Anti-satellite weapon
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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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[edit] History
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 and the first successful interception, of the US satellite P78 SolWind, was on September 13, 1985.
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 staging of nuclear weapons in space, but does not ban the attacking of satellites with nuclear weapons directly targeted by ground- or air-launched missiles.
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 kamikaze satellites, space mine dispensers and single-use space interceptors.
The USSR went for a kamikaze satellite approach because it would be the simplest and cheapest to implement. The designs were named 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 1970's onwards (see Terra-3), with a number of US spysats reportedly being 'blinded' during the 70's and 80's. In 2006 China was also suspected of blinding US spy satellites. [3] The USSR also experimented with military space stations with a capability for anti-satellite duty in its Almaz program.
[edit] ASAT in the era of Strategic Defense
The era of the Strategic Defense Initiative 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. One 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 1980's 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 80's, the Soviet Union also started developing a counterpart to the US air-launched ASAT system, using modified MiG-31 'Foxhounds' (at least one of which was completed) as the launch platform. In 1985, the United States successfully destroyed one of its own satellites using a missile. [4]
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 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 Vladimir Putin government 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).
[edit] 2007 Chinese missile test
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At 5:28 p.m. EST January 11, 2007, the People's Republic of China successfully destroyed a defunct Chinese weather satellite, FY-1C. The destruction was carried out by a modified medium-range ballistic missile with kinetic ASAT warhead.[1] FY-1C was a weather satellite orbiting Earth in polar orbit at an altitude of about 537 miles (865km), with a mass of about 750 kg. Launched in 1999, it was the fourth satellite in the Feng Yun series. This test raised concern in some other countries, partly because the Chinese government refused to publicly confirm whether or not the test had occurred until January 23, 2007 but mainly because of the potentially damaging space debris this test created and the implications it may have for a space arms race. The EU presidency stated, "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]
