Stanley K. Borowski and Leonard A. Dudzinski

Glenn Research Center, Cleveland, Ohio

“2001: A Space Odyssey” Revisited—The

Feasibility of 24 Hour Commuter Flights

to the Moon Using NTR Propulsion

with LUNOX Afterburners

NASA/TM—1998-208830/REV2 AIAA–97–2956

June 2003

https://ntrs.nasa.gov/search.jsp?R=20030067859 2018-05-15T18:28:50+00:00Z
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Stanley K. Borowski and Leonard A. Dudzinski

Glenn Research Center, Cleveland, Ohio

“2001: A Space Odyssey” Revisited—The

Feasibility of 24 Hour Commuter Flights

to the Moon Using NTR Propulsion

with LUNOX Afterburners

NASA/TM—1998-208830/REV2

National Aeronautics and

Space Administration

Glenn Research Center

Prepared for the

33rd Joint Propulsion Conference

cosponsored by the AIAA, ASME, SAE, and ASEE

Seattle, Washington, July 6–9, 1997

AIAA–97–2956

June 2003
Acknowledgments

The authors wish to express thanks to their respective organizations for support during the course of this study.

One of the authors, Dr. Stanley Borowski, would like to express his gratitude to the following individuals for their

contributions to this paper: Kriss Kennedy (NASA/JSC) for his preliminary assessment of the PTM mass;

noted space artist, Pat Rawlings (SAIC) for artwork depicted on the cover and in Figures 3, 8, 10, and 11;

Melissa McGuire (Analex) for her assistance in the preparation of tables and figures used in this paper.

Available from

NASA Center for Aerospace Information

7121 Standard Drive

Hanover, MD 21076

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22100

Available electronically at http://gltrs.grc.nasa.gov/GLTRS

Document Change History

NASA/TM—1998-208830/REV1, December 2001.

The printing, numbered as NASA/TM—1998-208830/REV1, December 2001, replaced the previous version,

NASA/TM—1998-208830, December 1998.

Nontechnical changes were made to the text and the figures were recreated to improve the quality.

Page 11, figure 6(a): changed to 5 t Cargo

This printing, numbered as NASA/TM—1998-208830/REV2, June 2003, replaces the previous version,
NASA/TM—1998-208830/REV2 1

“2001: A SPACE ODYSSEY” REVISITED—THE FEASIBILITY OF

24 HOUR COMMUTER FLIGHTS TO THE MOON USING

NTR PROPULSION WITH LUNOX AFTERBURNERS

Stanley K. Borowski* and Leonard A. Dudzinski**

National Aeronautics and Space Administration

Glenn Research Center

Cleveland, Ohio 44135

Phone: 216–977–7091 and 216–977–7107

ABSTRACT

The prospects for “24 hour” commuter flights

to the Moon, similar to that portrayed in 2001: A

Space Odyssey but on a more Spartan scale, are

examined using two near term, “high leverage”

technologies—liquid oxygen (LOX)-augmented

nuclear thermal rocket (NTR) propulsion and

“lunar-derived” oxygen (LUNOX) production. Ironrich volcanic glass, or “orange soil,” discovered

during the Apollo 17 mission to Taurus-Littrow, has

produced a 4% oxygen yield in recent NASA

experiments using hydrogen reduction. LUNOX

development and utilization would eliminate the

need to transport oxygen supplies from Earth and

is expected to dramatically reduce the size, cost

and complexity of space transportation systems.

The LOX-augmented NTR concept (LANTR)

exploits the high performance capability of the

conventional liquid hydrogen (LH2)-cooled NTR

and the mission leverage provided by LUNOX in a

unique way. LANTR utilizes the large divergent

section of its nozzle as an “afterburner” into which

oxygen is injected and supersonically combusted

with nuclear preheated hydrogen emerging from

the engine’s choked sonic throat—essentially

“scramjet propulsion in reverse.” By varying the

oxygen-to-hydrogen mixture ratio, the LANTR

engine can operate over a wide range of thrust and

specific impulse (Isp) values while the reactor core

power level remains relatively constant. The thrust

augmentation feature of LANTR means that “big

engine” performance can be obtained using

smaller, more affordable, easier to test NTR

engines. The use of high-density LOX in place of

low-density LH2 also reduces hydrogen mass and

tank volume resulting in smaller space vehicles. An

implementation strategy and evolutionary lunar

mission architecture is outlined which requires

——————————————————————

*Ph.D./Nuclear Engineering, Senior Member AIAA

**Aerospace Engineer, Member AIAA

only Shuttle C or “in-line” Shuttle-derived launch

vehicles, and utilizes conventional NTR-powered

lunar transfer vehicles (LTVs), operating in an

“expendable mode” initially, to maximize delivered

surface payload on each mission. The increased

payload is dedicated to installing “modular” LUNOX

production units with the intent of supplying

LUNOX to lunar landing vehicles (LLVs) and then

LTVs at the earliest possible opportunity. Once

LUNOX becomes available in low lunar orbit

(LLO), monopropellant NTRs would be outfitted

with an oxygen propellant module, feed system

and afterburner nozzle for “bipropellant” operation. Transition to a “reusable” mission architecture

now occurs with smaller, LANTR-powered LTVs

delivering ~400% more payload on each piloted

round trip mission than earlier expendable “all LH2”

NTR systems. As initial lunar outposts grow to

eventual lunar settlements and LUNOX production

capacity increases, the LANTR concept can

enable a rapid “commuter” shuttle capable of

24 hour “one-way” trips to and from the Moon.

A vast deposit of “iron-rich” volcanic glass beads

identified at just one candidate site—located at

the southeastern edge of Mare Serenitatis—

could supply sufficient LUNOX to support daily

commuter flights to the Moon for the next

9000 years!

INTRODUCTION

Approximately 30 years have passed since the

debut of Stanley Kubrick and Arthur C. Clarke’s hit

movie 2001: A Space Odyssey.

1 For many of us

this film brought to life the exciting possibilities

awaiting humankind beyond the Apollo program—

images of commercial spaceplanes, large orbiting

space stations and commuter flights to sprawling

settlements on the Moon. Less than six months

after experiencing the thrill of Dr. Heywood Floyd’s

commuter flight to the Moon on the big screen,

Apollo 8 would orbit our celestial neighbor ten

times on Christmas Eve, followed seven months
NASA/TM—1998-208830/REV2 2

later by the historic lunar landing mission of

Apollo 11. For the authors, the images of the Apollo

astronauts, their spacecraft and the stunning alien

landscapes of Hadley Rille, Descartes and the

Taurus-Littrow valley, all there for the taking,

imprinted on our minds a future vision of lunar

settlement no less dramatic than that portrayed in

2001. After all NASA would have nearly 30 years to

develop the necessary technologies. Unfortunately, national support and public interest in the

Apollo program soon waned, Apollo missions 18,

19 and 20 were canceled, and the resources for a

“post-Apollo” program that envisioned artificial

gravity space stations in both Earth and lunar orbit,

a permanent lunar base and a nuclear rocketpowered human mission to Mars by 1981 never

materialized.

Today, with 2001 just 4 years away, the images

in Kubrick and Clarke’s film seem very distant, and

2100: A Space Odyssey a more appropriate title

for the movie. Although NASA no longer

possesses the systems to send humans to the

Moon, it is poised to begin construction of the

International Space Station (ISS)2 and is currently

engaged in a cooperative agreement with industry

partner, Lockheed Martin, to demonstrate the

technology for a single-stage-to-orbit reusable

launch vehicle (RLV)3. Beyond the ISS, the

Agency’s strategic plan for the Human Exploration

and Development of Space (HEDS)4 envisions the

development and utilization of extraterrestrial

resources and revolutionary propulsion technologies to provide routine and affordable human

space travel to the Moon initially, and then Mars.

However, flat or declining budgets for the

foreseeable future pose a serious threat to

NASA’s ability to develop the high leverage

technologies it needs to open the space frontier to

the public sector.

This paper discusses two key technologies—

”lunar-derived” liquid oxygen (LUNOX) production

and LOX-augmented nuclear thermal rocket

(LANTR) propulsion. These technologies can be

developed in the next 10 to 15 years and can

provide the basis for an “economical” lunar

transportation system (LTS), that can evolve with

time to rival the operational capabilities presented

in 2001 albeit on a more “Spartan” scale. The

LUNOX extraction process, system mass and

power requirements, and features of a commercial

LUNOX production facility are discussed first. This

is followed by a description of the LANTR concept

and a discussion of its operational and performance characteristics. An implementation strategy,

along with mission and transportation system

ground rules and assumptions, is then presented

and used in an evolutionary lunar mission

architecture that compares chemical and NTRpowered lunar transportation vehicles operating

without and with LUNOX. A typical “24 hour”

commuter flight to the Moon is then described

which includes the mission ∆V estimates, a

description of the LANTR-powered commuter

shuttle, and the requirements on the LUNOX

production facility needed to support weekly

flights to the Moon. The paper concludes with a

brief discussion of the potential benefits of LANTR

propulsion for human missions to Mars and beyond.

LUNOX: “THE MOON’S FIRST COMMERCIAL

PRODUCT”

“Lunar-derived” oxygen has been frequently

cited5 as the most promising initial resource to be

developed on the lunar surface. By providing a

local source of oxygen for life support systems,

fuel cells and the “oxygen-rich” chemical rocket

engines used on lunar landing vehicles, initial

mass in low Earth orbit (IMLEO), launch costs

and LTS size and complexity can all be

reduced. Greater quantities of high value cargo

(e.g., people, processing equipment and scientific

instruments) can also be transported in place of

bulk LOX propellant further reducing LTS costs.

Another important reason for considering lunar

oxygen as a potential commercial product is its

abundance. Nearly half the mass of the Moon’s

surface material is oxygen5 and a variety of techniques6 have been identified for its extraction.

Hydrogen reduction of iron oxide in the mineral

“ilmenite” (FeTiO3) has received considerable attention in the past.7,8 The reduction process produces

iron metal, titanium oxide and high temperature

water vapor which is subsequently electrolyzed to

produce the oxygen resource and the hydrogen

catalyst. Conceptual design studies7,8 of LUNOX

production facilities using an “ilmenite-rich” basalt

(lunar rock) feedstock indicated oxygen extraction

efficiencies of ~1% and a mining requirement of

~186 t of lunar material per ton of LUNOX

produced (assuming a 50% basalt content in the

mined material). Using lower ilmenite content lunar

soil or “regolith” as feedstock eliminated the need

to crush and grind tons of rock for ilmenite

extraction but it increased the mining mass ratio to
NASA/TM—1998-208830/REV2 3

~327 t of soil per ton of LUNOX. Preliminary

estimates7 of LUNOX plant mass and power levels

for a soil feedstock system are shown in Figures 1

and 2 as a function of the annual production rate.

0

5 0

100

150

200

250

300

350

400

0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8x103

• Ilmenite Reduction

• Soil Feed

• Nuclear Power 

• 90% Plant Duty Cycle 

• 35% Mining Duty Cycle Nuclear Power

Total cumulative plant mass (t)

Benefication

Mining

Processing

Figure 1.—Variation of LUNOX Production Plant Component Mass With Annual Production Rate.

LUNOX production rate (t/yr)

Total Mass

(w/30% Margin)

0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8x103

• Ilmenite Reduction

• Soil Feed

• Nuclear Power 

• 90% Plant Duty Cycle 

• 35% Mining Duty Cycle 

Benefication

Mining

Processing

Figure 2.—Variation of LUNOX Production Plant Power With Annual Production Rate.

LUNOX production rate (t/yr)

Total Power

(w/30% Margin)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Total cumulative plant power (MWe) 
NASA/TM—1998-208830/REV2 4

Recent reduction experiments9,10,11 performed

at the NASA Johnson Space Center have

produced significantly higher oxygen yields (~3 to

4%) using samples of “iron-rich” mare soil and

volcanic glass, and indicated a direct correlation of

oxygen yield with soil iron content. The iron-rich

volcanic glass, or “orange soil,” discovered during

the Apollo 17 mission to the Taurus-Littrow

valley,12,13 is a particularly attractive feedstock option. It exists in large quantities, is fine grained

and could be fed directly into a LUNOX production

plant with little or no processing prior to reduction.

A 4% oxygen yield also translates into an order of

magnitude reduction in the amount of mined

material (~25 t of volcanic glass feedstock per ton

of LUNOX) and a lowering of the mass and power

requirements for both the production plant and its

support vehicles.

How might a commercial LUNOX operation

develop? The current RLV program could provide

a viable blueprint. An industry-operated, privatelyfinanced venture, with NASA as its initial

customer, could accelerate development of the

necessary technologies, reduce operating costs

to the government,14 stimulate additional commercial lunar activities and underwrite eventual

development of lunar settlements. Commercial operations could also open up space to more private

citizens involved in the particular enterprise and lead

to an eventual lunar tourism business. Space tourism to low Earth orbit (LEO) has been proposed15,16

as a large potential private sector market that could

enable a commercially viable RLV service. After

trips to LEO, the Moon would be the next logical

extension of a space tourism industry.

Our vision of a commercial LUNOX enterprise is

illustrated in Figure 3. Located near the

southeastern edge of Mare Serenitatis (latitude:

~21° North / longitude: ~29° East), not far from the

Taurus-Littrow valley, lies a vast deposit of iron-rich

volcanic glass beads that covers thousands of

square kilometers, is tens of meters thick and

could yield hundreds of millions of tons of LUNOX.

In the left foreground, two lunar industrialists

discuss planned expansions at the LUNOX facility,

while to the northwest, modular production units,

resembling oil rigs on Earth, generate copious

amounts of LUNOX which is stored in wellinsulated tanks adjacent to the facility. To the

north, a bottom-loaded, “Sikorsky-style” LLV lifts

off from the surface carrying a “mobile” LUNOX

tanker vehicle to a propellant depot in LLO, while

at the adjacent landing pad, a second LLV awaits

servicing prior to its next mission. In the right

foreground, increased numbers of government

and industry personnel have taxed the capabilities

of several previously landed habitat modules

necessitating construction of an inflatable dome

for added living space. The dome is covered by an

outer layer of bagged regolith and an inner layer of

hydrogenous material (e.g., plastic, water) to provide

shielding against GCR and secondary neutron

radiation. Lastly, nuclear reactors will be critical to

providing a good return to investors in the LUNOX

enterprise. They provide abundant power at low

mass to support continuous operation of the

teleoperated surface vehicles, production units and

habitat modules even during the two-week lunar

night. As production capacity increases, the LUNOX

enterprise can expand its commercial operations to

include metals processing (e.g., iron and titanium),

power generation, maintenance and operations of

surface-based LLVs and LLO propellant depots,

and ultimately a lunar tourism industry.

“REVOLUTIONARY PROPULSION THROUGH

EVOLUTIONARY DEVELOPMENT”

A variety of lunar transportation system concepts were examined by NASA17 and the Synthesis

Group18 in the late 1980’s and early 1990’s. Most

of these used liquid oxygen and hydrogen

(LOX/LH2) chemical propulsion and were expendable or partially reusable at best. The reusable

designs used a large aerobrake to return the LTV

back to LEO while the LLV was expended in LLO.

Concurrent with these studies, the individual

benefits of extraterrestrial resources and NTR

propulsion were also being examined. The

importance of LUNOX for both reducing the direct

expense of going to the Moon and increasing the

viability of a “self-sufficient” long-term lunar base

was highlighted by the Synthesis Group in its

Space Resource Utilization architecture.18,19

During the same time period, NTR propulsion

was examined by Glenn Research Center (GRC)

because of its high specific impulse (Isp ~850-

1000 s) and engine thrust levels (~15-75 klbf).

Analysis of a lunar NTR system20 indicated a

number of attractive mission benefits which

included: (1) an “all propulsive” mission architecture; (2) full recoverability of both the NTRpowered LTV and its LLV payload at mission end

(see Figure 4); and (3) a lower IMLEO than that of the

partially reusable, aerobraked chemical system.
NASA/TM—1998-208830/REV2

5

Figure 3.—"Commercial" LUNOX Facility Depicting Modular Production Units, Reusable Surface-based LLVs, Nuclear Power Systems and Habitation Modules for Industry and Government Personnel. Converted Passenger Transport Module Prepares to Dock at Lunar Base Airlock.
NASA/TM—1998-208830/REV2 6

Reusability of the NTR system from the outset,

however, required investing in a supporting LEO

infrastructure—specifically a LH2 propellant depot

or expendable tanker— to refuel the vehicle for the

next mission. The use of low density LH2 as reactor

coolant and exhaust propellant also increased LTV

size and necessitated large diameter (~10 m)

payload shrouds to launch vehicle components.

To exploit the performance capability of the NTR,

reduce vehicle size and capitalize on the availability

of LUNOX at the Moon, an innovative propulsion

concept was proposed by GRC and Aerojet21,22

which combines conventional LH2-cooled NTR

and supersonic combustion ramjet (scramjet)

technologies. Known as the LOX-augmented NTR

(LANTR), it provides the basis for a “revolutionary”

LTS architecture possessing a variety of engine,

vehicle and mission benefits.

LANTR: “THIS IS NOT YOUR FATHER’S NTR”

The LANTR concept is a “trimodal” engine which

can operate as a conventional LH2-cooled NTR, a

bipropellant LOX/LH2 engine and a power reactor.

Its principal components include a nuclear fission

reactor and nozzle to heat and expand propellant,

hydrogen and oxygen feed systems and tankage,

and a closed Brayton cycle system for electric

power generation and engine “cooldown” assist.

During LANTR operation, oxygen is injected into

the large divergent section of the NTR nozzle

which functions as an “afterburner” (see Figure 5).

Here, it burns spontaneously with the reactorheated hydrogen emerging from the LANTR’s

sonic nozzle throat adding both mass and chemical

energy to the rocket exhaust—essentially “scramjet

propulsion in reverse.”

Figure 4.— Fully Reusable NTR Lunar Scenario.

NTR/LEV Propulsive Return

(LEV w/Crew Returns to ISS;

NTR Remains in LEO)

NTR

Resupplied

by Tanker

Lunar Orbit Insertion Followed

by NTR/LEV Separation

Lunar Excursion Vehicle

on Lunar Surface

NTR/LEV Rendezvous 

& Docking for Return

NTR/LEV Trans-Lunar Injection

(LEV Serviced at ISS)

ISS
NASA/TM—1998-208830/REV2 7

augmentation feature means that “big engine”

performance can be obtained using smaller, more

affordable, easier to test NTR engines. Shortened

burn times also extend engine life and can improve

“life cycle costs”—an important consideration in

realizing “low cost access through space.”

Similarly, reactor preheating of hydrogen before

oxygen injection and combustion results in

higher Isp values than found in LOX/LH2 chemical

engines operating at the same mixture ratio

(~100 s at MR = 6). Lastly, the increased use of

high-density LOX in place of low-density LH2, and

the ability to resupply or “reoxidize” LANTR

vehicles with LUNOX in LLO prior to Earth return,

are expected to significantly reduce vehicle size

and mass while increasing delivered payload.

A POSSIBLE STRATEGY FOR IMPLEMENTING

LUNOX AND LANTR TECHNOLOGIES

An “evolutionary” mission architecture employing lunar orbit rendezvous has been examined

by GRC which attempts to: (1) reduce “up-front”

investment costs for in-space infrastructure;

(2) eliminate the need for a new large heavy lift

booster; (3) maximize surface payload per lunar

Downstream nozzle injection in LANTR isolates

the reactor core from oxygen’s damaging effects

and a “cascade” scramjet injector developed by

Aerojet21 helps control the oxygen addition and

heat release within the nozzle to keep the flow

supersonic. The cascade injector design also

offers the potential for increased penetration,

mixing and combustion of the oxygen injectant in

the supersonic hydrogen flow while minimizing

shock losses and nozzle wall “hot spots,” thereby

maximizing engine performance and life. The high

reactor outlet pressure of LANTR (~2000 psia) also

enables high area ratio nozzles (ε = 500 to 1),

important for combustion efficiency, at reasonable

size and mass.

The LANTR has the potential to be an extremely

versatile propulsion system. By varying the

oxygen-to-hydrogen (O/H) mixture ratio (MR), the

engine can operate over a wide range of thrust

and Isp values (Figure 5) while the reactor core

produces a relatively constant power output. For

example, as the MR varies from 0 to 7, the engine

thrust-to-weight ratio for a 15 klbf NTR increases by

~440% —from 3 to 13— while the Isp decreases by

only ~45%—from 940 to 515 seconds. This thrust

Figure 5.—Schematic/Characteristics of LOX-Augmented NTR.

Reactor

Core

Nozzle

Throat

Hydrogen

Coolant/

Propellant

Subsonic

Hot H2

(Tex ~ 2,600 to 3,100 K)

Supersonic

Combustion

and

Thrust

Augmentation

(Tex LOX + ∆TC ≥ 3,500 K)

Injection

Supersonic

H2

LOX

O/H MR = 0.0

1.0

3.0

5.0

7.0

941

772

647

576

514

5

2,900

925

762

642

573

512

10

2,800

Isp (sec)

891

741

631

566

508

35

2,600

14.0

7.4

4.1

3.0

2.5

Tankage

Fraction (%)

3.0*

4.8

8.2

11.0

13.1

T/Weng

Ratio

Life (hrs)

Tex (°K)

*For 15 klbf LANTR with chamber pressure = 2,000 psia and ε = 500 to 1
NASA/TM—1998-208830/REV2 8

landing mission; and (4) minimize LTS “recurring

costs.” To satisfy these objectives, a series of

cargo and piloted missions are envisioned which

use expendable “all LH2” NTR systems initially to

maximize the surface payload delivery while

minimizing IMLEO requirements. The reduced

IMLEO and size of the expendable vehicles also

allows component delivery to LEO using a cargo

version of the Space Shuttle (Shuttle C) or an “inline” Shuttle-derived launch vehicle (SDV), each

with a lift capability of ~66 tons. The advantages

of using Shuttle C would be a low development

cost and the ability to use much of the existing

infrastructure (e.g., assembly buildings and

launch pads) at the Kennedy Space Center.

The increased payload on each expendable

NTR flight would be dedicated to delivering

“modular” LUNOX production facilities. The intent

here is to develop and use LUNOX to reoxidize

LLVs and LTVs at the earliest possible opportunity

and to then transition to a reusable LANTR

architecture to improve “life cycle costs.” Accrued

government cost savings and industry profit from

LUNOX usage could then be reinvested gradually

to develop additional “in-space” assets, such as

LEO and LLO propellant depots, to support

further reusability and eventually routine commuter

flights to the Moon.

LUNAR MISSION / TRANSPORTATION SYSTEM

GROUND RULES AND ASSUMPTIONS

The ground rules and assumptions for the

evolutionary mission architecture examined in this

study are summarized in Table 1. Provided are

details on outbound and return payloads, parking

orbits, mission velocity change (∆V) requirements

and duration, and Earth-to-orbit (ETO) launch

vehicle characteristics. In addition to the three

primary ∆V maneuvers (four for the NTR system)

indicated, midcourse correction maneuvers are

also performed using a storable, bipropellant RCS

system. Table 2 includes details on primary and

auxiliary propulsion, cryogenic tankage, thermal

protection and boiloff rates, and contingency

factors used in this study.

Table 1. Reference Lunar Mission Ground Rules and Assumptions

• Payload Outbound:

• Payload Inbound:

• Parking Orbits:

9.9 t

0.8 t

5.0 - 10.0 t

5.0 t

35.7 – 46.0 t

9.9 t

0.8 t

0.5 t

407 km

300 km

LTV crew module

Crew (4) and suits

Lunar surface payload

LLV crew module

“Wet” LLV stage

LTV crew vehicle

Crew (4) and suits

Lunar samples

Circular (Earth Departure)

Circular (lunar arrival/departure)

• Trans-lunar injection DV assumed to be 3100 m/s + g-losses

• Lunar orbit capture/trans-Earth injection DV’s assumed to be 915 m/s

• Earth return: Direct capsule entry

• Earth gravity assist disposal DV assumed to be 194 m/s (for NTR missions)

• Mission duration: 54 days* (2 in LEO, 7 in transit, 45 days at Moon)

• ETO type/payload capability: Shuttle C or SDV / 66 t to 407 km circular

• LTV assembly scenario: 2 ETO launches with EOR&D (IMLEO < 132 t)

*Chemical TLI and NTR “core” stages in LEO for 30 days prior to second ETO launch.
NASA/TM—1998-208830/REV2 9

An aluminum-lithium alloy “Weldalite” (Ftu =

111 ksi, ρ = 0.0976 lbm/in3 = 2700 kg/m3), has been

used in previous NASA contractor studies23 of

expendable, two-stage chemical LTV systems,

and is also assumed here for construction of the

lunar NTR’s LH2 and LOX propellant tanks. Wall

thicknesses for the LH2 tanks were calculated

based on a 35 psi internal pressure and included

hydrostatic loads using a “3g” load factor with a

safety factor of 1.5. A 2.5 percent ullage factor was

also assumed in this study. A 50 psi internal

pressure was assumed for the LOX tanks resulting in

wall thicknesses of ~0.1 inches.

A two-inch helium-purged, multilayer insulation

(MLI) system (at 50 layers per inch) is assumed for

thermal protection of the cryogenic tanks. This

insulation thickness exceeds the “ground hold”

thermal protection requirements for “wet-launched”

LH2 tanks which need a minimum of 1.5 inches of

helium-purged insulation.24 The installed density of

the “2 inch MLI system” is ~2.62 kg/m2, and

the resulting LH2 boiloff rate in LEO is ~1.31 kg/m2/

month (based on an estimated heat flux of ~0.22

W/m2 at a LEO sink temperature of ~240 K). In lunar

orbit, where the sink temperature and heat flux are

estimated to be ~272 K and 0.32 W/m2, respectively,

the LH2 boiloff rate increases by ~46% to 1.91

kg/m2/month. The corresponding boiloff rates for

LOX are shown in Table 2. Finally, a 0.25 mm thick

sheet of aluminum (corresponding to ~0.682 kg/m2)

is included in the total tank weight estimates to

account for micrometeoroid protection.

CHEMICAL AND NTR COMPARISON RESULTS

Figure 6 compares the relative size, mass and

surface payloads for several piloted LTS options

which include a LOX/LH2 chemical system and

several NTR systems operating without and with

LOX-augmentation. Components for each piloted

and cargo mission are delivered to LEO using two

Shuttle C or SDV launches and assembled via a

Table 2. Lunar NTR / LANTR Transportation System Assumptions

• NTR / LANTR

Systems:

• RCS System:

• Cryogenic

Tankage:

Thrust / Weight

Fuel / Propellants

Isp

External Shield Mass

Flight Reserve

Residual

Cooldown (effective)

Propellant

Isp

Tankage

Material

Diameter 

Geometry

Insulation

LH2/LOX Boiloff*

= 15 klbf/4904 lbm (LH2 NTR)

= 15 klbf/5797 lbm (LANTR @ MR=0.0)

= Tricarbide/Cryogenic LH2 and LOX

= 940 s (@ O/F MR = 0.0/LH2 only)

= 647 s (@ O/F MR = 3.0)

= 514 s (@ O/F MR = 7.0)

= 2.84 kg/MWt of reactor power

= 1% of total tank capacity

= 1.5% of total tank capacity

= 3% of usable LH2 propellant

= N2O4/MMH

= 320 s

= 5% of total RCS propellants

= “Weldalite” Al/Li alloy

= 4.6 - 7.6 m

= Cylindrical tanks with ÷2/2 domes

= 2 inches MLI + micrometeoroid debris shield

= 1.31/2.44 kg/m2

/month (LEO @ ~ 240 K)

= 0.56/0.90 kg/m2

/month (in-space @ ~ 172 K)

= 1.91/3.68 kg/m2

/month (LLO @ ~ 272 K)

• Contingency Engines, shields and stage dry mass = 15%

*Assumes 3 x “Lockheed Eqn” heat flux estimates for MLI Dt ~ 2 inches
NASA/TM—1998-208830/REV2 10

simple rendezvous and docking maneuver. The

chemical LTS (Figure 6a) utilizes a “two stage”

LTV. The first ETO flight delivers the trans-lunar

injection (TLI) stage while the second ETO flight,

launched 30 days later, delivers the lunar orbit

insertion/trans-Earth injection (LOI/TEI) stage, crew

module, and single stage LLV with its surface

payload.

Following rendezvous and docking and 2 days

of system checkout in LEO, the TLI stage uses its

5 RL10-derivative engines (with Isp~465 s) to

inject the piloted LOI/TEI stage and lander

elements on a translunar trajectory after which the

TLI stage is jettisoned. Three RL 10-derivative

engines are used in the LOI/TEI stage to capture into

and depart from lunar orbit after completion of the

45-day landing mission. The ~36 t LLV uses five

throttleable RL 10s and can deliver ~5 t of surface

payload on the piloted missions. On cargo missions,

the 5 t crew module on the LLV can be removed and

payloads on the order of ~28 t can be delivered on

“1-way” trips to the lunar surface.

The expendable “all LH2” NTR vehicle is a “two

tank” stage (Figure 6b). The first ETO flight

delivers the “core” stage which is powered by two

small 15 klbf bimodal engines21,22 each capable of

generating ~15 kWe of electrical power using a

closed Brayton cycle power conversion unit

(CBC/PCU). The bimodal NTR design considered

here was developed jointly by Aerojet,25 Babcock

and Wilcox and Energopool in the Commonwealth

of Independent States (CIS) under a contract to

GRC’s Nuclear Propulsion Office. The CBC/PCU is

enclosed within the conical extension of the

stage thrust structure which also provides support

for an ~40 m2 heat pipe radiator required for the

two engine system. Other elements on the NTR

“core” stage include: (1) two external radiation

shields for crew protection; (2) a 7.6 m diameter by

17.5 m long LH2 tank; (3) a forward cylindrical

adaptor housing the RCS system, avionics and

auxiliary power, and docking system; and

(4) forward and aft cylindrical band skirts. The

mass of the “dry” core stage, and its RCS and

LH2 propellant loads are 16.0, 0.4, and 49.3 t,

respectively, for a total mass at liftoff of ~65.7 t.

The “core” stage total length is a little over 24 m,

well within the 27.4 m payload length limit of the

Shuttle C-Block 1 / SDV launch vehicle designs.

The second ETO launch delivers another 66 t to

LEO which consists of a second, smaller LH2 tank

and its “conical” core stage adaptor, the piloted

LTV crew module, and the LLV with its payload.

The “in-line” LH2 tank is 4.6 m in diameter and

9.0 m long and has a 9 t LH2 propellant capacity.

After rendezvous and docking, the 46 m long

NTR LTV and its payload depart for the Moon.

A “single burn” Earth departure scenario includes

gravity losses of ~392 m/s. The TLI burn duration is

~47.5 minutes and the total mission burn time for the

two 15 klbf NTRs is ~61.4 minutes.

Because of its high Isp (~940 s), the NTRpowered LTV can transport a larger (~44 t) piloted

LLV to the Moon capable of landing ~9 t of surface

payload—an 80% increase over the chemical

system for the same IMLEO. The same LLV, minus

the 5 t crew module, can deliver ~34 t of payload

to the lunar surface on “1-way” cargo missions.

After lunar orbit rendezvous and docking of the

piloted LLV with the LTV, and transfer of crew and

lunar samples to the LTV crew module, the LLV is

jettisoned and the NTR core stage performs a TEI

burn to return to Earth. Following a 3.5 day transit,

the LTV crew module separates for its ballistic

reentry to Earth, while the NTR LTV performs a

final small (~194 m/s) Earth perigee burn which

places the spent stage on a “long-term disposal”

trajectory into heliocentric space. This same disposal scenario is repeated on cargo missions.

Performance Impact of Introducing LUNOX and

then LANTR Technologies

The first significant step towards reducing space

transportation costs is achieved when lunar outpost assets and LUNOX production levels become

sufficient to support a lunar surface-based LLV. By

not having to transport a “wet” LLV to LLO on

each flight, the expendable NTR stage now has

sufficient propellant capacity to operate in the

“reuse mode” (Figure 6c) while transporting up to

~9 t of payload to LLO. An expendable, Shuttle

C-class propellant tanker would be used to refuel the

stage with ~58 t of LH2 before each new mission.

Also, with ~19.1 t of LUNOX required by the LLV

for each round trip to and from LLO, LUNOX

production levels will depend on the number of

cargo and piloted missions conducted annually.
NASA/TM—1998-208830/REV2 11

Next, as LUNOX becomes available in LLO, the

two 15 klbf NTRs would be outfitted with a LOX

propellant feed system and afterburner nozzles for

bipropellant operation. Transition to a “LANTRbased” lunar architecture now begins with smaller,

reusable LTVs (Figure 6d) delivering ~38 t of cargo

and “Earth-supplied” propellants to LLO on each

flight (> 400% payload increase). Surface-based

LLVs would be used to transport crew and cargo to

the Moon. They would also deliver LUNOX to LLO

to “reoxidize” the LANTR LTV and then return to

the Moon with “Earth-supplied” LH2 for future use

in LLVs and LUNOX production facilities.

In transitioning from an expendable to reusable

mission architecture, the LLV loses some of its

cargo delivery capability. This is due to the fact that

the lander’s tankage and propellant load (~22.3 t of

LOX/LH2 at MR = 6) was sized to deliver ~9 t of

surface payload on the initial expendable piloted

missions. When the LLV (which has a “dry” mass of

11.4 t including its 5 t crew cab) operates from the

lunar outpost, ~11.5 t of propellant is used in

ascending to LLO for rendezvous with the LTV.

This estimate assumes an ascent ∆V of ~1900 m/s

and an Isp of ~465 s for the LLV. To land ~20.5 t of

cargo and 4 crew on the lunar surface requires

~18.2 t of propellant assuming a descent ∆V of

~2000 m/s. The 10.8 t of LOX/LH2 propellant

remaining in the LLV after ascent is therefore

inadequate to transport this much cargo.

In the mission strategy we adopt here, the

LANTR LTV doubles as a “tanker” vehicle and is

loaded with additional propellant that is transferred

to the LLV after rendezvous. This “topping off” of

the LLV’s tanks with ~7.4 t of LOX/LH2 propellant

allows the crew and its entire cargo shipment to be

delivered to the surface on one round trip LLV

mission. The reusable LTV shown in Figure 6d

operates at a MR = 3 (Isp ~647 s) both outbound

and inbound, refuels with ~21.2 t of LUNOX for

Earth return, and is a smaller overall vehicle than its

expendable “all LH2” counterpart, even with its

Figure 6.—Relative Size/Mass of Chemical and NTR Vehicles Without and With LOX Augmentation.

IMLEO (t) = 132 132 98 152 196

LH2

LH2

LH2

LH2 LH2

LH2 LH2 LH2

4.6 m 4.6 m

4.6 m

~44 m

4.6 m

LOX

LOX LOX

LOX

a) "84 hr"

 Expendable

 Chemical

 LOX/LH2

b) "84 hr"

 Expendable

 NTR LH2 Only

c) "84 hr"

 Reusable NTR

 LH2 Only d) "84 hr"

 Reusable

 LANTR LTV

 With LUNOX

e) "24 hr" Shuttle

 Reusable LANTR

 With LUNOX

15 t

"Commuter"

 Module

24 t

Cargo/

14 t LH2

8.8 t

Cargo/

No

Lander

9 t

Cargo 5 t

Cargo

7.6 m 7.6 m

7.6 m

7.6 m
NASA/TM—1998-208830/REV2 12

increased performance. The oxygen tank holds

~62 t of LOX of which ~6.4 t is used for “topping

off” the LLV and the remainder for the LTV’s TLI

and LOI maneuvers. The LH2 tank is 7.6 m in

diameter, 15 m in length and holds ~39 t of LH2. Of

this amount ~11 t is cargo. Two autonomous LLV

“tanker” flights (see Figure 3), each supplying

~10.6 t of LUNOX to the orbiting LANTR LTV,

return to the Moon with ~10 t of LH2 necessary to

support the three LLV flights required for each

subsequent LTV mission. With time, the deployment

of a propellant depot in LLO will eliminate the need

for LOX transport by the LTV . This will increase the

LTV’s delivery capability of cargo and LH2 propellant

to ~24 t and 14 t, respectively (see Figure 6d).

Compared to monopropellant NTRs, the LANTR

engines are ~5% longer (an expansion ratio of

500 to 1 is used for improved LOX combustion

efficiency) and ~6% heavier (attributed to the

larger nozzle and the addition of the LOX

propellant feed system). However, at a MR = 3,

the thrust output (F) from the two 15 klbf

LH2-cooled NTRs is increased by ~275% to ~82.5

klbf. This augmented thrust level significantly

reduces the TLI burn duration and gravity losses to

~17.2 minutes and ~72 m/s, respectively, compared

to 47.5 minutes and 392 m/s for the expendable

“all LH2” 30 klbf NTR system. Total mission burn

time is also cut in half to ~28.9 minutes compared

to ~61.4 minutes for the expendable system.

Also, because the LANTR engine’s fuel lifetime is

~5 hours at a hydrogen exhaust temperature

of ~2900 K (see Figure 5), the LANTR system

can perform ~10 round trip lunar missions before

being replaced thereby reducing overall LTS

recurring costs.

The reusable LANTR LTV has an IMLEO of

~151.8 t which includes the 17.9 t “dry” stage, a

10.7 t piloted LTV crew module, 20.5 t of nonpropellant cargo, and RCS, LH2, and LOX propellant

loads of ~1.7, 39 and 62 t, respectively. During initial

deployment, the entire LANTR LTV, including its

RCS and LH2 propellant loads, can be launched on

a single Shuttle C or SDV. The LOX tank would

require on-orbit filling from an expendable tanker or

propellant depot. For subsequent piloted missions,

the total mass needed to outfit and refuel the LTV

stage is ~123.2 t which again can be delivered using

two 66 t-class Shuttle C /SDV launch vehicles.

Approximately 76.5 t of LUNOX (~21.2 t for LTV

return, ~19.1 t for the piloted LLV, and ~36.2 t for

the two tanker LLVs) must be produced to support

each reusable LTV mission. At a low LUNOX

production capacity (~12 to 24 t/year), small

automated LUNOX units with teleoperated mining

equipment would be delivered to LLO by monopropellant NTR and later LANTR systems, and

then transported to the lunar surface using “onboard” chemical propulsion systems.26 As capacity

increases to hundreds of tons per year and more,

surface assembly of larger production units will be

required to avoid the mass penalties associated

with delivering increased numbers of low-rate

production plants.7

A TYPICAL “COMMUTER TRIP” TO THE MOON

With LUNOX production underway and a

reusable LANTR-based LTS in service, initial lunar

outposts will grow into permanent settlements

staffed by visiting scientists and engineers

representing both government and private

commercial ventures (see Figure 3). Eventually,

frequent flights to the Moon of shortened duration

could also become commonplace. The LANTR

concept can enable a rapid “commuter” shuttle

capable of 24 hour “1-way” trip times to and from

the Moon, about what it now takes to travel from

Washington, D.C. to Sydney, Australia. Shortening transit times will require significant increases in

both the outbound and inbound ∆V budgets

(see Figure 7) and necessitate multiple spacecraft

engines for improved reliability and increased

passenger safety. In the Apollo program, a 3.5 day

trip to the Moon required an outbound ∆V of

~4.1 km/s. For the 24 hour “1-way” trip times examined here, the required ∆V budget is ~6.9 km/s!

The LANTR-based “commuter” shuttle, illustrated in Figure 8 and on our cover page, is a

modified version of the “all LH2” NTR vehicle and is

capable of delivering a 15 t passenger module to the

Moon in a single day. In addition to utilizing LANTR

engines, the other principal vehicle modification is

the use of LOX instead of LH2 in the small “in-line”

propellant tank located ahead of the LH2 “core”

stage (Figure 6e). In our reference commuter flight,

we assume the LANTR shuttle uses only “Earthsupplied” LH2 in traveling to and from the Moon with

“Earth-supplied” LOX and LUNOX used only on the
NASA/TM—1998-208830/REV2 13

Figure 7.—TLI and LOI ∆V Variation with "1-way" Flight Time (300 km Lunar Orbit).

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

 One-Way Flight Time (hrs)

V (km/s)

24 36 48 72 84 96

TLI V

LOI V

Free Return

Transfer Time

Elliptical

Earth Departure

Hyperbolic

Earth Departure

Figure 8.—A LANTR-powered Transfer Stage Leaves Earth Orbit Carrying a Passenger

 Transport Module on a "24 Hour" Trip to the Moon.
NASA/TM—1998-208830/REV2 14

outbound and inbound mission legs, respectively.

To extend the service lifetime of the lunar shuttle, the

LANTR engines are also operated at a reduced

hydrogen exhaust temperature of ~2600 K which

increases fuel lifetime to ~34.5 hours compared to

~5 hours at 2900 K (see Figure 5).

During the transit out to the Moon, the twin

LANTR engines operate at a MR = 4 (F~100 klbf

and Isp~595 s) while on the return trip to Earth, a

MR = 6 (F~126 klbf and Isp~537 s) is used. These

conditions provide both near optimum performance levels and vehicle components of sufficient

size to allow deployment using 2 Shuttle C flights.

The initial and resupply propellant needs of the

“24 hour” LANTR shuttle are provided by a LEO

propellant depot assumed to be in existence

during this period. The commuter shuttle’s LOX

tank is 4.6 m in diameter, ~7.5 m long and holds

~112 t of Earth-supplied LOX for the outbound

lunar flight. It is resupplied in LLO with ~94 t of

LUNOX for the 24 hour trip back to Earth. The

LANTR shuttle uses the same size LH2 tank as the

expendable NTR system to maximize hardware

commonality and reduce development costs. It carries ~46 t of LH2 required for the round trip mission.

The “24 hour” LANTR shuttle has an IMLEO of

~195.6 t that includes the 21.3 t “dry” vehicle, the

15 t passenger module, and RCS, LH2 and LOX

propellant loads of ~1.5, 45.5 and 112.3 t,

respectively. Total engine burn time for the

“24 hour” mission is just under 47 minutes with the

longest single burn being the TLI maneuver at

~21.2 minutes. With a 34.5 hour fuel lifetime, a

typical LANTR shuttle could perform ~44 missions.

Assuming a four ship fleet with weekly trips to the

Moon, each LANTR shuttle would make 13 lunar

flights per year resulting in a service life of

~3.3 years. Near the end of life, the shuttle’s LH2

core stage could be used to deliver cargo to the

Moon or Mars before being disposed of in heliocentric space. The 15 t passenger transport module is

~4.6 m in diameter and ~8 m long, and can be

delivered to orbit using the current Space Shuttle

or the next generation RLV.

To support weekly commuter flights to the Moon

will require annual LUNOX production levels of

~11,000 t/yr (see Table 3). Approximately 4900 t

are used by the LANTR shuttles and just under

6000 t by four second-generation “Sikorsky-style”

LUNOX tanker LLVs which fly one supply mission

to the LLO propellant depot each week over the

course of a year. Each tanker LLV has a “dry”

mass of ~10.9 t and carries ~33.6 t of LOX/LH2

propellant in addition to the ~30 t “mobile” tanker

vehicle with its 25 t LUNOX payload.

A preliminary assessment of plant mass, power

level, regolith throughput, and required mining

area has been made assuming a LUNOX operation

employing eleven modular units each with a

production capacity of 1000 t/yr. Table 4 compares

characteristics for two LUNOX plants—one based

on hydrogen reduction of ilmenite7 and the other

on “iron-rich” volcanic glass. The advantages of

using volcanic glass feedstock are apparent and

indicate mass and power requirements ~68% and

80% that of an ilmenite reduction plant using a soil

feedstock. The 4% O2 yield using volcanic glass

beads (“orange soil”) also translates into more than

an order of magnitude reduction in the amount of

mined regolith. To produce ~11,000 t of LUNOX

annually will require a regolith throughput of

~2.75 x 105 t/yr and a soil mining rate of ~90 t per

hour assuming a 35% mining duty cycle (i.e., 70%

of the available lunar daylight hours). While this

number is large, it is modest compared to terrestrial

coal and proposed lunar helium-3 mining activities.

For example, with a single 1000 MWe “coal-fired”

power plant consuming about sixty 100 ton train

cars of coal per day, the annual U.S. production

rate for coal exceeds 500 million tons! Similarly,

proposals for mining helium-3 on the Moon27 to

support a future fusion-based power economy in

the U.S. would require the processing of

~2.8 billion tons of regolith to obtain the 20 t of He3

needed annually (see Table 4).

Because of the abundance of oxygen in the

lunar regolith, the scale of the mining operation to

support routine commuter flights to the Moon is

not unrealistic. Figure 9 illustrates the areal extent

and potential LUNOX yield from our candidate

mining site at the southeastern edge of Mare

Serenitatis. Assuming an area of ~2000 km2, a

mining depth of ~5 m, a soil density representative

of the Apollo 17 orange soil (ρ ~1.8 t/m3), and a MMR

of 25 to 1, a LUNOX yield of ~700 million tons is

possible. Also illustrated in Figure 9 are the required

mining areas needed to support weekly,

as well as, daily commuter flights to the Moon.

Even at the higher production rate of ~77,000 t/yr,

there are sufficient LUNOX resources at this one

site to support daily lunar commutes for the next

9000 years and many more sites of “iron-rich”

volcanic glass have been identified.28
NASA/TM—1998-208830/REV2 15

Table 3. LUNOX Requirements for “24 Hour” Commuter Flights to the Moon

24 Hour “1-way” Transits (15 t / 20 Passenger Transport Module):

LTV: (94.0 t LUNOX / mission*) x 52 weeks / year = 4888 t / year

LLV: (28.8 t LUNOX / flight+

) x (1 flight / LLV / week)

 x 4 LLVs x 52 weeks / year = 5990 t / year

 Total LUNOX Rate =10878 t / year

*Assumes LUNOX Usage on “Moon-to-Earth” Transit only

+

Assumes LLV Transports ~25 t of LUNOX to LLO and Returns to

 Lunar Surface with Empty 5 t “Mobile” LUNOX Tanker Vehicle

Table 4. Comparison of Different Lunar Mining Concepts

—Plant Mass, Power and Regolith Throughput—

• Hydrogen Reduction of Ilmenite 7

: (LUNOX Production @ 1000 t/year)

• Plant Mass (Mining, Beneficiation, Processing and Power) = 244 t

• Power Requirements (Mining, Beneficiation and Processing) = 3.0 MWe

• Regolith Throughput ( assumes soil feedstock @ 7.5 wt% ilmenite

 and mining mass ratio (MMR) of 327 t of soil per ton of LUNOX ) = 2.3x105

 t/yr

• Hydrogen Reduction of “Iron-rich” Volcanic Glass : (LUNOX Production @ 1000 t/yr)

• Plant Mass (Mining, “limited” Beneficiation, Processing and Power) = 167 t

• Power Requirements (Mining, “limited” Beneficiation and Processing) = 2.4 MWe

• Regolith Throughput (“limited” beneficiation, direct processing of “iron-rich”

volcanic glass (“orange soil”) with 4% O2 yield and MMR = 25 to 1) = 2.5x104

 t/yr

• Lunar Helium-3 Extraction : (5000 kg (5 t) He3

/year)

• Mobile Miners (150 miners required each weighing 18 t/ = 2700 t

 each miner produces 33 kg He3

 per year)

• Power Requirements (200 kW direct solar power/miner) = 30.0 MW

• Regolith Throughout (processing and capture of Solar Wind

 Implanted (SWI) volatiles occurs aboard the miner) = 7.1x108

 t/yr
NASA/TM—1998-208830/REV2 16

How might a typical “commuter” trip to the Moon

proceed? A possible scenario might start with

passengers boarding a future transatmospheric

shuttle or a passenger version of the RLV for a

flight to the International Space Station (ISS).

There they would enter a “passenger transport

module” (PTM) containing its own life support,

power, instrumentation and control, and auxiliary

propulsion systems. The PTM provides the

“brains” for the LANTR-powered shuttle and is

home to the 18 passengers and 2 crew members

while enroute to the Moon. After departing from

the ISS, the PTM docks with a fully fueled LANTR

shuttle awaiting it a safe distance away. At the

appropriate moment, the LANTR engines are

powered up and the shuttle climbs rapidly away

from Earth (Figure 8). Acceleration levels

experienced by the passengers during Earth

departure range from ~0.23 gE to ~0.46 gE near the

end of the TLI burn.

Following a 24 hour trip to the Moon, the LANTR

shuttle arrives in LLO where the PTM detaches

and docks with a waiting LLV (Figure 10). A

commercial propellant depot provides a

convenient staging point for LLO operations

supplying the LANTR shuttle with LUNOX for Earth

return and the “Sikorsky-style” LLV with Earthsupplied LH2 needed to deliver the PTM to the

lunar surface. From here the PTM is lowered to a

“flat-bed” surface vehicle and electronically

engaged providing it with surface mobility (see

Figure 11). The PTM then transports itself to the

lunar base airlock for docking and passenger

unloading (shown in lower right foreground of

Figure 3). The scenario is reversed on the return

trip to Earth where peak acceleration levels reach

~1.2 gE at the end of the Earth orbit capture burn.

CONCLUSION

The revolutionary performance capability discussed in this paper is the result of combining two,

relatively near term, “high leverage” technologies.

Together, LANTR propulsion and LUNOX have an

“effective Isp” of ~1500 to 2000 s which is equivalent

to that predicted for advanced “gas core” NTR

systems. Using chemical propulsion, a fully reusable “advanced technology” system (propellant mass

fraction of 0.88 and Isp of ~480 s), would require

Figure 9.—Required Mining Areas and LUNOX Production Rates to Support 

 Routine Commuter Flights to the Moon.

28 mi

A = 0.2 km .1 mi .3 mi 2

7.7 x 104 t/yr

A = 0.03 km2

1.1 x 104 t/yr

*Assume

 depth = 5.0 m

 soil = 1.8 t/m3

 MMR = 25:1

~

A = 2000 km2

MLUNOX = 7 x 108 tons* ~
NASA/TM—1998-208830/REV2 17

Figure 10.—A Surface-based LLV Prepares to Dock with a Passenger Transport Module Delivered to Lunar

 Orbit by the LANTR-powered Transfer Stage.
NASA/TM—1998-208830/REV2 18

Figure 11.—After Landing on the Lunar Surface, the Passenger Transport Module Departs for the Lunar

 Settlement Aboard a "Flatbed" Surface Transport.
NASA/TM—1998-208830/REV2 19

IMLEO and LUNOX production levels 2 to 3 times

higher than LANTR to perform the same commuter

flight.

In addition to enabling commuter flights to the

Moon, the LANTR concept is expected to dramatically improve space transportation performance

wherever extraterrestrial sources of LOX and LH2

can be acquired such as the Martian system, mainbelt asteroids and the Galilean satellites Europa,

Ganymede, and Callisto. In the future, reusable

biconic-shaped LANTR-powered ascent/descent

vehicles, operating from specially prepared landing

sites on Mars, could be used to transport modular

payload elements to the surface while resupplying

orbiting transfer vehicles with propellants needed

to reach refueling depots in the asteroid belt. From

there, the LANTR-powered transfer vehicles could

continue on to the “water rich” moons of the

Jovian system, providing a reliable foundation for

the development and eventual human settlement

of the Solar System.

This December (1997) marks the 25th anniversary of the Apollo 17 mission to Taurus-Littrow and

unfortunately, the termination of both the Apollo

and NERVA nuclear rocket programs. In the notso-distant future, the technological progeny from

these two historic programs— LUNOX and LANTR—

could provide the traveling public the type of

revolutionary space transportation portrayed in 2001:

A Space Odyssey and in Clarke’s novel29 by the

same name thereby allowing future Dr. Floyds the

opportunity to make “...utterly without incident and in

little more than one day, the incredible journey of

which men had dreamed for two thousand years....”

a routine flight to the Moon.

REFERENCES

1. 2001: A Space Odyssey, produced and

directed by S. Kubrick, screenplay by S. Kubrick

and A.C. Clarke, a Metro-Goldwyn-Mayer (MGM)

film released 1968.

2. D.A. Brown, “International Space Station Faces

Further Delays, Controversy,” Launchspace,

(June/July 1997), pp. 30–34.

3. M.H. Kaplan, “The Reusable Launch Vehicle: Is

the Stage Set?” Launchspace, (March 1997),

pp. 26–30.

4. The Strategic Plan—NASA’s Enterprise for the

Human Exploration and Development of Space,

National Aeronautics and Space Administration,

(January 1996).

5. T.S. Sullivan and D.S. McKay, Using Space

Resources, NASA Johnson Space Center (1991).

6. L.A. Taylor and W.D. Carrier III, “The Feasibility

of Processes for the Production of Oxygen on the

Moon,” in Engineering, Construction & Operations

in Space III, New York, 1992, pp. 752–762.

7. E.L. Christiansen, et al., “Conceptual Design of

a Lunar Oxygen Pilot Plant,” Eagle Engineering

Report No. 88–182, Eagle Engineering, Inc.,

Houston, Texas (July 1, 1988).

8. W.R. Stump, et al., “Support to Extraterrestrial

Propellant Leveraging Trade Study,” Eagle

Engineering Report No. 89–251, Eagle Engineering, Inc., Houston, Texas (August 15,1989).

9. C.C. Allen, R.V. Morris, and D.S. McKay, “Experimental Reduction of Lunar Mare Soil and Volcanic

Glass,” Journal of Geophysical Research, 99, 23,

173 (November 1994).

10. C.C. Allen and D.S. McKay, “Lunar Oxygen

Production—Ground Truth and Remote Sensing,”

AIAA–95–2792, American Institute of Aeronautics

and Astronautics (July 1995).

11. C.C. Allen, “Prospecting for Oxygen on the

Moon,” Ad Astra, (Nov./Dec. 1996), pp. 34–39.

12. W.H. Gregory, “Apollo 17 Photos Confirm Color

of Soil Discovered at ‘Shorty’,” Aviation

Week & Space Technology, (January 1, 1973),

p. 15.

13. W.H. Gregory, “Orange Soil Could Revive

Lunar Projects,” Aviation Week & Space Technology, (January 1, 1973), pp. 41–44.

14. M.B. Duke and M. Treadwell, “A Proposal for

Risk Sharing in the Development of a Lunar

Oxygen Plant,” in Engineering, Construction, and

Operations in Space II: Vol. 1, New Mexico, 1990,

pp. 41–49.
NASA/TM—1998-208830/REV2 20

15. T.F. Rogers, “The People Payload: Does the

U. S. Space Transportation Industry Take Space

Tourism Seriously?” Ad Astra, (March/April 1995),

pp. 36–39.

16. L. David, “NASA Begins Space Tourism

Enterprise Assessment—Findings Could Influence

the Future of X-33,” Space News, (September 18–

24,1995).

17. C.C. Priest and G.R. Woodcock, “Space Transportation Systems Supporting a Lunar

Base,” AIAA–90–0422, American Institute of

Aeronautics and Astronautics (January 1990).

18. America at the Threshold—America’s Space

Exploration Initiative, Report of the Synthesis

Group, Available from the Superintendent of

Documents, U.S. Government Printing Office,

Washington, DC 20402 (May 1991).

19. “Analysis of the Synthesis Group’s Space Resource Utilization Architecture,” ExPO Document

XE–92–004 (February 1992).

20. S.K. Borowski, “The Rationale/Benefits of

Nuclear Thermal Rocket Propulsion for NASA’s

Lunar Space Transportation System,” AIAA–91–

2052, American Institute of Aeronautics and

Astronautics (June 1991).

21. S.K. Borowski, et al., “A Revolutionary Lunar

Space Transportation System Architecture Using

Extraterrestrial LOX-Augmented NTR Propulsion,”

AIAA–94–3343, American Institute of Aeronautics

and Astronautics (June 1994).

22. S.K. Borowski, D.W. Culver, and M.J. Bulman,

“Human Exploration and Settlement of the Moon

Using LUNOX-Augmented NTR Propulsion,” in

Proc. 12th Symposium on Space Nuclear Power

and Propulsion, AIP Conf. Proc. No. 324, January

1995, Vol. 1, pp. 409–420.

23. “Space Transfer Vehicle Concepts and

Requirements Study,” Martin Marietta, Denver,

Colorado, Marshall Space Flight Center Space

Transportation Week #5 Report, December 4, 1991.

24. R.H. Knoll, R.J. Stochl, and R. Sanabria, “A

Review of Candidate Multilayer Insulation Systems

for Potential Use on Wet-Launched LH2 Tankage for

the Space Exploration Initiative Lunar Mission,”

AIAA–91–2176, American Institute of Aeronautics

and Astronautics (June 1991).

25. D.W. Culver, V. Kolganov, and R. Rochow,

“Low Thrust, Deep Throttling, US/CIS Integrated

NTRE,” 11th Symposium on Space Nuclear

Power Systems, Albuquerque, New Mexico,

(January 9–13, 1994).

26. B.K. Joosten and L.A. Guerra. “Early Lunar

Resource Utilization: A Key to Human Exploration,”

AIAA–93–4784, American Institute of Aeronautics

and Astronautics (September 1993).

27. I.V. Sviatoslavsky, “Processes and Energy Costs

for Mining Lunar Helium-3,” in Workshop

Proc. on Lunar Helium-3 and Fusion Power,

NASA CP–10018 (1988), pp. 129–146.

28. B.R. Hawke, C.R. Coombs, and B. Clark, “Pyroclastic Deposits as Sites for Lunar Bases,”

in Engineering, Construction, and Operations in

Space II: Vol. 1, New Mexico, 1990, pp. 78–87.

29. A.C. Clarke, 2001: A Space Odyssey, based on

a screenplay by S. Kubrick and A.C. Clarke,

a Signet Book, published by The New American

Library, Inc., (July 1968), p. 61.

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26

“2001: A Space Odyssey” Revisited—The Feasibility of 24 Hour Commuter

Flights to the Moon Using NTR Propulsion with LUNOX Afterburners

Stanley K. Borowski and Leonard A. Dudzinski

Nuclear thermal rocket; NTR; Lunar oxygen; LUNOX; In-situ resource utilization; High

thrust; Nuclear propulsion; Moon; Spacecraft; Lunar; LOX-augmented NTR; LANTR

Unclassified -Unlimited

Subject Categories: 12, 15, 16, and 20 Distribution: Nonstandard

Prepared for the 33rd Joint Propulsion Conference cosponsored by the AIAA, ASME, SAE, and ASEE, Seattle, Washington, July 6–9, 1997. Responsible person, Stanley K. Borowski, organization code 6510, 216–977–7091.

The prospects for “24 hour” commuter flights to the Moon, similar to that portrayed in 2001: A Space Odyssey but on a more Spartan scale, are examined using two

near term, “high leverage” technologies—liquid oxygen (LOX)-augmented nuclear thermal rocket (NTR) propulsion and “lunar-derived” oxygen (LUNOX)

production. Iron-rich volcanic glass, or “orange soil,” discovered during the Apollo 17 mission to Taurus-Littrow, has produced a 4% oxygen yield in recent NASA

experiments using hydrogen reduction. LUNOX development and utilization would eliminate the need to transport oxygen supplies from Earth and is expected to

dramatically reduce the size, cost and complexity of space transportation systems. The LOX-augmented NTR concept (LANTR) exploits the high performance

capability of the conventional liquid hydrogen (LH2)-cooled NTR and the mission leverage provided by LUNOX in a unique way. LANTR utilizes the large

divergent section of its nozzle as an “afterburner” into which oxygen is injected and supersonically combusted with nuclear preheated hydrogen emerging from the

engine’s choked sonic throat—essentially “scramjet propulsion in reverse.” By varying the oxygen-to-hydrogen mixture ratio, the LANTR engine can operate over a

wide range of thrust and specific impulse (Isp) values while the reactor core power level remains relatively constant. The thrust augmentation feature of LANTR

means that “big engine” performance can be obtained using smaller, more affordable, easier to test NTR engines. The use of high-density LOX in place of lowdensity LH2 also reduces hydrogen mass and tank volume resulting in smaller space vehicles. An implementation strategy and evolutionary lunar mission

architecture is outlined which requires only Shuttle C or “in-line” Shuttle-derived launch vehicles, and utilizes conventional NTR-powered lunar transfer vehicles

(LTVs), operating in an “expendable mode” initially, to maximize delivered surface payload on each mission. The increased payload is dedicated to installing

“modular” LUNOX production units with the intent of supplying LUNOX to lunar landing vehicles (LLVs) and then LTVs at the earliest possible opportunity. Once

LUNOX becomes available in low lunar orbit (LLO), monopropellant NTRs would be outfitted with an oxygen propellant module, feed system and afterburner

nozzle for “bipropellant” operation. Transition to a “reusable” mission architecture now occurs with smaller, LANTR-powered LTVs delivering ~400% more

payload on each piloted round trip mission than earlier expendable “all LH2” NTR systems. As initial lunar outposts grow to eventual lunar settlements and LUNOX

production capacity increases, the LANTR concept can enable a rapid “commuter” shuttle capable of 24 hour “one way” trips to and from the Moon. A vast deposit

of “iron-rich” volcanic glass beads identified at just one candidate site—located at the southeastern edge of Mare Serenitatis—could supply sufficient LUNOX to

support daily commuter flights to the Moon for the next 9000 years!

June 2003