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Anti-satellite weapon
From Wikipedia, the free encyclopedia
Anti-satellite weapons (ASATs) are space weapons designed to destroy satellites for strategic military purposes. Currently, only the USA, the former USSR and the People's Republic of China are known to have developed these weapons, with India claiming the technical capability to develop such weapons.[1][2] On January 11, 2007, China destroyed an old orbiting weather satellite, the world's first test since the 1980s.
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The development and design of anti-satellite weapons has followed a number of paths. The initial efforts by the USA and the USSR were using air-launched missiles from the 1950s; many more exotic proposals came afterwards.
Air-launched missiles were the first approach because the basic technology was well known. The US began tests of such a system in 1959 but initial results were very discouraging, the first test launch missed by over 6,000 m, and after further failures the project was halted in 1963. Simultaneous U.S. Navy projects were also abandoned although smaller projects did drag on until the early 1970s. The USSR began a similar program in 1967 and actually built and deployed ASAT missiles from around 1976. Stung by the Soviet deployment, the USAF revived its own ASAT program. From 1977 Vought developed an ASAT to attack satellites in Low Earth orbit (LEO), the three stage missile was fired by an F-15 Eagle in a steep climb and carried a miniature homing vehicle (MHV) to track and then destroy the target kinetically. The first test was in 1983.
Another area of research was into 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). The USSR had also researched directed energy weapons, under the Fon project from 1976, but the technical requirements needed of the high-powered gas dynamic lasers and neutral or charged particle beam systems seemed to be beyond reach. In the early 80s, the Soviet Union also started developing a counterpart to the US air-launched ASAT system, using modified MiG-31 'Foxhounds' (at least six of which was completed) as the launch platform. In 1982, the United States tested its own anti-satellite systems called the Air Launched Miniature Vehicle (ALMV). The system consisted of a modified F-15 that carried the anti-satellite missile (ASM) directly under the central line of the plane. The F-15 was modified for this specific purpose and it provided the missile with a backup battery, its own microprocessor and a data link for midcourse guidance systems. The first launch of the anti-satellite missile took place in January 1984. The missile was aimed at a point in space. Three anti-satellite missiles were launched against celestial infrared sources.
The first successful interception was on September 13, 1985. The modified F-15 took off from Edwards Air Force Base, climbed to 80,000 feet and vertically launched the anti-satellite missile. The target was the Solwind P78-1, a US gamma ray spectroscopy satellite orbiting at 555 km, which was launched in 1979.[3]
The use of high altitude nuclear explosions (see DOMINIC I, Program 437) to destroy satellites was considered after the tests of the first conventional missile systems in the 1960s. Existing guidance technology was insufficient to ensure a strike while a nuclear blast would be sufficient if the weapon was within 1,000 km of the target. However the drawbacks of this excessive destructive radius and the potential of more extensive radiation and EMP damage meant that nuclear ASAT systems did not reach test phase. However, the US adapted the nuclear armed Nike Zeus for 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 ASAT which ran until 1972. The US also detonated a number of high altitude nuclear weapons in other tests. A 1.4 Mt blast at 400 km over the Pacific in 1958 damaged three satellites and also disrupted power transmission and communications across the Pacific. The Outer Space Treaty of 1967 banned the orbiting or otherwise stationing of nuclear weapons in space, but does not ban the attacking of satellites with nuclear weapons directly targeted by ground- or air-launched missiles.
An anti-satellite mission can be accomplished by any weapon capable of disrupting the communication between the satellite and the command and control center. The disruption could be in its orbital system, the information link or the terrestrial communication system. Other concepts considered included manned and unmanned ASAT from orbit. A manned space vehicle would rendezvous with a satellite and then either disable or capture it. The military use of automatic self-destruct in satellites would have made this hazardous and the concept was soon altered to a manned vehicle equipped with stand-off weapons. Unmanned orbital ASAT suffered the same problems as air-launched attacks: guidance and interception systems could not be developed sufficiently well to ensure an intercept. Other ideas in addition to the unmanned orbital ASAT included space mine dispensers and single-use space interceptors.
The USSR went for the Istrebitel Sputnikov (IS) (Interceptor of satellites, or literally "Destroyer of satellites"). Development work began in the early 1960s and the first test flights were made in 1968. The project was halted in 1972 under the terms of SALT I but the system was still deployed and testing of new versions continued up until around 1982 when the entire concept was scrapped, possibly in favour of more advanced orbital ASAT systems; whether such designs were actually ever deployed is still a matter of heated debate. The Soviet Union also experimented with large, ground-based ASAT lasers from the 1970s onwards (see Terra-3), with a number of US spysats reportedly being 'blinded' during the 70s and 80s. In the mid-1970s, it was estimated at least three-fourths of the satellites in orbit were intended for military purposes. In 2006 China was also suspected of blinding US spy satellites. [4] The USSR also experimented with military space stations with a capability for anti-satellite duty in its Almaz program.
The USSR utilized the co-orbital anti-satellite system which consisted of a missile armed with conventional explosives. 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 satellite. The missile is guided by an onboard radar. The radar paints the target satellite and provides the coordinates to the missile, directing it to its target and detonates, incapacitating the satellite with shrapnel fragments. The missile, which weighs 1400 kg., may be effective up to one kilometer from a target. Soviet anti-satellite system tests, although primitive, have been largely successful. Between October 1968 and June 1982, the former Soviet Union successfully launched nine missiles out of the intended fourteen tests with its radar guided guidance system.
The era of the Strategic Defense Initiative (proposed in 1983) focussed primarily on the development of systems to defend against nuclear warheads, however, some of the technologies developed may be useful also for antisatellite use.
After the Soviet Union collapsed, there were proposals to use this aircraft as a launch platform for lofting commercial and science packages into orbit. Recent political developments (see below) may have seen the reactivation of the Russian Air-Launched ASAT program, although there is no confirmation of this as yet.
The Strategic Defense Initiative gave the US and Russian ASAT programs a major boost; ASAT projects were adapted for ABM use and the reverse was also true. The initial US plan was to use the already developed MHV as the basis for a space based constellation of about 40 platforms deploying up to 1,500 kinetic interceptors. By 1988 the US project had evolved into an extended four stage development. The initial stage would consist of the Brilliant Pebbles defense system, a satellite constellation of 4,600 kinetic interceptors (KE ASAT), of 100 lb (45 kg) each, in Low Earth orbit, and their associated tracking system. The next stage would deploy the larger platforms and the following phases would include the laser and charged particle beam weapons that would be developed by that time from existing projects such as MIRACL. The first stage was intended to be completed by 2000 at a cost of around $125 billion.
Research in the US and Russia was proving that the requirements, at least for orbital based energy weapon systems, were, with available technology, close to impossible. Nonetheless, the strategic implications of a possible unforeseen breakthrough in technology forced the USSR to initiate massive spending on research in the 12th Five Year Plan, drawing all the various parts of the project together under the control of GUKOS and matching the US proposed deployment date of 2000.
Both countries began to reduce expenditure from 1989 and the Russian Federation unilaterally discontinued all SDI research in 1992. Research and Development (both of ASAT systems and other space based/deployed weapons) has, however reported to have be been resumed under the government of Vladimir Putin as a counter to renewed US Strategic Defense efforts post Anti-Ballistic Missile Treaty. However the status of these efforts, or indeed how they are being funded through National Reconnaissance Office projects of record, remains unclear. The U.S. has begun working on a number of programs which could be foundational for a space-based ASAT. These programs include the Experimental Spacecraft System (XSS 11), the Near-Field Infrared Experiment (NFIRE), and the space-based interceptor (SBI).
At 5:28 p.m. EST January 11, 2007, the People's Republic of China successfully destroyed a defunct weather satellite, FY-1C. The destruction was reportedly carried out by a modified medium-range ballistic missile DF-21 with a kinetic ASAT warhead[1]similar in concept to the American Exoatmospheric Kill Vehicle. FY-1C was a weather satellite orbiting Earth in polar orbit at an altitude of about 537 miles (865 km), with a mass of about 750 kg (1,650 lb). Launched in 1999, it was the fourth satellite in the Feng Yun series. The missile was lauched from a mobile Transporter-Erector-Launcher (TEL) vehicle at Xichang () and the warhead destroyed the satellite in a head-on collision at an extremely high relative velocity.
This test raised concerns in some other countries, partly because the China did not publicly confirm whether or not the test had occurred until January 23, 2007 but mainly because of fears that it could prompt or accelerate an "arms race" in space. The EU stated that "...a test of an anti-satellite weapon is inconsistent with international efforts to avert an arms race in outer space and undermines security in outer space." [2]. These concerns were also reflected in public statements from the governments of the United States, Canada, Australia and Japan. According to CNN, global security analysts stated at the time that the test was most likely aimed at the United States. [3]