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Thank you for your assistance

Does the United States

Need Space-Based Weapons?

Spacy

COLLEGE OF AEROSPACE DOCTRINE,

RESEARCH, AND EDUCATION

AIR UNIVERSITY

Does the United States Need

Space-Based Weapons?

WILLIAM L. SPACY II

Major, USAF

CADRE Paper

Air University Press

Maxwell Air Force Base, Alabama 36112-6610

September 1999
Disclaimer

Opinions, conclusions, and recommendations expressed or implied within are solely those of the

author, and do not necessarily represent the views of Air University, the United States Air Force,

the Department of Defense, or any other US government agency. Cleared for public release:

distribution unlimited.

ISBN 1-58566-070-1

ii
CADRE Papers

CADRE Papers are occasional publications sponsored by

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cated to promoting understanding of air and space power

theory and application, these studies are published by the Air

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All military members and civilian employees assigned to Air

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Manuscripts should deal with air and/or space power history,

theory, doctrine or strategy, or with joint or combined service

matters bearing on the application of air and/or space power.

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iii

Contents

Chapter Page

DISCLAIMER . . . . . . . . . . . . . . . . . . . ii

FOREWORD . . . . . . . . . . . . . . . . . . . vii

ABOUT THE AUTHOR . . . . . . . . . . . . . . . ix

 1 INTRODUCTION . . . . . . . . . . . . . . . . . 1

Space Weaponization Debate . . . . . . . . . . 1

Overview . . . . . . . . . . . . . . . . . . . . 6

Notes . . . . . . . . . . . . . . . . . . . . . . 8

 2 SPACE-BASED WEAPONS . . . . . . . . . . . . 9

Directed Energy Weapons . . . . . . . . . . . . 10

Direct Impact Weapons . . . . . . . . . . . . . 22

Defending Space-Based Assets . . . . . . . . . 32

Technological Factors Bearing on

 Space-Based Weapons . . . . . . . . . . . . 37

Summary . . . . . . . . . . . . . . . . . . . . 41

Notes . . . . . . . . . . . . . . . . . . . . . . 42

 3 SEEKING CONTROL OF SPACE:

 GROUND-BASED ALTERNATIVES

FOR SPACE CONTROL . . . . . . . . . . . . . . 51

Defensive Counterspace . . . . . . . . . . . . 51

Offensive Counterspace . . . . . . . . . . . . . 55

Nondestructive Approaches to Offensive

Counterspace . . . . . . . . . . . . . . . . . . 55

Destructive Approaches to Offensive

 Counterspace . . . . . . . . . . . . . . . . . 59

Conclusions . . . . . . . . . . . . . . . . . . 65

Notes . . . . . . . . . . . . . . . . . . . . . . 67

 4 ATTACKING TERRESTRIAL TARGETS:

 GROUND-BASED ALTERNATIVES FOR

FORCE APPLICATION . . . . . . . . . . . . . . . 71

Alternatives to Orbital Bombardment . . . . . . 72

Ballistic Missile Defense . . . . . . . . . . . . 82

v
Chapter Page

Radio Frequency Weapons . . . . . . . . . . . 88

Conclusion . . . . . . . . . . . . . . . . . . . 89

Notes . . . . . . . . . . . . . . . . . . . . . . 91

 5 POLITICAL IMPLICATIONS . . . . . . . . . . . . 95

Treaty Implications . . . . . . . . . . . . . . . 95

International Reaction . . . . . . . . . . . . . 97

Domestic Resistance . . . . . . . . . . . . . . 98

Space as Sanctuary . . . . . . . . . . . . . . . 100

Notes . . . . . . . . . . . . . . . . . . . . . . 101

 6 CONCLUSIONS AND RECOMMENDATIONS . . . 105

Conclusions . . . . . . . . . . . . . . . . . . 105

Recommendations . . . . . . . . . . . . . . . 107

Notes . . . . . . . . . . . . . . . . . . . . . . 110

GLOSSARY . . . . . . . . . . . . . . . . . . . . 111

BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . 113

Table

 1 Space-Based Weapons for Space Control . . . . . 66

 2 Ground-Based Options for Space Control . . . . . 66

 3 Space-Based Weapons for Force Application . . . 90

 4 Ground-Based Alternatives . . . . . . . . . . . . 90

vi
Foreword

The United States Air Force is said to be evolving into an air

and space force on its way to becoming a space and air force.

An integral part of this transition involves the possibility of

deploying weapons in space. While there is a growing litera -

ture about the need for weapons in space or, conversely the

need to ensure that space remains a weapons-free sanctuary,

little has been written about what space-based weapons can

and cannot bring to the battlefield.

A decision to put weapons in space—or to refrain from doing

so—should be based on a firm understanding about what

such weapons can be expected to achieve. More specifically

since numerous orbital weapons concepts have been advocated as natural evolutions of surface and airborne weapons,

it would appear useful to compare those proposed spacebased systems with their terrestrial counterparts.

Does the United States Need Space-Based Weapons? by Maj

William L. Spacy II evaluates the theoretical capabilities of orbital

weapons and compares them to weapons already in existence

and to emerging concepts proposed for development. His pri -

mary objective is to suggest where future investments should

be made if the United States is to protect its increasingly im -

portant space-based assets and retain its position as a global

leader able to project military power wherever necessary.

Originally written as a master’s thesis for Air University’s

School of Advanced Airpower Studies (SAAS), Does the United

States Need Space-Based Weapons? received the Air Force

Historical Foundation Award as the best SAAS thesis for aca -

demic year 1997–98. We commend Major Spacy’s work to

anyone seriously interested in one of the great strategic policy

issues of our day.

 JAMES R. W. TITUS

Dean of Research 

Air University 

vii

About the Author

Maj William L. Spacy II (BS, United States Air Force Academ y

[USAFA]; MS, Air Force Institute of Technology [AFIT]; MA,

United States College of Naval Command and Staff) is a C-17

pilot at Charleston Air Force Base (AFB), South Carolina. He

was commissioned upon graduation from the USAFA in 1983.

Following completion of undergraduate pilot training, Major

Spacy served at Zweibrücken Air Base, Germany, flying the

C-23. He transitioned to the C-130 in 1988 and served at

Dyess AFB, Texas. He then attended AFIT and earned a degree

in aeronautical engineering with specialization in propulsion.

Following graduation, he was assigned to the C-17 System

Program Office as a systems integration engineer. Major Spacy

is a 1998 graduate of the School of Advanced Airpower Stud -

ies, Maxwell AFB, Alabama.

ix
Chapter 1

Introduction

It’s politically sensitive, but it’s going to happen. Some

people don’t want to hear this, and it sure isn’t in vogue ...

but—absolutely—we’re going to fight in space. We’re going

to fight from space and we’re going to fight into space.

—Gen Joseph W. Ashy 

former commander in chief

United States Space Command

The world may be on the verge of a new era of warfare, one

where battles are not only fought within the biosphere of the

earth but also in the space surrounding it. Recent conflicts

have shown the tremendous advantages conferred upon those

who have the advantage of space-based assets, limited though

they are, to helping forces navigate, communicate, and spy

upon their enemies. Some argue that fighting in space itself is

inevitable, while others hold that space should be maintained

as a sanctuary, free of weapons. The purpose of this study is

not to argue for or against the weaponization of space, but

rather to examine the kinds of weapons that have been pro -

posed for use in space and compare their capabilities with

those of their surface-based counterparts. In making this

analysis, the efficacy of various concepts will be measured by

balancing three measures: cost, technical feasibility, and each

weapon’s ability to provide the advantages of using space to

the United States (US) and her allies or denying such advan -

tages to an enemy.

Space Weaponization Debate

The United States currently enjoys an overwhelming advantage in space-based surveillance, communications, and navi -

gation aids. Protecting these assets and maintaining US domi -

nance in space is potentially critical to the defense of US

national interests. As US national space policy indicates, lead -

ers at the highest levels of government recognize this potential

1
vulnerability. The policy explicitly states that national security

space activities must deter, warn, and if necessary, defend

against enemy attack. It also states that “[the Department of

Defense] shall maintain the capability to execute the mission

areas of . . . space control, and force application.” Finally,

current policy stipulates that “the United States will develop,

operate and maintain space control capabilities to ensure free -

dom of action in space and, if directed, deny such freedom of

action to adversaries.”1

The leadership of the United States Air Force (USAF) sup -

ports this policy and believes that implementing it will almost

inevitably require deploying weapons in space. This outlook is

evident in numerous speeches and official statements. Even

before Gen Joseph W. Ashy made the statement quoted above,

USAF Vice Chief of Staff Thomas S. Moorman Jr. said in a

June 1996 speech:

Undoubtedly the most provocative subject in any discussion of the

future of space is the subject of space weapons and the likelihood of

their use. Here I am referring to the broadest categories: Space-based

lasers to shoot down hostile ICBMs, space weapons that attack other

satellites, or weapons released from space platforms that destroy

terrestrial targets. Today, these kinds of systems clearly break the

current thresholds of acceptability. . . . But the 21st century could

well see a change.2

This sentiment was echoed again by the commander in chief

of US Space Command (USSPACECOM), Gen Howell M. Estes

III, in his comments to Congress: “Space remains on the

cutting edge—support to our warfighter, even the potential for

war itself, is moving from Earth into space.” 3

 This outlook will

likely shape US space initiatives in the immediate future.

The pressure toward weaponizing space received additional

impetus in response to President William Jefferson Clinton’s

recent line-item veto of three space weapon-related programs:

Clementine II, the Army Kinetic-Kill Anti-Satellite (ASAT) program, and the Military Space Plane. These cancellations

prompted 43 high-ranking retired military leaders to issue an

open letter to the president urging him to change his decision.

This letter refers to space-based missile defense and neutraliz -

ing enemy satellites as “missions the United States military

must be prepared to perform.”4

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2
It is often assumed that defending space-based assets, and

neutralizing weapons that make use of space, require the de -

ployment of weapons in space. While space-based weapons

should not be dismissed from consideration without a thor -

ough evaluation, this evaluation appears to have been skipped

in the technological push to develop space-based weapons.

The following major questions have yet to be adequately ad -

dressed. What do space-based weapons have to offer that

other forms of military power lack? What are space-based

weapons likely to cost, both in terms of dollars and in lost

opportunities for pursuing other systems? A related concern is

what capabilities these weapons will confer upon other na -

tions if they eventually emulate a US deployment. This study

addresses these questions and determines what space-based

weapons can be expected to bring to the table. To begin, we

will summarize the arguments on both sides of the space

weaponization debate.

Arguments for Weaponizing Space

The arguments in favor of weaponizing space center

around the fact that the United States relies heavily on

space-based assets for both military and commercial needs.

Protecting these assets will become increasingly important

as access to space becomes cheaper and the technology

needed for this access becomes more available. As General

Estes said before Congress: “Increased reliance on space

systems means improved capabilities, but also new vulner -

abilities. . . . The U.S. must be able to control the medium of

space to assure our access and deny the same to any adver -

sary.”5

 Gen John Michael “Mike” Loh, USAF, Retired, former

commander of Air Combat Command, echoed this concern

at a Center for Security Policy roundtable discussion titled

“The Need for American Space Dominance.” In outlining US

dependence on space-based assets, General Loh noted that

“it is almost frightening when you . . . look at how little we

have allowed for the protection . . . of those assets.” 6

 While

these statements do not explicitly call for space-based weap -

ons to effect this control, a key underlying assumption of

this argument is that space-based weapons are needed to do

SPACY

3
the job. As a consequence no restrictions should be placed on

their development, testing, and eventual deployment.

Another line of argument in favor of space-based weapons,

or at least an argument for why they are inevitable, devolves

from the fact that every environment accessible to man has

eventually become an arena for combat. This line of reasoning

was noticeable in then-Secretary of the Air Force Sheila E.

Widnall’s address to the National Security Forum in May

1997: “You have, first off, a fundamental question of whether

we will place weapons in space. We have a lot of history that

tells us that warfare migrates where it can—that nations en -

gaged in a conflict do what they can, wherever they must. At a

very tender age, aviation went from a peaceful sport, to a

supporting function, very analogous to what we do today in

space—to a combat arm. Our space forces may well follow

that same path.”7

 This argument holds that the evolution of

warfare will inevitably require placing weapons in space in

order to fulfill a multitude of military roles. These roles in -

clude defending against ballistic missile attack, defending

space-based assets (the space control mission), and attacking

terrestrial targets (the force application mission).

Some take the argument a step further, believing that it is

probably too late to head off the weaponization of space. Maj

Gen Robert Dickman, the DOD space architect, made this

argument in 1997.

To hope that there will never be conflict in space is to ignore the past.

As space access becomes routine, ... as national security becomes a

matter of information dominance as well as other military strength,

the risk-benefit assessment for interfering with space capabilities will

change. Tomorrow, space won’t provide a sanctuary for systems that

can provide a decisive edge in combat, any more than the air or the

ocean depths do today. Tomorrow, commercial endeavors will look to

the government for protection, as they have on land and at sea for

over 200 years.8

The main contention of the argument is that space today is

analogous to aviation prior to World War I. The transition of

aviation from being a support service to being a combat arm

will soon be emulated by space systems. Any attempt to

thwart this process is not only doomed to fail but will also

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4
leave the United States vulnerable to attack from nations that

aggressively pursue space weaponization.

Arguments against Weaponizing Space

Today the United States is in an enviable position: It is the

only nation on earth that can project nonnuclear combat

power to anywhere on the globe. Never before has a single

nation had such an uncontested ability to intervene in events

around the world. However, this capability comes at great

expense. From long-endurance submarines to fleets of combat

aircraft and their supporting tankers, the physical assets nec -

essary to provide this capability are extensive and were only

made possible by a sustained effort during the long years of

the cold war. In addition to the equipment, large numbers of

military personnel require years of intensive training and continual practice to make the system work. With the demise of

the Soviet Union, the United States is free to intervene any -

where that it chooses, so it would appear to be in the best

interests of the United States to maintain the status quo.

In developing this world-spanning power-projection capability, the United States has come to rely heavily on space-based

assets for communication, navigation, and surveillance. Protecting these capabilities, or denying an enemy similar ones,

is essential if US armed forces are to remain dominant on the

battlefield. That doing this requires the development and de -

ployment of space-based weapons does not necessarily follow;

in fact, deploying space-based weapons is just as likely to

place other space-based assets in jeopardy. 9

 Indeed, the proliferation of space-based weapons may even give potential adver -

saries the ability to strike at the United States without incur -

ring the enormous costs of US-style armed forces.

If the United States develops and deploys space-based

weapons for controlling space, self-interest dictates that other

countries will follow suit. As with other technology, the great -

est costs are normally incurred in the initial research and

development (R&D) required to evolve a concept into a

weapon. Once a new weapon has been deployed it is much

easier, and less expensive, to observe the operational system,

determine how it must operate, and then duplicate it. By

SPACY

5
doing this initial R&D, the United States will be paving the

way for other nations to follow. The result may well be that

assets which are now safe—because no other nation has a

pressing need to develop weapons to attack them—will be -

come vulnerable to attack because other nations will feel com -

pelled to emulate the United States and deploy space-based

weapons of their own.

The argument against space-based weapons for attacking

airborne or surface targets is very similar. If the United States

deploys such weapons, other nations may feel compelled to do

likewise. In this case, the United States would not only be

making a segment of its defense system vulnerable to attack

but also could very well make US cities vulnerable. Unfriendly

nations with orbital weapons capable of attacking terrestrial

targets would be able to strike the United States, or anywhere

else on the globe, without investing the tremendous resources

necessary to field a US-style military. This would, in effect,

negate our present ability to intervene wherever it is in our

interest to do so, since a country possessing these orbital

weapons would be able to strike back. With the technology

necessary to launch satellites even now becoming widely

available, the number of countries capable of deploying spacebased weapons is growing. This proliferation of technology

makes US development of space-based weapons fraught with

peril.

In consideration of the arguments outlined herein, it seems

to be much more in the interest of the United States to advo -

cate a treaty banning space-based weapons entirely. Given the

current international climate of antipathy toward weaponizing

space, such a treaty is entirely plausible. Admittedly, spacebased weapons are probably inevitable in the long term; how -

ever, their eventual deployment can probably be delayed for

decades, if not longer, with a carefully written treaty.

Overview

As is evident in the preceding summaries, arguments have

traditionally focused on why weapons should or should not be

deployed in space. These arguments typically ignore questions

about exactly what space-based weapons can do that more

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6
conventional weapons are unable to do or can only accom -

plish at great cost. Any decision about placing weapons in

space, either for or against, should be based on a firm founda -

tion of knowledge about what these weapons are, how much

they are likely to cost, and what other options are available for

accomplishing the same missions. The purpose of this study

is to evaluate proposed space-based weapons and compare

them with their terrestrial counterparts so that an informed

decision about weaponizing space can be made.

The concepts are based on open-source documentation of

space weapon concepts currently being pursued or under consideration. The nature of these weapons is such that many of

them can be used for more than one purpose. In an attempt to

construct a logical and easily understood analysis, the types

of weapons and their capabilities are discussed in several

chapters. Chapter 2 lays out the concepts for space-based

weapons that have been proposed, their expected capabilities,

and the technological risks involved in pursuing them. Chap -

ter 3 focuses on alternatives to space-based weapons that

could allow the United States to achieve space control. Terres -

trial-based weapons and concepts for accomplishing both de -

fensive counterspace and offensive counterspace will be compared to the space-based alternatives. Chapter 4 focuses on

terrestrial alternatives to space-based force application weapons, including ballistic missile defense (BMD). Since many of

the weapons discussed in these chapters are in the earliest

phases of development, very little data regarding the expected

cost of complete systems is available. Cost data is mentioned

where it is available, but for the most part cost is treated

qualitatively.

Chapter 5 provides a brief overview of the potential political

implications of deciding to weaponize space. This topic is quite

extensive and worthy of an extensive research effort in itself.

Since others have already published works on this subject,

this study only highlights the most significant implications,

leaving further to the interested reader. 10 Finally, chapter 6

summarizes the conclusions that can be drawn from the ma -

terial presented and offers recommendations about the next

steps to be taken regarding the decision to weaponize space.

SPACY

7
Notes

1. “Fact Sheet: National Space Policy” (Washington, D.C.: White House

National Science and Technology Council, 1996), 1–6.

2. Gen Thomas S. Moorman Jr., vice chief of staff, USAF, “The Chal -

lenges of Space Beyond 2000,” address to the 75th Royal Australian Air

Force Anniversary Airpower Conference, Canberra, Australia, 14 June

1996; on-line, Internet, 9 January 1998, available from

http://www.af.mil/news/speech/current/The_Challenges_of_Spac

e_Bey.html.

3. Gen Howell M. Estes III, commander in chief, North American Aero -

space Defense Command and US Space Command, statement before the

Senate Armed Services Committee, Washington, D.C., 13 March 1997.

4. James A. Abrahamson et al., open letter to President Clinton, in -

cluded in the Center for Security Policy press release No. 98-P7, 15 January

1998.

5. Ibid.

6. “Summary of the Center for Security Policy High-Level Roundtable

Discussion of ‘The Need for American Space Dominance,’” attachment to the

Center for Security Policy press release No. 98-16P, 23 January 1998, 5;

on-line, Internet, 28 January 1998, available from

http://www.security-policy.org/papers/98-P16at.html.

7. The Honorable Sheila E. Widnall, secretary of the Air Force, “The

Space and Air Force of the Next Century,” address to the National Security

Forum, Maxwell Air Force Base (AFB), Ala., 29 May 1997; on-line, Internet,

9 January 1998, available from

http://www.af.mil/news/speech/current/The_Space_and_Air_Force_of_.htm l.

8. Maj Gen Robert Dickman, “The Evolution of Space Operations and

Warfare,” address to the American Institute of Aeronautics and Astronautics (AIAA) Symposium, Huntsville, Ala., 23 September 1997; on-line, Internet, 2 February 1998, available from

http://www.acq.osd.mil/space/architect/spcweb.html.

9. David W. Ziegler, Safe Heavens: Military Strategy and Space Sanctuary Thought (Maxwell AFB, Ala.: Air University Press, 1998).

10. Pericles Gasparini Alves, Prevention of an Arms Race in Outer Space:

A Guide to the Discussions in the Conference on Disarmament (New York:

United Nations Institute for Disarmament Research, 1991), annex A, pt. 2,

79; and Karl Mueller, “Space Weapons and U.S. Security: Why and How to

Avert a Dangerous Potential Revolution,” research paper, School of Ad -

vanced Airpower Studies (SAAS), Maxwell AFB, Ala., September 1997.

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8
Chapter 2

Space-Based Weapons

What we want to do in or from space is affected greatly by

our judgments as to what is technologically possible.

Although we should not permit defense policy to be driven

simply by what is technologically possible, regardless of

careful consideration of strategic need and desirability,

neither should we close our minds to the possibility that

new technology may change dramatically the terms of

strategic policy debate.

—Colin S. Gray 

American Military Space Policy

As Colin S. Gray aptly put it, the decision of whether to

deploy weapons in space should not be based only on the fact

that it is technologically possible to do so. It is equally impor -

tant to determine if such weapons are truly needed. Creating

new weapons merely because it is possible to do so can have

unfortunate consequences. A historical example of such a technological imperative producing a weapon of questionable value

is the Nazi rocket program of World War II. Approximately two

billion marks (500 million 1942 dollars) produced enough V-2

rockets to deliver about 6,000 tons of high explosives against

the Allies—a quantity that is only about four times that

dropped during a single Royal Air Force (RAF) raid on the

Peenemünde rocket development center itself.1

 While this effort was not the sole cause of the Nazi downfall, it certainly

absorbed resources that could have been better used else -

where. The current era of austere defense budgets makes it

imperative that the US military avoid a similar miscalculation.

Because letting technology alone drive the development of

weapons can have serious repercussions, it is necessary to

evaluate weapon concepts carefully to determine whether they

have the potential to serve national defense needs. The pur -

pose of this chapter is to lay out the types of space-based

weapons currently being considered for development, how

9
they are envisioned to be used, and what technological factors

bear on the decision to deploy them.

Missions for Space-Based Weapons

Space-based weapons are being considered for two categories of missions: space control and force application. The

space control mission includes protecting US and allied space

assets, attacking enemy assets, and denying an enemy access

to space. The primary means for accomplishing these tasks

are either launch suppression or destroying or degrading the

performance of enemy satellites. These actions can be either

defensive, protecting friendly assets, or offensive, denying the

enemy the benefits of space-based assets. Potential force ap -

plication missions include BMD and attacking airborne or ter -

restrial targets. Of these, BMD has received the most atten -

tion, even more than space control. The main reasons for this

are the United States’s pursuit of a high profile and costly

BMD development program called the Strategic Defense Initiative (SDI)—often referred to as Star Wars, 2

 and the prohibition

of space-based BMD systems in the Treaty on the Limitation

of Anti-Ballistic Missile Systems (1972).

The concepts being explored to perform these tasks run the

gamut from direct impact kinetic energy weapons (KEW) to

high-energy lasers (HEL) that can destroy satellites across

thousands of kilometers (km). The weapon concepts being ex -

plored for space control missions are very similar to those for

force application missions; particularly those developed for

BMD. In fact, many of the proposed weapons can be used for

more than one mission. Because of this inherent multiuse

nature, weapon concepts are discussed individually, and prospective missions are delineated for each of them.

Directed Energy Weapons

Directed energy weapons (DEW) include laser, radio fre -

quency (RF), and particle beam weapons. Only the first two

types of weapons are discussed here since particle beam

weapons have fallen out of favor for a variety of reasons. 3

 Even

lasers have their problems, and while the idea of reaching

CADRE PAPER

10
across thousands of kilometers at the speed of light to destroy

a target is alluring,4

 the associated technical problems are

considerable.

Lasers

The potential for using lasers as weapons was recognized

almost from the moment they were first discovered in 1960,

but producing beams with enough power has always been

problematic. Lasers have several characteristics that seem to

make them ideal candidates for space-based weapons. Using

lasers in space eliminates the need for them to compensate for

distortion caused by atmospheric turbulence, a major concern

for terrestrial laser weapon concepts.5

 A laser can strike at the

speed of light and hit a target almost instantaneously. Since

light has no mass, lasers are not constrained by orbital dy -

namics and can fire against any target within their line of

sight. Unfortunately, lasers also have drawbacks that make

using them as weapons more complicated than is often as -

sumed.

The basic parts of a laser weapon system are the laser itself,

its power supply, the systems necessary to track targets and

point the laser, and the command and control (C 2

) systems

necessary to employ it. Major subcomponents of the laser are

the resonance chamber and the mirrors needed to focus and

aim the beam. The size of these components, as well as that of

the power source, vary with the type of laser and the beam

power to be produced.

Laser beams can be created in a number of ways and the

characteristics of the beam depend on the manner of its crea -

tion. The first lasers used solid crystals such as rubies and

have demonstrated the highest power levels, up to 10,000

megawatts (MW), but only in very short pulses. Attempts to

deliver more energy to a target by generating multiple pulses

inevitably create heat problems that shatter the crystals. 6

These lasers are also not very good at converting electricity

into laser energy, with efficiencies generally less than about

1–2 percent.7

 Continuous wave lasers, which emit a constant

beam rather than pulses, have also been investigated and

show greater promise for use as weapons. Each type of laser

SPACY

11
has its own drawbacks; the ones being considered for use as

weapons attempt to mitigate these problems to arrive at a

practical system.

The main problem with making a laser into a weapon is

generating a reliable, high-power beam with good beam qual -

ity. For the role most often discussed, space-based BMD, the

energy density necessary to fatally weaken the skin of a liq -

uid-fueled ballistic missile may be as low as 1 kilojoule per

square centimeter (KJ/cm2

).8 The more robust construction of

solid fuel ballistic missiles, coupled with fairly simple counter -

measures (such as ablative coatings), may raise this level as

high as 30 KJ/cm2

.

9

 Richard L. Garwin, a physicist at IBM in

the Thomas J. Watson Research Center and consultant for

Los Alamos Science Laboratory, calculates that for a missile

hardness of 20 KJ/cm2

, a laser must focus a 25-MW beam

into a spot 1 meter (m) in area for 6.7 seconds if it is to deliver

energy to the target fast enough to burn through the casing. 10

This calculation assumes the missile does not rotate, which

is another relatively simple countermeasure. It is reasonable

to assume that the testing and deployment of space-based

laser weapons by the United States will prompt potential

adversaries to take these basic precautions. For this reason

a laser capable of producing a 25-MW beam and focusing it

into a spot of 1 square meter (m2

) at a range of 3,000 km for

7 seconds will form the baseline for discussion in this

study.11

To date, the most powerful continuous wave lasers created

by the United States generate only 1–2 megawatts. While one

current design (the Alpha laser) is said to be scalable to

greater power levels, these higher power levels would require

massive space structures. The lasing chamber of the Alpha

laser (the chamber that produces the beam) is over 2 meters

long and produces a “megawatt power” beam. 12 If this is interpreted to be 1–2 megawatts, and the optimistic assumption is

made that the laser is linearly scalable, then the chamber

would have to be 25–50 meters (82–164 feet) long in order to

produce a 25-MW beam.13

Building lasers with enough power is only one of the hurdle s

to overcome before practical laser weapons become a reality.

Other obstacles include creating highly reflective mirrors able

CADRE PAPER

12
to focus and direct the powerful beams without overheating.

To point the mirrors, steerable assemblies precise and agile

enough to maintain the beam on a moving target for the re -

quired seven seconds (for BMD) and then rapidly slew to an -

other target must also be developed. The problem is that there

is a relationship between the wavelength of the laser, mirror

size, engagement range, and power delivered to the target. 14

For ranges of 3,000 to 4,000 km, the laser’s mirror would

have to be 10 to 14 meters (33–45 feet) in diameter. 15 These

mirrors must be pointed accurately enough to prevent devia -

tions of more than tens of centimeters while the weapon trav -

els about 50 km in one direction and the target travels about

40 km in another.16 While aiming devices with the requisite

precision and accuracy have been demonstrated, 17 these demonstrations have been made with the laser and its associated

pointing equipment firmly bolted to the earth, not floating in

space. The tests also did not have to track targets moving as

fast as an intercontinental ballistic missile (ICBM) and have

not incorporated the large mirrors necessary to handle lasers

powerful enough to be weapons.

In order for a laser weapon’s mirror to minimize phase er -

ror, it is created out of segments that are individually moved

by actuators.18 The large structures needed to support these

mirrors are difficult to maneuver quickly for retargeting. Al -

though the Ballistic Missile Defense Organization (BMDO) es -

timates retargeting to require as little as “0.5 seconds for new

targets requiring small angle changes,”19 this seems optimistic. A point of reference that runs counter to this claim is the

Hubble space telescope, which has a three-second settling

time for even the smallest adjustments and takes several min -

utes for retargeting. While it is not designed to be a weapon,

the Hubble space telescope is much smaller, with a singlepiece mirror that is only 2.4 meters in diameter. 20 The momentum that must be overcome to maneuver larger structures will

likely require similar amounts of time even if significant ad -

vances are made. While BMD lasers may not need to be moved

through large angles for reaiming if the targets are clustered

together, more dispersed targets may require this capability.

The type of laser currently being developed for use as a

weapon is the chemical laser. This variety produces a beam by

SPACY

13
mixing chemicals at low pressure. When mixed, these chemi -

cals react in a way very similar to rocket fuel, but in this case

the result is intense light with the energy concentrated in a

very narrow band of wavelengths. The products of the com -

bustion are high-temperature corrosive gases that must be

continuously removed from the chamber for the lasing process

to continue. One of the major problems to be overcome if

lasers are to be successfully made into space-based weapons

is providing enough chemical fuel to power them. The lasers

will consume approximately 375–750 kilograms (kg) of chemi -

cals per second, and engaging 10 ballistic missiles requiring 7

seconds each would require 26,250–52,500 kg—57,750–

115,500 pounds (lb) of chemicals.21 Supplying these chemicals

to an orbiting satellite would be a major logistical challenge.

The need for large quantities of chemicals appears to make

space-based chemical lasers unfeasible, but with efficiencies

of about 25 percent, chemical lasers have the best combina -

tion of efficiency and power generation of any lasers being

investigated today.22

The mechanics of processing large quantities of gas to gen -

erate the laser beam also complicate the system. Current

plans call for venting the spent gas overboard to dispose of

it.23 It is assumed that the vacuum of space will prevent the

hot corrosive gases from damaging the laser; however, with

flow rates of hundreds of kilograms per second, there may be

a tendency for the gas to form a cloud around the satellite. It

will also be necessary to vent the exhaust in multiple direc -

tions so that the resulting forces cancel each other out and do

not move the satellite.

Chemical lasers appear to have serious drawbacks, but the

alternatives are even less promising. Lasers that require elec -

tricity to generate the beam have been largely eliminated from

consideration as weapons because of the difficulty in generat -

ing enough power in space. Compared to chemical laser effi -

ciencies of 25 percent, the 0.01 percent efficiency of electri -

cally driven helium-neon lasers is paltry indeed. 24 Due to the

inherent losses in generating electricity in the first place, the

conversion efficiency of an electrically driven laser makes find -

ing an adequate power source a major problem.

CADRE PAPER

14
Even if electrically driven lasers were 100 percent efficient

at converting electricity into beam power, this approach would

be impractical. Unless nuclear power is used, it is probably

not even possible to generate enough electrical power.25 Solar

power is impractical because at 130 watts per square foot

(w/ft2

), solar energy is not dense enough to power a weapon. 26

Even if 100 percent of the solar energy available were con -

verted into laser energy, it would take about 192,000 square

feet of solar collectors to produce the 25 megawatts necessary

for a laser weapon. Given the limitations of today’s technology,

solar cells only produce about 10 watts per pound (w/lb). This

means that a 25-megawatt laser would require 2.5 million

pounds of solar cells, and this figure does not include the

batteries that would be needed to store the energy if the

weapon was to be usable in the absence of sunlight. Even if

current efforts to increase solar cell efficiency to 50 w/lb are

successful, 500,000 lbs just for solar cells is still impractical.

It becomes apparent that despite their drawbacks, chemical

lasers are the best such option available today.

Another constraint is imposed by the need to keep ranges

down to 3,000 to 4,000 km, at least for engaging ballistic

missiles. To do this, the lasers must be in fairly low orbits of

about 1,000 km. Low orbits in turn require a large number of

satellites if continuous coverage of a target area is to be main -

tained. For example, in the BMD role the number of satellites

required to stop a massive missile launch (1,400 missiles)

from the Soviet Union would have been 460 even under very

optimistic assumptions.27 Obviously if the projected threat

comprises significantly fewer missiles, then the number of

satellites can be reduced.

The current US program to develop laser weapons for the

BMD mission is the space-based laser (SBL) program. The

objective of this program is to provide the United States with a

BMD system effective against both short-range (theater) and

ICBMs. To defend against ballistic missiles, the SBL would

engage them in the boost phase while they were still accelerat -

ing. Destroying a missile early is important because once

the rocket motor cuts off it has enough velocity to reach the

target country. Boost-phase destruction causes the missile to

fall short of the target, ideally on the enemy’s territory. The

SPACY

15
front-running candidate for the SBL is a hydrogen-fluoride

chemical laser based on the Alpha laser developed under the

SDI. In 1991 this laser demonstrated the capability to produce

megawatt power in a simulated space environment. According

to Lt Col John R. London III, SBL program integrator at

BMDO, the envisioned system would consist of a constellation

of 20 satellites operating at an altitude of 1,300 km and would

provide “planetary coverage” for both theater and ICBMs. 28

Using consumption rates of 375–750 kgs, this system would

require 1,155,000 to 2,310,000 pounds of chemicals just to

give each of 20 weapons the ability to fire 10 bursts of seven

seconds each. This is more than just a small logistical prob -

lem; it is a fundamental weakness of the concept. 29

The space control mission also appears to be an ideal one

for orbital lasers. The great distances inherent in space opera -

tions, coupled with the large amounts of energy required to

change orbits, pose considerable problems when attempting to

physically intercept an enemy satellite. Using lasers as ASAT

weapons seems to offer the prospect of sidestepping these

problems in the same way that they do for BMD. Unfortu -

nately, designing orbital lasers to attack satellites incurs

many of the same problems encountered with designing them

to attack ballistic missiles, although the physical characteristics of satellites may make them easier to damage.

If they could be built, orbital lasers with the ability to de -

stroy ballistic missiles in the boost phase would probably also

be capable of destroying satellites. Orbital dynamics ensures

that the relative velocity between two satellites in similar or -

bits would probably be within the range of velocities for which

an orbital laser designed to engage an ascending ballistic mis -

sile would have to contend. The pointing accuracy and track -

ing capability needed for a BMD laser should also be adequate

to track a satellite in a crossing orbit, a situation where the

need to quickly slew the weapon would be the greatest. 30 Similarly, the range at which BMD lasers are being designed to

operate would also be adequate for the ASAT mission. How -

ever, designing an orbital laser to be effective against both

ballistic missiles and satellites would require some additional

capability.

CADRE PAPER

16
Satellites have some characteristics that make using lasers

against them difficult. The “kill mechanism” by which lasers

can destroy satellites is different from that used to destroy

ballistic missiles. Ballistic missiles have an extremely bright

infrared (IR) signature during launch and a fragile structure

that would collapse catastrophically, and visibly, if signifi -

cantly damaged. Satellites are built quite differently. While

satellites generally have delicate components, such as solar

cells and optical sensors, that are vulnerable to laser attack,

the destruction of these components would be difficult to ver -

ify. Causing greater damage, or damaging satellites without

vulnerable sensors, may be necessary for verification pur -

poses. Determining which part of a satellite to target, and

then focusing the beam on that part for the requisite length of

time, promises to be no more difficult than focusing a laser on

an ascending ballistic missile. However, the much fainter IR

signatures of satellites also require a different mechanism for

target acquisition and tracking.

An additional point to consider when deciding whether to

use orbital lasers in the ASAT role is that it would probably be

necessary to place them in orbits different from those opti -

mized for BMD. Ideally an ASAT laser would be placed in an

orbit that allowed it to pass within lethal range of the maxi -

mum number of targets, albeit over a considerable period of

time. Such an orbit is unlikely to be the same as those of a

satellite constellation optimized to keep the most likely missile

threats within range. This fact would diminish any savings to

be gained by exploiting the multiuse nature of orbital lasers.

One problem orbital lasers definitely will not be able to solve

is the difficulty associated with attacking satellites at truly

long distances. Ideally, an ASAT laser would be able to attack

more than just the satellites in neighboring orbits. Unfortunately, the problems of constructing a laser capable of engag -

ing targets at a range of 3,000 km are compounded as the

range increases. For instance, if a weapon in low earth orbit

(LEO)31 were to engage military communication satellites in

geosynchronous earth orbits (GEO), it would need a range of

almost 30,000 km.32 Designing a weapon with such a long

range increases the size of the mirror needed to focus the

beam, unless shorter wavelength lasers can be devised. As

SPACY

17
mentioned earlier, there is a direct relationship between mirro r

size and the range of the weapon. A laser that had a range of

30,000 km would require a mirror 99 meters (325 feet) in

diameter if current chemical lasers were to be used. These

large mirrors must also be agile enough to keep the laser

beam on the target long enough to do damage. Building such

enormous structures capable of maneuvering with this much

agility would be a major technological achievement.

To overcome the difficulty of operating at extremely long

range, it would be possible to deploy some weapons in orbits

just below GEO, for instance 3,000 km lower so that the

lasers being developed for BMD could be used. Unfortunately

the cost of doing so would be very high. If the massive weap -

ons envisioned for BMD were to be placed in orbits with an

altitude of 27,000 km, which would allow them to cruise past

a satellite in GEO about every 161⁄2 hours, then massive

boosters would be required both to deploy them initially and

to refuel the lasers if it became necessary. While lasers operat -

ing at shorter wavelengths would solve some of these prob -

lems,33 these lasers have yet to produce enough power to be

feasible weapons.34

Thus if a space-based laser could be made to work as a

BMD weapon, it could also be modified to have considerable

ASAT capability. The primary changes needed for this new

mission would be the ability to detect the much fainter IR

signature of distant satellites, and to deploy the weapons in

orbits optimized for ASAT operations. While some target satel -

lites would pass within lethal range of SBL platforms dedi -

cated to BMD, using precious shots from the only weapon

capable of intercepting a ballistic missile in the boost phase,

just to destroy a satellite, may not be wise. Conversely, dedi -

cating weapons as sophisticated as orbital lasers to ASAT op -

erations, by deploying them into ASAT-optimized orbits, would

be an expensive solution. These considerations become par -

ticularly germane when orbital lasers are compared with the

other options for performing the space control mission that

will be discussed in chapter 3.

Another proposed use for space-based lasers is the force

application mission of attacking airborne or surface targets.

However, the only laser being considered for development as

CADRE PAPER

18
an orbital weapon is the Alpha chemical laser that operates at

a wavelength of 2.7 microns.35 This wavelength was chosen in

part because the laser energy is heavily absorbed by water

vapor in the atmosphere, which is considered to be a safety

feature because it prevents unintended collateral damage

when ballistic missiles are being engaged. 36 While this may be

a safety feature for the SBL, it makes the laser of little use for

engaging airborne or surface targets.

Using other wavelengths could allow space-based lasers to

have some capability against airborne and surface targets. If

shorter wavelengths were used, another advantage would be

that the mirrors that aim the beams could be made smaller. 37

Unfortunately, there remains the major problem of producing

a laser with a significantly better combination of wavelength

and power.

While Alpha-type lasers would be ineffective against surface

targets, the nature of airborne targets makes any such weap -

ons of questionable use even against high-flying aircraft.

While combat aircraft are specifically designed to be able to

withstand considerable damage and still complete their mis -

sion, the cockpit canopy of an aircraft is vulnerable to laser

attack. In fact, the types of lasers being considered for BMD

weapons are very effective at vaporizing Plexiglas, provided

they can dwell on the target for long enough. Something that

may make this difficult is that the flight path of an aircraft is

much less predictable than that of a missile, although this

may be offset by the fact that they also move much more

slowly. However, given the power levels required of BMD la -

sers, it is probable that burning through the canopy of an

aircraft at high altitude would not be difficult.

If a space-based laser were powerful enough to penetrate

the canopy of an aircraft, another problem is that the detec -

tion and tracking system needed for attacking aircraft is dif -

ferent from one which exploits the very hot and bright plume

of a ballistic missile or the reflected light of a satellite against

the background of space. This is because it would be very

difficult to use an optical or IR tracking system to detect and

track the relatively small, cool signature of an aircraft against

the background of the earth. Furthermore, the weapon would

need some means of determining where on the aircraft the

SPACY

19
beam must be focused, a far from trivial problem at the ranges

involved. Giving an orbital laser the ability to detect and track

aircraft would require yet another set of sensors and addi -

tional software to overcome these problems. Changes such as

these would add cost and complexity to an already expensive

weapon.

Similar to giving BMD lasers an ASAT capability, the addi -

tion of a counterair capability would further complicate the

decision of which targets to attack. Fuel limitations would

mean that every aircraft engaged would be one less ballistic

missile (or satellite) that could be shot down. Given the fact

that there are other weapons that are very good at shooting

down aircraft, and that the same is not true of ballistic mis -

siles, using lasers to engage high-flying aircraft does not ap -

pear very attractive.

Another potential obstacle to using SBLs against airborne

targets may be the 1980 United Nations (UN) Conventional

Weapons Convention. This convention, or more specifically

Protocol IV, signed in January 1997, prohibits using weapons

that are designed “as one of their combat functions to cause

permanent blindness to unenhanced vision.”38 As long as a

space-based laser is designed to destroy the aircraft or kill the

pilot, it would be legal. But if the laser lacks the power to do

more than blind the pilot, then using it against aircraft could

be deemed illegal. This situation may not be as far-fetched as

it initially appears. If an orbital laser were designed primarily

for other missions, its capability against aircraft could very

easily be limited to blinding the pilot. Using it in such a mode

would clearly be illegal, and citing this potential capability, as

part of a rationale for developing the system would only bol -

ster the arguments of those who oppose it. 39

Once the problems of transforming a laser into a viable

weapon have been solved, it will still be necessary to make it

robust enough to survive years of inactivity in the hostile

environment of space. From the threat of being struck by

space debris, to environmental factors such as radiation,

charged particle bombardment, and the thermal cycling inher -

ent in the frequent passages from day to night, space is a

challenging environment in which to operate. While all satel -

lites must contend with these problems, lasers are particularly

CADRE PAPER

20
delicate. Lasers are extremely dependent on the precise alignment of their components if they are to work. As demonstrated

by the near failure of a recent test of the MIRACL laser, it is

difficult to get a high-power laser to work reliably on the

ground.40 Building such a laser to withstand the rigors of

launch and subsequent storage in orbit will be extremely chal -

lenging. Couple these difficulties with the consequences of fail -

ure, since weapons by definition are only used in times of dire

need, and the prospects of a feasible SBL grow much dimm er.

To be practical as space-based weapons, lasers must be

devised that combine the qualities of high efficiency, short

wavelength, high power, and low cost in a package robust

enough to withstand the rigors of space. With all of these

hurdles to overcome, an SBL weapon will not be feasible with -

out a number of fundamental breakthroughs in laser physics

and engineering.

Radio Frequency Weapons

Another family of DEWs are radio frequency (RF) weapons.

These weapons would be deployed in geosynchronous orbit

and use large antennas to direct RF energy at enemy elec -

tronic systems. RF weapons would use very large antennas

the size of which would determine the size of the beam reach -

ing the earth’s surface. Antennae diameters of 100 meters

would yield six-mile-diameter beams while 1,000-mete rdiameter antennas could produce much more intense beams

as small as one mile in diameter. Within the beam’s footprint,

power densities would be about 10 watts per square meter

(w/m2

) and could burn out unprotected electronics and thor -

oughly disrupt even shielded systems.41

A major factor weighing against RF weapons is the consider -

able technological advances necessary to make them feasi -

ble.42 One major obstacle is the development of the advanced

antennas that would be necessary. While it may eventually be

possible to construct inflatable structures for antennas that

are 100 meters in diameter,43 larger antennas are envisioned

to use a “virtual” structure where hundreds or thousands of

microsatellites would be arranged in a very precise formation

and operate in concert. The difficulty lies in the fact that each

SPACY

21
of them must maintain position relative to the others. Con -

stantly changing position precisely enough to create a “virtual”

structure will require large amounts of maneuvering propellant

and is unlikely to be feasible within the foreseeable future. 44

Considering the hurdles in orbital antenna technology that

must be overcome before space-based directed-energy weapons are feasible, it is unlikely that such systems can be fielded

until the cost of routine access to space is reduced to the

point that extensive experimentation can be undertaken. In

light of this, technologically less challenging weapons are also

being investigated.

Direct Impact Weapons

Although laser and RF weapons appear to have many desir -

able properties, direct impact weapons are more feasible given

current technology. Weapons that use either KE or that pass

near enough to a target for an exploding fragmentation device

to destroy it are being considered for a number of applications.

In the arena of space control, ASAT weapons using ea ch of

these methods have been proposed and tested. For the force

application mission, space-based weapons using these methods have been proposed for attacking surface and airborne

targets.

Kinetic Energy Antisatellite Weapons

Direct impact KEWs rely on the large velocity differentials

inherent in orbital dynamics to destroy a target. Given that a

satellite in LEO travels at a velocity of approximately 7.8 kilo -

meters per second (km/s), and that one pound of anything

moving at 3 km/s has KE equivalent to a pound of high explo -

sive,45 hitting something at these speeds can be catastrophic.

If the target is as fragile as a satellite, then only small

amounts of mass are needed for destruction upon impact.

However the problem of actually hitting a target is complex.

A space-based KE ASAT must be placed in an orbit that

allows for a responsive intercept time. While there are a multi -

tude of orbits that can accomplish this for any given target,

the easiest way to visualize the problem is to consider an orbit

CADRE PAPER

22
that crosses the target’s orbit numerous times during a day. If

the ASAT’s orbit is either higher or lower than that of the

target, a relatively small booster motor could change it so that

the ASAT intersects the target’s orbit. Using the most eco -

nomical transfer orbit would require only modest amounts of

propellant, although it would be necessary to time the inter -

cept so that the target would be at the intersection point of the

orbits when the ASAT arrived.46 An important consideration

for a space-based ASAT is preventing the enemy from knowing

that a satellite is in fact a weapon. Fortunately non-ASAT

satellites are placed in a wide variety of orbits and an ASAT

could almost always be placed in a suitable orbit that would

not reveal its nature.

A cursory overview of the interception process makes it

seem fairly straightforward. For the United States, tracking

satellites is not a difficult task, but in order to destroy one it is

necessary to predict its future position with a high degree of

accuracy. This accuracy is needed so that the interceptor can

be placed close enough to the target for on-board sensors to

see the target and make the final corrections for a direct

impact. These last two steps are the most challenging.

What makes intercepting satellites so difficult is the combi -

nation of the large closing velocity inherent in KE space weap -

ons and the relatively small size of the target. While the larg -

est satellites may be about the size of a Greyhound bus, this

bus is traveling at 7.8 km/s in LEO, about 17,500 miles per

hour (MPH). In addition to the velocity of the target, the veloc -

ity of the intercepting weapon adds a complicating factor.

Since the orbital altitude of a satellite determines its velocity,

at the point of interception the velocities of the two satellites

may be similar in magnitude but different in direction. 47 Thus

the closing velocity will be the vector sum of the velocities of

the target and the weapon. Since KE ASATs rely on the veloc -

ity differential for destructive energy, it is necessary to keep

closing velocities fairly high, a factor which complicates the

interception process.

Once placed in an intersecting orbit, the interceptor must

be able to “see” the target far enough away to allow it to make

the final corrections needed for interception. This maneuver is

not trivial even for the low closing velocities of 1,000 to 2,000

SPACY

23
MPH that are typical of air-to-air missiles fired at aircraft.

Closing speeds more than 10 times greater make hitting a

satellite much more difficult. Since only a direct impact will

destroy the target, it is essential to determine the target’s

position and velocity with a great degree of accuracy. The

combination of needing to see a target at long range coupled

with the agility necessary to make timely adjustments yields a

complex weapon. While steps can be taken to increase the

probability of a hit, such as dispersing a cloud of small steel

pellets, the problem of ensuring a “kill” is still a difficult one. It

should be noted that the feasibility of a KE weapon h as already

been demonstrated by the United States, while a co-orbital

system was demonstrated by the Soviet Union, although both

of these systems were ground based. 48

Co-orbital Antisatellite

Another method for attacking enemy satellites is a co-orbital

or near co-orbital approach. A co-orbital ASAT is one that

closes slowly with its target, similar to the space shuttle ren -

dezvousing with satellites in need of repair. A co-orbital ASAT

uses an exploding warhead to destroy the target rather than

the KE from a velocity differential. The main problem with this

type of ASAT is that it usually takes at least one orbital period,

about 90 minutes for LEO and longer for higher orbits, to

match orbits with the target satellite. If the ASAT is to remain

inconspicuous (i.e., if the ASAT’s orbit is to disguise the na -

ture of the weapon), this method will also require that it make

larger maneuvers than a KE weapon to complete an intercep -

tion, especially if the target is in a different orbital plane.

These factors dictate an interceptor with more maneuvering

capability than an ASAT using a high-speed impact, although

the interceptor would not have to be as agile.

Once a co-orbital vehicle starts on its intercept course, the

target’s owners could detect the maneuver and initiate countermeasures. The long time to interception may give the target

time for either defensive actions or evasive maneuvers, de -

pending on its capability. Between the slower intercept and

the requirement for a larger more maneuverable vehicle, the

CADRE PAPER

24
high-speed (KE) approach seems to hold the most promise for

a direct impact weapon.

Space Mines

An additional ASAT concept is the space mine. This type of

weapon is similar to the co-orbital ASAT except in this case

the weapon is placed into an orbit near the target satellite well

before any hostilities break out. The problems inherent with

this approach are similar to those of the co-orbital ASAT,

compounded by the need to make the approach unobserved.

As mentioned above, attempting to close with another satellite

usually requires a large vehicle expending large quantities of

propellant. In contrast, a viable space mine would require a

more covert method of approach.

One method is to design a very small stealth weapon that is

slowly moved into position over a long period of time. The

weapon’s orbit can be chosen so that it will not approach the

target for days or weeks after launch, essential if an adversary

isn’t to become suspicious. When it does approach the target,

the weapon will have a low relative velocity. If done properly,

only a short firing of the thruster will then be required to

match orbits and “park” the weapon near the target. When

needed, the weapon can be activated and destroy the target by

closing the final distance and exploding. The problem with

this concept is that this type of weapon must be deployed well

in advance of when it is needed, a fact that places consider -

able demands on its design.

One major problem with the space mine is the need to

perform station-keeping maneuvers (to keep itself near the

target) while simultaneously keeping its most stealthy aspect

pointed toward the earth (in order to avoid detection). Most

potential target satellites maneuver often to accomplish their

mission, and even targets in geostationary orbits must make

adjustments to maintain their position. These maneuvers will

have to be mimicked by the mine if it is to maintain its posi -

tion relative to the target. Thus the mine should be small and

stealthy to avoid detection but may need a considerable

amount of propellant to do its job. While there are electrically

driven ion thrusters that do not consume much propellant,

SPACY

25
they require large amounts of power and produce only micro -

scopic amounts of thrust.49

Another major problem associated with designing a longlived space mine is providing a power source for the weapon.

Since it may be many years before the mine is detonated, a

long-term power source is necessary. If an electric propulsion

system is used, this problem becomes even more critical. Most

satellites meet their electrical needs by using solar power.

However solar panels are not very compatible with a stealth

satellite because they cannot always be oriented to provide a

minimal radar cross-section. Most other power sources, such

as batteries or fuel cells, cannot provide enough power for

long enough to do the job. One potential solution, nuclear

power, has other problems. Aside from the political outcry

against using nuclear power in orbit, which may not matter

with a weapon whose utility depends on absolute secrecy, the

thermal signature of a nuclear-powered satellite may make it

less than ideal for a space mine. 50 While breakthroughs in

technology may someday provide the means for surmounting

the problems inherent in creating effective space mines, the

costs of doing so may well be significant. 51

Kinetic Energy Weapons for Force Application

KEWs are also being considered for the force application

missions of BMD and orbital bombardment of very hard, highvalue, terrestrial targets. Orbital bombardment seeks to de -

stroy targets by converting the KE associated with the

weapon’s high velocity (5 to 11 km/s) into work and heat.

Such projectiles could have a number of configurations, including long thin rods, ultrahard penetrating warheads, or

warheads that fragment shortly before impact.

As with most weapons, trade-offs must be made when de -

signing weapons for orbital bombardment. To attain velocities

in the range of 10 to 11 km/s, satellites must be in orbits with

an altitude of more than 40,000 km, but these high-altitude

orbits sacrifice responsiveness to achieve high-impact veloci -

ties. For instance, a weapon in a 40,000 km orbit would need

about five hours to reach the earth’s surface and would have

an impact velocity of about 10 km/s. The actual time required

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26
to hit a specific target would probably be longer since it is

unlikely that the weapon would be in the proper position to

initiate an immediate attack. Lower orbits could yield shorter

response times; for instance a satellite placed in a 500-mile

(926 km) orbit could strike in less than 12 minutes if the

orbital geometry was ideal. The trade-off is that a weapon in

LEO would impact at less than 5 km/s. 52

One design for such a KE projectile is a thin, heavy, metallic

rod one to two meters in length. Such a weapon could be used

against hard targets that are not too deeply buried. Depending

on what they are made of, the rods can penetrate two to three

times their length into a target. As long as the rod impacts at

a velocity in excess of 3 km/s, the depth it penetrates depends

exclusively on the composition of the target and the rod, with

only slight differences among specific hard target materials. 53

The mechanism used for penetration is progressive erosion of

the tip of the rod coupled with progressive erosion of the

substance being penetrated. The pressure generated at the tip

of the rod causes both the rod and the target to liquefy in the

vicinity of the tip. As the rod penetrates the target, its progress

is similar to that of a high-pressure jet of water penetrating

earth. The results of hitting a target with one of these rods is

similar to boring a hole, placing in the hole an amount of

explosive comparable in weight to that of the rod, and deto -

nating it. For example, a two-meter rod weighing 50 pounds

and penetrating to a depth of six to eight meters is similar to

detonating 50 pounds of explosive in a hole slightly larger in

diameter than the rod. As long as the rod penetrates to the

interior of the target, the results are devastating. 54 A drawback

of this type of weapon is that very deep targets would necessi -

tate rods too massive to be practical. 55

Another method for making use of the high velocities pro -

vided by orbital weapons is to use an ultrahard penetrator

with an explosive warhead. With this approach the weapon

remains intact and can penetrate much deeper than eroding

rods. After it has reached a preset depth, based on time from

initial impact, or enters a zone of low resistance, like a room

or tunnel, the warhead detonates. From a feasibility stand -

point, materials hard enough to remain intact during the

penetration phase are still being investigated. While thes e

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27
materials may make impact velocities of up to 4 km/s possibl e,

this capability has yet to be demonstrated. Materials readily

available, such as tungsten carbide, are generally unable to

withstand impact at velocities much in excess of 1.5 km/s;

above this velocity the weapon has the characteristics of a

very short eroding rod.56

For orbital bombardment of softer targets, a weapon could

be designed to slow down considerably before impact. Since

speeds of Mach 6 to 8 (4,500 to 6,000 MPH) are all that is

necessary for small hardened projectiles to penetrate all but

the most heavily armored vehicles,57 extremely high velocities

are not required. These lower velocities can allow the weapon

to maneuver to attack moving targets, like surface ships or

armored formations. Shortly before impact, the weapon would

explode into a cloud of high-velocity projectiles. The detona -

tion height and the projectiles would be optimized to achieve

the desired effects against the type of target being attacked.

In addition to problems with orbital timing and responsive -

ness, precisely hitting a terrestrial target from orbit is far from

simple. While it is probably feasible to hit a target as large as

an armored formation with an area-type weapon when its

location is precisely known, striking small, truly hard targets

is far more difficult. Even assuming that the location of the

target is precisely known, which is feasible for fixed targets,

the weapon must be aimed accurately enough that atmos -

pheric disturbances will not deflect it too severely. To aim the

weapon, it is necessary to release it at a very precise location

and velocity. Great improvements in accuracy have been

achieved for ICBM warheads, but while 100 meter accuracies

are good enough for nuclear weapons, they are not nearly

good enough for attacking hard targets with KE weapons. 58

Solving this problem will be essential if weapons moving at

orbital velocities are to be used against very hard targets.

The conventional method for improving the accuracy of

weapons, providing guidance and course corrections during

the last seconds before impact, is not likely to work for highspeed orbital weapons. Even if a target could be designated

with a laser, in which case conventional laser-guided weapons

would probably be a more sensible choice, it would be difficult

for a projectile moving at orbital speeds to “see” the laser early

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28
enough to make corrections. In fact, because of the plasma

surrounding a weapon reentering the atmosphere at velocities

in excess of 4.6 km/s,59 it is unlikely that signals of any kind

could reach the weapon. While adequate terminal guidance

systems are available for comparatively slow-speed weapons,

those for orbital weapons travelling at 3 to 11 km/s will re -

quire significant improvements, such as ultraprecise inertial

navigation units, before they can be considered feasible.

Common Aero Vehicle

A concept that could solve some of the technical problems

associated with orbital bombardment deals with the problem

of high reentry velocities by using a maneuverable reentry

vehicle. Deployed from an orbiting satellite, the weapon would

slow from orbital speeds to speeds low enough to dispense

conventional munitions. As it slowed, the weapon would be

capable of aerodynamically maneuvering thousands of kilometers to either side of the orbital track without needing addi -

tional propellant.60

A weapon of this type has been proposed by the Armament

Product Group at Eglin Air Force Base, Florida, and is called

the common aero vehicle (CAV). Air-launched suborbital mis -

siles or ICBMs, as well as orbital platforms could deliver the

CAV. If an orbital system were pursued, it would be possible

to station large numbers of CAVs in LEO and de-orbit them

when needed. With guidance, navigation, and aerodynamic

controls within the atmosphere, the CAV would dispense its

submunitions at the appropriate geographic location. Prior to

releasing them, the CAV would provide each individual sub -

munition with target location coordinates.61 The submunitions

dispensed by the CAV would be optimized for force application

missions, such as antiarmor, area denial, or hard-target pene -

tration.62 While the CAV overcomes the problem of accurately

delivering weapons by slowing down and dispensing smart

submunitions, it gives up the advantage of being able to hit

hard targets at orbital velocities. This may be necessary given

the state of current technology, however.

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29
Kinetic Energy Weapons for Ballistic Missile Defense

Although DEWs appear to have many properties desirable

for BMD, their technological immaturity prompted the SDI

program to start developing KEWs to fill this role. The specific

project initiated for this program, and continued for SDI’s

successor program, global protection against limited strikes

(GPALS), was Brilliant Pebbles (BP). 63

Brilliant Pebbles is a KEW system designed to defend

against a ballistic missile attack. As envisioned for the GPALS

concept, BP would consist of 700 to 1,000 individual intercep -

tors (small missiles called pebbles) deployed into approxi -

mately 27 different orbits at an altitude of about 400 km (250

miles).64 This deployment architecture would provide the capability to stop a limited strike of up to 200 missiles by destroy -

ing them during the boost phase of their flight. 65 It would be

effective against all ballistic missiles except those with ranges

less than 400–600 km or maximum altitudes lower than

80–100 km.66 Moving at about five miles/sec, the BP intercep -

tors would destroy their targets by direct impact.

A system comprised of such a large number of individual

interceptors requires a sophisticated system to control it. Two

approaches to this problem have been proposed. The first is to

design a system architecture that relies on cross-linking the

individual interceptor satellites so that the ground control sys -

tem is able to contact individual satellites and the satellites

are able to communicate with each other. Cross-linking allows

the majority of the computing power necessary for directing

an attack to reside on the ground, an important consideration

in a system that must simultaneously engage many targets

without wasting multiple interceptors on any single one.

A less centralized approach is to give each interceptor al -

most total autonomy. With this design, the interceptors would

be activated through a system of communication satellites,

after which each one would determine which target to attack.

As described by Lowell Wood of the Lawrence Livermore Na -

tional Laboratory, “Each pebble would carry so much prior

knowledge and detailed battle strategy and tactics, would

compute so swiftly and would see so well that it could perform

its purely defensive mission with no external supervision or

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30
coaching.”67 Aside from the moral reluctance of many to give

any weapon so much autonomy, a major problem with this

concept is to devise a computer/software combination that

can do the job. To be practical, it must be cheap, small,

require little power while it waits, and be smart enough to

know which targets will be attacked by other pebbles and

which target to attack itself. Even with the incredibly rapid

progress being made in computer technology today, developing such a sophisticated computer small enough for missile

guidance is unlikely to be possible for quite some time.

With an optimistically estimated cost of $55 billion (in 1988

dollars), BP was to be an extremely complex and very expen -

sive system.68 In addition to C2

, there were also significant

technical challenges in building interceptors with the requisite

speed, range, and agility. These factors, coupled with a myriad

of political considerations ranging from concerns about

weaponizing space to the need to trim the budget, prompted

Congress to cancel the program. Nevertheless, with further

technological development, the concept behind Brilliant Pebbles has potential as either a BMD or ASAT system.

Weapons That Degrade Enemy Satellites

As an alternative to destruction, a target satellite may be

captured or merely disabled, for instance by spraying paint on

its solar cells or optical instruments. More sophisticated concepts involve disabling or degrading some critical subsystem

of a target satellite, such as the attitude control system.

A potential advantage of weapons that degrade or disable

enemy satellites is the possibility of using them covertly. The

overall effect of doing this might extend far beyond the en -

emy’s loss of the satellite. Surreptitiously disabling or degrad -

ing an enemy satellite could cause the enemy to waste valu -

able time reevaluating and possibly redesigning the failed

satellite. As a minimum, the satellite will probably have to be

replaced. In any case, unless the United States is at war with

the other nation, any tampering with its satellites must be

concealed . . . which makes this particularly attractive.

Depending on the overall strategy, the problems associated

with this approach could be somewhat easier to solve than

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31
those of the space mine. If the weapon is to disable the target

satellite immediately upon arrival, then there is no need for a

long-term power source. This approach would permit the design

of much smaller weapons that would be harder to detect but

would effectively be a ground-based system. If the weapon is not

to be used immediately (i.e., to be space-based), the problems

with this concept would be similar to those of the space mine.

Defending Space-Based Assets

Unlike ground warfare, where the defense is normally thought

to have the advantage, fighting a war in space is one in which

the opposite is true. In space warfare, as in ground warfare, the

attacker has the advantage of choosing the time, strength, and

direction of the attack. However the defender in space enjoys few

of the advantages enjoyed by a land-based counterpart. Space

has no terrain that can be prepared for defense, valuable assets

cannot be dug-in, and the enemy cannot be forced to attack

from a specific direction. In sum, given an opponent with the

capability to attack one’s space-based assets, the defender is

faced with a considerable dilemma.

The number of nations with the ability to develop weapons

capable of attacking space-based assets, at least those in LEO,

is increasing steadily. Direct ascent ASAT weapons are well

within the capabilities of any nation able to place a satellite in

orbit and possibly some capable of building only sounding rock -

ets. Since a direct ascent ASAT does not have to achieve orbit,

the booster to lift it can be relatively small and simple. In con -

trast to the boosters required to place a few hundred kilograms

into orbit, one that only has to lift it a thousand kilometers

weighs an order of magnitude less, only a few metric tons. This

is within the capabilities of many sounding rockets developed by

nations pursuing space-launch capabilities or large ballistic

missiles. While a sophisticated KE ASAT would be out of reach

even for many nations with the requisite boosters, a barrage of

rockets fired into the path of a satellite and exploding into

swarms of pellets could be effective. Given the relatively low cost

of the boosters, this type of attack may be considered feasible

by those nations possessing them. 69

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32
The ability to track satellites with precision is also neces -

sary for a direct ascent ASAT. Unfortunately for the defender,

this information is not difficult to come by. Organizations

such as the Canadian Space Society routinely post the orbital

elements of satellites on a computer bulletin board. These

elements are determined through the observations of informal

groups of satellite observers and may be accurate enough for a

barrage type of attack. With a concerted effort, a fairly simple

tracking system could be developed to refine satellite tracking

enough to greatly improve the probability of a barrage attack

being effective.70 While the low probability of kill achievable

with this type of attack would never be good enough to satisfy

the United States,71 it presents too much of a threat for the

defender to ignore, particularly when that state depends heav -

ily on space-based assets.

Bodyguards

One approach for defending satellites is the “bodyguard”

concept. A bodyguard is a satellite that orbits near a highvalue satellite and defends it against ASAT weapons, including

space mines.72 These bodyguards could be designed around

either DE or physical impact weapons. While the idea of sta -

tioning a defensive weapon near a satellite seems logical at

first glance, its problems actually mirror those inherent in the

offensive ASAT systems discussed above.

When designing a bodyguard, it is first necessary to deter -

mine what type of threat it will defend against, and how much

cueing information will be provided by off-board sensors. If it

is not feasible for the United States to deploy space-based

ASATs, then it is arguably just as infeasible for a prospective

adversary to do so. This assumption would limit the problem,

since only ground-based ASATs would need to be defended

against. Couple this with the fact that the United States al -

ready has the capability to track any boosters launched from

the surface of the earth, and the capabilities required for a

bodyguard drop dramatically. Launch warning and booster

tracking would make attacks on satellites difficult to conceal,

although a determined foe might realize this and pursue or -

bital ASATs regardless of their other drawbacks. An additional

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33
tactic would be for an adversary to launch an ASAT into an

orbit that appeared to have no relation to the target, for in -

stance a geosynchronous transfer orbit, and then have the

ASAT change orbits later in its trajectory. While such an ap -

proach would entail a much more sophisticated weapon and a

much larger booster, a peer competitor could realistically

build such a system. Unless the United States begins carefully

evaluating the potential for this type of attack and closely

tracks all maneuvers enemy satellites make once they are on

orbit,73 this type of attack could approach a target from any

direction with little warning. For the purposes of this analysis,

it is assumed that these steps are taken and that a bodyguard

system would know the direction and time of any attacks.

The HEL may at first appear to be an excellent candidate for

the job of bodyguard. Unfortunately, designing a laser for

bodyguard work presents more problems than using lasers as

ASAT or BMD weapons. Since the orbits of potential targets

are well known before an ASAT is even launched and for BMD

a network of sensors need only focus on the earth and detect

very bright and relatively slow-moving targets, these missions

are somewhat easier.74 In contrast, bodyguards must be effective against ASATs that may be either moderately easy to see

and very fast moving (relative velocities of 20+ km/s) in the

case of KE ASATs, or very slow moving and very difficult to

detect, for space mines.

To be effective, HEL bodyguards must be optimized for

ranges almost as long as those needed for BMD. Even with a

relatively slow-closing velocity of 4 km/s, a laser would need

to engage the ASAT at a range of 1,000 km just to allow

sufficient time (250 seconds) for damage assessment and for

the protected asset to make a modest maneuver to avoid the

disabled ASAT by a safe margin. Admittedly, the vastness of

space makes an ASAT achieving a kill without terminal guid -

ance unlikely, but prudence would likely dictate that the pro -

tected asset be maneuvered in order to be sure of avoiding

destruction. (Given a sophisticated ASAT, avoidance maneuvers made before it was disabled would be futile since the

ASAT could compensate for them.) Assuming this nominal

range of 1,000 km, the greatest drawback of a DE bodyguard

is probably its cost. With performance requirements close to

CADRE PAPER

34
those of a BMD system, and given the near-term state of the

art, a HEL based bodyguard might cost far more than the

satellite being defended.

Other DEWs, such as RF weapons, could also theoretically

perform the bodyguard function. However, a problem with

these weapons is the difficulty in determining when the ASAT

has been “killed.” Since the weapons only disrupt the elec -

tronics of the ASAT, there may be no way to know if the

defense was effective. Another problem is that disrupting the

ASAT’s electronics might not change its orbit, which may al -

ready be an intercept trajectory. Similar to the HEL body -

guard, the asset may have to be moved just to be on the safe

side. Another drawback to an RF bodyguard is that an enemy

ASAT will probably be shielded from all but the strongest RF

attacks. For these reasons it is unlikely that RF weapons will

be actively considered for the bodyguard role.

Considering the needed performance capabilities, KE-based

bodyguards will also be expensive. Against fast-moving KE

ASATs, both good sensors and high maneuverability would be

necessary. As with DE weapons, a KE bodyguard intercepting

a KE ASAT faces the same challenges as KE ASATs them -

selves. It may not need to constantly scan for hostile satellites

if it can depend on an overarching detection system, but it

must be able to track the ASAT far enough away to make

interception possible. Given the nature of orbital dynamics

and KE ASATs, it will be most effective to intercept the ASAT a

long distance from the protected asset (to minimize the chance

that debris generated by the interception will finish the ASAT’s

job). Intercepting a fast-moving satellite at long ranges dic -

tates a very large weapon with a large amount of Δv available.75 In light of these facts, a bodyguard designed to counter

a KE ASAT will probably look much like its nemesis but must

be able to react and travel much faster.

Assuming a robust space-tracking system, the most common threats should be fairly easy to defend against. These

threats are the direct ascent ASAT, the co-orbital ASAT, and to

a lesser extent the space mine. A direct-ascent ASAT is one

that is launched from the earth directly into the path of the

target. It is a KE weapon that uses the velocity differential, in

excess of 8 km/s, to destroy the target. These weapons are

SPACY

35
usually considered to be effective only against satellites in

LEO, since attacking satellites in higher orbits would require

an inordinately large booster. A direct-ascent ASAT does not

actually enter orbit, and by its nature must be firing its

booster almost until interception. Because these ASATs must

be launched from almost directly underneath the orbital path

and shortly before the target satellite is overhead, the problem

of detecting the ASAT and training a weapon on it is consider -

ably reduced. A bodyguard satellite could be similar to a BP

interceptor, with considerably reduced requirements regarding

the number of sensors, their field of view, the range of the

interceptor, and complexity of the control system. In essence

all that would be needed is a relatively simple system to scan

the earth in front of the satellite and along its direction of

travel. This sensor would be coupled to a very fast missile

having a range of several hundred kilometers (as opposed to

thousands for BMD).

The co-orbital ASAT is another threat that would be rela -

tively easy to defend against. Since launch detection and tra -

jectory tracking would provide warning of an impending at -

tack, the bodyguard could be oriented in the proper direction

without the need to do its own scanning. Once the target was

acquired, the same type of interceptor used against a direct

ascent ASAT could be launched at the co-orbital weapon. De -

fending against a co-orbital attack would be far less demand -

ing than the direct ascent attack because the relative veloci -

ties would be much slower and any system designed for the

latter should be more than adequate for the former.

The space mine may present greater challenges to an orbital

bodyguard. If space mines can be designed to be stealthy,

including virtually eliminating their IR signature, then a major

problem with defending against them may be detecting their

presence. Detecting a satellite that is trying to stealthily close

with the protected asset requires sensors that can scan in

virtually all directions. The sensors must also be equally good

at detecting IR sources against the cold background of space

as well as the much warmer background of the earth. While

these capabilities may make a bodyguard somewhat more

complicated than one only effective against nonstealth ASATs,

CADRE PAPER

36
the problems are likely not insurmountable. If it can be de -

tected, the space mine should be fairly easy to neutralize.

The biggest potential drawback for a bodyguard is the likely

cost of such a system. While it would probably be most effi -

cient for a bodyguard to have a service life comparable to that

of the asset being protected, this requirement dictates a very

capable weapon that can withstand years of inactivity with no

maintenance and still reliably accomplish its mission. Even

deploying enough of them to defend only military satellites

would be expensive; deploying enough to defend civilian satel -

lites as well would be cost-prohibitive. 76

To summarize, the bodyguard concept suffers from most of

the same problems, as do the weapons it is intended to protect

against. In addition, the bodyguard has the disadvantage of

being purely defensive, although it would have at least some

offensive ASAT capabilities. Being defensive, the bodyguard

system would have to be able to detect, track, intercept, and

destroy an enemy ASAT with advance warning consisting of

little more than the general direction in which to direct its

sensors. A system with these capabilities probably can be

constructed, but it will not be cheap.

Other Concepts for Defending Space-Based Assets

Alternatives to bodyguards include derivatives of both BMD

and ASAT concepts. The most notable of these are groundbased lasers to destroy enemy ASATs, which will be discussed

in chapter 3, and the previously discussed space-based BMD

system which could prevent an enemy from launching any

satellites at all. Other concepts such as counter-ASATs, either

KE or explosive, would in essence be the bodyguards just

described. Regardless of which concept proves to be most

promising, each would rely on an extensive surveillance sys -

tem of some kind, either self-contained or deployed separately.

Technological Factors Bearing

on Space-Based Weapons

If a system to defend satellites is to be fielded, then it will

probably require a space-based surveillance system to provide

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37
continuous protection. While relying on current systems for

launch detection and trajectory tracking may be adequate,

there remains the possibility of an a enemy ASAT making

large orbital changes while it is out of sight of the current US

surveillance system. One option for correcting this potential

shortfall would be to bolster the current US ground-based

surveillance system. Unfortunately, if such a system is to pro -

vide continuous coverage for all US satellites, this approach

requires a worldwide network of ground stations. Obtaining

these ground stations could prove to be problematic.

Another option is some sort of space-based surveillance sys -

tem, but developing such a system would be a major en deavor.

While the United States possesses space-based systems to warn

against missile launches and nuclear detonations, spacebased systems to monitor satellites in orbit have not yet been

built. Such a system would have to deal with a much more

diverse array of targets and survey a much larger volume of

space than do current systems. If the system were comprised

of a network of cross-linked surveillance satellites, a large

number of ground stations would not be necessary; however,

such a space-based system may itself need protection. Re -

gardless of which method is used, a surveillance system effec -

tive against space mines must be capable of detecting small,

stealthy satellites at great ranges.

Surveillance for Space Control

Since ASAT weapons deployed in space (particularly space

mines) would be fairly small and have relatively weak IR sig -

natures, any passive surveillance system will require large

numbers of satellites in a variety of orbits. An approach using

such active surveillance systems as radar may require fewer

satellites; however, each one will require large amounts of

power and still may be defeated by stealthy ASAT weapons.

Regardless of the approach taken, a system designed for space

surveillance would probably have to be deployed in multiple,

nongeosynchronous orbits to provide adequate coverage. Using multiple orbits would considerably increase the complexity

and cost of the system. While the technical difficulties associ -

ated with such a system pale in comparison to those of the

CADRE PAPER

38
space-based weapons themselves, it would still constitute a

large additional expense. However, if a satellite defense is to

be effective against a determined peer competitor, it will re -

quire a more comprehensive surveillance system than is avail -

able today.

System Architecture

Until now this discussion has focused on the types of spacebased weapons that have been proposed, their potential capa -

bilities, and the technological challenges that must be over -

come to make them feasible. What has not been discussed,

and what has been neglected in virtually all discussions of

space-based weapons, are the steps that must be taken to

knit these different weapons into a robust system.

Ideally, a system architecture will ensure that the spacebased weapons are used in a mutually supporting and coordi -

nated manner. It will have to include a tracking and targeting

system that can determine such information as how quickly a

target must be destroyed and which satellite or method of

intercept will have the highest probability of kill. This informa -

tion must then be fused and presented in such a manner that

a decision maker can quickly select the optimum response.

The vast number of variables involved may well argue for a

computer to make the decision. This alone would entail a

whole new discussion about the desirability of letting a com -

puter decide to employ weapons. 77

While the computer and communication technology needed

for an effective command and control system is advancing

much more rapidly than is the development of orbital weap -

ons, the cost of the requisite system, as well as its vulnerabili -

ties, will weigh heavily in any decision to deploy space-based

weapons.

Cost and Responsiveness of Space Lift

Perhaps the most important economic factor affecting the

decision to deploy space-based weapons is the cost and avail -

ability of space lift. This factor is particularly true of systems

requiring large constellations of satellites, like Brilliant Pebbles. Launch costs currently range from about $4,300/lb for a

SPACY

39
Delta II to $10,000/lb for the space shuttle, 78 and comprise 25

to 30 percent of a satellite’s total cost. 79 By reducing costs

one-half, the evolved expendable launch vehicle (EELV) would

greatly improve the affordability of space-based weapons. 80 Reducing launch costs by a factor of 10, the goal of many new

launch concepts (National Aeronautics and Space Administration’s X-33 program being the most prominent) could radically

alter the economics of space-based weapons.81

Another facet of operating in space is achieving routine ac -

cess. Routine access entails the ability to launch and/or re -

cover multiple spacecraft in a manner and with regularity

similar to that enjoyed by aircraft. While closely related to

cost, routine access requires a robust and redundant launch

system that may entail large investments. This investment will

be necessary if space-based weapons systems requiring large

constellations of satellites are to be deployed. Systems such as

a Brilliant Pebbles-type BMD will need to launch many re -

placement satellites for those that malfunction or reach the

end of their service life. Fortunately, the ever-increasing rate

of commercial space launches is prompting a rapid growth in

companies offering launch services. The boosters these companies develop could also be used for military launches, al -

though there is currently such a backlog of satellites waiting

to be launched that the system is far from responsive. 82

The peacetime demand for launching and replacing orbital

weapons will most likely increase in the event of hostilities.

This demand alone may dictate an increased ability to launch

large numbers of spacecraft quickly. If an enemy should de -

velop the capability to strike US launch facilities with spacebased weapons of his own, the need for a robust launch sys -

tem is even more obvious.

This last concern brings out an aspect of the launch cost

and access problem that may not be readily apparent. While

the advantages of reduced cost and increased space access for

the United States are obvious, the options this will give poten -

tial adversaries may be equally important. As the technology

necessary for cheap and routine access to space proliferates,

more nations will be able to launch their own satellites and

hence their own space-based weapons.

CADRE PAPER

40
Summary

As US national leaders ponder the wisdom of placing weap -

ons in orbit, it is necessary to determine what these weapons

can be expected to do. This chapter outlined the potential

capabilities and limitations of space-based weapons. At this

point some tentative conclusions suggest themselves.

Lasers have been proposed as ideal weapons for both space

control and boost-phase BMD. Their primary advantage is a

laser’s ability to strike in any direction at the speed of light.

Unfortunately, they have major limitations in terms of the

power levels available with current technology, the need for

large quantities of chemical fuel, and the enormous space

structures needed to support them.

Kinetic energy and co-orbital weapons have also been pro -

posed for space control and BMD but not without problems

too. These include timing constraints placed upon them by

orbital mechanics, the vast distances that must be covered to

reach a target, and the large amounts of propellant needed to

make all but the simplest attack.

Bombardment weapons that exploit the KE inherent in or -

bital weapons have considerable potential but require improvements in precision guidance and warhead materials to

be widely useful. A partial solution to this problem may be

such a concept as the CAV, but a major selling point of orbital

weapons, their high-impact velocity and its potential effective -

ness against deeply buried hardened targets, is sacrificed to

achieve greater precision against softer targets. However,

given the limitations of currently available materials, this may

not be a significant loss.

Finally, this brief analysis indicates that defending satellites

is at least as difficult as attacking them. The bodyguard con -

cept looks good at first glance, but actually entails all of the

problems of conventional ASATs with the added need to be

able to react to attacks with minimal warning. Bodyguard

satellites would force effective ASATs to be more sophisticated

and minimize threats from enemies other than peer competi -

tors, but a decision to deploy these weapons must take their

costs and limitations into consideration.

SPACY

41
Notes

1. Michael J. Neufeld, The Rocket and the Reich: Peenemünde and the

Coming of the Ballistic Missile Era (New York: Free Press, 1995), 199, 273,

and 282.

2. Phillip Clark, ed., Jane’s Space Directory (Coulsdon, England: Jane’s

Information Group, Sentinel House, 1997), 165. In May 1993, the SDI was

renamed the Ballistic Missile Defense Organization (BMDO) and was re -

focused to concentrate on ground-based defenses, primarily against theater

missiles with a much smaller continuing effort aimed at a national missile

defense capability.

3. Clark, 169. Despite some promising results in a 1989 test, the US

neutral particle beam program was eventually canceled in 1994. Aside from

cost considerations, major remaining challenges included development of a

suitable power source.

4. Joseph C. Anselmo, “New Funding Spurs Space Laser Efforts,” Aviation Week & Space Technology, 14 October 1996, 67. According to Dan

Wildt, TRW’s space-based laser integration program manager, a spacebased chemical laser “would have a ‘lethal range’ of 4,000 to 5,000 kilome -

ters.”

5. Turbulence distorts the wave front of a laser beam as it travels

through the atmosphere, lessening its ability to deliver energy to a target.

The problem is greatly reduced when propagating a beam from space to the

ground.

6. Michael J. Muolo, Space Handbook: An Analyst’s Guide, vol. 2 (Maxwell AFB, Ala.: Air University Press, December 1993), 251–52.

7. Anthony E. Siegman, Lasers (Mill Valley, Calif.: University Science

Books, 1986), 68.

8. Colin S. Gray, American Military Space Policy: Information Systems,

Weapon Systems and Arms Control (Cambridge, Mass.: Abt Books, 1982), 56.

9. Ibid.; Duncan S. Lennox, ed., Jane’s Strategic Weapon Systems

(Coulsdon, England: Jane’s Information Group, Sentinel House, 1997), Tab:

Offensive Weapons, Issue 26 January 1998. In contrast to a liquid-fueled

missile’s thin aluminum skin containing highly volatile, pressurized fuel, a

solid-rocket motor uses a glass-reinforced plastic case coated with epoxy

resin built to act as the combustion chamber. The considerably thicker

walls of this design will require the laser to deliver more energy before it

bursts. Examples of missiles that use this type of construction include most

submarine-launched ballistic missiles, the US Minuteman III, the

Peacekeeper, and the Army tactical missile system.

10. Richard L. Garwin, “How Many Orbiting Lasers for Boost-Phase In -

tercept?” Nature, 23 May 1985, 286–90; and John Tirman, ed., The Fallacy

of Star Wars (New York: Vintage Books, 1983), 105. Garwin also cochaired a

study by the Union of Concerned Scientists which discusses the feasibility

of orbital lasers in detail.

11. Garwin, 288; and John R. London III and H. A. Pike, “Fire in the

Sky: U.S. Space Laser Development from 1968,” Paper no. 97-2306 (New

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42
York: American Institute of Aeronautics and Astronautics [AIAA], 1997), 8.

The requirement of a 3,000-km range for a space-based laser is derived

from analyses of the number of satellites required to provide global protec -

tion against a massive missile attack by the Soviet Union. While current

initiatives for orbital lasers are not intended to counter such a massive

attack, this criterion still seems to be the baseline. Evidence of this is the

development of components for an 11 m diameter lightweight mirror for the

US space-based laser program which implies a range of about 3,200 km.

12. London and Pike, 6. The actual power levels achieved by military

lasers are classified. For the purposes of this study the term megawatt

power is interpreted to be 1–2 megawatts. This is based on the assumption

that power levels much above these would be referred to as “multimeg awatt.”

13. The chamber probably cannot be made with a larger diameter be -

cause the flow of gases through the chamber would be changed signifi -

cantly. Similarly, flow rates for the chemicals probably cannot be increased

since they are presumably optimized for maximum power already. This

leaves lengthening the chamber as the only method for creating more pow -

erful beams.

14. Garwin, 288.

15. Hans Bethe and Richard L. Garwin, “Appendix A: New BMD Tech -

nologies,” Daedalus: Weapons in Space 2, no. 114 (Summer 1985): 338–39.

These mirrors are for IR lasers operating at a wavelength of 2.7 μm. The

wavelength of the laser determines the beam diffraction, this in turn drives

mirror size since the proper mirror size will minimize diffraction for a laser

operating at a particular range. This relationship between wavelength, mir -

ror diameter, and range, means that lasers using shorter wavelengths

would require smaller mirrors. [R = (πd/4λ) S, where R is the range, d is the

mirror diameter, λ is the wavelength of the laser, and S is the diameter of

the spot the laser makes on the target] This study assumes that laser

weapons will have a perfect mirror of the optimum size for the weapon’s

range.

16. Garwin, 288; and David Dooling, “Ballistic Missile Defense,” IEEE

Spectrum, September 1997, 59. At an altitude of 1,300 km, the planned

altitude for the US space-based laser, the weapon will be traveling at about

7.2 km/s and cover about 50 km during a seven second firing. [v = sqrt( μ /r),

where r is the radius of the circular orbit and μ is the gravitational parameter for the earth (398,600 km3/s2

)]. The accelerating missile will cover a

slightly shorter distance.

17. John Pike, “Space Based Laser,” FAS Space Policy Project Special

Weapons Monitor, 3, on-line, Internet, 7 February 1998, available from

http://www.fas.org/spp/starwars/program/SBL.htm. “In 1991, the spaceborne Relay Mirror Experiment (RME), relayed low-power laser beam from a

ground site to low-earth orbit and back down to a scoring target board with

greater pointing accuracy than needed by SBL.”

18. When a laser beam is created it is composed of a single phase front

and maintaining this front is essential to achieving maximum power. If the

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43
beam is to be effective at distances on the order of thousands of kilometers,

it must be expanded to illuminate a large mirror that is designed to focus

the beam so that it achieves its smallest spot size at the desired distance.

Since fabricating a large single-piece mirror is extremely difficult (and al -

most as difficult to launch), large mirrors are created from smaller segments

that can be individually adjusted. Doing this makes it possible to minimize

distortions so that the beam that leaves the focusing mirror maintains its

single phase front.

19. “National Missile Defense Exoatmospheric Kill Vehicle,” BMDO Fact

Sheet 97-01 (September 1977): 2.

20. Bethe and Garwin, 339.

21. Dooling, 59; and John R. London III, space-based laser program

integrator, BMDO, interviewed by David Dooling, 1997. The Star Lite dem -

onstration laser satellite will require 30 kg/s to “operate at megawatt levels”

according to London. With the assumption that “megawatt levels” means

1–2 megawatts, 25 megawatts should require a reactant flow 12.5 to 25

times greater (375–750 kgs) assuming linear scalability. This latter assump -

tion may be somewhat optimistic considering the dynamics of chemical

lasers.

22. Geoffrey E. Forden, “COILed to Strike,” IEEE Spectrum, September

1997, 46.

23. Dooling, 58.

24. Siegman, 65.

25. Karl Grossman, “Nuclear Gamble,” Progressive, September 1997, 20;

and “Topaz 2 Go-Ahead to Speed U.S. Thermionic Effort,” Aviation Week &

Space Technology, 6 April 1992, 28. Even using nuclear power would be

problematic. The reactors required to produce the 25 megawatts needed for

a laser, assuming 100 percent conversion from electrical to laser energy, are

not the types currently used in space. For instance, the controversial Cass -

ini space probe, launched in October 1997, used a plutonium-based reactor

that only produced an average power of 745 watts. Even the Topaz 2 reactor

purchased from Russia by the Bush administration is only thought to be

scalable up to 50–70 kW, not the megawatt levels needed for laser weapons.

Reactors capable of producing enough power for lasers would need to be of

an entirely new kind. Such a reactor would entail a development program of

its own, provided a design with enough capacity is even feasible.

26. Muolo, vol. 2, 151.

27. Bethe and Garwin, 339–43. Optimistic assumptions include instantaneous retargeting and only five seconds needed to destroy a missile.

Further derivations raise the number to 1,344 satellites to stop a 3,000-

missile launch, assuming perfect reliability.

28. Dooling, 59; and BMDO Fact Sheet 97-01, 2.

29. The total number of missiles the system would be able to destroy is

not given in Dooling, London and Pike, or BMDO Fact Sheet 97-01.

30. An orbital laser designed for BMD would have to be able to engage a

missile launched on an intersecting trajectory that crossed at 90 degrees to

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44
the laser. The crossing velocity during such an engagement would be close

to the burnout velocity of the ballistic missile, about 5 km/s. If such a

weapon were to be capable of engaging a missile at fairly close range, then it

must be capable of moving at a fairly high angular rate. In contrast, a low

earth satellite crossing the laser’s orbit at 90 degrees would cross at a

higher velocity (about 7 km/s) but could be engaged at a range that would

keep the needed angular rate within the capability of the weapon.

31. John V. Evans, “New Satellites for Personal Communications,” Scientific American, April 1998, 73. Low earth orbits are considered to be those

with altitudes up to 2,000 km.

32. Assuming the most favorable alignment of a LEO weapon in a 1,000-

km orbit, firing from directly beneath the higher altitude satellite, the laser

would need a range of about 29,000 km to reach a satellite in GEO. (GEO

satellites orbit at an altitude of about 30,000 km.)

33. Tirman, 105. For example a laser operating at ultraviolet wave -

lengths could be focused into a 1 meter diameter spot at a range of 30,000

km using a mirror only about 11 meters in diameter. Unfortunately the

infrared telescope needed to track a ballistic missile, or satellite, at these

ranges would still need a mirror 100 to 150 meters in diameter. Visible light

telescopes would be smaller, but they offer the opponent more options for

countermeasures, such as painting the satellite black. Infrared signatures,

on the other hand, are virtually impossible to suppress in space. (It should

be noted that black satellites would have severe heat build-up problems

that would make their infrared signature even more pronounced.)

34. Geoffrey E. Forden, “A Panoply of Lasers,” IEEE Spectrum, September 1997, 42.

35. London and Pike, 3.

36. Anselmo, 67. According to TRW’s space-based laser integration pro -

gram manager, Dan Wildt, “the beam would be absorbed by water vapor

before it reached the surface of the Earth.”

37. For instance, an ultraviolet laser (operating at 0.3μ) with the same

range as the SBL would need a mirror only 3.75 meters in diameter.

38. W. Hays Parks, “Memorandum of Law: Trauvaux Preparatoires and

Legal Analysis of Blinding Laser Weapons Protocol,” Army Lawyer, June

1997, DA-PAM 27-50-295, 33–41; and Thalif Deen, “UN Protocol Brings

Laser Blinding Ban into Force,” Jane’s Defence Weekly, 11 February 1998,

6. The protocol went into force on 30 January 1998 when it was ratified by

the twentieth nation, Hungary.

39. It should be noted that the Alpha laser is considered to be “eye safe”

because it operates at a wavelength greater than 1.44 μm, although at the

power levels under discussion here it would probably boil the water in a

pilot’s eyes if the explosive decompression of burning through the cockpit

canopy wasn’t enough to throw the aircraft out of control and break the

laser weapon’s “lock.” Were they to be used in order to reduce mirror size

and improve atmospheric penetration, wavelengths shorter than 1.44

SPACY

45
microns could be limited to blinding pilots if they were used at their maxi -

mum range.

40. Bill Gertz, “Shared Satellite Laser Test Weighed,” Washington Times,

2 January 1998, A1.

41. New World Vistas, Air and Space Power for the 21st Century , Space

Applications Volume (Washington, D.C.: USAF Scientific Advisory Board,

1995), 84–85.

42. Ibid. Surprisingly, generating enough power is not a problem for RF

weapons. Between the much lower power densities necessary to damage

electronics with electromagnetic radiation, and the huge “gain” achieved by

advanced antenna designs (the projected 130 dB gain of a 100-me ter-diameter

antenna would produce a 10-million megawatt beam from a 100 KW power

source) the power requirements are quite modest, especially when com -

pared to lasers.

43. Michael A. Dornheim and Joseph C. Anselmo, “Complex Antenna Is

Star of Mission 77,” Aviation Week & Space Technology, 27 May 1996,

58–59. Space shuttle mission 77, launched on 19 May 1996, carried “the

most complex and precise inflatable space structure ever,” an inflatable

antenna measuring about 15 m (50 ft) in diameter. The experiment was

perhaps the first step toward the RF weapons described in New World

Vistas. While the experiment did not actually test the transmission or re -

ception capabilities of the antenna, the inflation and control tests were

considered to be successful. Many more tests will be necessary before

antennas as large as 100 meters in diameter will be feasible.

44. Muolo, 23–81. Since each satellite would be in its own orbit around

the earth, those that are not either in front of or following the center

satellite would be in different orbital planes. Since they are in their own

orbits, the satellites on either side of the center satellite would change sides

twice during each orbit, crossing the center each time they crossed the

equator. While it may be theoretically possible to maintain position relative

to the center of the formation, each satellite would require a large amount

of propellant to do so.

45. Joseph A. Smith, advanced concepts engineer, Lawrence Livermore

Laboratories, interviewed by the author, 11 February 1998.

46. Roger R. Bate, Donald D. Mueller, Jerry E. White, Fundamentals of

Astrodynamics (New York: Dover Publications, 1971). With a little more fuel,

a considerable number of trajectories that could decrease the time required

to intercept would be possible, but in the majority of cases it would take

more than one orbital period.

47. If the interceptor satellite is descending from a higher orbit, or as -

cending from a lower orbit, then its velocity will be higher or lower than that

of the target respectively.

48. “Defense Department Plans Next Test Firing of Air-Launched ASAT

System,” Aviation Week & Space Technology, 23 September 1985, 20; and

Richard L. Garwin, Kurt Gottfried, and Donald L. Hafner, “Antisatellite

Weapons,” Scientific American 250, no. 6 (June 1984): 47–49.

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46
49. Muolo, 130–32. For instance 200 kilowatts are required for a single

motor to produce one pound of thrust. In light of the discussion made with

respect to lasers, the size of a power source needed to provide 200 KW over

long periods of time would probably forfeit most of the savings in size over

conventional propulsion. In addition, such small thrust levels may be in -

adequate for keeping the space mine close to a maneuvering satellite.

50. Muolo, 154–57.

51. It would be much easier to develop a nonstealth space mine, since

such a weapon would avoid the greatest obstacles associated with one that

must remain undetected. However, the United States is unlikely to pursue

such a weapon. Not only would its deployment mark a clear break from the

traditional sanctuary status of space, it would yield few benefits in return.

The low-tech nature of an overt space mine would make it relatively easy for

other nations to duplicate, and given the fact that the United States has

demonstrated the ability to destroy satellites with lower profile groundbased weapons (and that there are relatively few satellites we would want to

destroy in the first place) it offers few benefits.

52. A satellite deorbited over the North Pole and impacting at 60 degrees

north latitude would impact at approximately 5.1 km/s if it were assumed

that the earth has no atmosphere. The atmospheric drag due to reentry

would slow the weapon somewhat, but this can be minimized by proper

design. Calculating the precise impact velocity of a theoretical weapon

shape is beyond the scope of this study.

53. Joseph A. Smith, advanced concepts engineer, Lawrence Livermore

National Laboratory, University of California, interviewed by the author, 12

May 1998. Above 3 km/s, the depth of penetration is a function of the

square root of the density ratio of the rod to the target material [ √(ρrod/ρtarget)]

and is largely unaffected by increasing the impact velocity. For example, a

tungsten rod penetrating concrete will penetrate approximately three times

its own length.

54. Ibid.

55. Ibid. A length-to-diameter ratio of 15 to 20 is required for these

weapons to be effective. As an example, a rod three meters long and 15 cm

in diameter would have length-to-diameter ratio of 20. If this rod was made

from tungsten (density 19.3 gm/cm3

), then it would weigh 1,022 kg (2,250

lbs). This is rather massive for a device to penetrate only about nine meters

(30 ft). In order to penetrate really deep, a rod as long as the space shuttle’s

cargo compartment, about 13.7 meters (45 ft), would have a diameter of

0.68 meter (2.25 ft), weigh 95,976 kg (211,148 lbs) and penetrate 41 meters

(135 ft).

56. Smith interview.

57. Ibid.

58. Lennox, Tab: Offensive Weapons, LGM-118 Peacekeeper and LGM

30G Minuteman III, Issue 26 January 1998. The accuracy of current US

ICBMs is reported to range from 90 meters circular error probable for the

Peacekeeper to 120 meters for the Minuteman III.

SPACY

47
59. W. Williamson et al., “Technical Analysis of a Contingency Conven -

tional Surgical Strike System” (Albuquerque, New Mex.: Sandia National

Laboratories, June 1995), 42. Document is now declassified. The space

shuttle encounters a communications and telemetry blackout until it decel -

erates below 15,000 ft/s (4,572 m/s) and descends below 180,000 ft. It is

reasonable to assume that guidance commands would also be blocked until

these conditions are reached.

60. Greg Jenkins, Office of the Armament Product Group manager, Eglin

AFB, Fla., briefing to the author, February 1998.

61. Ibid. Upon reentry the common aero vehicle would determine guid -

ance and navigation updates from either an inertial reference system (INS)

closely coupled with the global positioning system and/or an INS which

uses stellar “fixes” for updates.

62. Jenkins interview.

63. United States General Accounting Office, Report to Chairman, Committee on Armed Services, US Senate: Strategic Defense Initiative, Estimates of

Brilliant Pebbles’ Effectiveness Are Based on Many Unproven Assumptions

(Washington, D.C.: General Accounting Office [GAO], 1992), 2. Hereafter

referred to as GAO/NSIAD-92-91.

64. Ibid., 8–10.

65. Statement of Stephen J. Hadley, assistant secretary of defense for

international security policy, quoted in William Matthews, “DOD Restruc -

turing SDI to Fit a Changing World,” Air Force Times, 25 February 1991, 30.

66. GAO/NSIAD-92-91, 15. Shorter-range ballistic missiles do not leave

the atmosphere, and due to problems similar to those encountered with

orbital bombardment, the BP system is not designed to operate within it.

Long-range missiles fired with depressed trajectories present similar problems since they do not leave the atmosphere until shortly before they burn

out.

67. Jonathan Jacky, “Throwing Stones at ‘Brilliant Pebbles,’” Technology

Review, 20 October 1989, 21.

68. United States General Accounting Office, Report to the Chairman, Leg -

islation and National Security Subcommittee, Committee on Government Operations, House of Representatives: Strategic Defense Initiative, Need to Examine Concurrency in Development of Brilliant Pebbles, GAO/NSIAD-91-154

(Washington, D.C.: GAO, March 1991), 6. GAO determined that the sched -

ule upon which this cost estimate was based entailed a great deal of risk

due to the highly concurrent nature of the development. It is reasonable to

assume that had the system been pursued further, it would have cost

considerably more than $55 billion.

69. Allen Thomson, “Satellite Vulnerability: A Post-Cold War Issue?”

Space Policy, February 1995, 25.

70. Ibid., 20–21.

71. Ibid. Thomson provides a detailed review of what a low-tech adver -

sary could accomplish against an enemy satellite. A barrage-type attack

would require launching tens of rockets to achieve even a 50 percent prob -

CADRE PAPER

48
ability of destroying a target. Since the United States would by definition be

using an ASAT against another space-capable foe, the low odds coupled

with the escalatory nature of such an attack would make it an untenable

option. If the United States is going to run the risks of attacking satellites,

then the decision makers will demand a virtual guarantee of success. Con -

versely, a nation that relies heavily on large, expensive, space-based assets

cannot totally ignore even such a limited threat. However there are solu -

tions that do not require space-based weapons.

72. “Air Force 2025 in Detail: Part II AF Worries That Space Mines May

Threaten Future Ops,” Military Space 13, no. 23 (11 November 1996): 7.

73. Muolo, vol. 2, 74–84. It is apparent from descriptions of the US

system that the detailed tracking necessary to counter attacks by a deter -

mined foe will not be possible without substantial steps being taken to

bolster current capabilities.

74. Although ballistic missiles reach high velocities at burnout, they

initially start from rest and provide a very bright IR source for a period of at

least one minute.

75. Muolo, 70. “Δv available” is a direct measure of the ability of a

satellite to change its orbit. Large orbit changes require large Δv, for instance changing the inclination of a satellite in a 400-km-altitude orbit by

90 degrees (an admittedly extreme change) requires a Δv greater than the

existing orbital speed. Intercepting an ASAT that is approaching at an angle

of 90 degrees will likely require even more energy and an improbable

amount of lead time.

76. Evans, 72–73. While the number of low-altitude military satellites is

fairly limited today, a trend towards larger numbers of smaller satellites in

lower orbits would drive up the costs of protecting them. If civilian satellites

are to be defended, then the numbers are already prohibitive as five com -

munications networks alone are in the process of launching a total of more

than 500 satellites into LEO.

77. National Defense Authorization Act for FY 1988–89, H.R. 1748, Divi -

sion A, Title II, Part C, Subpart 1, sec. 224. One barrier to giving computers

the ability to fire weapons is a law passed by Congress. This law stipulates

that “no agency of the Federal government may pay for, fund, or otherwise

support the development of command and control systems for strategic

defense in the boost or post-boost phase against ballistic missile threats

that would permit such strategic defense to initiate the directing of damag -

ing or lethal fire except by affirmative human discretion at an appropriate

level of authority.”

78. John R. London III, LEO on the Cheap: Methods for Achieving Drastic

Reductions in Space Launch Costs (Maxwell AFB, Ala.: Air University Press,

1994), 5; and Peter Spiegel, “Free Launch?” Forbes, 24 February 1997, 76.

These figures are in 1993 dollars. More recently, Daniel Goldin, the NASA

administrator, confirms a cost of $10,000 per pound for the shuttle.

79. London, 1; and G. Harry Stine, “Opening the Spaceways,” Barron’s,

19 May 1997, 62. The SDIO projected the launch costs of Brilliant Eyes, the

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49
sensors that were to cue the Brilliant Pebbles weapons, to be 25 percent of

total life-cycle cost. Similarly Motorola estimates launch costs to comprise

about 30 percent of the total cost of its Iridium communications satellite

constellation.

80. Joseph C. Anselmo and Bruce A. Smith, “Cost Drives EELV,” Aviation Week & Space Technology, 6 January 1997, 27.

81. Spiegel, 23–24; Joseph C. Anselmo, “Launchers See Nothing But

Blue Skies Ahead,” Aviation Week & Space Technology, 7 April 1997, 41;

and William W. Bruner III, “National Security Implications of Inexpensive

Space Access” (master’s thesis, School of Advanced Airpower Studies, Max -

well AFB, Ala., June 1995). NASA administrator Goldin cited a tenfold

reduction launch costs as the target for the X-33 program. Alternatively

Kistler Aerospace estimates launch costs of $2,000 per pound for LEO

launches on a vehicle designed to use off-the-shelf components. Bruner

discusses the military implications of reduced launch costs.

82. Anselmo, “Launchers See Nothing But Blue Skies Ahead,” 42. Arian -

space is forecasting $30–40 billion of spacecraft launches over the next

decade, excluding military. Also, according to John Perkins, vice president

of launch services for Hughes Telecommunications and Space, capacity of

industry to produce satellites “far outstrips global launch capacity.” 

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50
Chapter 3

Seeking Control of Space:

Ground-Based Alternatives for Space Control

The United States has become highly dependent on spacebased assets. The space control mission seeks to protect these

assets and deny an enemy access to space. Many of the or -

bital space control weapons were outlined in the previous

chapter. Most of the missions these weapons would be capa -

ble of doing could also be accomplished by either surfacebased or airborne systems. The purpose of this chapter is to

compare space-based weapons with these alternatives.

Defensive Counterspace

Maintaining access to space requires that all parts of a

complex system be protected. The main components of this

system are the satellites themselves, the ground stations that

control them, and any mobile ground stations capable of re -

ceiving satellite-generated data. The latter range from handheld “cell phones” to tactical terminals capable of receiving

satellite imagery. Each of these components, as well as the

communication links between them, are susceptible to attack.

Protecting this system is the essence of defensive counter -

space.

Probably the most vulnerable part of the system is the net -

work of ground stations. Given the fact that they are relatively

few in number and are “soft” targets with known locations,

attacks against ground stations should be expected in the

event of war.1

 While it is possible to deploy mobile ground

stations, using them will almost certainly degrade the effi -

ciency of the system.2

 Equally vulnerable are the facilities

needed to launch satellites into orbit. Although they are some -

what more difficult to destroy, the need to defend launch

facilities is potentially greater because they are fewer in

number and making them mobile is extremely difficult. As

potentially critical as these vulnerabilities may be, defending

them is more a matter for conventional security arrangements

51
than space-based assets. However, it is important to note that

any investments made in space-based weapons would be

wasted if the ground stations needed to make use of them

were neutralized. Aside from this rather critical point, defend -

ing ground stations will not be discussed any further here.

Protection through Redundancy

Until very recently, US satellites have tended to be fairly

large, very capable, and very expensive. These satellites pre -

sent an opponent with lucrative targets, where the loss of even

one would often constitute a dramatic loss in capability. This

is particularly true for current generation reconnaissance sat -

ellites since these are very capable, relatively few in number,

and very vulnerable owing to their need to be in LEOs. Fortu -

nately, deploying defensive space weapons is only one way to

protect these assets.

One option for mitigating this vulnerability is to deploy large

numbers of less capable satellites. These satellites could pro -

vide the same capability as a larger satellite by working in

concert. For a satellite communication (SATCOM) system,

each satellite would carry part of the load. If needed, the

satellites could be placed fairly close together in orbit and

their deployment geometry could be optimized to balance sur -

vivability with the need to emulate a much more capable sat -

ellite. Alternatively, the United States could move away from

placing communication satellites in geosynchronous orbit and

transition to a large constellation of satellites in lower orbits.

The commercial sector is now using such an approach to

provide global cellular telephone capability.

Reconnaissance satellites could also be designed as a dis -

tributed network. Experiments conducted by the Clementine

spacecraft demonstrated that even very small and inexpensive

satellites could collect militarily useful data. 3

 While the highest resolution imagery may still require large satellites, a net -

work of small satellites could meet many needs and would

provide graceful degradation in the event one is lost. In con -

trast to the loss of a single highly capable satellite, which

could be crippling, the remaining satellites in a network would

still provide significant capability. With total costs on the o rder

CADRE PAPER

52
of only 12 percent of that of large satellites, small satellites

seem to be the next logical step. 4

Rapid Reconstitution

An additional step that can be taken to assure access to

space is to develop a responsive space-lift capability. The abil -

ity to prepare and launch a satellite within days could quickly

replenish combat losses. This approach would be most costeffective for small, cheap satellites but would also be effective

for larger satellites, particularly if an enemy had only a limited

number of ASAT weapons. Spares that are stored on the

ground until needed would offer more than just the ability to

replenish combat losses quickly. Since they would be accessi -

ble while in storage, ground spares could be upgraded so that

they incorporate the latest technology when they are eventually launched. The Defense Support Program made use of this

concept in the 1980s, when unneeded spare satellites were

upgraded to become more capable replacements. 5

 Designing

spare satellites to allow for upgrades would capitalize on their

availability during storage, an attribute that makes such a

strategy even more attractive than attempting to actively de -

fend obsolescing hardware in orbit.

The United States is already pursuing several concepts that

seek to exploit responsive launch capability. One employs

relatively small tactical reconnaissance satellites that would

be deployed by a reusable space plane. The satellite/space

plane combination would have a life span of about a year in

orbit and the ability to make orbital plane changes of up to 20

degrees. This maneuverability provides the capability to alter

orbits to meet mission requirements while the concept, as a

whole, would allow the satellite to be recovered along with the

space plane. The fact that the tactical satellites would only be

deployed in the event of war coupled with their considerable

ability to maneuver, would make these satellites difficult for

an adversary to track and engage.

The defensive measures just discussed seek to assure ac -

cess to space through essentially passive means. The spacebased assets are not defended but instead are made resistant

to attack. While these approaches might not provide as much

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53
protection as a truly effective defensive system, creating such

a defensive system is problematic. The approaches outlined

above would, on the other hand, assure continued use of

space-based assets in the event of attack and present an ad -

versary seeking to attack them with a much greater challenge.

These approaches should also be much cheaper than spacebased weapons, and may in fact be all that is needed.

Active Defense

If it is determined that passive measures will not provide

adequate protection for space-based assets, more active methods are available. As outlined in chapter 2, the only method

that appears to be feasible is a bodyguard concept for use

against direct-ascent and co-orbital ASATs. While the Brilliant

Pebbles concept for BMD has the potential to be effective in

this role, its high cost is only one of the factors that make it a

controversial proposition.

A potentially less controversial, and less expensive, method

of defending space-based assets is to attack the enemy’s ASAT

capability on the ground. Similar in concept to an offensive

counterair strategy, such an approach is well founded in air -

power doctrine. When applied to the satellite defense problem,

attacking ASAT weapons on the ground is even less compli -

cated. Whereas combat aircraft are normally dispersed to

many airfields in time of war, ASATs will be restricted to

relatively few easily identifiable launch sites. Once hostilities

begin, these sites will be open to attacks by conventional as -

sets such as stealth aircraft and cruise missiles.

An additional point about passive defense bears consideration. While nuclear weapons are not a primary focus of this

study, rapid reconstitution may be the best way to overcome

the effects of a high-altitude nuclear detonation. 6

 While the

international political repercussions may prevent most potential adversaries from using nuclear weapons even in space,

there are those who may not be dissuaded. If one of these

nations develops and uses nuclear ASATs, space-based defensive weapons may be of little use. The ability to quickly reco nstitute space-based assets may well be the only practical solution.

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54
Offensive Counterspace

Space-based ASAT weapons have the potential to deny an

enemy the use of his space-based systems. These concepts are

expensive and pose many technical challenges. Alternatives to

space-based weapons have the potential to be equally effec -

tive, more flexible, more technologically feasible, and less ex -

pensive.

Nondestructive Approaches

to Offensive Counterspace

The least expensive approach to denying an enemy access

to space is only practical against nations that rely on leasing

third-party assets. This has the potential to become prevalent

as commercial enterprises devoted to providing communications and surveillance become more common. In these situations, it may be possible to convince the corporations or

nations providing the service to cut off access during a con -

flict. In fact doing much more may be politically unfeasible,

since direct attacks would be difficult to justify even if it could

be proven that a corporation was providing an adversary with

satellite support.

Diplomacy

Unfortunately diplomatic pressure may not be effective

since corporations will stand to lose customers if they cannot

be relied upon in emergencies. This approach also requires

the United States to have considerable international support

and would be problematic in situations where the United

States is acting unilaterally.7

The potential problems with a diplomatic approach were

highlighted during the Persian Gulf War of 1991. The Iraqi

government had been buying satellite imagery from the

French company SPOT Image prior to the war, but interna -

tional condemnation of Iraqi actions prompted the company to

cut off access. SPOT Image also refused to provide imagery to

television and other media organizations, thus preventing Iraq

from gathering the information from these sources. A potential

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55
shortcoming of this approach is illustrated by the fact that

SPOT Image retained the option of selling imagery to the me -

dia if another source started doing so. In fact, the Earth Ob -

servation Satellite Company (EOSAT) did start selling imagery

to the media, although it was prohibited from selling directly

to Iraq by the US embargo. Fortunately the images available

from EOSAT were of a lower resolution than those produced

by SPOT (30 m versus 10 m) and SPOT Image held to its

initial decision.

Nondestructive Jamming

A more practical approach to denying an enemy use of his

space-based assets may be to jam the communication links

between the satellites and the ground stations. Since this

approach would not damage the satellites, the fact that they

may be owned by third parties would be less of a factor.

Jamming the communications between satellites and their

ground stations may prove difficult because the large antennas used by ground stations are highly directional and jam -

ming them could require inordinate amounts of power. An

additional problem would be positioning the jamming platform

within line of sight of the target ground station. Such an

approach would be contingent on having total air supremacy,

a condition that may not always prevail. Some satellit edependent communication systems, on the other hand, are

easier to jam. These systems rely on lower power, nondirec -

tional antennas on the ground, and sensitive receivers on the

satellite. Operational problems with current SATCOM systems

indicate that high-power jamming of a satellite may be suffi -

cient to block communications.8

An important objective of most conflicts has been disrupting

the enemy’s C2

 system. In conventional wars against small,

less sophisticated enemies (for instance Iraq), it has usually

been easy to do this. New developments in communications

may make this more difficult in the future. Cellular telephone

systems with global coverage are now being built. These sys -

tems use large constellations of satellites in low orbit to carry

phone calls around the world. 9

 A relatively small nation, such

as Iraq, could easily purchase enough capacity on these sys tems

CADRE PAPER

56
to provide military communications throughout its country.

While such a service would be expensive, it would cost much

less than building an entire SATCOM system. The problems it

creates for any country attempting to disrupt this type of com -

munication system may make it a particularly attractive option.

When attempting to disrupt an enemy’s C2

 network, it

would be problematic for the United States to destroy the

third-party commercial satellites that comprise it. Destroying

all of the satellites would not only be very expensive in terms

of the weapons required but also the corporations owning the

satellites and the other nations of the world would probably

condemn such actions. While the United States could ignore

international opinion if the cause were important enough, a

less controversial solution would be preferable. Ideally it

would be possible to persuade the corporation running the

system to deactivate service to an opponent, but this may not

always be the case. The best method for disrupting these

communications may prove to be conventional jamming of the

handheld phones the field commanders would be using. While

this is not a very elegant solution, it may be the only feasible

one since any large-scale interference with a satellite-based

telephone system would have global repercussions.

If an adversary owns and maintains its space-based assets,

then the United States would have freer reign in disrupting

them. One method would be to prevent the satellites from

receiving commands from the ground. While jamming the

large, highly directional antennas of the ground stations might

be difficult, the antennas on the satellites are much more

vulnerable. The results of jamming these signals would vary

from slow degradation of the orbit, to disrupting SATCOM

networks, to preventing reconnaissance satellites from being

tasked. This latter effect may be useful, but its effectiveness

would be difficult to verify, since it might not be obvious that a

reconnaissance satellite is no longer performing its mission.

Another type of jamming is possible against reconnaissance

satellites that take visual or IR pictures. This nondestructive

concept would make use of portable devices that track a satel -

lite while it is overhead and train a laser on it. Experiments

have shown that even low-power lasers can temporarily blind

optical sensors.10 The simplicity and low-power requirements

SPACY

57
of these systems are such that they could easily be deployed

on small vehicles and, with further development, could be

made man-portable. The drawback of this approach is similar

to that of jamming command signals: Its effectiveness would

be very difficult to verify. Since it would not be possible to tell

if a satellite was actually blinded, there would be no way to

determine that the enemy remained unaware of troop disposi -

tions or whatever other information was to be denied him.

In spite of the drawbacks, using lasers to temporarily blind

reconnaissance or surveillance satellites has the potential to

deny an enemy the use of third-party satellites without un -

duly antagonizing the third party. One strategy may be to

declare a total exclusion zone over the theater of operations

and give warning that any satellites in the region would be

liable to engagement by potentially damaging lasers. It would

then be the responsibility of the satellite’s owner to ensure

that the satellite was oriented so as to protect its sensors. In a

variation of this approach, small satellites could be built to

rendezvous with the satellite in question and verify that the

satellite was indeed pointed away from the area of concern.

While such an approach may not be able to determine if a

noncooperative satellite was damaged by a subsequent laser

engagement, complaints of satellite damage from the satellite’s

owner could provide the required feedback.

Rather than jamming, a potentially more effective approach

may be to take command of a problem satellite. It may be

possible to break the codes used to command the maneuvers

of a satellite and send it spurious instructions. If transmitters

were placed so that they could overpower legitimate com -

mands, or send commands when the legitimate transmitters

are out of range, then a satellite could be prevented from

performing its mission. In contrast to jamming a satellite, the

reactions of the satellite would make it possible to verify that

the attack had been successful.

Another alternative along these lines is to develop a satellite

capable of physically moving an uncooperative satellite. Such

devices have been proposed for regaining control of malfunc -

tioning satellites that are trapped in useless orbits or not

responding to maneuver commands. The same device could be

used to disrupt control of a third party or enemy satellite by

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58
maneuvering it so that it could not take pictures of the desig -

nated area. If the satellite’s owners were unable to monitor

other spacecraft in orbit, then this assault could well be made

surreptitiously.

Alternatives to physically destroying an enemy’s spacebased assets offer the least controversial approaches to deny -

ing an enemy access to space. From diplomatic efforts with

third party providers to jamming C2

 links, nondestructive

methods have the potential to be both effective and inexpen -

sive. These approaches would be most effective against a less

capable foe, while a peer competitor may have the ability to

counter them. Considering the potential implications of an

enemy’s unhindered access to space, it is also prudent to

consider more definitive measures for space control.

Destructive Approaches to

Offensive Counterspace

While nondestructive approaches to space control have

considerable potential, circumstances may dictate more violent measures. The least technologically challenging destructive approach is to destroy the ground stations needed to

communicate with satellites. This method is similar to the

jamming options discussed above in that it attacks the com -

munication links that make space-based assets useful. Relatively large, fixed ground stations are necessary both to con -

trol satellites and to receive the information they are

gathering. While the potential exists to develop mobile ground

stations, most systems in use today rely on stations whose

locations are known with a high degree of accuracy. These

ground stations are soft targets that are extremely vulnerable

to either sabotage or conventional attack by systems cur -

rently in the inventory.

The effects of attacking ground stations would be very simi -

lar to those of jamming. While the destruction of the ground

station would be readily apparent, the possibility would exist

that an as yet undiscovered ground station would take over

the function of the one destroyed. As with jamming, changes

in the behavior of the satellite might not be great enough to

confirm the effectiveness of the attack. It is for these reasons

SPACY

59
that many ASAT advocates decry the efficacy of this a pproach.11

Even if a future adversary develops mobile ground stations, it

is unlikely that they will be as capable as the fixed stations,

the destruction of which will thus degrade the usefulness of

the space-based assets.

Destroying Adversaries’ Space-Based Assets

The most certain method of denying an enemy the use of his

space-based assets is to physically destroy the satellites themselves. Doing this from the ground makes use of the same

principles as the space-based methods discussed in the pre -

ceding chapter. Ground-based directed energy weapons, KE

ASATs, and co-orbital ASATs are the three major types of

weapons.

Ground-based lasers seem to offer many advantages over

their space-based counterparts. In addition to not needing to

withstand long-term storage in space, the availability of large

supplies of chemical fuel and the lack of constraints on their

size make ground-based lasers much more practical. A prob -

lem with ground basing is that the earth’s atmosphere tends

to absorb laser energy, weakening the attack. An associated

problem is the need to correct for atmospheric distortion of

the beam that disrupts the phase front and weakens it fur -

ther. Taken together, these problems present significant obstacles to using lasers to do much more than burn out a

satellite’s sensors. On the other hand, the ability to build a

laser as large as is necessary to generate the required amount

of power, and the lack of size constraints in building sophisti -

cated devices to keep the beam aimed and focused, suggest a

potential for effective ground-based laser weapons. 12 In any

case it seems prudent to invest in more ground-based laser

research before initiating the costly process of modifying these

weapons for use in space.

The type of ASAT favored by the United States has been,

and is currently, the direct ascent ASAT. Direct ascent ASATs

are characterized by the fact that they do not actually enter

orbit but attempt to loft a device into the path of an oncoming

satellite. Due to the speeds involved, these devices have been

likened to shooting a bullet at a bullet. In general, the ASAT is

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60
launched into the path of a satellite from a location on or near

the satellite ground track, and shortly before the target satel -

lite arrives overhead. The kill mechanism is the kinetic energy

inherent in the velocity differential between the vertically as -

cending ASAT and the orbiting satellite. With a velocity differ -

ential of about 17,500 MPH for a low orbiting satellite, a direct

hit will assure destruction.

While the United States has pursued several ASAT pro -

grams in the past, only one has actually intercepted an orbit -

ing satellite.13 This ASAT was an air-launched system comprised of an F-15 fighter aircraft and a two-stage missile. The

first-stage motor of the missile was a modified short-range

attack missile (SRAM) and the second stage an Altair motor.

The 17-foot-long missile was to loft a miniature homing vehi -

cle weighing about 15 kg into the path of a target satellite,

whereupon it would make the final corrections needed for a

direct impact.14 The system was successfully tested against a

satellite on 13 September 1985.15 The program was canceled

in 1988 when Congress voted to continue a two-year-old ban

on further tests against objects in space. 16

Another direct ascent ASAT is under development in the

United States. The Army’s KE ASAT program is a groundbased two-stage missile that delivers a “kill vehicle” into the

path of the target satellite. Launched by a derivative of the

Minuteman booster, the kill vehicle optically tracks the target

satellite and deploys a sail-like debris mitigation device

shortly before impact. While the capability of the system is

classified, it is claimed that a single launch site will be able to

“reach any satellite in low earth orbit.” 17 Considering its much

more powerful booster, the KE ASAT will probably be effective

against satellites in orbits much higher than the 320 nautical

miles demonstrated by the air-launched ASAT.

An alternative approach to an ASAT weapon is to match

orbits with the target satellite and destroy it with an explosion

in close proximity. The Soviet Union built and tested such a

system during the 1970s and 1980s. The Soviet designs

placed the ASAT in an orbit that was similar to that of the

target satellite and intercepted the target in one or two orbits.

The system used either radar or IR/optical sensors to home in

on the target and exploded into a swarm of pellets when it

SPACY

61
came within range. Of the two sensors used, the IR/optical

system failed in every test while the radar system was suc -

cessful 64 percent of the time. As with the direct ascent sys -

tems discussed above, the Soviet system was limited to satel -

lites in LEO, although the demonstrated maximum altitude

was considerably higher at 1,710 km. 18

Another potential co-orbital ASAT could be a derivative of

the device to control uncooperative satellites mentioned above.

Obviously if a satellite can attach itself to an uncooperative

target to maneuver it into a more favorable orbit, then it can

just as easily attach itself and explode. While destroying a

satellite will leave little doubt as to which nation was respon -

sible, particularly during a war, such an approach would pro -

duce much more definitive results. In terms of practicality,

using such a device against high-altitude orbits could prove to

be more costly than is necessary.

If it becomes necessary to attack satellites that do not

descend to low altitudes (hundreds to possibly several thou -

sand kilometers), direct ascent attacks will probably be un -

feasible. As the target satellite’s orbital altitude increases,

the size of the booster needed to reach it must also increase.

Eventually the booster required becomes too large to be

practical. A better method is to place an ASAT into a more

efficient transfer orbit and then deploy a small attack vehi -

cle when it nears the target. While this would not be a

co-orbital intercept, expending resources on a co-orbital

weapon is probably not necessary. The closing velocities be -

tween a satellite in a transfer orbit and the target satellite

would be small enough to make the final tracking and clos -

ing maneuvers much simpler than those of a direct ascent

ASAT.19 No nation is currently developing such a system (at

least publicly), but the ability to do so is inherent in the

technology required to place a satellite in high-earth orbit

and many countries have this capability. 20 Given sufficient

incentive, developing an ASAT weapon capable of reaching

geosynchronous satellites should be only a moderately chal -

lenging technological effort for a space-faring nation.

Regardless of whether a co-orbital or direct ascent

ASAT is considered, ground-based weapons have inherent advantages over their space-based counterparts. Given a wisely

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62
selected launch site, ground-based weapons have the ability

to attack satellites in virtually any orbital inclination. Air- or

sea-launched weapons would have a similar capability. This

inherent flexibility would allow fewer ground-based than

space-based weapons to provide a similar amount of capability.

While it will take one ASAT to destroy one satellite regard -

less of where the ASAT is based, space-based ASATs are even

more limited in that they will probably only be capable of

destroying one particular satellite. For a space-based ASAT to

destroy an enemy satellite, it must be deployed in an orbit

that will permit it to intercept its target with the propellant

available on board. If the ASAT is to be kept reasonably small,

then it will probably be limited to engaging satellites that are

in similar orbits. In most circumstances this lack of maneu -

verability will limit the ASAT to being able to attack only a few

targets, often only one. If the enemy is unknown, then enough

ASATs must be deployed to engage all probable targets. A

ground-based system would avoid such limitations. If the

launch site is located on the equator, then an ASAT will be

able to engage satellites in any orbital plane. With the addition

of larger boosters and orbital transfer vehicles, satellites in the

highest orbits could also be attacked.

The responsiveness of ground-based weapons would also be

nearly as good as that of their space-based counterparts. With

the possible exception of the space mine, intercepting a satel -

lite with a satellite will often take as long or longer than

intercepting it from the ground. The nature of orbital dynam -

ics is such that the time necessary to achieve the orbital

geometry required for a space-to-space intercept will often be

as long as waiting for an optimum launch opportunity from

the ground. Ground-based weapons have the additional advantage of being accessible for maintenance and modifications, should they be necessary.

It is also probable that ground-based weapons would cost

less than their space-based counterparts. Although both sys -

tems would require boosters of about the same size, what

would make a space-based system more expensive is the addi -

tional complexity needed for a weapon to survive months or

years in orbit and then perform flawlessly. 21 Ground-based

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63
weapons, on the other hand, could be stored in climate-controlled buildings or silos until they were needed.

Preventing Launch of Adversaries’ Space-Based Assets

The potential for using a BMD system to deny an enemy

access to space was discussed in chapter 2. While using a

preexisting BMD system for this purpose may be feasible,

the costs of doing so must be weighed against those of using

other assets. An effective BMD system would be capable of

reaching across hundreds of miles to intercept a ballistic

missile within seconds of its launch. Space-based weapons

capable of accomplishing such a mission will not be cheap.

Expending these expensive-to-replace weapons against an

ascending satellite booster does not appear to be the most

cost-effective approach to space control. More important,

creating such a system just to perform a job that could be

more easily accomplished by conventional weapons would

be even less prudent.

Virtually all space launches are made from fixed locations

that are well known. All of these sites are within the range of

either stealth aircraft or cruise missiles. The facilities needed

to prepare the satellites and boosters for launch are highly

vulnerable, especially during the days prior to a launch when

the vehicle is positioned on the launch pad. In this position

the satellite and booster are little more than a large bomb

being readied for a carefully controlled detonation. Since the

status of an upcoming launch is readily evident to US air -

borne or satellite reconnaissance, timing an attack to take

advantage of this most vulnerable condition is relatively easy.

A conventional attack on such a target will not only destroy

the particular satellite, it will most likely cause severe damage

to the launch complex and prevent or delay subsequent

launches as well.

To mitigate this vulnerability, a potential foe could choose to

create mobile launch systems. The sea-launch system being

developed by an international consortium will be such a sys -

tem and will provide the capability to launch from virtually

anywhere on the world’s oceans. 22 However, it will also be

quite vulnerable since it employs very large, slow-moving ves -

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64
sels. A number of platforms, from attack submarines to landbased bombers could destroy these vessels with little diffi -

culty. Air-launched systems would present a more difficult

target, but current systems are only capable of launching the

smallest satellites into the lowest orbits. If it became neces -

sary to deny an enemy even this limited capability, then at -

tacks against the airfields from which the systems operate

would be little different from attacks against any other militar -

ily significant airfield and could be carried out using other

methods.

An often-cited problem with the idea of attacking satellite

launch facilities is the possibility that political considerations

will place these facilities off-limits. Whether this is because a

third party is launching an adversary’s satellites or that such

attacks would be deemed too escalatory, attacking launch fa -

cilities may not be possible. However, potential restraints on

the use of force in a particular scenario do not necessarily

mean that developing and deploying a boost-phase intercept

system is a good idea. If developed, the ground-based ASATs

mentioned above should be more than adequate for denying

an enemy access to space-based assets. In light of these alter -

natives, the billions of dollars needed to create a space-based

system to attack satellites during their boost phase could be

better spent in other areas.23

Conclusions

Space-based weapons have the potential to perform the

space control mission, but only with high costs and high tech -

nological risk. Ground-based weapons also have the potential

to meet the requirements of the space control mission. What

is more, they offer similar capabilities at potentially lower cost

and appear to have more flexibility. Tables 1 and 2 provide a

comparison of the relative strengths of the various systems in

terms of some key measures. Some may question the need for

any kind of space control weapons, but if they are deemed

necessary, the best options appear to be ground-based

launch-on-demand weapons.

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65
Table 1

Space-Based Weapons for Space Control

Response

Time

Technical

Risk

Reliability Vulnerability

to Attack

Verifiability

of Effects

Cost

SBL Very Good Extremely

High ? High Good Very High

Space Mines Excellent High Fair Medium Very Good High

KE Good High Fair High Excellent High

Co-Orbital Good High Fair High Very Good High

KE Launch

Suppression Very Good Very High ? High Excellent Very High

Table 2

Ground-Based Options for Space Control

Response

Time

Technical

Risk

Reliability Vulnerability

to Attack

Verifiability Cost

NonDestructive

Measures

Coerce

Providers ? None Unknown N/A Poor Low

Jamming

Satellites Good Low Med-High Low Poor Low

Blinding

Satellites Good Low Med-High Low Poor Low

Attack

Ground

Stations

Good Low High Low Very Good Medium

Interfere

with Enemy

Satellites

Good Medium Medium Low

Excellent

(positive

feedback)

Med-High

KE

Weapons

Army KE

ASAT Good Medium High Low Excellent Med-High

F-15/ASAT Good Medium High Low Excellent Med-High

Co-Orbital

Attacks

Ground to

LEO Good Medium High Low Very Good Med-High

Ground to

GEO Good Medium High Low Good Med-High

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66
Notes

1. Michael J. Muolo, Space Handbook, A War Fighter’s Guide to Space,

vol. 1 (Maxwell AFB, Ala.: Air University Press, December 1993), 75–79. For

example the US system is comprised of three space operations centers

located in the United States and nine remote tracking stations scattered

around the world.

2. In order to be mobile, a ground station would have to rely on commu -

nication links that are also mobile. This virtually rules out the use of land

communications with their high bandwidth and resistance to jamming.

Mobile systems would probably rely on microwave or radio communications

that not only carry less information but also are more susceptible to inter -

ference. Other losses in efficiency may be caused by the need to periodically

move the station in order to prevent its discovery and destruction.

3. Pedro L. Rustan, “Clementine Test Results,” research results, Ballistic

Missile Defense Organization (Washington, D.C.: Pentagon, 31 October

1994), 1; and Moonglow (Washington, D.C.: Naval Research Laboratory,

June 1994), 28. Clementine incorporated seven sensors, along with the

attitude control, power, and the computer systems required to control and

point them, for a total dry weight of only 500 lbs. Its Lidar High Resolution

Camera weighed only 1,250 grams and produced images with a resolution

equivalent to 6 meters from a distance of 380 km.

4. Michael R. Stamm, “How Technology Is Changing the Optimum Size

of Satellites,” research paper (Kirtland AFB, New Mex.: Phillips Laboratory,

December 1994), 67–70. A constellation of 143 satellites, weighing 100 kg

and operating in 367 km orbits, provides the same coverage and resolution

as a constellation of four satellites, weighing 10,000 kg and operating at

3,666 km. Each of these would meet the need for 10 percent instantaneous

global coverage at a resolution of one meter (or equivalently, 1 m resolution

of a given point on earth for 10 percent of the time). The importance of this

is that 100 kg satellites can do the same job for only 12 percent of the cost

of the larger satellites.

5. J. Cushman, “To Detect ICBM Launch, AF Seeks Invulnerable Warn -

ing Satellites,” Defense Week, 16 January 1984, 1 and 10.

6. The effects of a high-altitude nuclear detonation include an electro -

magnetic pulse (EMP) produced during the detonation and the creation of

large quantities of charged particles that can become trapped in the Earth’s

radiation belts. The EMP can damage or destroy the electronic components

of unhardened satellites that are within line of sight of a detonation, and

even hardened satellites can be rendered inoperative for days or weeks due

to the effects of either the EMP or the charged particles.

7. Peter B. De Selding and Andrew Lawler, “SPOT Halts Sales of Gulf

Area Imagery,” Space News, 13–19 August 1990, 3; Renee Saunders,

“EOSAT Sees High Demand for Gulf Images,” Space News, 24–30 September 1990, 3; and Cynthia A. S. McKinley, “When the Enemy Has Our Eyes:

Proliferation of Space Surveillance and Reconnaissance Capability” (masSPACY

67
ter’s thesis, School of Advanced Airpower Studies, Maxwell AFB, Ala., June

1995).

8. Personal experience in the C-17 System Program Office. Development

of the C-17 SATCOM communication equipment showed that even an

authorized user transmitting at an unauthorized high-power level effectively

blocked out users with the standard low-power transmitters. While this

problem has been addressed, the high-power transmitters in question were

not designed as jammers. Equipment specifically designed to jam this sys -

tem would likely be even more effective.

9. Michael A. Dornheim, “Vandenberg Launches Eight Satellites,” Aviation

Week & Space Technology, 23 February 1998, 41. The system nearest to

deployment began service late in 1998 and employed 66 satellites. Called

“Iridium,” the system had 51 satellites in orbit as of March 1998.

10. Bill Gertz, “Shared Satellite Laser Test Weighed,” Washington Times,

2 January 1998; and Maj Mark Jelonek (PhD, laser physics), interviewed by

the author, 12 May 1998. Even relatively low-power lasers have demon -

strated the capability to damage the optical sensors of satellites. A test was

conducted that directed a 30-watt laser at an orbiting test satellite (the test

was supposed to be made with the two megawatt MIRACL laser but it

malfunctioned). Even such a low-powered laser caused enough damage to

create “a lot of panic” in the Pentagon. In a related area, the Starfire optical

range at the Phillips Laboratory used a tracking system constructed from

an Atari computer and electronic parts available at retail outlets.

11. “Kinetic Energy Anti-Satellite Program (KE ASAT) Background and

Overview,” briefing by Rockwell International Corporation and Rocketdyne,

1997; on-line, Internet, 29 March 1998, available from

http://www.fas.org/spp/military/program/asat/brief9711/index.html. Not

surprisingly, mobile ground stations are cited as a justification for building

the KE ASAT by the contractor team developing the weapon.

12. It should be noted that airborne lasers could also be used in the

ASAT role. Such an approach would yield increased mobility and avoid

firing the laser through most of the atmosphere. However, drawbacks such

as drastically reduced power availability and limitations on laser size are

such that this concept seems questionable, at least with current technol -

ogy.

13. Curtis Peebles, Battle for Space (New York: Beaufort Books, 1983),

820–901. The United States developed several ASAT systems in the 1960s,

including Program 505 Nike-Zeus, Program 437 Thor, and SAINT. The first

two were direct ascent systems using nuclear weapons as the kill mecha -

nism. While both were successfully tested with simulated warheads, neither

actually destroyed a target satellite. The SAINT system was to be a co-or -

bital device to inspect, and if necessary destroy, enemy satellites. Technical

problems forced termination of the program before any flights were actually

made.

14. “USAF Vehicle Designed for Satellite Attack,” Aviation Week & Space

Technology, 14 January 1985, 21.

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15. “Defense Department Plans Next Test Firing of Air-Launched ASAT

System,” Aviation Week & Space Technology, 23 September 1985, 20. The

target satellite was an Air Force test program satellite 11.3 feet long, 6.8

feet in diameter, and weighing 1,936 lbs. It was in a 320-nautical-mile polar

orbit with an inclination of 97.7 degrees.

16. Eric J. Lerner, “ASAT Nears the End,” Aerospace America, February

1988, 9. The political resistance to tests against orbital targets along with

large cost overruns persuaded the Air Force to cancel the program.

17. “Kinetic Energy Anti-Satellite Program (KE ASAT) Background and

Overview.” One point not mentioned in the slide briefing is that the kill

vehicle uses a visible light tracking system that may require daylight at -

tacks. “KE ASAT Hover Test Is Highly Successful,” 12 August 1997; on-line,

Internet, 7 February 1998 available from

http://www.fas.org/MhonArc/BMDList_archive/msg00249.html.

18. Richard L. Garwin, Kurt Gottfried, and Donald L. Hafner, “Antisatel -

lite Weapons,” Scientific American 250, no. 6 (June 1984): 47–49.

19. Whereas intercepting a satellite in LEO requires systems capable of

handling velocity differentials on the order of 8 km/s, the velocity differential

between a transfer orbit and a satellite in GEO is only about 1.4 km/s.

20. Phillip Clark, ed., Jane’s Space Directory (Coulsdon, England: Jane’s

Information Group, Sentinel House, 1997). The nations currently able to

place satellites in geosynchronous orbit include the United States, Russia,

Ukraine, Japan, China, and France. The other members of the European

Space Agency also have access to GEO, but political ramifications may

make launching weapons somewhat problematic. In addition, India is considered to be close to having the capability to launch satellites into GEO.

21. Since the energy needed to reach a given satellite is the same re -

gardless of when it is expended, both ground- and space-based systems

would require boosters of about the same size.

22. Mark Ward, “Business in Space,” Inside Science, 24 May 1997, 4.

(Inside Science is a supplement within New Scientist.) The sea-launch system is a joint venture between Boeing, the Norwegian shipbuilder Kvaerner,

and Russian and Ukrainian aerospace firms RSC-Evergia and NPO-Yuzhnoye. The system employs a movable oil rig as a launch platform and has a

specially built ship that transports a preprepared rocket out to the rig for

launch.

23. While a system designed merely for launch suppression may not

need to be as capable as a BMD system, an estimate of the cost may be the

global protection against limited strike system envisioned to stop a small

ballistic missile attack, and projected to cost $46 billion. “Sounding Taps

for Star Wars and the Stealth Bomber,” Defense Monitor XX, no. 5 (1991): 2.

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Chapter 4

Attacking Terrestrial Targets:

Ground-Based Alternatives for

Force Application

. . . a sword of Damocles [to] hang over the heads of the

imperialists when they decide the question whether or not

to unleash war.

—Nikita Khrushchev 

Pravda, 9 December 1961

Possibly the most controversial types of space-based weapons are those designed to attack targets on the ground or in

the air. The idea of having weapons orbiting overhead, await -

ing a signal to begin raining down upon whomever the United

States determines to be an enemy is alarming to many na -

tions. Because of the political costs of deploying such weap -

ons, the United States should only build them if there are

compelling advantages to be gained from doing so. The two

main categories of orbital force application weapons currently

being considered for development are those for BMD and at -

tacking surface targets. Airborne targets that remain within

the atmosphere are extremely difficult to attack directly and

are only discussed in passing. The primary purpose of this

chapter is to compare the potential capabilities of orbital bom -

bardment, space-based BMD, and space-based RF weapons

with those of their terrestrial counterparts.

Lasers will receive only brief attention in this chapter for the

simple reason that they are virtually ineffective against sur -

face targets and have the potential to attack only the highest

flying airborne targets. Due to a combination of atmospheric

absorption and the limited amount of power available once in

orbit, lasers operating on known principles are incapable of

delivering significant amounts of power against ground tar -

gets. Even if a space-based laser could generate 25 mega -

watts, the amount needed for an effective space-based BMD

system, it would be of little use against ground targets, which

71
are much more robustly built. More relevant to the force

application mission are weapons that operate on the betterunderstood principles of physical impact.

Alternatives to Orbital Bombardment

The various proposals for space-based force application

weapons were discussed in detail in chapter 2. Before any of

these concepts are actively pursued, it is necessary to deter -

mine if there are alternatives that can perform the same mis -

sions. After a brief review of the orbital weapons, this chapter

evaluates which systems already in the inventory can accom -

plish these missions. Finally, launch-on-demand concepts are

reviewed to evaluate what potential they may have for meeting

the same needs.

Orbital bombardment weapons can theoretically attack any

point on the surface of the earth with little or no warning. The

surprise nature of these attacks, the defender’s virtual inabil -

ity to counter an attack from space once it has been launched,

and attributes such as high-impact velocities have been the

traditional reasons for advocating orbital bombardment weapons.1

 A careful analysis of these claims, and the difficulties in -

herent in attempting to capitalize on them, indicates that they

have shortcomings that make conventional weapons superior.

As outlined in chapter 2, orbital bombardment weapons

have significant inherent drawbacks. Achieving the greatest

impact velocities (10 to 11 km/s) requires high-altitude orbits

from which the time needed to hit a target is on the order of

hours even under optimum conditions.2

 This relatively long

time tends to detract from the surprise nature claimed for

orbital weapons, while the increased velocities are of compara -

tively little value. Weapons delivered from LEO would have

better response times and their impact velocities (on the order

of four to five km/s) are more than adequate, but they would

be more vulnerable to enemy attack.

Another drawback of orbital weapons, at least for the near

future, is that impact velocities of more than 1.5 km/s are of

little use. The materials available for constructing penetrating

warheads are inadequate to withstand greater impact velocities and penetrate into deeply buried hard targets. Eroding

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72
rods, on the other hand, are limited by the fact that they only

penetrate two to three times their own length into the ground

and hence are also unable to penetrate deeply buried targets.

These drawbacks are quite significant; they imply that orbital

bombardment weapons have serious limitations, at least for

the foreseeable future.3

Provided they can be precisely located, deeply buried hard -

ened structures comprise a hitherto invulnerable target set

against which orbital bombardment weapons may be effective.

These targets are constructed hundreds of feet below the sur -

face. If new materials that are only now being investigated

prove to be as good as expected, 4

 it will be possible to destroy

such targets with orbital weapons. In contrast, current conventional weapons are unable to affect targets buried more

than 50 to 60 feet beneath the surface. 5

When deciding to attack hardened targets, it is worthwhile

to consider just exactly what is important enough to protect so

carefully. During World War II these targets ranged from Adolf

Hitler’s bunker in Berlin to underground weapons factories

used to build V-2 rockets. More recently, hardened targets

have included C2

 facilities such as Cheyenne Mountain, the

US underground C2 center in Colorado, and the various bunkers used by Iraq to protect command and communication

nodes. The advent of precision weapons has made burying

some of these types of facilities ineffective. For instance, if a

nation were to place its weapons factories in underground

bunkers today, it would be fairly easy to strike the entrances

and exits every few days to prevent raw materials from being

taken in and finished products from being delivered to the

field. Recent technological developments may also lead to a

reduced need to place communication nodes underground. As

communication networks transition from landlines to satellite

systems, the ground links may become as small as a hand -

held telephone.6

 With the added impetus of orbital bombardment weapons continually passing overhead, nations and cor -

porations alike might decide to make their communication

systems completely independent of vulnerable ground nodes.

The countermeasures available to an opponent also need to

be considered before a new weapon system is developed. If a

facility is dear enough to a nation, then it is possible to make

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73
it virtually immune to attack, even from orbital weapons. Re -

inforced concrete has been the material of choice for con -

structing underground bunkers. However, to protect truly important assets, it is better to bore deep into solid granite.

Granite is more than three times as strong as reinforced con -

crete against a projectile traveling at one km/s, and is still

almost 20 percent stronger if hit at four km/s. 7

 While it is

much more difficult to bore into solid granite than it is to dig a

hole, build a concrete bunker, and then bury it, if something

is important enough, then extreme measures may well be

taken to ensure its protection. If a target is placed deep

enough into a granite massif, then even nuclear weapons will

be unable to destroy it. Attempts to use orbital bombardment

weapons against such a target would be equally futile.

If the high-value asset is at all portable, a much easier and

less expensive method of protection may be to make it mobile.

The 1991 Gulf War against Iraq showed how difficult it could

be to find even relatively large vehicles, such as mobile Scud

missile launchers, in a relatively barren desert environment.

Some targets are too large to make mobile and do not merit

the heroic measure of tunneling kilometers into granite. These

targets are the ones for which orbital weapons would be best

suited, but conventional weapons ranging from artillery to

long-range bombers can also attack most of them. The

weapon needed to attack a particular target will depend on

factors such as the needed promptness of the response and

how well the target is defended. While no single conventional

weapon has the range and hitting power theoretically available

with orbital weapons, a variety of conventional weapons can

destroy almost all of the targets that would be vulnerable to

orbital bombardment. In addition, most of the targets that can

only be attacked from space will be equally vulnerable to sub -

orbital weapons.

If space-based weapons are to be used to attack targets

other than deeply buried hard targets, their suitability is even

more questionable. As discussed in chapter 2, the CAV is a

concept that could be employed as a space-based weapon. The

global positioning system-guided CAV would be a maneuver -

ing reentry vehicle with considerable cross-range capability. It

would provide a means for dispensing submunitions from

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74
orbital weapons to make them effective against a more diverse

array of targets. The submunitions that have been proposed

would be able to engage maneuvering targets, both airborne

and surface, as well as area targets. However, these kinds of

targets are even more vulnerable to conventional weapons

than are hard targets.

Conventional Missiles

Conventional missiles are able to attack and destroy many

of the same targets that orbital weapons would be used

against. For some targets, short-range ballistic missiles such

as the Army tactical missile system could be used. Designed

to dispense various types of submunitions, these groundlaunched missiles are most effective against area targets such

as armored or infantry formations. Improvements being undertaken to make this system effective against hard targets

will add to these capabilities.8

 Their relatively short ranges, on

the order of hundreds of kilometers, also limit the use of these

missiles to the vicinity of the ground battle.

Air- and sea-launched cruise missiles are another alternative to orbital weapons. With ranges up to 1,300 km for non -

nuclear missiles and ranges of 2,500 km for nuclear-tipped

versions, these vehicles already have the ability to destroy

many of the targets suggested for orbital weapons. 9

 Initially

designed with the limitations of the Strategic Arms Limitation

Talks II Treaty in mind,10 current cruise missile designs are

somewhat limited in range and some targets deep within en -

emy territory may be beyond their reach. Newer missiles

should be better, with the advanced cruise missile reported to

have a range of 3,000 km. 11 Since these missiles are basically

small, autonomous aircraft, further extensions of their range

would be relatively straightforward. Even with today’s limitations, cruise missiles carried on aircraft, submarines, or ships

have the ability to hit most important targets.

Originally intended for nuclear strike, cruise missiles have

been modified to dispense submunitions against up to four

separate targets apiece.12 Aside from a somewhat limited

range, the main shortcoming of cruise missiles is their limited

capability against hardened targets. This weakness is now

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75
being addressed by the development of new warheads. With

currently deployed warheads, a typical cruise missile has the

ability to penetrate approximately four meters of reinforced

concrete. This quality makes them effective against many

hardened surface targets, such as aircraft shelters, and even

some underground installations. New warhead designs have

the potential to penetrate six to nine meters of compacted soil

and then still penetrate 3.6 to 5.5 meters of concrete. While

this capability is still less than that of orbital bombardment

weapons, this improvement threatens all but the most deeply

buried targets.13

Another disadvantage of cruise missiles when compared

with orbital bombardment weapons is their responsiveness. If

sufficient numbers are deployed, orbital weapons should be

able to hit a target anywhere on earth within a matter of

hours.14 In contrast, unless a submarine is in the region or

the target is within range of pre-positioned aircraft, most mis -

siles will generally not be available for at least a day or two. In

most cases this should be adequate, but better responsiveness

can still be attained without having to resort to orbital weapon s.

Problems with cruise missile responsiveness and penetration

capability could be overcome by using ICBMs that are modified

to carry nonnuclear KE weapons. ICBM-launched KE weapons

would not be able to strike at the 11 km/s of some orbital

concepts, but the 5 km/s they are able to achieve is still more

than current penetrating warheads are able to withstand. This

makes ICBMs equal to orbital weapons in hitting power, at least

until materials technology advances dramatically.

Unfortunately, using ICBMs to deliver KE weapons has

many problematic drawbacks, not the least of which is accu -

racy. ICBMs have been made very accurate over the years, but

accuracy good enough for nuclear weapons is inadequate for

precision weapons aimed at hardened targets. Improving the

accuracy of the missiles will face the same problems as orbital

weapons; the speeds of reentry into the atmosphere (5–6

km/s) make communicating with a warhead virtually impossi -

ble.15 Absent an inertial navigation system that is sufficiently

accurate, destroying deeply buried hard targets will be difficult.

Until technology catches up, the CAV may be able to solve

the problem of giving ICBMs a conventional attack capability.

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76
Since the CAV concept evolved from research into maneuver -

able ballistic missile reentry vehicles, launching them with

ICBMs is inherently feasible. The ICBM/CAV combination

could provide the United States with a conventional global

strike capability that is just as responsive as the current nu -

clear strike capability. This, however, may be its greatest flaw.

The main drawback for using ICBMs to deliver conventional

weapons, either KE weapons or CAVs, may be the rather

heavy nuclear baggage associated with them. Regardless of

what they carried, ICBM launches would look exactly like a

nuclear attack. While this aspect may be minimized by con -

structing new launch sites, necessary since launches made

from current silos drop expended booster stages on the United

States and Canada, even using alternate launch sites would

probably cause anxiety among less-than friendly countries.

Assurances from the United States regarding the nature of the

warheads and their intended targets may be enough to pre -

vent third-party nations from launching back, but the potential for escalation could exist.

Manned Bombers

Manned aircraft also have the ability to destroy most of the

targets suggested for orbital weapons. Fighter and bomber

aircraft have long been used against the array of targets for

which the CAV is designed, and now have the ability to drop

precision weapons that can penetrate many hardened struc -

tures. With global range, B-52 or B-1 bombers can carry

cruise missiles to launch points within range of most targets

that are of interest. Increased range for cruise missiles would

bring virtually all targets within range of the bomber/cruise

missile combination.

Manned bombers also have the potential to use ordnance

that would overcome some of the shortcomings of cruise mis -

siles with respect to hard targets. Rocket assist for bombs

designed to penetrate hard targets has been demonstrated to

increase their penetration capability. The rocket accelerates

the bomb to a velocity of about 1.2 km/s, far less than orbital

weapons, but still sufficient to penetrate more than 15 meters

of concrete.16 Virtually all aircraft capable of dropping laserSPACY

77
guided bombs can carry these weapons, but high-threat envi -

ronments will necessitate the use of stealth assets.

Stealth technology gives the B-2 the ability to strike any -

where on the globe, including areas with a robust antiaircraft

defense, with a very low probability of being intercepted. The

B-2 is already in the inventory, will be able to carry precision

weapons like the joint direct attack munitions (JDAM), and

can strike virtually all targets currently outside the range of

cruise missiles. Rocket assist and penetrating warheads are

being investigated for use with JDAM and would give the B-2

a striking power close to that of orbital weapons.

A disadvantage of manned bombers, including the B-2, is

their response time. Strikes against the most remote targets

will require the pre-positioning of aerial refueling aircraft so

that the bombers will be within range. This pre-positioning

combined with the relatively low speed of aircraft will generally

slow response time to days rather than hours. The need for

support aircraft and the crews to fly them also adds consider -

ably to the cost of delivering a strike. However, the hardware

costs have largely been paid once the aircraft have been ac -

quired, and the operations, maintenance, and personnel costs

pale in comparison to the expense of fielding a truly robust

orbital bombardment system.

Another potential drawback to manned bombers is the pos -

sible loss of effectiveness for stealth technology in the not-toodistant future. Were this to occur, many targets currently

vulnerable would become less accessible. Orbital weapons of -

fer the ability to strike these targets regardless of what hap -

pens to the effectiveness of stealth. On the other hand, im -

provements to cruise missiles also have the potential to make

these targets vulnerable and at much lower cost.

Transatmospheric Vehicles

For attacking targets that are not vulnerable to conventional

aircraft or missiles, launch-on-demand transatmospheric vehicles (TAV) have the potential to provide the same capabilities

as orbital weapons. TAVs are envisioned as reusable vehicles

that are able to place payloads in orbit or to deliver them

anywhere in the world in a matter of hours. TAVs could be

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78
either manned or unmanned, with unmanned TAVs being the

most feasible in the near to midterm. Most TAV concepts are

expected to land like aircraft and will either take off like air -

craft or will be launched from other aircraft. TAVs are also

expected to have much shorter turnaround times between

missions than current space lifters, with aircraft-like operations being the ultimate goal. 17

In essence, TAVs are merely a concept for providing lowcost, responsive space lift. The most promising concepts for

TAVs are those launched from carrier aircraft, since using

existing heavy lift aircraft significantly reduces the cost of the

first stage.18 A drawback to these designs is that they are

limited in size by the capacity of the carrier. With military

satellites gradually getting smaller, this limitation may not be

very significant. In fact, the military Technical Requirements

Document for TAVs specifies a desired payload size of 1,000

lbs, well within the capability of air-launched designs. 19 While

ground-launched single-stage-to-orbit (SSTO) vehicles may

prove better for launching medium or heavy payloads, they

are not likely to be as responsive as smaller air-launched

two-stage-to-orbit (TSTO) vehicles. SSTO vehicles are also

likely to be much more expensive to design and build and will

probably not be available as soon. 20

The ability to deliver payloads from space on short notice

makes TAVs an obvious alternative to space-based weapons.

Although they would be space weapons in some respects, the

fact that weapons delivered by TAVs would not be launched

until needed would make them less controversial than perma -

nent orbital platforms. Yet since TAVs would be traveling at

orbital speeds, they could deliver weapons with the same hit -

ting power as space-based weapons but with less controversy

and at lower cost.

An alternative to orbital TAVs is a suborbital concept called

HyperSoar that has been suggested by Preston Carter of the

Lawrence Livermore National Laboratory. A HyperSoar vehicle

would not actually attain orbit but would fly a profile that

skipped in and out of the atmosphere. Combined-cycle engines, which operate as either air-breathing engines or rockets

depending on the phase of flight, would power the aircraft.

The flight profile of skipping in and out of the atmosphere has

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79
the advantage over hypersonic flight within the atmosphere of

allowing the aircraft’s skin to cool during the time spent out -

side of the atmosphere. This concept has the advantage over

orbital TAVs of not requiring the Δv necessary to achieve orbit,

and hence it requires less powerful engines and uses less fuel.

A HyperSoar vehicle could also be used as the carrier aircraft

of a TSTO system, with the benefit of drastically reducing the

performance requirements of the second-stage vehicle. 21

Using a HyperSoar-type vehicle to deliver KE weapons has

the potential to be as effective as placing them in orbit. Travel -

ing at Mach 10 (3 km/s), weapons dropped by a HyperSoar

vehicle would need rocket assist to achieve velocities equal to

those of orbital weapon, but unless the materials improve -

ments discussed earlier are made, 1.5 km/s is as fast as is

currently useful. If rocket assistance is used, far less of it will

be required than would be needed for weapons dropped from

subsonic aircraft like the B-2. Hypersonic speeds, high-alti -

tude flight profiles, and their launch-on-demand operations

would make these vehicles even less vulnerable than either

orbital weapons or stealth aircraft. Thus orbital and suborbi -

tal TAV concepts have the potential to provide KE weapon

capabilities identical to those of orbital weapons.

TAVs are just one of the concepts available for delivering

weapons at orbital velocities without actually basing weapons

in space. Expendable boosters such as the Pegasus XL built

by Orbital Sciences Corporation could also provide this capa -

bility. While life-cycle cost analyses indicate that reusable

TAVs would be considerably cheaper, Pegasus is a proven

booster and meets many of the requirements for a launch-ondemand system to deliver weapons at orbital velocities. 22 Specifically, the Pegasus XL has a responsiveness of about 15

days and can lift a 1,100-pound payload into LEO. 23 Weapons

like the CAV could be designed to make use of this booster

but would be quite expensive to use, as launching a Pegasus

typically costs about $14 million. 24 While this might be feasible for a “silver bullet” weapon to be used against the highest

priority targets, it would be cost-prohibitive as a major part of

the force structure.

If it is deemed necessary to have a global multimission

strike capability, this need could be met by a system like the

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80
CAV coupled with either suborbital launch vehicles such as

ICBMs, expendable boosters such as Pegasus, or reusable

TAVs. Considering the problems with ICBMs mentioned above,

the other launch vehicles would probably be better alterna -

tives, with TAV concepts appearing to be the least expensive

for long-term operations.

Whether used for precision strikes against deeply buried

hard targets or to dispense area-type weapons, expendable or

reusable launch vehicles are viable alternatives to spacebased weapons. If placed on alert, each of the systems de -

scribed above could deliver KE weapons almost as quickly

as those placed in orbit. Launch-on-demand systems would

be as difficult to intercept as orbital weapons and would argu -

ably be more difficult to attack before launch than would spacebased weapons waiting in orbit. While launch-on-demand

KE weapons face most of the same technological hurdles

as do orbital KE weapons, they are likely to be much less

controversial.

It may be possible to develop and deploy an orbital bom -

bardment system at less cost than equivalent launch-on-de -

mand systems. The latter systems require the development of

a new class of lift vehicle, but a responsive orbital system

would have to be designed to withstand years of storage or be

periodically visited for maintenance, either of which entails

considerable expense. While potentially more expensive to de -

velop and deploy, a launch-on-demand system would have as

a by-product a responsive space-lift system that could be used

to launch other payloads. A dedicated orbital bombardment

system would provide no such benefit. If a responsive spacelift system were developed for other reasons, then the launchon-demand system would be even cheaper. It can be argued

that an orbital bombardment system could be made some -

what more responsive, but a launch-on-demand system would

have virtually the same capability at potentially lower cost.

If delivered from conventional aircraft, none of the weapons

discussed above, neither the KE weapons nor the types deliv -

ered by the CAV, are likely to engender any significant contro -

versy. While weapons launched from these aircraft may not be

effective against the deepest and hardest targets, one must

question whether this small target set is worth the extremely

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81
high cost of developing and deploying a weapon system spe -

cifically designed to strike it. If the answer is yes, then subor -

bital weapons or launch-on-demand orbital weapons could do

the same job at lower cost in terms of both dollars and contro -

versy than their space-based equivalents.

Ballistic Missile Defense

The boost-phase engagement portion of BMD is perhaps the

only mission for which orbital weapons are uniquely suited.

While space-based weapons have the potential to attack bal -

listic missiles before launch, these targets can also be at -

tacked by conventional and stealth aircraft, as well as ballistic

and cruise missiles. If the missile launchers in question are

mobile, then conventional aircraft are likely to be the only

systems that can search out and destroy them. Space-based

sensors may assist in this effort, but the flight times of orbital

weapons are such that mobile missiles will be likely to have

moved before the weapon arrives.25 Autonomous submunitions that may be designed for hunting mobile missiles will

favor neither space-based nor conventional systems since they

will be deliverable by either.

Space-based weapons can also attack ballistic missiles

after the boost phase, but a space-based system designed to

attack missiles in the coast phase would probably have to

be of a different design than one for boost-phase intercept.

Lasers designed for boost-phase intercept rely on the vul -

nerability of thin-skinned liquid fuel tanks under intense

loads to provide the mode of destruction; the warhead bus

or the warheads are much more robust targets while they

are coasting along. KE weapons designed to engage boostphase ballistic missiles would also be poor choices for postboost intercept. Due to differences in the equipment and

software needed to detect, identify, and track individual

warheads, significantly more capable interceptors would be

needed for a boost-phase system to be effective against postboost targets. While boost-phase weapons might be de -

signed to attack both types of targets, their already high

costs would undoubtedly increase further. 26 Orbital weapons

are by no means uniquely suited to attack post-boost ballistic

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82
missiles. In fact the current national mis sile defense (NMD)

program calls for post-boost-phase intercepts to be conducted

by ground-based upper and lower tier defenses.27

Attacking ballistic missiles during boost has a number of

advantages. First of all, a ballistic missile is most vulnerable

during this part of its trajectory. Tracking is simplified be -

cause the missile is easy to see due to its intense IR signa -

ture. Successful attacks during this phase are the most

effective since a missile during boost has not yet started

deploying multiple warheads or decoys. A final advantage to

boost-phase intercept is that the missile may fall back on

the launching nation and will at a minimum fall well short

of its target.

The boost phase is probably the only phase for which

orbital interceptors are uniquely suited. While some air -

borne concepts have been investigated or are being devel -

oped, all of these entail placing an aircraft fairly close to the

launch site. The concept with the longest range is the air -

borne laser (ABL), which is calculated to have an effective

range of several hundred kilometers against a Scud-type

missile.28 Ranges this short will make it nearly impossi ble

to place the large, highly vulnerable aircraft needed to

carry the lasers close enough to the launch sites of a

major adversary to be effective. Concepts that envision

air-launched missiles to perform the intercept suffer from

similar problems.

While aircraft capable of carrying missiles to intercept bal -

listic missiles may be made stealthy enough to loiter in the

vicinity of launch sites, these sites are likely to be too dis -

persed or mobile to allow a reasonable number of aircraft

to keep all of them within range. The aircraft would als o

be vulnerable during daylight hours, providing an adversary

with the simple option of launching during the day. Regard -

less of whether an air-launched boost-phase interceptor

uses lasers or missiles, virtual air supremacy will be neces -

sary if the aircraft are to be able to keep launch sites within

range.

There are alternatives other than orbital weapons to cir -

cumventing the need for air supremacy. It may be possible

to develop cheap, high-altitude, long-endurance unmanned

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83
Source: Ballistic Missile Defense Organization (BMDO); on-line, Internet, available from

http://www.acq.osd.mil/bmdo/bmdolink/images/nmd1.jpg.

A candidate infrared sensor designed for possible use in national missile defense was launched on 15 January 1998. This was the second successful flight

test conducted by BMDO’s National Missile Defense Joint Program Office.

Intended to assess the ability of an exoatmospheric kill vehicle sensor to

identify and track objects in space, the sensor was launched from the Army’s

Kwajalein Missile Range while a simulated warhead and decoys were launched

from Vandenberg Air Force Base, California.

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84
Source: Ballistic Missile Defense Organization (BMDO);

on-lline, Internet, available from

http://www.acq.osd.mil/bmdo/bmdolink/images/image2.jpg,

http://www.acq.osd.mil/bmdo/bmdolink/images/image3.jpg,

and

http://www.acq.osd.mil/bmdo/bmdolink/images/image4.jpg.

A sequence from IFT-10, the 10 June

1999 test of the Theater High Altitude

Area Defense (THAAD). Shown are

the missile’s maneuvering after

launch, an intercept sequence, and

the seeker image. THAAD is intended

to provide the upper tier of a twotiered defense against tactical ballistic

missiles.

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85
Source: Air Force Research Laboratory; on-line, Internet, available from http://www.afrl.af.mil/images/Pictures/abl-sor.jpg

or http://www.afrl.af.mil/images/Pictures/abl-sor.jpg.

A laser beam coming out of a 1.5-meter telescope at the Starfire Optical Range.

To improve the viewing of objects in space, the laser, computers, and deformable optics are used to cancel out atmospheric distortions. An improved

understanding of distortion is also critical to fielding laser weapons that will

work within or through atmosphere.

Source: Air Force Research Laboratory; on-line, Internet, available from http://www.afrl.af.mil.images/pictures/abl2.gif.

Depiction of the airborne laser (ABL). By carrying aloft a high-energy laser, the

ABL is intended to destroy theater ballistic missiles during the boost phase of

their flight while they are still over the launching country.

CADRE PAPER

86
aerial vehicles (UAV) capable of engaging ascending ballistic

missiles. These aircraft would need stealth characteristics

allowing them to loiter for days over a region of known

launch sites. They would also have to be inexpensive so that

enough could be deployed that they would flood a region of

suspected launch sites. When a ballistic missile is

launched, the aircraft would launch high-velocity missiles

designed to intercept ballistic missiles in the boost phase

and bring them down. Both the UAVs and the missiles

would need to be very sophisticated and would require con -

siderable resources to develop and deploy. However, it is

probable that a system such as this would be no more ex -

pensive, and would be more technologically feasible, than a

system which relies on orbital weapons.

If other concepts prove impractical, an orbital defense sys -

tem may be the only viable method for boost-phase intercep -

tion of ballistic missiles, but as outlined in chapter 2, it will be

a major technological challenge and very expensive. Vast

numbers of satellites will be required to provide coverage

against even a limited missile attack. Given the need to place

these weapons in LEOs, they will also present lucrative targets

for a ground-based ASAT system.

Setting aside technological and cost hurdles, the greatest

barrier to deploying a space-based BMD system may well be

treaty limitations. While international treaties do not prohibit

most other types of nonnuclear space-based weapons, the

Treaty on the Limitation of Anti-Ballistic Missiles (ABM) or the

1972 ABM treaty specifically prohibits space-based BMD sys -

tems. This treaty not only covers deploying orbital ABM weap -

ons but it also proscribes even testing the components of such

a system.29

Given the political will to do so (an admittedly unlikely

proposition considering domestic and international political

opposition to the idea), the United States could unilaterally

abrogate the ABM treaty. Unfortunately, this abrogation

would, by definition, occur during early testing of compo -

nents of the system, long before any kind of usable weapons

(even prototypes) have been built. If this abrogation is dis -

covered, which would be virtually certain considering the

kinds of tests that will be required, 30 other nations will take

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87
note and may start taking appropriate countermeasures.

The most straightforward of these would be simply to deploy

large numbers of missiles so as to overwhelm the system.

Given the large disparity in cost between building missiles

and deploying an orbital BMD system, building enough mis -

siles to overwhelm the BMD system should not be difficult,

especially if decoy missiles were to be used. 31 A potentially

even more effective way to circumvent an orbital BMD sys -

tem would be to produce long-range cruise missiles. Orbital

weapons would be virtually useless against cruise missiles,

and given their low technology and significantly lower cost,

many nations might opt to direct their energies toward pro -

curing these weapons.32

While it appears that orbital weapons are necessary if a

BMD system is to have a boost-phase component, the benefit

of an effective BMD system is itself questionable. The orbital

components of such a system would not only suffer from the

costs and difficulties outlined in chapter 2, but the deploy -

ment of such a system may well prompt the development of

countermeasures and alternative weapons that would render

a ballistic missile defense system irrelevant.

Radio Frequency Weapons

The orbital RF weapon is a concept that appears promising

but has little hard evidence to support the claims being made

for it. If forecast improvements in the technology of highpower RF systems and antennas occur, orbital RF weapons

could provide on-demand degradation or destruction of an

enemy’s electronic equipment, and jamming of his radar and

communications. Provided the previously examined difficulties

of controlling extremely large antennas in space are also over -

come, a relatively small number of RF weapons placed in

geosynchronous or Molniya orbits could provide global cover -

age. This capability would be available worldwide without

the need to deploy aircraft and equipment or put American

lives at risk.33

While space-based RF weapons appear to have great potential, the needed technological developments will probably entail considerable cost. Moreover, manned aircraft can also jam

CADRE PAPER

88
radar and communications. Although since the USAF has re -

cently retired much of its jamming capability in the form of

the EF-111 and Navy EA-6Bs will only be able to assume part

of the EF-111’s former role, more capability is arguably

needed. If this is true, the question becomes one of how to

best provide this capability.

As mentioned above, space-based RF weapons have the

potential to do much more than jam radar and communica -

tions, which is the limit of airborne systems. Moreover, the

space-based weapons would look much like large radio tele -

scopes or other inoffensive equipment, making them much

less controversial to deploy. However, spending the vast

sums of money needed to develop and eventually deploy

such a system seems questionable in an era of severely

limited defense spending. Investments in this technology

have the potential to yield huge dividends, much less invest -

ment would be needed to remedy any current shortfall in

jamming capability. As with many decisions made during a

period of austerity, the outcome will probably hinge more on

the short-term needs of the war fighter than on the potential

merits of orbital RF weapons.

Conclusion

From the foregoing discussion, it appears that the only mis -

sions for which space-based weapons are uniquely suited are

those of boost-phase ballistic missile defense and possibly RF

attack against enemy electronic equipment. The first of these

has significant treaty implications and both are concepts that

will require considerable time and resources to make them

into viable weapons. A qualitative assessment of the merits of

the weapons discussed in this chapter are found in tables 3

and 4. Whether or not these weapons are worth the time and

effort will hinge on a number of factors, not the least of which

are the international political implications of placing weapons

in space.

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89
Table 3

Space-Based Weapons for Force Application

Response

Time

Technical

Risk

Reliability Vulnerability

to Attack

Verifiability

of Effects

Cost

Orbital

Attack

Kinetic

Energy Excellent Very High ? High Good Very High

Common

Aero Vehicle Excellent Very High ? High Fair Very High

Ballistic

Missile

Defense

Excellent Very High ? High Good Very High

Radio

Frequency Excellent Very High ? Medium Fair Very High

Table 4

Ground-Based Alternatives

Response

Time

Technical

Risk

Reliability Vulnerability

to Attack

Verifiability

of Effects

Cost

NonDestructive

Measures

Conventional

Missiles Good None GenerallyVery Good Low Good Low

Manned

Stealth

Bombers

Good Low Generally

Very Good Low Very Good Low

Transatmospheric

Vehicles

Very Good High ? Very Low Good Very High

Other

Attack

Conventional

Missiles Good None GenerallyVery Good Low Good Low

Manned

Stealth

Bombers

Good Low Generally

Very Good Low Very Good Low

Transatmospheric

Vehicles

Very Good High ? Very Low Good Very High

Airborne

Jammers Good Low GenerallyVery Good Medium Fair Medium

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90
Notes

1. Ivan Bekey, “Force Projection from Space,” New World Vistas, Air and

Space Power for the 21st Century, Space Applications Volume (Washington,

D.C.: USAF Scientific Advisory Board, 1995), xviii and 83–84.

2. To attain velocities in the 10 to 11 km/s range, satellites must be in

orbits with an altitude of more than 40,000 km. The transfer time from a

40,000 km orbit to impacting the earth’s surface is about five hours and

would yield an impact velocity of about 10 km/s. The time to hit a target on

the earth would probably be longer since it is unlikely that the weapon

would be in the proper position to initiate an immediate attack.

3. Joseph A. Smith, advanced concepts engineer, Lawrence Livermore

National Laboratory, University of California, interviewed by author, 11

February 1998.

4. Ibid. New materials called nanolaminates have the potential to with -

stand impact velocities of up to 14,000 ft/s (4.3 km/s).

5. Mark Hewish, “Adding New Punch to Cruise Missiles,” Jane’s International Defense Review, no. 31, 31 January 1998, 41–42.

6. John V. Evans, “New Satellites for Personal Communications,” Scientific American, April 1998, 74–75. Motorola’s Iridium system is an example

of such a system. Iridium will allow people to make a phone call (or send a

fax or connect to the Internet) from anywhere in the world using only a

small handheld telephone.

7. Preston Carter, “HyperSoar, A Concept for Global Reach—Global

Power,” Lawrence Livermore National Laboratory, University of California,

briefing to the author, 15 January 1998. Comparison is based on the

stagnation pressure at the tip of a penetrating body, which is proportional

to the maximum stress on the penetration.

8. Duncan S. Lennox, ed., Jane’s Strategic Weapon Systems (Coulsdon,

England: Jane’s Information Group, Sentinel House, 1997), Issue 26, January 1998. Block 3 Army tactical missile systems will carry a hard targetpenetrating warhead.

9. Lennox.

10. Ibid.; and Kenneth P. Werrell, The Evolution of the Cruise Missile

(Maxwell AFB, Ala.: Air University Press, 1985), 175–76. While the Strategic

Arms Limitation Talks II Treaty, which remains unratified, did not limit the

ranges of air-launched cruise missiles, ground- and sea-launched cruise

missiles could be tested up to ranges of 2,500 km but could not be de -

ployed. The fact that deployed sea-launched cruise missiles have a range of

2,500 km argues that the treaty is being ignored.

11. Lennox.

12. Ibid., RGM/UGM 109 Tomahawk.

13. Hewish.

14. Approximately 36 satellites placed in 90-minute orbits could strike

targets anywhere on the earth within about 45 minutes provided they had

the ability to maneuver 1,000 km from orbital track during descent. These

SPACY

91
maneuvers would reduce their impact velocity by a significant amount.

More satellites or longer permissible wait times would alleviate this problem.

15. W. Williamson et al., Technical Analysis of a Contingency Conven -

tional Surgical Strike System (Albuquerque, New Mex.: Sandia National

Laboratories, June 1995), 42. Document is now declassified. As mentioned

in chapter 2, at speeds in excess of about 4.6 km/s the plasma surrounding

a reentry vehicle prevents it from being able to transmit or receive signals.

16. Hewish, 42.

17. Michael A. Rampino, Concepts of Operations for a Reusable Launch

Vehicle (Maxwell AFB, Ala.: Air University Press, 1997).

18. Daniel Gonzales et al., Proceedings of the RAND Project AIR FORCE

Workshop on Transatmospheric Vehicles, RAND Report MR-890-AF (Santa

Monica, Calif.: RAND, 1997), 31–40. When used to launch TAVs, carrier

aircraft are essentially the first stage of a two-stage-to-orbit booster. This

allows the TAV landing gear to be designed to support only landing loads,

rather than the much greater fully fueled take-off weight. Using modified

commercial aircraft as carriers allows the use of proven designs and greatly

lowers development costs.

19. Gonzales et al., 13–14.

20. Mel Eisman and Daniel Gonzales, Life Cycle Cost Assessments for

Military Transatmospheric Vehicles, RAND Report MR-893-AF (Santa

Monica, Calif.: RAND, 1997), 30–31.

21. Carter briefing. A potential problem for the HyperSoar concept is

that the combined cycle engine concept has yet to be proven feasible.

22. Eisman and Gonzales, 30 and 31.

23. Gonzales et al., 15.

24. Forecast International/DMS Market Intelligence Reports: Space Systems Forecast, April 1998, Tab: Space Vehicles, Section: “Pegasus Winged

Launch Vehicle,” 1.

25. Conduct of the Persian Gulf War: Final Report to Congress (Washington, D.C.: DOD, 1992), 167. Barring extraordinary luck with orbital posi -

tioning, even a LEO system would have at about a 45-minute response at

best. The Gulf War against Iraq showed that this is not fast enough, since

mobile Scuds were launched and then repositioned within about 10 min -

utes.

26. United States General Accounting Office, Report to the Chairman, Leg -

islation and National Security Subcommittee, Committee on Government Operations, House of Representatives: Strategic Defense Initiative, Need to Ex -

amine Concurrency in Development of Brilliant Pebbles, GAO/NSIAD-91-154

(Washington, D.C.: GAO, March 1991), 6. As discussed in chapter 2, the

Brilliant Pebbles orbital BMD system would probably have cost in excess of

the projected $55 billion.

27. “National Missile Defense Exoatmospheric Kill Vehicle,” BMDO Fact

Sheet 97-01 (September 1997): 1. The exoatmospheric kill vehicle (EKV) is a

key part of the ground-based interceptor (GBI) portion of the national mis -

sile defense system being developed by the BMDO. The EKV is to acquire,

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92
track, and destroy ballistic missiles during the midcourse phase of their

trajectories.

28. Geoffrey E. Forden, “The Airborne Laser,” IEEE Spectrum, September

1997, 49.

29. Pericles Gasparini Alves, Prevention of an Arms Race in Outer Space:

A Guide to the Discussions in the Conference on Disarmament, UNIDIR/91/79, Annex A (New York: United Nations Institute for Disarmament

Research, 1991), 63 and 64.

30. In orbital testing of either a laser or missile interceptor against a

ballistic missile, the locations of the missile test ranges will make it virtually

impossible to keep the tests secret.

31. “Sounding Taps for Star Wars and the Stealth Bomber,” Defense

Monitor XX, no. 5, 1991, 2. Unguided, or only marginally guided, ballistic

missiles which would be little more than rocket motors and fuel tanks

would be considerably cheaper than the real thing. They would be orders of

magnitude cheaper than the optimistically estimated $46 billion needed to

provide the limited coverage of the GPALS system described in chapter 2.

“Sounding Taps for Star Wars and the Stealth Bomber,” Defense Monitor

XX, no. 5, 1991, 2.

32. Forecast International/DMS Market Intelligence Reports: Missiles,

1998, Tab: D, Sections: “AGM-109/BGM-109 Tomahawk,” 2, and “LGM30F/LGM-30G Minuteman,” 1. Cruise missiles are much cheaper than bal -

listic missiles as well, with a BGM-109 Tomahawk cruise missile costing

$1.1 million (in 1998 dollars), much less than the LGM-30G Minuteman III

costing $4.2 million (in 1978 dollars).

33. Bekey, 84–85.

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93
Chapter 5

Political Implications

By trying too quickly to arm itself for the future space

battlefields, the United States could lose the very peaceful

means of getting rid of a few thousands of enemy nuclear

warheads without firing a single shot.

—Pierre Lefevre 

Le Soir, 22 October 1997

Deploying weapons in space could usher in a new era in

warfare. While some say that this is inevitable, others main -

tain that space can and should be maintained as a weaponfree sanctuary. As suggested by the passage above, even a

limited test against an orbiting satellite can spark interna -

tional censure. The political repercussions of actually deploy -

ing weapons in space are likely to be much greater. If a deci -

sion to deploy orbital weapons is to be consciously made, and

not merely the unthinking result of technical feasibility, then

the political implications must be carefully weighed. While a

thorough discussion of these implications is beyond the scope

of this study, the following overview should familiarize the

reader with the most significant points.

Treaty Implications

Any deployment of orbital weapons would have to take into

account current treaties regarding the use of space. Of pri -

mary concern are the following treaties:

• United Nations Charter (1945),

• Nuclear Test-Ban Treaty (1963),

• Treaty on the Principles of the Activity of States in the

Exploration and Use of Outer Space Including the Moon

and Other Celestial Bodies (1967),

• Treaty on the Limitation of Anti-Ballistic Missile Systems

(1972),

95
• Convention on the Prohibition of Military or Any Other

Hostile Use of Environmental Modification Techniques

(1977), and the

• Agreement Governing the Activities of States on the Moon

and Other Celestial Bodies (1979).1

Taken together, these treaties and conventions prohibit placing

nuclear or other weapons of mass destruction in orbit around

the earth or the moon, prohibit placing military installations or

weapons on the moon or other celestial bodies, and declare

that space is to be used exclusively for “peaceful purposes.” 2

Aside from WMD, the treaty implications of deploying orbital

weapons are somewhat vague. The preamble to the Outer

Space Treaty of 1967 stipulates that space will only be used

for peaceful purposes. While peaceful purposes are never

clearly defined in the treaty itself, it incorporates by reference

the UN Charter that defines peaceful purposes to include the

inherent right of self-defense.3

 The vagueness of the definition

peaceful purposes has prompted considerable discussion of its

meaning. Interpretation ranges from banning any types of

weapon whatsoever to permitting purely defensive weapons to

be deployed. None of the proposed interpretations would per -

mit the deployment of offensive weapons in space. 4

The problem with attempts to limit space-based weapons to

those that are defensive is that most space-based weapons—like most other weapons—are difficult to categorize. This

fact has been noted by the UN Conference on Disarmament,

which cites the dual ASAT/ABM capability of many defensive

ABM concepts as making the systems potentially offensive. 5

This is mirrored by the potential dual capability of many ASAT

concepts which, given their potential ABM capability, would

be in violation of the 1972 ABM treaty. While some argue that

the ABM treaty has outlived its usefulness and is in fact no

longer even valid,6

 the lack of a clear distinction between of -

fensive and defensive orbital weapons makes any deployment

controversial.

The ABM treaty is the most restrictive treaty currently in

force that bears on weaponizing space, which limits the

United States and the Soviet Union each to a single groundbased ABM site.7

 The treaty is unusual since it does not spec -

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96
ify each type of system that is prohibited; instead it is written

to prohibit everything and then lists exceptions, the one

ground-based system permitted for each signatory. The effect

of this structure is that new technologies that could be used

as ABM weapons are automatically excluded. Interpreting the

treaty has led to considerable controversy, such as whether

orbital mirrors used to aim ground-based lasers at satellites

would be components of an ABM system. Since these mirrors

could be used to aim the laser at a ballistic missile, many

nations hold that they would be proscribed, regardless of the

mission for which they were intended. 8

 As long as it remains

in force, the 1972 ABM treaty will greatly complicate any at -

tempt to place weapons in orbit.

International Reaction

The international political implications of space-based

weapons are already evident. Speaking through the UN Secre -

tariat of the Conference on Disarmament, many nations have

raised concerns about the destabilizing effects of placing

weapons in orbit. The main concern centers on the possibility

of an arms race in space. 9

 Not only is the deployment of US

ASAT weapons likely to prompt other nations to try to match

this capability but also the deployment of even a limited BMD

system could spark such a race, since most BMD concepts

will also be able to perform the ASAT role. If the Brilliant

Pebbles portion of SDI had worked, it would not only have

provided defense against a ballistic missile attack but would

also have enabled the United States to virtually close off space

access to the rest of the world. This condition would have

been possible because the capability needed to stop even a

limited missile attack is enough to prevent other nations from

launching any satellites at all. While some might desire this

kind of control, it is unlikely that the international community

would willingly acquiesce to such a move.

Today, the United States is in the enviable position of being

the only superpower to survive the cold war. Many models of

political interaction would predict that a nation with so much

power would prompt other nations to form alliances against

it.10 The fact that this has not happened is arguably a result of

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97
past US restraint in exercising power. For instance, during the

cold war the United States allowed the other North Atlantic

Treaty Organization members much more say in the structure

of the organization and its decision-making processes than

was necessary given their dependence on the US nuclear um -

brella.11 This reluctance to aggressively use military power to

further US interests has prompted other nations to trust that

the United States will not abuse its military superiority. A

unilateral move to put weapons in space could undermine this

trust.

One example of options open to other nations responding to

a unilateral weaponization of space on the part of the United

States is especially worthy of note. This response would be for

another nation to deploy nonstealth space mines near each

orbiting US weapon. Once these weapons were in place, the

nation launching them would need only to explain what they

were and the conditions under which they would be used.

These weapons would be relatively inexpensive to design and

produce, and if parked next to a multibillion-dollar spacebased laser, could negate the utility of the laser. 12 Furthermore, if overt space mines were deployed in response to

space-based weapons, it is almost certain that they would be

placed near other US military satellites as well.

In light of international opposition, unilaterally deploying

weapons in space has little to recommend it. Such an offen -

sive attitude (in both senses of the word) would do little to

generate international support for actions such as the 1991

Gulf War. Some may argue that the United States’s current

position of power makes international support irrelevant and

that the United States did not need a coalition to defeat Iraq,

but the costs of acting unilaterally would undoubtedly have

been much higher. It seems unwise to alienate potential allies

at the same time that force reductions may make acting uni -

laterally difficult or impossible.

Domestic Resistance

As the first openly proposed plan for putting weapons in

space, the Strategic Defense Initiative generated more controversy than any previous space weapon system. The arguments

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98
against SDI centered on three general areas: the strategic

instability that would be generated by pursuing a nuclear

advantage, the inherent infeasibility of the concepts being ex -

plored, and the projected expense of the programs. Taken

together, these problems spelled the end of SDI. Those who

thought that the program was technologically unfeasible and

a waste of money were able to garner support from those who

deemed a successful program to be politically destabilizing

and likely to lead to nuclear holocaust. Regardless of the mer -

its of the arguments, the domestic political resistance became

such that SDI was eventually terminated. 13

Tests of the F-15 ASAT system also generated domestic con -

troversy. Some of the concerns verged on paranoia, such as

using the weapons to destroy Soviets early warning satellites

so that the United States could launch a preemptive nuclear

strike.14 Others thought ASATs should never be developed be -

cause using weapons in space is an intrinsically bad idea. 15

While neither of these arguments was decisive, they added to

the political resistance against the program. The final demise

of the successful F-15 ASAT system has been attributed to

cost overruns and a congressional ban on further testing

against targets in space. The USAF canceled the program in

March 1988 and turned over ground-based ASAT development

to the Army.16

If the controversy surrounding a recent US test firing of a

ground-based laser at a satellite is any indication, opposition

to using weapons in space remains strong today. This opposi -

tion continues to be directed against all weapons intended to

engage targets in space, regardless of where they are based.

The test firing of the MIRACL laser against an orbiting satellite

prompted at least three articles in the New York Times alone,

much more than would normally be expected for feasibility

tests of a potential future weapon. This time the arguments

centered on the even more relevant point of exactly who had

the most to lose were a space weapons race to start. 17 The fact

remains that using weapons in space is still extremely contro -

versial, and actually placing weapons in space is certain to be

more so.

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99
Space as Sanctuary

Space has long been treated as something of a sanctuary

and kept free of weapons, a situation that is somewhat curi -

ous given the intense competition in technology and arms

between the United States and the Soviet Union during the

cold war. The reasons for this traditional sanctuary status are

somewhat ambiguous, beginning with an initial inability to

build practical weapons, and gradually becoming a situation

in which both sides had more to lose from space-based weap -

ons than they had to gain. 18

As soon as the United States began using reconnaissance

satellites to determine Soviet military strength, the Soviets

used the UN to try to get them banned. Once the Soviets

attained a similar capability, these initiatives tapered off. At

that point, the early 1960s, both nations were actively devel -

oping ASAT capabilities and focused their efforts on groundbased weapons using nuclear warheads. The choice of nuclear

weapons was based mainly on the fact that the technology for

nonnuclear ASAT weapons was too immature to make them

viable in the near term. Space-based ASATs were dismissed

for many of the reasons outlined in chapters 2 and 3. 19

The latter stages of the cold war brought about an apparent

reevaluation of the need for ASAT weapons. The last Soviet

ASAT test was on 18 June 1982, and during the early 1980s

the Soviet Union submitted to the UN a number of draft trea -

ties for controlling weapons in space. 20 The US response to

this initiative can be said to have been made by Congress in

September 1985, shortly after the successful test of the F-15

ASAT. This response was in the form of a moratorium on

ASAT testing for one year, which would be renewed as long as

the Soviets did not test any more ASATs of their own. A Re -

publican-led Congress allowed the moratorium, which prohibited tests against objects in space, to lapse in 1995. 21 The tacit

agreement not to pursue further ASAT capability seems to

have been the result of both nations’ growing reliance on

space-based assets combined with the difficulty inherent in

fully protecting them.22

While the post-cold-war environment does not present the

United States with potential opponents as powerful as the

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100
Soviet Union, US dependence on space-based assets is greater

than ever. Even in relatively small-scale contingencies, US

forces rely heavily on space-based intelligence, navigation,

and communications. Current initiatives promise to increase

our reliance on them even further and include building satel -

lites to gather real-time targeting information about ground

targets, much like the airborne joint surveillance, target at -

tack radar system or JSTARS provides today. 23 As the search

for invulnerability continues to move from aircraft to satellites,

a space sanctuary strategy would benefit the United States

now more than ever.

Regardless of whether a space sanctuary is a feasible goal,

placing weapons in space will generate both domestic and

international opposition. It is even possible that a unilateral

move by the United States would generate so much ill will,

that other nations would band together in opposition. 24 Even if

this did not happen, the political implications of placing weap -

ons in space would be high and would have to be factored into

any such decision. Given the limited advantages offered by

space-based weapons, adverse political implications make developing them truly questionable.

Notes

1. Glenn H. Reynolds and Robert P. Merges, Outer Space: Problems of

Law and Policy, 2d ed. (Boulder, Colo.: Westview, 1997), 48–134; and Philip

D. O’Niell Jr., “The Development of International Law Governing the Military

Use of Outer Space,” in National Interests and the Military Use of Space,

William J. Durch, ed. (Cambridge, Mass.: Ballinger Publishing Co., 1984),

169–200.

2. Pericles Gasparini Alves, Prevention of an Arms Race in Outer Space: A

Guide to the Discussions in the Conference on Disarmament, UNIDIR/91/79,

Annex A (New York: United Nations Institute for Disarmament Research,

1991), 56–80 and Annexes A and C.

3. Ibid., 143.

4. Ibid.,12–13.

5. Ibid., 35.

6. Jon Kyl, ”An Effective Antimissile Strategy,” Wall Street Journal, 22

May 1997. Senator Kyl argues that since the Soviet Union dissolved, there

is no longer a treaty. He led a senate movement to block a memorandum of

understanding designating Russia, Ukraine, Kazakhstan, and Belarus as

successors to the USSR and to keep the treaty in force.

SPACY

101
7. Under current interpretation this is now Russia, Ukraine, Kazakhstan,

and Belarus.

8. Duncan S. Lennox, ed., Jane’s Strategic Weapon Systems (Coulsdon,

England: Jane’s Information Group, Sentinel House, 1997), Issue 26, January 1998.

9. Alves, pt. 2.

10. Stephen M. Walt, Origins of Alliances (Ithaca, N.Y.: Cornell University Press, 1987); and Michael W. Doyle, Ways of War and Peace (New York:

W. W. Norton & Co., 1997), 161–94.

11. John Lewis Gaddis, We Now Know: Rethinking Cold War History

(Oxford: Camden Press, 1997), 288–89.

12. Although similar in many respects to the space mine concept dis -

cussed in chapter 2, a nonstealth space mine would avoid the most prob -

lematic difficulties associated with one that must remain undetected. Spe -

cifically, two of the biggest constraints, size and power source, would be

eliminated. Since a nonstealth space mine could be as big as necessary, it

could carry ample propellant to carry out its mission and electrical power

could be supplied by solar cells. Building such a space mine would present

few, if any, significant technological challenges. All that would really be

needed would be a moderately maneuverable spacecraft packed with explo -

sives. The guidance and control system would be no more complex than

that needed to rendezvous with another spacecraft, so such a weapon

would be a relatively inexpensive to build and deploy.

13. Crockett L. Grabbe, Space Weapons and the Strategic Defense Initiative (Ames, Iowa: Iowa State University Press, 1991); Charles L. Glaser,

Analyzing Strategic Nuclear Policy (Princeton, N.J.: Princeton University

Press, 1990); and Steven E. Miller and Stephen Van Evera, eds., The Star

Wars Controversy (Princeton, N.J.: Princeton University Press, 1986).

14. R. Jeffrey Smith, “Antisatellite Weapon Sets Dangerous Course,” Science 222, 14 October 1983, 140–42. A commentary in Science opened with:

“The United States is about to test an ASAT that has no obvious target

except Soviet early-warning satellites.” The article stipulates that the real

reason the United States was developing the F-15 ASAT was not to target

the low-altitude satellites as was advertised, but so that it could be up -

graded to eliminate Soviet early warning satellites allowing the United

States to conduct a preemptive nuclear strike.

15. Charles A. Monfort, “ASATs: Star Wars on the Cheap,” Bulletin of the

Atomic Scientists 45, no. 3 (April 1989): 10–13.

16. Phillip Clark, ed., Jane’s Space Directory (Coulsdon, England: Jane’s

Information Group, Sentinel House, 1997), 164.

17. William J. Broad, “Military Is Hoping to Test-Fire Laser against Sat -

ellite,” New York Times, 1 September 1997, A-1. John E. Pike, the director

of space policy for the Federation of American Scientists, a group opposed

to antisatellite weapons, is quoted as saying that “Shooting a satellite is

shooting ourselves in the foot,” presumably because showing the world how

to disable our own satellites would be counterproductive. Follow-up articles

CADRE PAPER

102
and editorials also condemned the test: Letter to the Editor by Eugene J.

Carroll Jr., deputy director, Center for Defense Information, Washington,

“Space Laser Test Sows Military Hubris,” New York Times, 5 September

1997, A-34; and William J. Broad, “The Air Force Aims to Test Its Space

Destroyer,” New York Times, 7 September 1997, IV-2.

18. David W. Ziegler, Safe Heavens: Military Strategy and Space Sanctuary Thought (Maxwell AFB, Ala.: Air University Press, 1998); Paul B. Stares,

The Militarization of Space, U.S. Policy, 1945–1984 (Ithaca, N.Y.: Cornell

University Press, 1985); Walter A. McDougall, The Heavens and the Earth: A

Political History of the Space Age (Baltimore: Johns Hopkins University

Press, 1985); and R. Cargill Hall, “Origins of U.S. Space Policy: Eisenhower,

Open Skies, and Freedom of Space,” in Exploring the Unknown, John M.

Logsdon, ed. (Washington, D.C.: Government Printing Office, 1995), chap.

2.

19. In the early 1960s it was more technologically feasible, and cheaper,

to build a direct ascent ASAT with a nuclear warhead than it was to develop

a more sophisticated orbital rendezvous system. Curtis Peebles, Battle for

Space (New York: Beaufort Books, 1983), 77.

20. Richard L. Garwin, Kurt Gottfried, and Donald L. Hafner, “Antisatel -

lite Weapons,” Scientific American 250, no. 6 (June 1984): 45 and 47.

21. Broad, A-12.

22. Alves. Alves discusses related concerns that have been voiced by

many other nations.

23. Barbara Starr, “U.S. Team to Work on New Target-Tracking Satel -

lite,” Jane’s Defence Weekly 29, Issue 12, 7.

24. Walt; and Doyle.

SPACY

103
Chapter 6

Conclusions and Recommendations

The United States enjoys an overwhelming advantage in

space-based intelligence, communications, and navigation

systems. This advantage gives the United States a decisive

edge in military conflict by providing commanders at all levels

with an unprecedented awareness of the battlefield. Protecting

these assets and maintaining US dominance in space are

critical to the defense of US national interests. What part

space-based weapons will play in providing continued protec -

tion of these systems remains to be determined.

Conclusions

Near-term efforts should focus on protecting our ability to

use space-based assets. As this study shows, the best method

for protecting these assets does not appear to be deploying

weapons in space. The nature of orbital dynamics and the

limited capabilities of DEWs conspire to make space-based

assets inherently difficult to defend.

Space Control

Assuring access to space-based assets through proliferation

is the least controversial means and is probably sufficient

provided no other nation is aggressively pursuing ASAT weap -

ons. Currently, no other nation appears to be seeking these

weapons, and while attacking satellites is easier than defend -

ing them, the weapons needed are still very expensive. A na -

tion considering even an unsophisticated ASAT weapon would

have to weigh its cost against the cost of weapons that more

directly impact national security, such as armored ground

forces, aircraft, or ballistic missiles.

Were a nation to decide to develop such a simple ASAT, the

added technological problems inherent in making the launch

sites mobile would be more than many nations could overcome. Immobility in conjunction with the near imposs ibility of

105
hiding the launch sites would leave them vulnerable to con -

ventional attack in the event the weapons were ever used.

The combination of expense and vulnerability should keep

most potential opponents from pursuing these weapons.

With the threat to our space-based assets low for the fore -

seeable future, developing an orbital defensive system appears

to be imprudent. Were the United States to begin developing

space-based weapons to counter a limited direct ascent ASAT,

the dual-use nature of such a weapon would make even test -

ing it a violation of the 1972 ABM treaty. 1

 This is assuming

that the considerable technological challenges involved with

developing them could even be overcome. As discussed in

chapter 5, these orbital weapons would have serious political

repercussions even without the ABM treaty.

The other side of the problem, denying enemies access to

space, is also best solved without placing weapons in orbit.

The same factors of orbital dynamics and laser physics that

make defensive weapons impractical also make space-based

ASAT weapons equally problematic. This is not to say that

ASATs are infeasible, only that putting them in orbit yields no

advantage. Denying an enemy access to space-based assets

will probably require some ASAT capability. A conservative

approach would be to develop ground-based, launch-on-demand weapons capable of disabling or destroying an enemy’s

space-based assets.

Ballistic Missile Defense

Deploying the most widely discussed type of space-based

weapon, a space-based BMD system, does not appear to be an

attractive long-term strategy. Assuming a totally effective

space-based system could be affordably created, doing so has

the potential to prompt potential adversaries to redirect their

weapons development into other areas, such as long-range

cruise missiles. Cruise missiles are almost as hard to stop as

ballistic missiles, although for different reasons. While ballistic

missiles are easily detected but are extremely difficult to inter -

cept, advanced cruise missiles would be much easier to inter -

cept, but only if they could be detected. A totally effective BMD

system would inevitably inspire methods for its circumvention.

CADRE PAPER

106
If the system relied on space-based weapons, then the political

resistance to fielding it might be almost as great a hurdle to

overcome as the technological challenges.

Orbital Bombardment

Even with no consideration given to the political conse -

quences, the types of space-based weapons that make the

least technological sense at this time are orbital bombard -

ment weapons. Conventional weapons such as stealth bombers

and cruise missiles can destroy nearly all of the targ ets envisioned for orbital bombardment. For the few remaining tar get

sets, such as deeply buried hardened targets, suborbital

weapons appear to hold as much promise as orbital concepts.

Suborbital systems, whether expendable missiles or TA Vs,

can produce the same results while being less vulnerable to

preemptive destruction and with far less controversy. In addition, systems like HyperSoar or other sub-orbital TAVs

should not be as controversial as orbital weapons, since

these systems only pass through space, much like ballistic

missiles.

Recommendations

Few nations with access to space view the United States

with antipathy, but this could change as less friendly natio ns

gain space capabilities. If the United States starts deploying

weapons in space unilaterally, even some friendly nations

may change their outlook and nations that already view the

United States with suspicion may decide that space-based

weapons will now be worth the heretofore prohibitive ex -

pense. While the consequences may or may not be th is

severe, they certainly do not argue in favor of deploying

these weapons.

If, in spite of restraint on the part of the United States,

another nation should decide to start an ASAT or other orbital

weapons program, then the United States is in a good position

to win any ensuing arms race. The United States has already

invested large sums of money and time investigating space control and force application weapons. Given the long lead times

SPACY

107
needed to develop them, any nation attempting to deploy

space weapons of its own would need a similar amount of

time. This lead time combined with the difficulty inherent in

keeping the needed orbital tests secret should give the United

States ample warning.

What should be done now with regard to weapons for

space control and force application? Based on this study, a

twofold course of action appears to be needed for the defen -

sive counterspace mission. First, we should assure the use

of space for friendly forces by transitioning to larger num -

bers of small satellites to meet the needs currently being

fulfilled by fewer, larger satellites. Second, the course of

action should be to develop an inexpensive, responsive

space launch capability.

The US military is already starting to design and develop

smaller satellites; this trend should continue and be empha -

sized. While some missions will still require large satellites,

large numbers of small satellites can do many missions

equally well. Small satellites can be launched more cheaply

and replaced more easily. They also have advantages of grace -

ful degradation under attack and present an enemy with hun -

dreds of relatively low-value targets, each of which is both

difficult and expensive to eliminate.

The second course of action is intimately connected to the

first, for large constellations of satellites will require large

numbers of space launches to put them in orbit. Doing this

economically will call for significantly lower space launch

costs. Studies indicate that small satellites can be most eco -

nomically launched by reusable launch systems. Responsive

reusable launch systems, such as the proposed military space

plane or the HyperSoar concept, would have the ability to

quickly reconstitute any systems damaged during combat.

They would also constitute an infrastructure for deploying

launch-on-demand ASAT weapons should those become necessary. Given the likely costs, both economic and political,

aggressively pursuing space-based weapons concepts does not

seem prudent at this time.

To fulfill offensive counterspace needs, the United States

should continue development of ground-based weapons to

jam or disable enemy satellites. In order to maintain our

CADRE PAPER

108
current lead, the United States should continue research into

space-based weapons concepts, but not to the point of con -

ducting orbital tests. If another nation starts down the road to

space-based weapons, then there should be ample time to

perform the tests necessary for deploying our own weapons

first.

Orbital bombardment weapons do not appear to offer

enough advantages to be worth the cost, either politically or

economically. Development of these weapons should be de -

layed until conventional weapons are no longer viable. Should

this eventually happen, then suborbital weapons can perform

the same missions at lower cost.

The more exotic weapons, such as the RF weapons dis -

cussed in chapter 2, are interesting but are based on un -

proven and untested theories. These concepts should be ex -

plored further but do not seem to warrant large investments

at this time.

The decision to put weapons in space or to refrain from

doing so should be based on a firm foundation of knowledge

about what these weapons can be expected to do. Unfortu -

nately, such information has been scarce in most recent

discussions of the issue, but there seem to be no clear

benefits to building orbital weapons at this time. In the few

cases where orbital weapons appear to be the only answer,

the questionable need for the weapons does not seem to

justify the potential costs.

Some of the proposals outlined above (suborbital space

planes or missiles and ground-based launch-on-demand

weapons) may be space weapons in a general sense but are in

fact no more space weapons than are high-altitude aircraft or

ICBMs. By focusing development on weapons that only travel

through space, some of the controversy surrounding them

may be mitigated.

Reflecting on the quote which opened this paper: we already

fight through space; fighting into space looks feasible and we

should plan for the eventuality. Fighting in space shows little

promise, while fighting from space looks impractical for the

foreseeable future, with or without treaties.

SPACY

109
Notes

1. While the treaty only prohibits testing components of systems that

could be used as an ABM system in the ABM mode, the difference between

intercepting ballistic missiles in the boost phase and intercepting ASAT

missiles in the boost phase is insignificant. Prohibitions in the ABM treaty

against testing components capable of being used as space-based ABMs

would probably include weapons to counter direct ascent ASATs, since they

could later be incorporated into an orbital BMD system.

CADRE PAPER

110
Glossary

ABL airborne laser

AIAA American Institute of Aeronautics and

Astronautics

ASAT antisatellite

BMD ballistic missile defense

BMDO Ballistic Missile Defense Organization

BP Brilliant Pebbles

C2 command and control

CAV common aero vehicle

cm3 cubic centimeter

DE directed energy

DEW directed-energy weapons

EELV evolved expendable launch vehicle

EOSAT Earth Observation Satellite Company

GEO geosynchronous earth orbit

gm gram

GPALS global protection against limited strikes

HEL high-energy laser

ICBM intercontinental ballistic missile

IEEE Institute of Electrical and Electronics

Engineers

IR infrared

JDAM joint direct attack munitions

KE kinetic energy

KEW kinetic-energy weapon

111
kg kilogram

kg/m3 kilogram per cubic meter

KJ/cm2 kilojoules per square centimeter

km kilometer

km/s kilometer per second

KW kilowatt

lb pound

LEO low earth orbit

m meter

MW megawatt

MPH miles per hour

NMD national missile defense

R&D research and development

RAF Royal Air Force

RF radio frequency

SATCOM satellite communication

SBL space-based laser

SDI Strategic Defense Initiative

SRAM short-range attack missile

SSTO single-stage-to-orbit vehicle

TAV transatmospheric vehicles

TSTO two-stage-to-orbit vehicles

UAV unmanned aerial vehicles

UN United Nations

US United States

USAF United States Air Force

USSPACECOM United States Space Command

w/ft2 watts per square feet

w/m2 watts per square meter

112
Bibliography

Abrahamson, James A., et al. “Open letter to President

Clinton.” Included in the Center for Security Policy Press

release No. 98-P7, January 1998.

“Advanced Anti-Satellite System in Offing.” Rockets and

Missiles, 18, no. 22 (30 May 1966): 69–70.

“Air Force 2025 in Detail: Part II AF Worries That Space Mines

May Threaten Future Ops.” Military Space 13, no. 23 (11

November 1996): 7.

Alves, Pericles Gasparini. Prevention of an Arms Race in Outer

Space: A Guide to the Discussions in the Conference on

Disarmament. UNIDIR/91/79. New York: United Nations

Institute for Disarmament Research, 1991, Annex A, pt. 2.

Anselmo, Joseph C. “Launchers See Nothing But Blue Skies

Ahead.” Aviation Week & Space Technology, 7 April 1997,

41–42.

———. “New Funding Spurs Space Laser Efforts.” Aviation

Week & Space Technology, 14 October 1996, 67.

Anselmo, Joseph C., and Bruce A. Smith. “Cost Drives EELV.”

Aviation Week & Space Technology, 6 January 1997, 27.

Bate, Roger R., Donald D. Mueller, and Jerry E. White.

Fundamentals of Astrodynamics. New York: Dover

Publications, 1971.

Baucom, Donald R. The Origins of SDI, 1944–1983. Lawrence,

Kans.: University Press of Kansas, 1992.

“Belgium: Star Wars Has Come Down to Earth.” Foreign Media

Reaction Daily Digest. USIA Office of Research and Media

Reaction. Washington, D.C.: US Information Agency, 22

October 1997. On-line. Internet, 26 April 1998. Available from

http://www.fas.org/spp/military/program/ASAT/9719

22-miracl-mr.htm.

Bethe, Hans, and Richard L. Garwin. “Appendix A: New BMD

Technologies.” Daedalus: Weapons in Space, 2, no. 114

(Summer 1985).

113
Broad, William J. “The Air Force Aims to Test Its Space

Destroyer,” New York Times, 7 September 1997.

———. “Military Is Hoping to Test-Fire Laser against Satellite.”

New York Times, 1 September 1997.

Bruner, William W., III. “National Security Implications of

Inexpensive Space Access.” Master’s thesis, School of

Advanced Airpower Studies (SAAS), Maxwell AFB, Ala.,

June 1995.

Carroll, Eugene J., Jr., deputy director, Center for Defense

Information, Washington, D.C. “Space Laser Test Sows

Military Hubris.” New York Times, 5 September 1997,

Letter to the Editor.

Clark, Phillip, ed. Jane’s Space Directory. Coulsdon, England:

Jane’s Information Group, Sentinel House, 1997.

Conduct of the Persian Gulf War. Washington, D.C.: Department of Defense, 1992.

Cushman, J. “To Detect ICBM Launch, AF Seeks Invulnerable

Warning Satellites.” Defense Week, 16 January 1984, 1

and 10–11.

Daehnick, Christian C. “Blueprints for the Future: Comparing

National Security Space Architectures.” Master’s thesis,

SAAS, Maxwell AFB, Ala., 1995.

Deen, Thalif. “UN Protocol Brings Laser Blinding Ban into

Force.” Jane’s Defence Weekly, 11 February 1998, 6–7.

“Defense Department Plans Next Test Firing of Air-Launched

ASAT System.” Aviation Week & Space Technology, 23

September 1985, 20–21.

De Selding, Peter B., and Andrew Lawler. “SPOT Halts Sales of

Gulf Area Imagery.” Space News, 13–19 August 1990, 3

and 21.

Dickman, Maj Gen Robert. “The Evolution of Space Operations

and Warfare.” Address. AIAA Symposium, Huntsville,

Ala., 23 September 1997. On-line. Internet, 2 February

1998. Available from

http://www.acq.osd.mil/space/architect/spcweb.html.

Dooling, David. “Ballistic Missile Defense.” IEEE Spectrum,

September 1997, 50–59.

Dornheim, Michael A. “Vandenberg Launches Eight Satellites.”

Aviation Week & Space Technology, 23 February 1998, 41.

114
Dornheim, Michael A., and Joseph C. Anselmo. “Complex

Antenna Is Star of Mission 77.” Aviation Week & Space

Technology, 27 May 1996, 58–59.

Doyle, Michael W. Ways of War and Peace. New York: W. W.

Norton & Co., 1997, Chapter 5.

Eisman, Mel, and Daniel Gonzales. Life Cycle Cost Assessments

for Military Transatmospheric Vehicles. RAND Report

MR-893-AF. Santa Monica, Calif.: RAND, 1997.

Estes, Gen Howell M., III. Commander in chief, North

American Aerospace Defense Command and US Space

Command. Statement before the Senate Armed Services

Committee, Washington, D.C., 13 March 1997.

Evans, John V. “New Satellites for Personal Communications.”

Scientific American, April 1998, 70–77.

“Fact Sheet: National Space Policy.” Washington, D.C.: White

House National Science and Technology Council, 1996.

Forden, Geoffrey E. “The Airborne Laser.” IEEE Spectrum,

September 1997, 40–49.

———. “COILed to Strike.” IEEE Spectrum, September 1997,

46.

———. “A Panoply of Lasers.” IEEE Spectrum, September

1997, 42.

Forecast International/DMS Market Intelligence Reports:

Missiles, 1998. Tab: D, Sections: “AGM-109/BGM-109

Tomahawk,” and “LGM-30F/LGM-30G Minuteman.”

Forecast International/DMS Market Intelligence Reports: Space

Systems Forecast, April 1998. Tab: Space Vehicles,

Section: “Pegasus Winged Launch Vehicle.”

Gaddis, John Lewis. We Now Know: Rethinking Cold War

History. Oxford: Camden Press, 1997.

Garwin, Richard L. “How Many Orbiting Lasers for BoostPhase Intercept?” Nature, 23 May 1985, 286–90.

Garwin, Richard L., Kurt Gottfried, and Donald L. Hafner.

“Antisatellite Weapons.” Scientific American 250, no. 6

(June 1984): 45–55.

Gertz, Bill. “Shared Satellite Laser Test Weighed.” Washington

Times, 2 January 1998, A1.

Glaser, Charles L. Analyzing Strategic Nuclear Policy. Princeton,

N.J.: Princeton University Press, 1990.

115
Gonzales, Daniel, et al. Proceedings of the RAND Project AIR

FORCE Workshop on Transatmospheric Vehicles. RAND

Report MR-890-AF. Santa Monica, Calif.: RAND, 1997.

Grabbe, Crockett L. Space Weapons and the Strategic Defense

Initiative. Ames, Iowa: Iowa State University Press, 1991.

Gray, Colin S. American Military Space Policy: Information

Systems, Weapon Systems and Arms Control. Cambridge,

Mass.: Abt Books, 1982.

Grossman, Karl. “Nuclear Gamble.” Progressive, September

1997, 20–23.

Hall, R. Cargill. “Origins of U.S. Space Policy: Eisenhower,

Open Skies, and Freedom of Space.” In Exploring the

Unknown. Edited by John M. Logsdon (Washington, D.C.:

Government Printing Office, 1995), chap. 2.

Hewish, Mark. “Adding New Punch to Cruise Missiles.” Jane’s

International Defense Review, no. 31, 31 January 1998,

40–45.

Horelick, Arnold L., and Myron Rush. Strategic Power and

Soviet Foreign Policy. Chicago: University of Chicago

Press, 1965.

Jacky, Jonathan. “Throwing Stones at ‘Brilliant Pebbles.’”

Technology Review, 20 October 1989, 20–21 and 76.

“KE ASAT Hover Test Is Highly Successful,” 12 August 1997.

On-line. Internet, 7 February 1998. Available from

http://www.fas.org/MhonArc/BMDList_archive/msg00

249.html.

“Kinetic Energy Anti-Satellite Program (KE ASAT) Background

and Overview.” Slide briefing by Rockwell International

Corp and Rocketdyne, 1997. On-line. Internet, 29 March

1998. Available from

http://www.fas.org/spp/military/program/asat/brief97

11/index.html.

Kyl, Jon. “An Effective Antimissile Strategy.” Wall Street

Journal, 22 May 1997.

Lennox, Duncan S., ed. Jane’s Strategic Weapon Systems.

Coulsdon, England: Sentinel House, 1997. Jane’s Information Group Issue 26, January 1998.

Lerner, Eric J. “ASAT Nears the End.” Aerospace America,

February 1988, 8–10.

116
London, John R., III. LEO on the Cheap: Methods for Achieving

Drastic Reductions in Space Launch Costs. Maxwell AFB,

Ala.: Air University Press, 1994.

London, John R., III, and H. A. Pike. “Fire in the Sky: U.S. Space

Laser Development from 1968.” Paper no. IAA-97-IAA.2.3.06.

American Institute of Aeronautics and Astronautics, 1997.

Matthews, William. “DOD Restructuring SDI to Fit a Changing

World.” Air Force Times, 25 February 1991.

McDougall, Walter A. The Heavens and the Earth: A Political

History of the Space Age. Baltimore: Johns Hopkins

University Press, 1985.

McKinley, Cynthia A. S. “When the Enemy Has Our Eyes:

Proliferation of Space Surveillance and Reconnaissance

Capability.” Master’s thesis, SAAS, Maxwell AFB, Ala.,

June 1995.

Miller, Steven E., and Stephen Van Evera, eds. The Star Wars

Controversy. Princeton, N. J.: Princeton University Press,

1986.

Monfort, Charles A. “ASATs: Star Wars on the Cheap.” Bulletin

of the Atomic Scientists 45, no. 3 (April 1989): 10–13.

Moonglow. Washington, D.C.: Naval Research Laboratory,

June 1994.

Moorman, Gen Thomas S., Jr. Vice chief of staff, USAF. “The

Challenges of Space Beyond 2000.” Address to the 75th

Royal Australian Air Force Anniversary Airpower Conference, Canberra, Australia, 14 June 1996. On-line.

Internet, 9 January 1998. Available from

http://www.af.mil/news/speech/current/The_Challenges_

of_Space_Bey.html.

Muolo, Michael J. Space Handbook: An Analyst’s Guide, vol. 2.

Maxwell AFB, Ala.: Air University Press, December 1993.

———. Space Handbook, A War Fighter’s Guide to Space, vol. 1.

Maxwell AFB, Ala.: Air University Press, December 1993.

“National Missile Defense Exoatmospheric Kill Vehicle.” Ballistic

Missile Defense Organization Fact Sheet 97-01, September

1997.

Neufeld, Michael J. The Rocket and the Reich: Peenemünde

and the Coming of the Ballistic Missile Era. New York: Free

Press, 1995.

117
New World Vistas, Air and Space Power for the 21st Century,

Space Applications Volume. Washington, D.C.: USAF

Scientific Advisory Board, 1995.

O’Niell, Philip D., Jr. “The Development of International Law

Governing the Military Use of Outer Space.” In National

Interests and the Military Use of Space. Edited by William

J. Durch. Cambridge, Mass.: Ballinger Publishing Co.,

1984.

Parks, W. Hays. “Memorandum of Law: Trauvaux Preparatoires

and Legal Analysis of Blinding Laser Weapons Protocol.”

Army Lawyer, June 1997, 33–41. DA-PAM 27-50-295.

Peebles, Curtis. Battle for Space. New York: Beaufort Books,

1983.

———. Guardians: Strategic Reconnaissance Satellites. Novato,

Calif.: Presidio Press, 1987.

Pike, John. “Space Based Laser.” FAS Space Policy Project

Special Weapons Monitor. On-line. Internet, 7 February

1998. Available from

http://www.fas.org/spp/starwars/program/SBL.htm.

Rampino, Michael A. Concepts of Operations for a Reusable

Launch Vehicle. Maxwell AFB, Ala.: Air University Press,

1997.

Reynolds, Glenn H., and Robert P. Merges. Outer Space:

Problems of Law and Policy, 2d ed. Boulder, Colo.:

Westview, 1997.

Rustan, Pedro L. “Clementine Test Results.” Unpublished

research results. Ballistic Missile Defense Organization,

Washington, D.C.: Pentagon, 31 October 1994.

Saunders, Renee. “EOSAT Sees High Demand for Gulf

Images.” Space News, 24–30 September 1990, 3.

Siegman, Anthony E. Lasers. Mill Valley, Calif.: University

Science Books, 1986.

Scott, William B. “USSC Prepares for Future Combat Missions

in Space.” Aviation Week & Space Technology, 5 August

1996, 51–52.

Smith, R. Jeffrey. “Antisatellite Weapon Sets Dangerous

Course.” Science 222, 14 October 1983, 140–42.

“Sounding Taps for Star Wars and the Stealth Bomber.”

Defense Monitor XX, no. 5 (1991): 2.

118
Spiegel, Peter. “Free Launch?” Forbes, 24 February 1997,

76–78.

Stamm, Michael R. “How Technology Is Changing the Optimum

Size of Satellites.” Research paper. Kirtland AFB, New Mex.:

Phillips Laboratory, December 1994.

Stares, Paul B. Space and National Security. Washington,

D.C.: Brookings Institution, 1987.

———. The Militarization of Space, U.S. Policy, 1945–1984.

Ithaca, N.Y.: Cornell University Press, 1985.

Starr, Barbara. “U.S. Team to Work on New Target-Tracking

Satellite.” Jane’s Defence Weekly 29, Issue 12, 7.

Stine, G. Harry. “Opening the Spaceways.” Barron’s, 19 May

1997, 62.

“Summary of the Center for Security Policy High-Level

Roundtable Discussion of ‘The Need for American Space

Dominance.’” Attachment to the Center for Security Policy

press release No. 98-16P, 23 January 1998. On-line.

Internet, 28 January 1998. Available from

www.security-policy.org/papers/98-P16at.html.

Thomson, Allen. “Satellite Vulnerability: A Post-Cold War

Issue?” Space Policy, February 1995, 19–30.

Tirman, John, ed. The Fallacy of Star Wars. New York: Vintage

Books, 1983.

“Topaz 2 Go-Ahead to Speed U.S. Thermionic Effort.” Aviation

Week & Space Technology, 6 April 1992, 28.

United States General Accounting Office, Report to Chairman,

Committee on Armed Services, US Senate: Strategic

Defense Initiative, Estimates of Brilliant Pebbles’

Effectiveness Are Based on Many Unproven Assumptions.

GAO/NSIAD-92-91. Washington, D.C.: General Accounting

Office, 1992.

United States General Accounting Office, Report to the Chairman,

Legislation and National Security Subcommittee, Committee

on Government Operations, House of Representatives:

Strategic Defense Initiative, Need to Examine Concurrency in

Development of Brilliant Pebbles. GAO/NSIAD-91-154.

Washington, D.C.: General Accounting Office, March 1991.

“USAF Vehicle Designed for Satellite Attack.” Aviation Week &

Space Technology, 14 January 1985, 21.

119
Walt, Stephen M. Origins of Alliances. Ithaca, N.Y.: Cornell

University Press, 1987.

Ward, Mark. “Business in Space.” Inside Science (supplement

within New Scientist), 24 May 1997, 1–4.

Werrell, Kenneth P. The Evolution of the Cruise Missile.

Maxwell AFB, Ala.: Air University Press, 1985.

Widnall, Sheila E., secretary of the Air Force. “The Space and

Air Force of the Next Century.” Address. National Security

Forum, Maxwell AFB, Ala., 29 May 1997. On-line.

Internet, 9 January 1998. Available from

http://www.af.mil/news/speech/current/The_Space_and

_Air_Force _of_.html.

Williamson, W., et al. “Technical Analysis of a Contingency

Conventional Surgical Strike System.” Albuquerque, New

Mex.: Sandia National Laboratories, June 1995. Document

is now declassified.

Ziegler, David W. Safe Heavens: Military Strategy and Space

Sanctuary Thought. Maxwell AFB, Ala.: Air University

Press, June 1998.

120
Does the United States Need

Space-Based Weapons?

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