Anti-satellite weapons (ASAT) are space weapons designed to incapacitate or destroy satellites for strategic or tactical purposes. Although no ASAT system has been used in warfare, a few countries (China, India, Russia, and the United States) have successfully shot down their own satellites to demonstrate their ASAT capabilities in a show of force. ASATs have also been used to remove decommissioned satellites.
ASAT roles include: defensive measures against an adversary's space-based and nuclear weapons, a force multiplier for a nuclear first strike, a countermeasure against an adversary's anti-ballistic missile defense (ABM), an asymmetric counter to a technologically superior adversary, and a counter-value weapon.Strauch, Adam. "Still All Quiet on the Orbital Front? The Slow Proliferation of Anti-satellite Weapons/Na Orbitalni Fronte Stale Klid? Pomala Proliferace Protisatelitnich Zbrani." Obrana a Strategie/Defence & Strategy 2014.2 (2014): 61. Web.
Use of ASATs generates space debris, which can collide with other satellites and generate more space debris. A cascading multiplication of space debris could cause Earth to suffer from Kessler syndrome.
History The first anti-satellite technologies were developed during the cold war, with the Soviet Istrebitel Sputnikov programme and the American SAINT. Since, other states have also developed or researched ASAT capabilities.
Soviet Union
The specter of bombardment satellites and the reality of ballistic missiles stimulated the Soviet Union to explore defensive space weapons. The Soviet Union first tested the Polyot interceptor in 1963 and successfully tested an orbital anti-satellite (ASAT) weapon in 1968. According to some accounts, Sergei Korolev started some work on the concept in 1956 at his OKB-1, while others attribute the work to Vladimir Chelomei's OKB-52 around 1959. What is certain is that at the beginning of April 1960, Nikita Khrushchev held a meeting at his summer residence in Crimea, discussing an array of defence industry issues. Here, Chelomei outlined his rocket and spacecraft program, and received a go-ahead to start development of the UR-200 rocket, one of its many roles being the launcher for his anti-satellite project. The decision to start work on the weapon, as part of the Istrebitel Sputnikov (IS) () program, was made in March 1961.
The IS system was "co-orbital", approaching its target over time and then exploding a shrapnel warhead close enough to kill it. The missile was launched when a target satellite's ground track rises above the launch site. Once the satellite is detected, the missile is launched into orbit close to the targeted satellite. It takes 90 to 200 minutes (or one to two orbits) for the missile interceptor to get close enough to its target. The missile is guided by an on-board radar. The interceptor, which weighs , may be effective up to one kilometre from a target.
Delays in the UR-200 missile program prompted Chelomei to request R-7 rockets for prototype testing of the IS. The Polyot 1 and 2, launched on 1 November 1963 and 12 April 1964 respectively, carried out one such intercept test in early 1964. Later in the year Khrushchev cancelled the UR-200 in favour of the R-36, forcing the IS to switch to this launcher, whose space launcher version was developed as the Tsyklon-2. Delays in that program led to the introduction of a simpler version, the 2A, which launched its first IS test on 27 October 1967, and a second on 28 April 1968. Further tests carried out against a special target spacecraft, the DS-P1-M, which recorded hits by the IS warhead's shrapnel. In November 1968, 4 years after Polyot 1 and 2 were tested for a potential Satellite intercept, Kosmos 248 was successfully destroyed by Kosmos 252 which came within the 'kill radius' and destroyed Kosmos 248 by detonating it's warhead. A total of 23 launches have been identified as being part of the IS test series. The system was declared operational in February 1973.
Testing resumed in 1976 as a result of the US work on the Space Shuttle. Elements within the Soviet space industry convinced Leonid Brezhnev that the Shuttle was a single-orbit weapon that would be launched from Vandenberg Air Force Base, manoeuvre to avoid existing anti-ballistic missile sites, bomb Moscow in a first strike, and then land.Shuttle Buran , see chronology section Although the Soviet military was aware these claims were false, Brezhnev believed them and ordered a resumption of IS testing along with a Shuttle of their own. As part of this work the IS system was expanded to allow attacks at higher altitudes and was declared operational in this new arrangement on 1 July 1979. However, in 1983, Yuri Andropov ended all IS testing and all attempts to resume it failed. Ironically, it was at about this point that the US started its own testing in response to the Soviet program.
In the early 1980s, the Soviet Union also started developing a counterpart to the US air-launched ASAT system, using modified MiG-31D 'Foxhounds' (at least six of which were completed) as the launch platform. The system was called 30P6 "Kontakt", the missile used is 79M6. The USSR also experimented with arming the Almaz space stations with Rikhter R-23 aircraft auto-cannons. Another Soviet design was the 11F19DM Skif-DM/Polyus, an orbital megawatt laser that failed on launch in 1987.
In 1987, Mikhail Gorbachev visited Baikonur Cosmodrome and was shown an anti-satellite system called "Naryad" (Sentry), also known as 14F11, launched by UR-100N rockets.
United States
In the late 1950s, the US Air Force started a series of advanced strategic missile projects under the designation Weapon System WS-199A. One of the projects studied under the 199A umbrella was Martin's Bold Orion air-launched ballistic missile (ALBM) for the B-47 Stratojet, based on the rocket motor from the Sergeant missile. Twelve test launches were carried out between 26 May 1958 and 13 October 1959, but these were generally unsuccessful and further work as an ALBM ended. The system was then modified with the addition of an Altair upper stage to create an anti-satellite weapon with a range. Only one test flight of the anti-satellite mission was carried out, making a mock attack on the Explorer 6 at an altitude of . To record its flight path, the Bold Orion transmitted telemetry to the ground, ejected flares to aid visual tracking, and was continuously tracked by radar. The missile successfully passed within of the satellite, which is suitable for use with a nuclear weapon, but useless for conventional warheads.
A similar project carried out under 199A, Lockheed's High Virgo, was initially another ALBM for the B-58 Hustler, likewise based on the Sergeant. It too was adapted for the anti-satellite role, and made an attempted intercept on Explorer 5 on 22 September 1959. However, shortly after launch communications with the missile were lost and the camera packs could not be recovered to see if the test was successful. In any event, work on the WS-199 projects ended with the start of the GAM-87 Skybolt project. Simultaneous US Navy projects were also abandoned although smaller projects did continue until the early 1970s.
The use of high-altitude nuclear explosions to destroy satellites was considered after the tests of the first conventional missile systems in the 1960s. During the Hardtack Teak test in 1958 observers noted the damaging effects of the electromagnetic pulse (EMP) caused by the explosions on electronic equipment, and during the Starfish Prime test in 1962 the EMP from a warhead detonated over the Pacific damaged three satellites and also disrupted power transmission and communications across the Pacific. Further testing of weapons effects was carried out under the DOMINIC I series. An adapted version of the nuclear armed Nike Zeus was used for an ASAT from 1962. Codenamed Mudflap, the missile was designated DM-15S and a single missile was deployed at the Kwajalein atoll until 1966 when the project was ended in favour of the USAF Thor-based Program 437 ASAT which was operational until 6 March 1975.
Another area of research was directed-energy weapons, including a nuclear-explosion powered X-ray laser proposal developed at Lawrence Livermore National Laboratory (LLNL) in 1968. Other research was based on more conventional lasers or masers and developed to include the idea of a satellite with a fixed laser and a deployable mirror for targeting. LLNL continued to consider more edgy technology but their X-ray laser system development was cancelled in 1977 (although research into X-ray lasers was resurrected during the 1980s as part of the SDI).
ASATs were generally given low priority until 1982, when information about a successful USSR program became widely known in the west. A "crash program" followed, which developed into the Vought ASM-135 ASAT, based on the AGM-69 SRAM with an Altair upper stage. The system was carried on a modified F-15 Eagle that carried the missile directly under the central line of the plane. The F-15's guidance system was modified for the mission and provided new directional cuing through the pilot's head-up display, and allowed for mid-course updates via a data link. The first launch of the new anti-satellite missile took place in January 1984. The first, and only, successful interception was on 13 September 1985. The F-15 took off from Edwards Air Force Base, climbed to and vertically launched the missile at the Solwind P78-1, a US gamma ray spectroscopy satellite orbiting at , which was launched in 1979. The last piece of debris from the destruction of Solwind P78-1, catalogued as COSPAR 1979-017GX, SATCAT 16564, deorbited 9 May 2004. Although successful, the program was cancelled in 1988.
USA-193 was an American reconnaissance satellite, which was launched on 14 December 2006 by a Delta II rocket, from Vandenberg Air Force Base. It was reported about a month after launch that the satellite had failed. In January 2008, it was noted that the satellite was decaying from orbit at a rate of per day. After publicly announcing its intention to do so a week earlier,Associated Press – Broken Satellite Will Be Shot Down on 21 February 2008, the US Navy destroyed USA-193 in Operation Burnt Frost, using a ship-fired RIM-161 Standard Missile 3 about 247 km (153 mi) above the Pacific Ocean. That test produced 174 pieces of orbital debris large enough to detect that were cataloged by the US military.Data retrieved from the U.S. military's public satellite catalog maintained at While most of the debris re-entered the Earth's atmosphere within a few months, a few pieces lasted slightly longer because they were thrown into higher orbits. The final piece of detectable USA-193 debris re-entered on 28 October 2009.
According to the US government, the primary reason for destroying the satellite was the approximately of toxic hydrazine fuel contained on board, which could pose health risks to persons in the immediate vicinity of the crash site should any significant amount survive the re-entry. On 20 February 2008, it was announced that the launch was carried out successfully and an explosion was observed consistent with the destruction of the hydrazine fuel tank.
The United States has since ceased the testing of direct-ascent anti-satellite missiles, having outlawed the practice in 2022.
Strategic Defense Initiative and the Cold War The era of the Strategic Defense Initiative (proposed in 1983) focused primarily on the development of systems to defend against nuclear warheads, however, some of the technologies developed may be useful also for anti-satellite use.