The last 40 years have seen the United States and Russia in a parallel and oftentimes mutually reinforcing path toward militarizing space. Space's initial military use was reconnaissance; the response of the United States and Russia/USSR to space reconnaissance missions has transitioned from the hostile days of 1960, when a US U-2 spy plane flying over the USSR was destroyed by anti-aircraft missiles, to the acceptance of imaging satellites used to verify arms control agreements as an essential component of national security. 

This transition has been uneasy. At times, both the United States and Russia/USSR were heavily investing in anti-satellite (ASAT) technologies, but some key transparency measures and the recognition that anti-satellite weapons were not in either state’s best interest slowed the drive toward deploying such weapons. This was manifested most notably by congressional bans and voluntary Russian moratoria on ASAT testing. At present, space has even greater military value, as satellites perform essential communications and navigation functions in addition to reconnaissance and verification missions. However, the United States appears to have renewed its interest in ASAT weapons.¹

Early ASAT Systems

The Soviet and then Russian armed forces have had specific anti-ballistic missile (ABM) and space defense programs since the 1950s.² It was recognized, even before satellites had actually been successfully launched into orbit, that satellites would have great military value. The advantages of satellites were made evident by US reconnaissance satellites, which were developed to maintain intelligence-gathering capability when it became clear that the Soviet Union would eventually be able to deny overflights of American U-2 spy planes.³ Anti-satellite capabilities were developed as part of the Soviet space defense program and were also residual capabilities of systems developed for other purposes. The United States also pursued ABM/ASAT systems, in part because of a perceived threat of Soviet "orbital bombardment systems."⁴ Because of the limitations of the guidance systems of the time, the early US interceptors were nuclear-tipped, allowing a successful ABM/ASAT attack without precision guidance. Russia began development in the 1960s (and still retains a new generation) of a limited missile defense of Moscow, which employs nuclear-tipped interceptors.⁵ Although such interceptors would be usable against satellites, they have long been recognized as a poor ASAT option, in part because nuclear explosions in space are indiscriminate and would destroy all nearby satellites and disrupt many more. Their use would also have contravened the Partial Test Ban Treaty of 1963.⁶

The United States was eager for its space reconnaissance mission to be seen as legitimate, and to protect itself from Soviet space weapons. The Soviets also saw that arms control in space was to their advantage, and were agreeable to the idea of a treaty. Conditions were right in 1967, as the United States had modified its position from the late 1950s, when its diplomatic initiatives centered around a ban on all military activity in and through space, which was seen by the Soviets as a ploy to slow down their superior long-range missile program. Despite the concerns of both superpowers that verification would be difficult, they signed the Outer Space Treaty in 1967, which prohibits the stationing of weapons of mass destruction in space or on celestial bodies, and declares a spirit of cooperation in space ventures.⁷

Russia's Main System: Co-Orbital ASAT

Russia's main and only dedicated ASAT system is the Co-Orbital ASAT system, in which a missile armed with conventional explosives is launched when a target satellite's ground track rises above the launch site and the ASAT is placed into an orbit close to that of the target.⁸ Within one or two orbits (between about 90-200 minutes), the 1,400 kg ASAT interceptor is intended to maneuver close to the satellite, guided by onboard radar, and then "dive" toward the target satellite, detonating and destroying the satellite with shrapnel fragments from the explosion. It is thought to be effective when detonated within a kilometer of the target, though the interceptor can approach the satellite to within tens of meters. The system's initial testing phase (1963-1972) consisted of approximately 20 launches (including launches of both target satellites and interceptors), seven interceptions, and five detonations.⁹ The initial tests confirmed the system could work from orbital altitudes of 230 to 1,000 kilometers and the system was declared operational. The Soviets temporarily ceased testing the system after signing the Anti-Ballistic Missile Treaty in 1972, which required not only that "Each Party undertakes not to develop, test, or deploy ABM [anti-ballistic missile] systems," but also prohibited interfering with the "national technical means of verification" of treaty compliance.¹⁰ These means have primarily been reconnaissance satellites, and the Soviet acceptance of these terms was viewed as a tacit acceptance of the legitimacy of such satellites.

The Soviets resumed testing of the Co-Orbital system in 1976.  At the time, the aerospace trade press was reporting a renewed US interest in anti-satellite technology, an interest that was largely generated by exaggerated reports of Soviet laser and particle beam ASAT/ABM technology. In addition, the Space Shuttle, which also had intrinsic anti-satellite capability, was in advanced development. The Soviets reportedly showed some success at extending the range of the Co-Orbital system to as low as 160 km and as high as 1,600 km, and at minimizing attack time by enabling the interceptor to maneuver to its target in a single orbit. Systems using optical and infrared sensor systems instead of onboard radar are thought to have had problems. At that time, the system was considered ready to operate. 

From 1978 to 1982, testing of the Soviet Co-Orbital ASAT weapon continued, at a pace of about one intercept a year.  This system is thought to be currently operational, although it has not been tested for many years. 

Both the United States and the Soviet Union appeared to be hedging their bets by pursuing anti-satellite arms control talks while pursuing anti-satellite technology, albeit at a low level.

Second Generation: US and Russian Air-Launched Missile ASAT Systems

In June 1982, the United States announced its intention to test a new-generation ASAT weapon, the Air-Launched Miniature Vehicle (ALMV). A two-stage missile would be launched from a high-altitude F-15 aircraft; the missile would ascend directly to a target satellite in low earth orbit and attempt to destroy or disrupt the satellite by the force of impact. This kill mechanism is referred to as "kinetic kill" since the satellite is destroyed by the large kinetic energy of the high-speed collision. Such a system had advantages over the Soviet Co-Orbital ASAT system: With the ALMV, it was not necessary to wait for an opportune launch time, and the time lapse between ASAT launch and target destruction was significantly reduced. At the time, it was reported that the Soviets/Russians were developing a similar ASAT weapon, launched from a MiG-31 aircraft, but there is no evidence this project was pursued seriously.

In the spring of 1983, President Reagan gave his "Star Wars" speech, announcing that he intended to focus US resources on developing a large-scale missile defense system. The missile defenses were expected to contain several types of space-based missile interceptors. The Soviet Union responded to this announcement by restarting in earnest research on its own missile defense systems. The Soviets also made diplomatic overtures, proposing a ban on space-based weapons and declaring a moratorium on testing ASAT systems.¹¹

The US ALMV system was tested twice in 1984, firing interceptors but not against targets. Its first and only test against a satellite was performed on October 13, 1985, when it destroyed an aging Solwind satellite in a 555 km orbit. The US Air Force continued to pursue this program aggressively, scheduling a number of tests for the following year. However, in December 1985, the Democratic-controlled House and the Republican-led Senate included in its budget authorization bill a ban on testing the ALMV on a target in space.¹² This decision was made only a day after the Air Force sent two target satellites into orbit for its next round of tests. The Air Force continued to test the ASAT system in 1986, but stayed within the limits of the ban by not engaging a space-borne target.

The ban on testing the ASAT system was renewed in 1986 and the Soviets continued to observe a voluntary moratorium on ASAT testing. In November 1987, the White House and Congress negotiated a compromise on arms control provisions in the authorization bill that extended the ban on ASAT testing but allowed the ban to be suspended should the Soviets resume their ASAT tests. The political opposition to pursuing the ASAT system appeared entrenched, and the Air Force, unable to perform its final tests, dropped development of the ALMV system.
 
The Soviets did honor their moratorium, although they continued pursuit of some missile defense technologies. Rumors circulated that the Soviets were developing a MiG-launched ASAT weapon similar in scope to the ALMV, but this was not confirmed. In 1987, a Soviet mission to launch what was reportedly a test platform for a future "space battle station" failed when the craft failed to reach orbit and fell into the Pacific Ocean.

Third-Generation ASAT Systems: US MIRACL Laser & KE-ASAT and Soviet Laser

In April 1988, the two Democratic chambers of Congress voted against extending the ASAT ban, but also eliminated the $100 million Department of Defense request for development of a ground-based ASAT system. The Air Force began plans for other ASAT programs, in particular a ground-based laser system. Both kinetic-kill and laser ASATs have relative advantages and disadvantages. Kinetic-kill vehicle systems provide an easily verifiable "kill" of a satellite and can be used in any weather; ground-based lasers, while susceptible to poor weather, produce less space debris and also allow for a covert satellite strike. The Army began speeding up plans for its own ground-based ASAT systems: a kinetic-kill vehicle launched from the ground (the kinetic-energy ASAT, or "KE-ASAT")¹³ and a ground-based laser system. The Army and Air Force's ground-based laser work converged around the Army's MIRACL laser, a megawatt-class chemical laser located at the White Sands Missile Range in New Mexico. 

Intelligence reports at this time suggested that the Soviets had developed a working anti-satellite laser system, and were able to pose a significant threat to satellites and ballistic missiles. The Soviets' success was given as motivation for further ASAT development; the ASAT system centered on the MIRACL laser was developed largely in 1989 and 1990. In July 1989, the Natural Resources Defense Council and the Soviet Academy of Sciences arranged for a US delegation to visit the Sary Shagan Laser-Ranging Facility in Kazakhstan, and from the consequent observations and discussions, it became clear that the work that was considered to be a Soviet laser ASAT project was not a significant threat and was certainly not near to being deployed as a space-based ASAT weapon.¹⁴ Subsequently, in their defense appropriations bills for 1991-1995, Congress included bans against using the MIRACL laser against an object in space.¹⁵

Although the Department of Defense formally terminated the Army's ground-based KE-ASAT program in 1993 and has not requested funding since then, Congress resurrected the program in 1996, adding $30 million to the budget for the program. Congress continued to support the program, appropriating $50 million in 1997, which President Clinton used a line-item veto to eliminate, and $37.5 million in 1998. Despite governmental reviews that said the program was in disarray,¹⁶ the support continued, although at much smaller levels of funding. In particular, although the DOD did not request money for the program, Congress authorized $7.5 million in 2000 and $3 million in 2001. No funding for the program was included in the FY2003 budget, and the strongest congressional advocate for this program, Senator Robert Smith (R-NH), was not re-elected in 2002. There appears to be scant interest in the program outside the Army, and Air Force officials have been openly critical of the program, stating that the risks of damaging friendly space assets through use of the KE-ASAT outweigh the system's usefulness.¹⁷ 

The ban on using the MIRACL laser against space targets lapsed in 1996, when the new Republican Congress opted not to renew it. In October 1997, the Air Force commissioned a test of an ASAT system based on the MIRACL laser. This system was directed toward a satellite orbiting 420 km above the Earth. The MIRACL laser apparently had technical difficulties, but the results of the test were startling. A lower-power (30-watt) laser intended for alignment of the system and tracking of the satellite was the primary laser source used during the test, and it appeared that this lower-power laser was sufficiently powerful itself to blind the satellite temporarily, although it could not destroy the sensor.¹⁸ That a commercially available laser and a 1.5 m mirror could be an effective ASAT highlighted a US vulnerability that had not been fully appreciated.  Although the Pentagon described the test as defensive (i.e., to learn about the vulnerability of US satellites to laser attack), many—in particular the Russians—expressed concern about the offensive capabilities of this system and whether it constituted a breach of the ABM Treaty,¹⁹ and formally requested negotiations on an ASAT weapon ban. 

Current ASAT Capabilities

The US armed forces and defense agencies have been directed to focus and reorganize their space control efforts. This has resulted in a number of bureaucratic changes, but as of yet, no new large-scale ASAT weapon initiatives have been mounted.  There is likely still some residual ASAT capability from the previous generation of systems, however.

The current capabilities of the Air Force's ALMV systems are not clear, as testing was never completed. Air Force officials have expressed disinclination toward using destructive, debris-generating ASATs, and even DOD advisors in favor of developing ASAT capabilities view nonreversible ASAT weapons as a last resort.²⁰ Although the Air Force has traditionally been the armed service most involved and interested in anti-satellite technology, it has not expressed interest in reviving this particular program. 

The December 2000 GAO assessment of the Army's KE-ASAT system reported that considerable work and funding would be needed to make the system ready for flight testing.  Following the DOD’s recommendation, the Army and its contractor Boeing have continued integration work and environmental compliance tests on three kill vehicles that consequently are to be placed in storage. Program officials in early 2003 believed the Bush administration and the Republican Congress might be more supportive of the program, while acknowledging that there would likely be significant political opposition to flight tests of the KE-ASAT.²¹ These officials have said that if they secured money and support for two flight tests, the system could have a contingency deployment capability within three years, although two of the three kill vehicles that had been built have been dismantled for use in other projects.²² No funds have been allocated in the presidential budget request or congressional add-ons since 2001, and no funding was included in the FY2004 budget request.

The MIRACL laser ASAT system has not been tested again, and, although the Army occasionally fires the laser for routine power tests, the program has been facing financial difficulty and its directors are seeking other uses for the laser.

Basic electronic warfare ASAT technology, such as jamming a satellite's uplink or downlink transmissions, is not particularly demanding, and this capability is probably widely held. Such ASAT attacks also have the advantage of being relatively covert and do not add debris to the space environment; however, it is difficult to confirm the success of such attacks. Jamming for specific users only, or permanent disabling, are more difficult, and it is not known which specific capabilities the United States and Russia have. However, it is likely both field electronic warfare techniques that are useful even out to geosynchronous orbit, especially against nonmilitary targets, which are relatively unprotected from such attacks. 

The former Soviet republics Russia and Ukraine continue to be invested in space, although military launches have decreased and commercial launches have increased. Russia is the only republic to retain a government space program. The existence of US intelligence satellites that initially encouraged Soviet ASAT capability development is no longer perceived as a major threat, and the Russians are currently considering cooperating with the United States on aspects of missile defense. The ASAT weapon-testing moratorium begun in 1983 continues to be respected. 

The Development of New Capabilities

Although no new dedicated ASAT programs had been initiated by the United States as of April 2003, the Bush administration had begun increasing the funding for and widening the scope of research and development of space-relevant technologies, including improved tracking of space objects, new launch and propulsion technologies, and development of lightweight sensors and kill vehicles. High-energy laser technology has also seen a large funding increase; supporting projects include development of the techniques necessary for propagating laser radiation through the atmosphere and an emphasis on decreasing the system weight to make transporting the laser system by airplane or launching it into space more feasible.  

Traditional satellite components are also being developed to be smaller and lighter. This may eventually permit the launch of "parasitic" microsatellites²³ (i.e., small craft that track and follow other satellites); this technology could prove useful for ASAT missions if the microsatellite were able to maneuver close enough to the target satellite to disrupt or destroy it. Microsatellites could also perform defensive functions for satellites.

Development of most of these new technologies into deployable offensive or defensive systems will take a number of years.  However, some of the systems the United States is currently developing to intercept ballistic missiles would have considerable inherent capability to be used as ASAT weapons, and could therefore significantly increase US ASAT capability.

Indeed, while the technologies being developed for long-range missile defenses may not prove very effective at defending against ballistic missiles, some could be much more effective against satellites, since, in many ways, attacking satellites is an easier task.²⁴ Satellites travel on predictable orbits that can be determined accurately by tracking from ground facilities, allowing the position of the satellite to be known at future times. The United States would have time to plan an attack, could choose the timing, and would have time to take as many shots as necessary to destroy it. In contrast, in a ballistic missile attack, the attacker would have the advantage of surprise and the defense less than 30 minutes to respond. In addition, an interceptor attacking a satellite would not have to deal with the severe countermeasure problem that would face a missile defense system. Current-generation satellites are not equipped to defend themselves. While future satellites might include defenses of some type, it will be difficult to overcome the advantages that an attacker has.

Endnotes

1. The January 2001 report of the Commission to Assess United States National Security and Space Management and Organization, chaired by Donald Rumsfeld shortly before he became Secretary of Defense in the Bush administration specifically calls for anti-satellite technology, stating that "The U.S. will require means of negating satellite threats, whether temporary and reversible or physically destructive.  The report is available at http://www.defenselink.mil/pubs/space20010111.html.

2. The Soviet space defense program is discussed in detail in the 1993-94 edition of Europe and Asia in Space, Nicholas L. Johnson & David M. Rodvold, pp. 346-348 and Russia’s Strategic Nuclear Weapons, Paul Podvig, editor, (Cambridge: 1991), MIT Press.

3. The Soviet Union began a diplomatic effort against US satellite reconnaissance by submitting a draft proposal to the United Nations Legal Subcommittee in June 1962, which states "The use of artificial satellites for the collection of intelligence information in the territory of foreign states is incompatible with the objectives of mankind in its conquest of outer space."

4. As reported in Paul B. Stares' book "The Militarization of Space: U.S. Policy, 1945-1984," in a 1964 pre-presidential election speech, Lyndon Johnson announced that "To insure that no nation will be tempted to use the reaches of space as a platform for weapons of mass destruction we began in 1962 and 1963 to develop systems capable of destroying bomb carrying satellites."

5. The United States also deployed a system using nuclear interceptors at Grand Forks, ND in 1975, but shut it down within months because of cost and lack of effectiveness.

6. The 1963 Partial Test Ban Treaty (PTBT) prohibits nuclear weapons tests "or any other nuclear explosion" in the atmosphere, in outer space, and under water.
 
7. The "Declaration of Legal Principles Governing the Activities of States in the Exploration and Use of Outer Space," signed by more than 90 countries, including the United States, bans weapons of mass destruction from space and stipulates that "The exploration and use of outer space…shall be carried out for the benefit and in the interests of all countries, irrespective of their degree of economic or scientific development, and shall be the province of all mankind…[and] shall be guided by the principle of co-operation and mutual assistance …"

8. During testing, the Co-Orbital ASAT interceptors were launched from the Baikonur launch site in Kazakhstan using the Tsyklon-2 booster.  The assumed similarity of the Tsyklon-2 and Tsyklon-3 launch pads imply that the ASAT system could also be launched from the Tsyklon-3 pads in Plesetsk, Russia, 800 km north of Moscow.

9. Detailed information about the testing program for the Soviet/Russian Co-Orbital ASAT program can be found in the article "IS Anti-Satellite System" by Anatoly Zak and the references therein, on http://www.RussianSpaceWeb.com.

10. Text of the treaty can be found at http://www.state.gov/www/global/arms/treaties/abm/abm2.html.

11. Soviet President Yuri Andropov said Moscow would impose a ''moratorium on such launchings for the entire period during which other countries, including the United States, will refrain from stationing in outer space anti-satellite systems of any type.''  "Andropov Says Nyet To Star Wars Weapons," by John Iams, UPI, 18 August 1983.

12. The ALMV testing bans are included in Public Laws: 99-145, 99-661, 100-180.

13. The Army’s KEASAT program’s program number is PE 0603892D.
 
14. "A Visit to Sary Shagan and Kyshtym," Science & Global Security, Vol. 1, Nos. 1-2 1989, p. 165.

15. The MIRACL laser testing bans are included in Public Laws 101-510, 102-190, 102-484, 103-160, and 103-337.
 
16. United States General Accounting Office Report “GAO-01-228R KE-ASAT Program Status”, 5 December, 2000.

17. Air Force Gen. Ralph Eberhart, commander-in-chief of U.S. Space
Command and the North American Aerospace Defense Command, told reporters that the damage that could be inflicted inadvertently on U.S. and friendly satellites by a kinetic energy anti-satellite (KE-ASAT) weapon may outweigh its usefulness. "Space Command Chief Questions Value of KE-ASAT," by Kerry Gildea, Defense Daily, 29 March, 2001.

18. John Donnelly, "Laser of 30 Watts Blinded Satellite 300 Miles High," Defense Week, 8 December 1997, p. 1.

19. Russian Foreign Ministry Spokesman Gennadi Tarasov stated "The question arises of how compatible such work is with progress achieved on joint measures to ensure compliance with the ABM treaty…The creation of anti-satellite weapons could sharply change the strategic situation," "Russia Issues Warning After US Laser Test," by Paul Richter, Los Angeles Times, 7 October 1997, p. 5.

20. In "Science Board Urges Development of Anti-Satellite Capabilities," by Emily Hsu, Inside Missile Defense, 5 April, 2000, a report by the Defense Science Board is quoted: "The task force notes that the authority to employ systems for the 'physical' destruction of an adversary's satellite is not likely when other 'reversible' means for accomplishing the objective are at hand. Only under the condition where the permanent removal of an adversary's space mission capability is in the national interest would the United States destroy a space system, and only then when directed by the National Command Authority."

21. "Possible Funding Boost in FY ’04 Budget Could Lead To KE-ASAT Flight Test," by Kerry Gildea, Defense Daily, 17 December, 2002.

22. Emily Hsu, "Program Officials Trying to Rebuild Support for Army KE-ASAT System," Inside Missile Defense, 5 March, 2003.

23. For an overview of current technology and current and planned mini/micro/nano satellite missions, see the website maintained by the researchers at Surrey Space Center, UK: http://www.SmallSatellites.org.

24. For a more detailed account, see D. Wright and L. Grego, "Anti-Satellite Capabilities of Planned US Missile Defense Systems," Disarmament Diplomacy, Dec. 2002-Jan. 2003, available at http://www.acronym.org.uk/dd/dd68/68op02.htm.