. F. Portree, 13 September 1999.

9. Richard Truly and Franklin Martin, “Briefing to NASA Employees,” presentation materials (26 July 1989).

10. Ivan Bekey interview by David S. F. Portree, 7 September 1999.
Endnotes

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 121

11. “NASA Accelerates Lunar Base Planning as Station Changes Draw European Fire,” Aviation Week & Space

Technology (18 September 1999): 26-27.

12. Humboldt Mandell interview by David S. F. Portree, 13 September 1999.

13. Cohen interview, 27 August 1999.

14. Ibid.

15. NASA, “Cost Summary,” unpublished chapter in Report of the 90-Day Study on Human Exploration of the

Moon and Mars, p. 2.

16. Ibid., p. 3.

17. Ibid.

18. Ibid., p. 4.

19. Ivan Bekey, “A Smaller Scale Manned Mars Evolutionary Program,” IAF-89-494 (paper presented at the

40th Congress of the International Astronautical Federation, Malaga, Spain, 7-12 October 1989), p. 6.

20. Bekey interview, 7 September 1999.

21. Rod Hyde, Yuki Ishikawa, and Lowell Wood, “An American-Traditional Space Exploration Program: Quick,

Inexpensive, Daring, and Tenacious, Briefing to the National Space Council” (Livermore, CA: LLNL Doc. No.

Phys. Brief 89-403, September 1989).

22. Day, “Doomed to Fail,” p. 81.

23. “Space Policy,” Aviation Week & Space Technology (30 October 1989): 15; John Connolly, personal communication.

24. Craig interview, 13 September 1999.

25. Roderick Hyde, Muriel Ishikawa, and Lowell Wood, “Mars in this Century: The Olympia Project,” UCRL98567, DE90 008356, Lawrence Livermore National Laboratory (paper presented at the U.S. Space

Foundation 4th National Space Symposium, Colorado Springs, Colorado, 12-15 April 1988).

26. R. A. Hyde, M. Y. Ishikawa, and L. L. Wood, “Toward a Permanent Lunar Settlement in the Coming Decade:

The Columbus Project” (Lawrence Livermore National Laboratory: UCRL-93621, DE86 006709, 19

November 1985).

27. Hyde, et al., “An American-Traditional Space Exploration Program,” p. 38.

28. Ibid., p. 3-4.

29. “Notice to NASA,” Aviation Week & Space Technology (15 January 1990): 15.

30. Committee on the Human Exploration of Space, Human Exploration of Space: A Review of NASA’s 90-Day

Study and Alternatives (Washington, DC: National Academy Press, 1990), p. x.
Endnotes

122 Monographs in Aerospace History

31. Ibid., p. 28.

32. Ibid., p. 3.

33. Ibid., pp. xii-xiii.

34. Ibid., p. x.

35. “Bush Calls for Two Proposals for Missions to Moon, Mars,” Aviation Week & Space Technology (12 March

1990): 18.

36. Breck Henderson, “Livermore Plan for Exploring Moon, Mars Draws Space Council Attention,” Aviation

Week & Space Technology (22 January 1990): 84.

37. Douglas Isbell, “Congress Says OK to Moon, Mars Work,” Space News (28 May-3 June 1990): 3, 20.

38. Douglas Isbell, “Ex-Astronaut Stafford to Head Moon-Mars Outreach Team,” Space News (4-10 June 1990): 4.

39. Mandell interview, 13 September 1999.

40. Andrew Lawler, “Bush: To Mars by 2019,” Space News (14-20 May 1990): 1.

41. Patricia Guilmartin, “House Kills Funding for Moon/Mars Effort,” Aviation Week & Space Technology (2 July

1990): 28.

42. “Darman Backs NASA,” Aviation Week & Space Technology (21 May 1990): 17.

43. Douglas Isbell and Andrew Lawler, “Senators Assail Bush Plan,” Space News (7-13 May 1990): 1.

44. “Bush Sets 2019 Manned Mars Objective,” Aviation Week & Space Technology (21 May 1990): 19.

45. Andrew Lawler, “Bush Moon-Mars Plan Handed First Defeat,” Space News (18-24 June 1990): 3.

46. NASA, Astronautics and Aeronautics 1986-1990 (Washington, DC: NASA SP-4027), pp. 272-73.

47. Craig Covault, “White House Endorses Plan for Shuttle, Station Scale-Back,” Aviation Week & Space

Technology (17 December 1990): 20; NASA, Astronautics and Aeronautics 1986-1990, p. 287.

48. “U.S. Astronaut to Visit Soviet Station, Cosmonaut to Fly on Shuttle,” Aviation Week & Space Technology (22

October 1990): 24.

49. “Senior Soviet Space Officials Outline Plan for Joint Mars Mission,” Aviation Week & Space Technology (19

November 1990): 67; Arnold Aldrich to Distribution, “Background Material on Cooperation with NPO

Energia” (29 June 1992).

50. Leonard David, “Faster, Cheaper Mars Exploration Proposed,” Space News (11-17 June 1990): 4.

51. Yuri Semyonov and Leonid Gorshkov, “Destination Mars,” Science in the USSR (July-August 1990): 15-18.
Endnotes

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 123

52. Ibid., p. 17.

53. Scientific Industrial Corporation “Energia,” Mars Manned Mission: Scientific/Technical Report (Moscow,

Russia: USSR Ministry of General Machinery, 1991), p. 1.

54. Ibid., p. 15.

55. SEI Synthesis Group, America at the Threshold: America’s Space Exploration Initiative (Washington, DC:

Government Printing Office, May 1991).

56. “Reaching Out,” Aviation Week & Space Technology (4 June 1990): 15; Craig Covault, “Exploration Initiative

Work Quickens as Some Concepts Avoid Station,” Aviation Week & Space Technology (17 September 1990):

36.

57. Astronautics and Aeronautics 1986-1990, p. 255.

58. Covault, “Exploration Initiative Work Quickens,” p. 36.

59. America at the Threshold, p. 52.

60. Ibid., p. 8.

61. Kent Joosten, personal communication.

Chapter 10

1. Kent Joosten, Ryan Schaefer, and Stephen Hoffman, “Recent Evolution of the Mars Reference Mission,”

AAS-97-617 (paper presented at the AAS/AIAA Astrodynamic Specialist Conference, Sun Valley, Idaho, 4-7

August 1997), p. 1.

2. Robert Zubrin with Richard Wagner, The Case for Mars (New York: Free Press, 1996), pp. 51-52; Benton

Clark interview by David S. F. Portree, 30 September 1999.

3. Zubrin and Wagner, The Case for Mars, p. 65.

4. Leonard David, “Faster, Cheaper Mars Exploration,” p. 37.

5. Robert Zubrin and David Baker, “Humans to Mars in 1999,” Aerospace America (August 1990): 30-32, 41.

For other examples, see Zubrin and Benjamin Adelman, “The Direct Route to Mars,” Final Frontier

(July/August 1992): 10-15, 53, 55; Zubrin and Christopher McKay, “Pioneering Mars,” Ad Astra

(September/October 1992): 34-41; Zubrin, “The Significance of the Martian Frontier,” Ad Astra

(September/October 1994): 30-37; Zubrin, “Mars: America’s New Frontier,” Final Frontier (May/June 1995):

42-46; Zubrin, “The Economic Viability of Mars Colonization,” Journal of the British Interplanetary Society

(October 1995): 407-414; Zubrin, “The Promise of Mars,” Ad Astra (May/June 1996): 32-38; Zubrin, “Mars on

a Shoestring,” Technology Review (November/December 1996): 20-31; Zubrin, “Sending Humans to Mars,”

Scientific American Presents (Spring 1999): 46-51; Zubrin, “The Mars Direct Plan,” Scientific American

(March 2000): 52-55.
Endnotes

124 Monographs in Aerospace History

6. Zubrin and Baker, p. 30.

7. Ibid, p. 31.

8. Martin Marietta, Manned Mars System Study (Mars Transportation and Facility Infrastructure Study),

Volume II, Final Report (Denver, CO: Martin Marietta, July 1990), pp. 4-11 - 4-16.

9. Zubrin and Baker, p. 41.

10. Michael Duke and Nancy Anne Budden, editors, Mars Exploration Study Workshop II (Houston: NASA CP3243, November 1993), p. iii.

11. Exploration Programs Office, “EXPO Mars Program Study, Presentation to the Associate Administrator for

Exploration,” presentation materials (9 October 1992).

12. Zubrin with Wagner, The Case for Mars, pp. 66-67.

13. David Weaver and Michael Duke, “Mars Exploration Strategies: A Reference Program and Comparison of

Alternative Architectures,” AIAA 93-4212 (paper presented at the AIAA Space Program and Technologies

Conference, Huntsville, Alabama, 21-23 September 1993).

14. Duke and Budden, Mars Exploration Study Workshop II.

15. Robert Zubrin and David Weaver, “Practical Methods for Near-Term Piloted Mars Missions,” AIAA 93-2089

(paper presented at the AIAA/SAE/ASME/ASEE 29th Joint Propulsion Conference, Monterey, California,

28-30 June 1993), p. 3. In a 30 September 1999 interview with the author, Benton Clark compared the Mars

Direct ERV volume per crewmember to “a telephone booth.” See also David S. F. Portree, “The New Martian

Chronicles,” Astronomy (July 1997): 32-37.

16. Kent Joosten, personal communication.

17. Donald Savage and James Gately, “Mars Observer Investigation Report Released” (Washington, DC: NASA

Headquarters Press Release 94-1, 5 January 1994).

18. Tim Furniss, “Red Light?” Flight International (6-12 October 1993): 28-29.

19. Kent Joosten, personal communication.

20. Donald Savage, James Hartsfield, and David Salisbury, “Meteorite Yields Evidence of Primitive Life on

Early Mars” (NASA Headquarters Press Release 96-160, 7 August 1996).

21. Everett Gibson, David McKay, Kathie Thomas-Keprta, Christopher Romanek, “The Case for Relic Life on

Mars,” Scientific American (December 1997): 58-65.

22. Kent Joosten, personal communication.

23. Associate Administrators for HEDS Enterprise and Associate Administrator for Space Science Enterprise

to Director, Jet Propulsion Laboratory, and Director, Lyndon B. Johnson Space Center, “Integration of Mars

Exploration Study and Planning,” 7 November 1996, p. 1.
Endnotes

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 125

24. Ibid., pp. 1-2.

25. Ibid., p. 2.

26. Douglas Isbell and Michael Braukus, “Space Science and Human Space Flight Enterprises Agree to Joint

Robotic Mars Lander Mission” (NASA Headquarters Press Release 97-51, 25 March 1997).

27. Stephen Hoffman and David Kaplan, editors, Human Exploration of Mars: The Reference Mission of the

NASA Mars Exploration Study Team (Houston: NASA SP-6017, July 1997).

28. Ibid., pp. 1-36 - 1-37, 1-41.

29. Ibid., p. v.

30. Kent Joosten, et al.

31. Michael Duke, editor, Mars Surface Mission Workshop, LPI Contribution 934 (Houston: Lunar and

Planetary Institute, 1998).

32. Mars Exploration Study Team, “Mars Exploration Study Program: Report of the Architecture Team” (presentation materials, 6 April 1999), p. 6. The three-pronged approach to Mars exploration apparently dates

from a March 1995 NASA Solar System Exploration Subcommittee meeting (Don Bogard, personal communication); it became widely applied to NASA Mars planning only after the McKay team’s announcement

in August 1996.

33. Duke, Mars Surface Mission Workshop, p. 8.

34. Bret Drake, editor, Reference Mission Version 3.0, Addendum to the Human Exploration of Mars: The

Reference Mission of the NASA Mars Exploration Study Team, EX13-98-036 (Houston: NASA Johnson Space

Center Exploration Office, June 1998), pp. 33-37.

35. David S. F. Portree, “Walk This Way,” Air & Space Smithsonian (October/November 1998): 45-46.

36. Nancy Anne Budden and Michael B. Duke, editors, HEDS-UP Mars Exploration Forum, LPI Contribution

955 (Houston: Lunar and Planetary Institute, 1998).

37. Michael Duke, editor, Second Annual HEDS-UP Forum, LPI Contribution 979 (Houston: Lunar and

Planetary Institute, 1999).
Humans to Mars: Fifty Years of Mission Planning, 1950–2000 127

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David S. F. Portree is an Arizona-based science writer and historian. His other NASA history publications

include Orbital Debris: A Chronology (with Joseph P. Loftus, Jr., 1999), NASA’s Origins and the Dawn of the

Space Age (1998), Walking to Olympus: An EVA Chronology (with Robert C. Trevino, 1997), and Mir Hardware

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Humans to Mars: Fifty Years of Mission Planning, 1950–2000 141

About the Author
Aaron, John, 73

Abbey, George, 94, 95

Acta Astronautica, 55

aerobraking, 16, 20, 21, 57, 59, 62, 63, 71, 72, 73, 79, 80,

89, 90, 92, 95, 96

Aerojet-General Corporation, 34, 35

Aeronutronic, 12, 13, 15, 16, 23; MEM description, 16 

18; see also EMPIRE

Aerospace Industries Association, 82, 85

Aerospace Technology, 39

Agnew, Spiro, 42, 44, 46, 47

Air Force—see United States Air Force

alcohol, 1

Aldrin, Edwin “Buzz,” 43; and cyclers, 63

ALH 84001, 94

American Astronautical Society (AAS): Symposium on

the Manned Exploration of Mars, 15, 35, 58; Fifth

Goddard Memorial Symposium, 30

American Astronomical Society, 24

American Institute of Astronautics and Aeronautics 

(AIAA), 74, 85; Aerospace America, 89; Steps to

Mars conference, 73-74; 3rd Manned Spaceflight 

Conference, 16

Ames Research Center (ARC)—see under NASA

Anders, William, 41

Anderson, Clinton, 5, 34, 35, 46, 52

Antarctica, 2, 94

Antoniadi crater, 17

Apollo Applications Program (AAP), 24, 26, 29, 30, 31,

32, 42, 46

Apollo mission modes: Direct-Ascent, 7, 8; Earth-Orbit 

Rendezvous (EOR), 7; Lunar Orbit Rendezvous 

(LOR), 8, 9; LOR impact on Mars plans, 8-9

Apollo Program, 2, 7, 8, 11, 12, 15, 18, 21, 24-27, 29, 30,

33, 37, 38, 40, 42, 45-49, 51, 53, 55, 58, 70, 73, 74,

77, 78, 82, 86, 94, 95, 98; poorly timed as lead-in 

to piloted Mars flights, 11; deviation from von 

Braun plan, 12

Apollo missions: Apollo 1, 30; Apollo 4, 33; Apollo 7, 40;

Apollo 8, 41, 49; Apollo 10, 86; Apollo 11, 43, 46,

47, 48, 57, 63, 70, 77; Apollo 13, 41; Apollo 15, 51;

Apollo 17, 60; Apollo 20, 48

Apollo-Soyuz Test Project, 57, 73

Apollo technology: Command and Service Module 

(CSM), 13, 21, 22, 26, 28, 30, 33, 36, 37, 39, 40, 41,

43, 57; Command Module (CM), 13, 14, 22, 25, 26,

33, 36, 37, 61, 81, 85, 86; Lunar Module (LM), 18,

21, 41, 43, 63; Lunar Roving Vehicle, 51; Service 

Module (SM), 13, 22; as source of Mars mission 

technology, 9, 21, 26, 58; see also Saturn rockets,

Saturn rocket modifications

Ares Vallis, 95

argon, 17, 58

Armstrong, Neil, 2, 43, 45, 67

Army—see United States Army

artificial gravity, 2, 8, 13, 14, 20, 21, 51, 59, 80, 81, 89, 90

Ash, Robert, 55, 56, 89, 90

Asteroid Belt, 13, 27, 29

Atlas missile, 13, 20

Atomic Energy Commission (AEC), 5, 12, 26, 33, 34, 35,

42, 52; Los Alamos National Laboratory (LANL),

34, 61, 62, 84, 86

Aviation Week & Space Technology, 30, 31, 41, 42, 43,

46, 48, 68, 69, 70, 74, 78, 86

Baikonur Cosmodrome, 74

Baker, David, 89-91

ballute, 38

Bay of Pigs, 6

Beggs, James, 73

Bekey, Ivan, 80; and Office of Exploration task force,

80-81

Bellcomm, 25, 29

Berlin Airlift, 1

Bialla, Paul, 82

Bible, Alan, 52

biological contamination, 17, 31, 45, 51, 95

Boeing Company, 44, 50, 73; Mars “cruiser” description,

36-39

Bonestell, Chesley, 2

Borman, Frank, 41

Boulder Center for Science and Policy, 63

British Interplanetary Society, 35

Bush, George, 67, 75, 77-85, 87; launches Space 

Exploration Initiative, 77-78; sets timetable for 

Americans on Mars, 83

Cannon, Howard, 40

Cape Kennedy, 53

Capitol Hill, 23, 29, 30, 49, 52; see also Congress

carbon dioxide, 17, 20, 23, 55, 56, 67, 90, 93

carbon monoxide, 55, 64, 90

Carter, Jimmy, 60

Case for Mars, The, 57, 58, 63, 67, 84, 87, 89; “Mars 

Underground,” 57, 58

Cecropia region, 17

Centaur upper stage, 13

Central Intelligence Agency—see under United States 

Government

Humans to Mars: Fifty Years of Mission Planning, 1950–2000 143

Index
cesium, 7, 8

Chaffee, Roger, 30

chemical propulsion, 5, 7, 12, 13, 16, 34, 50, 58, 84, 97, 98

Chernobyl, 84

Chryse Planitia, 54

Clark, Benton, 53, 56, 58, 63, 84, 89; “The Viking 

Results—the Case for Man on Mars,” 56, 58

Clinton, William, 85

Cohen, Aaron, 77, 78, 79, 80, 81

Cold War, 6, 73, 74, 77, 81

Collier’s, 2, 3, 7, 42, 98

Collins, Michael, 43; and NASA Advisory Council Task 

Force, 70

Congress, 5, 6, 7, 23, 24, 30, 31, 34, 35, 39, 40, 44, 52, 67,

77, 78, 82, 83; funds first NASA Mars study, 5;

response to NASA Space Task Group presenta

tion, 46, 47; response to Space Exploration 

Initiative, 78, 82-84; see also House of 

Representatives, Senate

conjunction-class mission, 2, 19, 37, 55, 56, 80, 89, 91

Connolly, John, vii

Cooke, Doug, 94

coriolis effect, 8

Cornell University, 74

Craig, Mark, 78

Crippen, Robert, 57

Crocco, Gaetano, 11, 12

Crocco-type flyby, 11, 15, 63

cyclers, 63, 64, 68

Darman, Richard, 77, 83

Deimos, 13, 53, 58, 81

Democrat, 5, 31, 32, 34, 39, 40, 41, 47, 52, 83

Department of Commerce—see under United States 

Government

Department of Defense—see under United States 

Government

Department of Energy, 81, 82, 85; Lawrence Livermore 

National Laboratory (LLNL), 81, 82

Department of State—see under United States 

Government

Department of Transportation—see under United 

States Government

Design Reference Mission (DRM), 89, 91, 94, 95, 96, 97;

cargo lander, 92, 93, 96, 98; Earth-Return Vehicle,

91, 92, 93, 96, 98; Habitat, 92, 93, 95, 96, 98; HighEnergy Elliptical Parking Orbit (HEEPO), 98;

Human Exploration of Mars: The Reference 

Mission of the NASA Mars Exploration Study 

Team, 95; Mars Ascent Vehicle (MAV), 91, 92, 93;

Mars Exploration Study Team, 91, 93; relation

ship to Mars Direct, 91-92; “scrubbed” DRM, 95,

98; Solar-Electric Transport Vehicle (SETV), 97,

98; surface payload, 96-97; “three-pronged 

approach” to Mars science, 97

Disney, Walt, 7

Dixon, Franklin, 16, 17, 18; “Manned Expeditions to 

Mars and Venus,” 30

Douglas Aircraft Company, 18

Dowler, William, 55, 56, 90

Dubridge, Lee, 42, 44

Dukakis, Michael, 83

Duke, Michael, 63, 96, 97, 98

Dunham, David, 64

Eagle Engineering, 68, 73

Economist, The, 49

Ehricke, Krafft, 13-15

electric propulsion, 5, 7, 8, 58, 68, 84, 85, 97

Eisenhower, Dwight, 5-7

EMPIRE (Early Manned Planetary Interplanetary 

Roundtrip Expeditions), 9, 11, 12, 14, 15, 18, 19,

21, 29, 35, 36, 73

encounter mission—see under piloted Mars flyby

Energia rocket, 74, 75, 84, 85; and Buran shuttle, 75

Explorer 1, 4, 6, 7, 47

Explorer 3, 6

Ezell, Edward, 21

Faget, Maxime, 12, 15, 21, 23, 30, 50, 85

Farquhar, Robert, 64

Finger, Harold, 35

First Lunar Outpost (FLO), 91

Fisher, William, 83

Flanigan, Peter, 49

Fletcher, James, 52, 69, 70

flyby—see piloted Mars flyby

Flyby-Landing Excursion Mode (FLEM), 29

Flyby-Rendezvous mode, 15, 16, 59

Ford, Gerald, 55, 82

Freeman, Fred, 2

Friedman, Louis, 55, 58, 59

Frosch, Robert, 60

Fulbright, J. W., 47

Future Projects Office—see under Marshall Space 

Flight Center

Gagarin, Yuri, 6

Gemini, 12, 29, 30, 31, 33

144 Monographs in Aerospace History

Index
General Dynamics, 12, 13, 14, 15, 18, 82; see also

EMPIRE

General Electric, 40

Genesis, 41

Glushko, Vladimir, 74

Gorbachev, Mikhail, 73, 74, 84, 85

Gore, Albert, 83

Gorshkov, Leonid, 74, 84

Gramm-Rudman deficit reduction legislation, 83

Gray, Edward, 25; “Manned Expeditions to Mars and 

Venus,” 30

Great Exploration, The, 81-82

Green, Bill, 83 

Griffin, Michael, 91

Grissom, Gus, 30

Gusev crater, 54

Haber, Heinz, 2

Habitability of Mars, The, 58

halo orbit, 64

Hammock, David, 15, 16

Hatfield, Mark, 46

heavy-lift rocket, 60, 61, 63, 68, 71, 72, 80, 84, 85, 86, 89,

91, 92, 96, 97; Advanced Launch System, 79; HL 

Delta rocket, 81; Nova rocket, 7, 9, 12, 13; Titan 

VI rocket, 81; see also Energia rocket, Saturn 

rocket, Saturn rocket modifications, Shuttlederived rocket

Hellas basin, 43

Hellespontus region, 43

Heppenheimer, T. A., 11

Hitler, Adolf, 13

Holland, Spessard, 31

Hollister, Walter, 63

Hoffman, Stephen, 89

Hotz, Robert, 31, 46

Houbolt, John, 8

House, William, 35

House of Representatives, 31, 32, 83, 84;

Appropriations Committee, 83; Science and 

Astronautics Committee, 47; Space Committee,

26, 31, 39, 68; Subcommittee on Housing and 

Urban Development and Independent Agencies,

83; Subcommittee on Space Science and 

Applications, 32, 69, 70

Hubble Space Telescope, 83

Human Exploration and Development of SpaceUniversity Partners (HEDS-UP), 98, 99.

Humphrey, Hubert, 40

Huntress, Wesley, 94, 95

hydrogen, 5, 13, 22, 26, 33, 34, 35, 36, 43, 44, 51, 55, 57,

61, 72, 81, 83, 89, 90, 92, 93

hydrogen peroxide, 56

inflatable structures, 1, 2, 3, 81, 97

In-Situ Resource Utilization (ISRU), 55, 56, 58, 62-64,

79, 80, 86, 89, 91, 92, 95, 99

integrated program, 26

Integrated Program Plan (IPP), 42-44, 48, 78

Interplanetary Shuttle Vehicle (ISV), 64

International Astronautical Federation Congress, 11, 80

International Sun-Earth Explorer-3, 64

International Space Year, 69

Internet, 98, 99

Jackson, Bruce, 15, 16

Jenkins, Morris, 50-51

Jet Propulsion Laboratory (JPL), 61, 63, 74, 77, 78, 79,

85, 87, 91, 93, 94, 95, 97; and Voyager, 25; and 

ISRU, 55

Johnson, Lyndon, 21, 24, 29-32, 34, 35, 39-42; cancels 

Reactor-In-Flight-Test (RIFT), 35; requests 

NASA’s post-Apollo plans, 24

Johnson Space Center (JSC), 15, 60, 61, 77, 79, 94;

Exploration Directorate, 87, 93; Exploration 

Office, 94, 95; Lunar-Mars Exploration Program 

Office, 78; Office of the Curator, 94; Planetary 

Projects Office, 93, 94; see also Manned 

Spacecraft Center

Johnson, U. Alexis, 42

Joosten, Kent, vii, 89

Jupiter (planet), 7, 53

Jupiter-C rocket, 7

Kaplan, Joseph, 2

Karth, Joseph, 32

Keaton, Paul, 61, 64

Kennedy, John F., 7, 8, 12, 24, 29, 33-35, 41, 48, 49, 75,

77; decision to go to the Moon, 5-6, 15; and 

nuclear rockets, 34-35

Kennedy, Robert, 39

Kennedy Space Center (KSC), 25, 29, 30, 33, 37, 49, 57,

80, 89; Pad 39C, 28, 31, 37

Kennedyesque proclamation, 78

kerosene, 33

Keyworth, George, 69

King, Martin Luther, Jr., 39.

Kirkpatrick, Jeane, 67

Klep, Rolf, 2

Koelle, Heinz, 11, 21

145

Index

Humans to Mars: Fifty Years of Mission Planning, 1950–2000
Kraft, Christopher, 85

Lagrange, Joseph, 64

Lagrange point station, 63, 68; as stepping stone to 

Mars, 64

Laird, Melvin, 42

Langley Research Center, 8, 15, 20, 32, 36, 42; supports 

ISRU research, 56

Launius, Roger, 41

Leadership and America’s Future in Space (Ride 

Report), 69-73, 81, 89

Lewis Research Center, 5, 6, 8, 9, 15, 19, 34, 85, 97, 98;

and first NASA Mars study, 5-6, 37; and Design 

Reference Mission, 97-98; see also NASA—Glenn 

Research Center at Lewis Field

Ley, Willy, 2, 3

Life Systems, 73

lifting body, 13, 15, 16, 17, 20, 23

lithium, 85

Lockheed Missiles and Space Company, 12, 13, 14, 29,

35; see also EMPIRE

Logsdon, John, vii, 48

Los Alamos National Laboratory (LANL)—see under 

Atomic Energy Commission (AEC)

Los Angeles Herald-Examiner, 43

Lovell, James, 41

Low, George, 41, 49, 52, 74

Lowell, Percival, 23, 53

Lunar and Planetary Institute, 97

Lunar Bases and Space Activities of the 21st Century, 61

Lunar Orbiter, 53

Lunokhod 2, 95

Manarov, Musa, 74

Mandell, Humboldt, 63, 79

Manned Mars Mission (MMM): study, 51, 61, 84; work

shop, 61, 64

Manned Spacecraft Center (MSC), 15, 16, 19, 25, 31, 32,

37, 41, 49, 50, 59, 60, 80; and Planetary Missions 

Requirements Group, 49-51; see also Johnson 

Space Center

Margaritifer Sinus region, 3

Mariner, 26, 53; Mariner 2, 12, 23; Mariner 4, 22, 23, 24,

25, 30, 37, 44; Mariner 6, 43-44, 53; Mariner 7, 43-

44, 46, 53; Mariner 9, 53, 54, 55, 95

Mars: affect of environment on unprotected human, 54;

atmosphere, 16, 17, 20, 21, 23, 24, 25, 37, 38, 54-

56, 67, 86, 90; canals, 2-4, 23; channels, 53, 54, 95;

dust, 53, 54, 97, 99; opposition, 3, 4, 18, 19, 53, 75;

permafrost, 53, 54; poles, 1, 17, 18, 43, 67; popular 

image, 23, 53, 54, 55; water, 17, 23, 53, 54, 55, 56,

81, 94, 98; as an abode of life, 2, 3, 15, 17, 23, 26,

29, 45, 51, 53, 54, 71, 89, 94, 97, 98; as base/set

tlement site, 2, 19, 21, 45, 55, 56, 60, 62, 63, 70, 71,

79, 80, 81, 89, 90, 91, 92, 93, 97; as revealed by 

Mariner 4, 23; as revealed by Mariner 9, 53, 55;

as revealed by Viking, 54-55

Mars and Beyond, 7

Mars Declaration, The—see under Planetary Society,

The

Mars Direct, 85, 89-92; small Earth-Return Vehicle, 91;

see also Design Reference Mission

Mars Exploration Study Team—see under Design 

Reference Mission

Mars Global Surveyor—see under Mars Surveyor 

Program

Mars Observer, 93, 94, 96

Mars Orbit Rendezvous (MOR), 9, 14, 15, 16, 29, 37, 63,

93; see also piloted Mars landers

Mars Pathfinder, 89, 95; renamed Sagan Memorial 

Station, 95

Mars Surface Sample Return (MSSR) lander—see 

under piloted Mars flyby

Mars Surveyor Program, 94, 95, 96; Mars Global 

Surveyor, 96, 98

Mars Transportation and Facility Infrastructure Study 

—see under Martin Marietta Corporation

“Mars Underground”—see under Case for Mars, The

Marshall Space Flight Center, 7, 9, 11, 12, 15, 18, 20, 21,

24, 25, 35, 44, 49, 55, 61, 73, 89; Future Projects 

Office, 11, 12, 18, 20, 21, 24, 44; Symposium on 

Manned Planetary Missions, 16, 21

Martian meteorite—see ALH 84001

Martin, Franklin, 77, 78

Martin Marietta Corporation, 15, 56, 73, 80, 85, 89, 90;

Mars Transportation and Facility Infrastructure 

Study, 73, 80

Matsunaga, Spark, 73

Mayo, Robert, 42, 44, 46-48

McGill University, 94

McKay, Christopher, 57, 58, 63

McKay, David, 94

Mendell, Wendell, 63

Mercury (planet), 53

Mercury, 12, 15, 31, 33; Freedom 7, 6

Meteor Crater, 98

meteoroids, 8, 13, 14, 17, 19, 23, 62, 97

methane, 38, 39, 55, 56, 90, 91, 92, 93

Mie crater, 54

Miller, George, 47

146 Monographs in Aerospace History

Index
Moon, 1, 2, 5, 6, 7, 9, 11, 14, 22, 24, 28, 29, 33, 34, 41, 42,

43, 45, 47, 48, 49, 53, 54, 60, 61, 64, 70, 77, 78, 79,

80, 81, 82, 83, 84, 86, 94, 95, 96; base site, 12, 43,

47, 60, 61, 68, 70, 73, 77, 78, 79, 81, 86, 89, 91;

“important for the long-range exploration of 

space,” 5, 8; source of oxygen propellant for Mars 

flight, 68, 78; stepping stone to Mars, 15, 63, 70,

73, 77, 78, 86

Morgenthaler, George, 15

Mueller, George E., 25, 26, 40, 42, 43, 46, 48

Murray, Bruce, 74

nanobacteria, 94

National Academy of Sciences, 61, 68; Space Science 

Board, 24; Space Research: Directions for the 

Future, 24

National Advisory Committee on Aeronautics 

(NACA)—see under United States Government

NASA (National Aeronautics and Space Administration),

4, 5, 6, 7, 8, 9, 11, 12, 15, 17, 23, 30, 32, 33, 35, 37,

40, 44, 46, 47, 48, 49, 51, 52, 55, 57, 58, 59, 61, 68,

73, 77, 78, 79, 81, 82, 83, 84, 85, 86, 89, 93, 94, 95,

98; Advisory Council Task Force, 70; Ames 

Research Center (ARC), 19, 49, 63; budget, 5, 23,

24, 25, 29, 30, 31, 32, 39, 40, 42, 46, 48, 49, 52, 59,

68, 70, 77, 78, 83, 84; Exploration Office, 87, 91, 93,

94; Glenn Research Center at Lewis Field, 5;

Goddard Space Flight Center, 64; Headquarters,

15, 25, 27, 82, 94; Human Exploration and 

Development of Space (HEDS) Enterprise, 94, 95;

Manned Planetary Mission Technology 

Conference, 15; Mars Conference, 68; Mission to 

Planet Earth, 69, 84; Office of Exploration, 70, 71,

73, 80, 90, 91; Office of Manned Space Flight 

(OMSF), 25, 27, 30, 40, 42; Planetary Missions 

Requirements Group (PMRG); 48-51, 80; Science 

and Technical Advisory Council, 42; Science and 

Technology Advisory Committee, 25; Space Science 

Enterprise, 94, 95; see also individual NASA 

Centers, Design Reference Mission, Jet Propulsion 

Laboratory (JPL), Planetary Joint Action Group

National Commission on Space (NCOS), 67, 68, 69, 70,

85, 89; Pioneering the Space Frontier, 67

National Press Club, 46

National Research Council (NRC), 77, 82; Committee 

on Human Exploration of Space (Stever 

Committee), 82

National Space Council—see under White House

National Space Society, 89

New York Times, 44

Newsweek, 74

Nicogossian, Arnauld, 94

Niehoff, John, 71, 72

nitric acid, 1

nitrogen, 17, 20, 23, 54

Nix Olympica, 43, 53—see also Olympus Mons

Nixon, Richard M., 6, 34, 40, 41, 42, 47, 48, 49, 52, 74,

82; supports Space Shuttle, 52; Task Force on 

Space, 41, 42, 46

North American Rockwell (NAR), 51, 44, 85; MEM 

description, 37-39

NPO Energia, 84, 85

nuclear reactor, 8, 34, 84, 89, 90

nuclear propulsion, 3, 5, 6, 8, 12, 14, 16, 25, 26, 29, 32,

34, 35, 36, 40, 46, 48, 50, 52, 61, 84, 86, 89, 92, 96,

97; Kiwi, 34, 35; NERVA (Nuclear Engine for 

Rocket Vehicle Application), 33, 34, 35, 36, 40, 41,

43, 44, 45, 48, 52, 96; NRX-A6 ground test, 35;

Reactor-In-Flight-Test (RIFT), 35; ROVER, 34

Nuclear Rocket Development Station (NRDS), 34, 40, 52

Nuclear Shuttle, 43-45

Office of Manned Space Flight (OMSF)—see under 

NASA

Old Dominion University, 55, 56

Olympus Mons, 53; see also Nix Olympica

opposition-class mission, 19, 36, 37, 80

Orbital Transfer Vehicle (OTV), 57, 59, 60, 61, 62, 68,

72, 73

Outreach Program—see under Space Exploration 

Initiative (SEI)

oxygen, 8, 17, 22, 33, 34, 38, 39, 51, 55, 56, 57, 61, 64, 68,

72, 73, 78, 79, 81, 89, 90, 91, 92, 93

Paine, Thomas, 33, 40-44, 46-49, 52, 63, 67-69

Peenemünde, 1, 13

Pentagon, 79; see also United States Government—

Department of Defense

periodic-orbit stations, 63; see also cyclers

PH-D Proposal, 58

Philadelphia Inquirer, 43

Phillips, Samuel, 82

Phobos (Martian moon), 13, 53, 58, 73, 74, 80, 81

Phobos spacecraft, 74-75

piloted Mars flyby, 11-13, 15, 21, 22, 24, 25, 26, 27, 30,

32, 58, 61, 62, 74; Apollo-based Earth-return capsule, 13, 14, 21, 22, 25, 26; automated probe cargo,

12, 13, 21, 22, 25, 26, 27, 28, 31, 32; “cool” versus

“hot” trajectory, 13; deviation from von Braun 

plan, 12; encounter mission, 30, 31; Experiment 

147

Index

Humans to Mars: Fifty Years of Mission Planning, 1950–2000
Module, 25, 27, 28, 29, 31, 32; “manned Voyager,”

25; Mars Surface Sample Return (MSSR) probe,

28, 29, 31, 32; Mission Module, 14, 25, 26, 27, 61;

and Mariner 2, 12; and Mariner 4, 22, 23; and 

“robot caretaker” justification, 12, 22, 23

piloted Mars lander, 80; Aeronutronic Mars Excursion 

Module (MEM), 15-18, 29, 45, 51; Flyby-Landing 

Excursion Module (FLEM) MEM, 29; FlybyRendezvous MEM, 15; Mars Excursion Vehicle 

(MEV), 14-15; Mars Landing Vehicle, 85; NAR 

MEM, 37-39, 44, 51, 85; NASA STG MEM, 44-45;

SAIC Mars lander, 59; TRW MEM, 20; von Braun 

gliders, 1-3, 23

piloted Mars orbiter, 12, 13, 14, 26, 58; see also PH-D 

Proposal

Planetary Joint Action Group (JAG), 24-32, 45;

Planetary Exploration Utilizing a Manned Flight 

System, 26, 27

Planetary Missions Requirements Group (PMRG)—see 

under NASA

Planetary Report, The, 59

Planetary Society, The, 58, 59, 71, 73, 74; fund early 

Mars ISRU research, 56; Mars Declaration, The,

67, 74; Steps to Mars conference, 73, 74

Pluto, 12, 35

post-Apollo space program, 9, 21, 24, 29, 41, 46, 49, 56,

87; see also Apollo Applications Program

post-Saturn rocket, 7, 9, 15, 21, 33; see also Nova rocket

Pravda, 74

President’s Science Advisory Committee (PSAC), 30,

35, 42, 49, 74; The Next Decade in Space, 49; The 

Space Program in the Post-Apollo Period, 30

Progress spacecraft, 84

Project Horizon, 11

Project Pathfinder technology development program,

70, 77, 78

Proton rocket, 74

Pueblo incident, 39

Quayle, Dan, 77, 78, 81, 82, 84

radiation, 6, 13, 14, 19, 23, 58, 62, 64, 71, 85, 90, 97;

spacecraft radiation shelter, 6, 8, 13, 21, 27, 51,

72, 73, 85

radioisotope power unit, 13, 21

Rall, Charles, 63

Rand Corporation, 19, 82, 85

Ranger program, 12, 14, 22, 53

Reagan, Ronald, 60, 67, 68, 69, 73, 74; and “Kennedystyle declaration,” 77

Redstone Arsenal, 7

Redstone missile, 7

Republican, 40, 41, 46, 60, 83

Ride, Sally, 69, 70, 71, 73, 78, 91

Ride Report—see Leadership and America’s Future in 

Space

RL-10 engine, 22

Roberts, Barney, 61, 62, 63

Rocket Team, The, 1

Roentgen Equivalent Man (REM), 6

Rogers Commission, 69

rover, 51, 53, 56, 58, 59, 74, 86, 90, 92, 93, 94, 97; and 

“walk-back” limit, 51; see also tractor

Ruppe, Harry, 11, 15, 21, 22

Ryan, Cornelius, 2

Sabatier, Paul, 55

Sabatier process, 55, 90

Sagan, Carl, 58, 73, 74; see also Mars Pathfinder—

Sagan Memorial Station

Saturn (planet), 53

Saturn rocket, 7, 8; “Big Shot,” 33; Saturn C-5, 13, 15;

Saturn I, 7; Saturn IB, 7, 11, 22, 36; Saturn V, 11,

13, 15, 21, 22, 28, 29, 31, 33-37, 39-41, 44, 48, 49,

52, 57, 74, 89, 91; Saturn V launch description, 33

Saturn rocket modifications: Improved Saturn V,

26, 27; MS-IVB stage, 26, 27, 28, 31; S-IIB stage,

22; uprated Saturn V, 36

Schaefer, Ryan, 89

Science Applications International Corporation (SAIC),

59, 68, 71, 72, 73, 81, 90; Piloted Sprint Missions 

to Mars, 71, 72; split/sprint mission mode, 71-73, 90

Science in the USSR, 84

Schachter, Oscar, 2

Schmitt, Harrison, 60, 61, 74, 84; “Chronicles Plan,” 60;

“Mars 2000 Millennium Project,” 61

Schriever, Bernard, 67

Sea of Tranquillity, 2, 22, 43; Tranquillity Base, 43

Seaborg, Glenn, 42, 44

Seamans, Robert, 25, 40, 42, 44, 46, 85

Semyonov, Yuri, 74, 84

Senate, 34, 52, 84; Appropriations Committee, 31, 32,

40; Foreign Relations Committee, 47; Majority

Leader, 34; Space Committee, 34, 40, 46, 68

Shepard, Alan, 6

Shuttle-derived vehicle, 61, 62, 63, 79, 96, 97; Ares rocket,

89-91; Shuttle-Z, 80

Singer, S. Fred, 58, 60

Sky & Telescope, 15

Smith, Margaret Chase, 46

148 Monographs in Aerospace History

Index
Smithsonian Institution: Air & Space Smithsonian, 63;

National Air and Space Museum, 77

Sohn, Robert, 19, 20, 90

Sojourner rover, 95, 98

solar array, 27, 28, 51, 58, 60, 68, 74, 85, 96, 97

solar flare, 6, 23, 27, 51, 64

Soviet Academy of Science, 61

Soviet Union, 4, 6, 34, 57, 73, 74, 75, 84, 85, 95

Soyuz spacecraft, 85

Space Cooperation Agreement, 73, 74

Space Exploration Initiative (SEI), 73, 77-87, 89, 91, 95;

America at the Threshold, 85, 87; cost estimate,

79-80; 90-Day Study, The, 77-82, 87, 89, 93, 95;

Outreach Program, 82, 83, 85, 87; Synthesis 

Group (Stafford Group), 82, 85, 86, 87, 89, 91, 93

Space News, 82

Space Nuclear Propulsion Office (SNPO), 34, 35

Space Shuttle, 42-46, 48-52, 55, 59, 60, 62, 63, 67, 68, 69,

70, 73, 75, 79, 80, 83, 85; Challenger, 67, 68, 69, 70,

74, 75; Columbia, 57, 60; Discovery, 75; External 

Tank (ET), 57, 80, 89; launch description, 57;

“myth of an economic Shuttle,” 67; orbiter, 57, 67;

Orbiter Maneuvering System (OMS), 57; Solid 

Rocket Boosters (SRBs), 57, 67, 80, 89; Space 

Shuttle Main Engines (SSMEs), 57, 80, 89; Space 

Transportation System (STS), 49; Spacelab, 57,

59; STS-1, 57, 60; STS-4, 60; STS-26, 75; STS-27,

75; STS-51L, 67; source of technology for Mars 

missions, 50, 51, 57, 58; see also Shuttle-derived 

vehicle

Space Station, 1, 2, 3, 6, 12, 24, 40, 42, 43, 44, 45, 46, 49

57, 59, 60, 61, 62, 63, 64, 67, 68, 69, 70, 71, 72, 74,

77, 81, 84, 85, 86, 91, 95; Dual Keel, 67, 68, 79, 84;

International Space Station, 85, 94; Mir, 74, 84,

85; Mir-2, 85; Phase I, 67, 68, 73; Phase II, 67, 70,

84; Salyut, 60, 61, 73; Skylab, 24, 48; Space 

Operations Center (SOC), 60; Space Station 

Freedom, 77, 78, 79, 80, 83, 84, 85, 86, 98; space

port versus laboratory, 60, 70; spaceport function 

de-emphasized, 60, 83-84; source of technology 

for Mars missions, 44, 57-59, 61, 63

space suit, 11, 17, 51, 81, 97, 98

Space Task Group (STG): progenitor of Manned 

Spacecraft Center, 15; charting NASA’s future,

42-46, 48, 49, 52, 68, 69, 78, 89; America’s Next 

Decades in Space: A Report to the Space Task 

Group, 47; Post-Apollo Space Program:

Directions for the Future, The, 47-48

Space Transportation System (STS)—see under Space 

Shuttle

Spacelab—see under Space Shuttle

split-sprint mission mode—see under Science 

Applications International Corporation

split mission architecture, 89

Sputnik 1, 4, 5, 34

Stafford, Thomas, 82, 85, 86, 91

Stanford University, 73, 94

Stever, H. Guyford, 82

Stone, Edward, 94, 95

Stuhlinger, Ernst, 7, 8, 9, 11

Sullivan, Kathy, 67

Surveyor program, 14, 53; Surveyor 4, 93

Symposium on the Manned Exploration of Mars—see 

under American Astronautical Society

telescope, 2, 3, 4, 11, 27, 28, 53

Tet Offensive—see under Vietnam

Texas A&M University, 71, 83

Tharsis Plateau, 53

Time, 74

Titov, Vladimir, 74

Titus, R. R., 29

Townes, Charles, 25, 41

tractor, 2, 3

Trafton, Wilbur, 94, 95

Traxler, Robert, 83

Truly, Richard, 77, 78, 79, 80, 82, 86

TRW Space Technology Laboratory, 19, 20

UMPIRE, 18-19, 21, 55

Unfavorable Manned Planetary Interplanetary 

Roundtrip Expeditions—see UMPIRE

United Aircraft Research Laboratories, 29

United States (U.S.), 1, 6, 12, 13, 22, 24, 31, 33, 34, 39,

43, 44, 47, 57, 58, 61, 67, 68, 73, 74, 75, 83, 84, 86,

93, 98

United States Air Force, 15, 34, 42, 85; Edwards Air 

Force Base, 58

United States Army, 4, 7; Army Ballistic Missile Agency 

(ABMA), 1, 7, 11; Corps of Engineers, 81; see also

U.S. government—Department of Defense

United States government: Central Intelligence 

Agency (CIA), 6, 61, 74; Department of 

Agriculture, 67; Department of Commerce, 67;

Department of Defense, 5, 39, 49, 82, 83, 85;

Department of State, 67; Department of 

Transportation, 67, 85; NACA (National Advisory 

Committee on Aeronautics), 5, 19; National 

Science Foundation, 67, 82; see also Atomic 

Energy Commission; Congress; Department of 

149

Index

Humans to Mars: Fifty Years of Mission Planning, 1950–2000
150 Monographs in Aerospace History

Energy; NASA; United States Air Force; United 

States Army; White House

University of Arizona, 67

University of Illinois Press, 1

University of Texas, 71

urban riots, 29, 31, 32

Utopia Planitia region, 54

V-2 missile, 1, 7

Valles Marineris, 53

Van Allen Radiation Belts, 6, 8, 58, 97, 98

Varsi, Giulio, 55, 56, 90

Vastitas Borealis region, 17

Venus, 12, 13, 20, 23, 26, 32, 37, 45, 53, 58, 62, 80

Vietnam, 24, 29-31, 39, 49; Tet offensive, 39

Viking, 32, 35, 48, 53-57, 60, 68, 74, 93, 95

von Braun, Wernher, 1-4, 6, 7, 11, 13, 19, 21, 23, 33, 42-

48, 98; career apogee, 44; Das Marsprojekt, 1, 3;

The Exploration of Mars, 3; The Mars Project, 1,

2, 7, 11, 19

Vostok 1, 6

Voyager Mars/Venus program, 24-26, 29-32, 35; as victim of piloted flyby planning, 32

Wallops Island, 60

Washington Evening Star, 41

Washington Post, 74

Webb, James, 24, 31, 39, 40, 41

weightlessness, 1, 3, 13, 28, 58, 64, 71, 84, 90

Whipple, Fred, 2

White, Ed, 30

White House, 29, 32, 35, 39, 40, 47, 49, 52, 60, 67, 68, 69,

73, 77, 78, 81, 83; Budget Bureau, 21, 24, 29, 35,

40, 42, 48; National Space Council, 24, 77, 78, 79,

81, 84, 86; Office of Management and Budget 

(OMB), 48, 49, 52, 69, 77; Office of Science and 

Technology Policy, 67; see also individual 

Presidents; President’s Science Advisory 

Committee (PSAC)

Wilkening, Laurel, 67

Wood, Lowell, 81

Working Group on Extraterrestrial Resources (WGER),

55

Yeager, Chuck, 67

Yeltsin, Boris, 85

Young, John, 57

zero gravity—see weightlessness

Zubrin, Robert, 89, 90, 91

Zuckert, Eugene, 15

Index
151

All monographs except #1 are available by sending a self-addressed 9 x 12” envelope for each monograph with

appropriate postage for 15 ounces to the NASA History Office, Code ZH, Washington, DC 20546. A complete listing of all NASA History Series publications is available at http://history.nasa.gov/series95.html on the World

Wide Web. In addition, a number of monographs and other History Series publications are available online from

the same URL.

Launius, Roger D., and Aaron K. Gillette, compilers. Toward a History of the Space Shuttle: An Annotated

Bibliography. Monograph in Aerospace History, No. 1, 1992. Out of print.

Launius, Roger D., and J.D. Hunley, compilers. An Annotated Bibliography of the Apollo Program. Monograph in

Aerospace History, No. 2, 1994.

Launius, Roger D. Apollo: A Retrospective Analysis. Monograph in Aerospace History, No. 3, 1994.

Hansen, James R. Enchanted Rendezvous: John C. Houbolt and the Genesis of the Lunar-Orbit Rendezvous

Concept. Monograph in Aerospace History, No. 4, 1995.

Gorn, Michael H. Hugh L. Dryden’s Career in Aviation and Space. Monograph in Aerospace History, No. 5, 1996.

Powers, Sheryll Goecke. Women in Flight Research at NASA Dryden Flight Research Center from 1946 to 1995.

Monograph in Aerospace History, No. 6, 1997.

Portree, David S. F., and Robert C. Trevino. Walking to Olympus: An EVA Chronology. Monograph in Aerospace

History, No. 7, 1997.

Logsdon, John M., moderator. Legislative Origins of the National Aeronautics and Space Act of 1958: Proceedings

of an Oral History Workshop. Monograph in Aerospace History, No. 8, 1998.

Rumerman, Judy A., compiler. U.S. Human Spaceflight, A Record of Achievement 1961-1998. Monograph in

Aerospace History, No. 9, 1998.

Portree, David S. F. NASA’s Origins and the Dawn of the Space Age. Monograph in Aerospace History, No. 10, 1998.

Logsdon, John M. Together in Orbit: The Origins of International Cooperation in the Space Station. Monograph in

Aerospace History, No. 11, 1998.

Phillips, W. Hewitt. Journey in Aeronautical Research: A Career at NASA Langley Research Center. Monograph in

Aerospace History, No. 12, 1998.

Braslow, Albert L. A History of Suction-Type Laminar-Flow Control with Emphasis on Flight Research. Monograph

in Aerospace History, No. 13, 1999.

Logsdon, John M., moderator. Managing the Moon Program: Lessons Learned Fom Apollo. Monograph in Aerospace

History, No. 14, 1999.

Perminov, V. G. The Difficult Road to Mars: A Brief History of Mars Exploration in the Soviet Union. Monograph in

Aerospace History, No. 15, 1999.

Humans to Mars: Fifty Years of Mission Planning, 1950–2000

NASA History Monographs
152 Monographs in Aerospace History

Tucker, Tom. Touchdown: The Development of Propulsion Controlled Aircraft at NASA Dryden. Monograph in

Aerospace History, No. 16, 1999.

Maisel, Martin, Giulanetti, Demo J., and Dugan, Daniel C. The History of the XV-15 Tilt Rotor Research Aircraft:

From Concept to Flight. Monograph in Aerospace History, No. 17, 2000 (NASA SP-2000-4517).

Jenkins, Dennis R. Hypersonics Before the Shuttle: A Concise History of the X-15 Research Airplane. Monograph in

Aerospace History, No. 18, 2000 (NASA SP-2000-4518).

Chambers, Joseph R. Partners in Freedom: Contributions of the Langley Research Center to U.S. Military Aircraft

of the 1990s. Monograph in Aerospace History, No. 19, 2000 (NASA SP-2000-4519).

Waltman, Gene L. Black Magic and Gremlins: Analog Flight Simulations at NASA’s Flight Research Center.

Monograph in Aerospace History, No. 20, 2000 (NASA SP-2000-4520).

NASA History Monographs