Anti-satellite weapons (ASAT) arespace weapons designed to incapacitate or destroysatellites forstrategic ortactical[1] purposes. Although no ASAT system has yet[update] been utilized inwarfare, a few countries (China,India,Russia, and theUnited States) have successfully shot down their own satellites to demonstrate[2] their ASAT capabilities in ashow of force.[3][4] ASATs have also been used to remove decommissioned satellites.[5]
ASAT roles include: defensive measures against an adversary's space-based and nuclear weapons, aforce multiplier for a nuclearfirst strike, a countermeasure against an adversary'santi-ballistic missile defense (ABM), anasymmetric counter to a technologically superior adversary, and acounter-value weapon.[6]
Use of ASATs generatesspace debris, which can collide with other satellites and generate more space debris.[2] A cascading multiplication of space debris could causeEarth to suffer fromKessler syndrome.
The first anti-satellite technologies were developed during the cold war, with the SovietIstrebitel Sputnikov programme and the AmericanSAINT.[7][8] Since, other states have also developed or researched ASAT capabilities.
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 thePolyot interceptor in 1963 and successfully tested an orbital anti-satellite (ASAT) weapon in 1968.[9] According to some accounts,Sergei Korolev started some work on the concept in 1956 at hisOKB-1, while others attribute the work toVladimir Chelomei'sOKB-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 theUR-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 theIstrebitel Sputnikov (IS) (lit. 'destroyer of satellites') 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'sground 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 1400 kg (3086 lb), may be effective up to one kilometre from a target.[citation needed]
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 theTsyklon-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 afterPolyot 1 and 2 were tested for a potential Satellite intercept, Kosmos 248 was successfully destroyed by Kosmos 252 which came within the 5km 'kill radius' and destroyed Kosmos 248 by detonating it's warhead.[10][11] A total of 23 launches have been identified as being part of theIS test series. The system was declared operational in February 1973.
Testing resumed in 1976 as a result of the US work on theSpace Shuttle. Elements within the Soviet space industry convincedLeonid Brezhnev that the Shuttle was a single-orbit weapon that would be launched fromVandenberg Air Force Base, manoeuvre to avoid existing anti-ballistic missile sites, bomb Moscow in a first strike, and then land.[12] Although the Soviet military was aware these claims were false,[citation needed] 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.[13] 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 modifiedMiG-31D 'Foxhounds' (at least six of which were completed) as the launch platform. The system was called 30P6 "Kontakt", the missile used is 79M6.[14][15] The USSR also experimented with arming theAlmaz space stations withRikhter R-23 aircraft auto-cannons. Another Soviet design was the11F19DM Skif-DM/Polyus, an orbital megawatt laser that failed on launch in 1987.[16]
In 1987,Mikhail Gorbachev visitedBaikonur Cosmodrome and was shown an anti-satellite system called "Naryad" (Sentry), also known as 14F11, launched byUR-100N rockets.[17]
In the late 1950s, theUS Air Force started a series of advancedstrategic missile projects under the designation Weapon System WS-199A. One of the projects studied under the 199A umbrella wasMartin'sBold Orionair-launched ballistic missile (ALBM) for theB-47 Stratojet, based on the rocket motor from theSergeant 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 anAltair upper stage to create an anti-satellite weapon with a 1770-kilometre (1100 mi) range. Only one test flight of the anti-satellite mission was carried out, making a mock attack on theExplorer 6 at an altitude of 251 km (156 mi). To record its flight path, theBold Orion transmitted telemetry to the ground, ejected flares to aid visual tracking, and was continuously tracked by radar. The missile successfully passed within 6.4 km (4 mi) of the satellite, which is suitable for use with a nuclear weapon, but useless for conventional warheads.[18]
A similar project carried out under 199A,Lockheed'sHigh Virgo, was initially another ALBM for theB-58 Hustler, likewise based on the Sergeant. It too was adapted for the anti-satellite role, and made an attempted intercept onExplorer 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 theGAM-87 Skybolt project. SimultaneousUS Navy projects were also abandoned although smaller projects did continue until the early 1970s.[citation needed]
The use ofhigh-altitude nuclear explosions to destroy satellites was considered after the tests of the first conventional missile systems in the 1960s. During theHardtack Teak test in 1958 observers noted the damaging effects of theelectromagnetic pulse (EMP) caused by the explosions on electronic equipment, and during theStarfish Prime test in 1962 the EMP from a 1.4-megaton-of-TNT (5.9 PJ) 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 theDOMINIC I series. An adapted version of the nuclear armedNike Zeus was used for an ASAT from 1962. CodenamedMudflap, the missile was designated DM-15S and a single missile was deployed at theKwajalein atoll until 1966 when the project was ended in favour of the USAFThor-basedProgram 437 ASAT which was operational until 6 March 1975.[citation needed]
Another area of research wasdirected-energy weapons, including a nuclear-explosion poweredX-ray laser proposal developed atLawrence Livermore National Laboratory (LLNL) in 1968. Other research was based on more conventionallasers ormasers 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 theSDI).[citation needed]
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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 theVoughtASM-135 ASAT, based on theAGM-69 SRAM with an Altair upper stage. The system was carried on a modifiedF-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'shead-up display, and allowed for mid-course updates via adata 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 fromEdwards Air Force Base, climbed to11613 m (38100 ft)[19] and vertically launched the missile at theSolwind P78-1, a US gamma ray spectroscopy satellite orbiting at 555 km (345 mi), which was launched in 1979.[20] 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.[citation needed]
USA-193 was an Americanreconnaissance satellite, which was launched on 14 December 2006 by aDelta II rocket, fromVandenberg 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 fromorbit at a rate of 500 m (1640 ft) per day.[21] After publicly announcing its intention to do so a week earlier,[22] on 21 February 2008, the US Navy destroyed USA-193 inOperation Burnt Frost, using a ship-firedRIM-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.[23] 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.[23]
According to the US government, the primary reason for destroying the satellite was the approximately 450 kg (1000 lb) of toxichydrazine 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.[24] 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.[25]
The United States has since ceased the testing of direct-ascent anti-satellite missiles, having outlawed the practice in 2022.[26][27]
The era of theStrategic 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.
The Strategic Defense Initiative gave the US and Soviet ASAT programs a major boost; ASAT projects were adapted forABM 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 theBrilliant Pebbles[28] defense system, asatellite constellation of 4,600 kinetic interceptors (KE ASAT) of 45 kg (100 lb) each inLow Earth orbit and their associated tracking systems. 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 asMIRACL. The first stage was intended to be completed by 2000 at a cost of around $125 billion.
Research in the US and the Soviet Union 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 the12th Five Year Plan, drawing all the various parts of the project together under the control ofGUKOS and matching the US proposed deployment date of 2000. Ultimately, the Soviet Union approached the point of experimental implementation of orbital laser platforms with the (failed) launch ofPolyus.
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 been resumed under the government ofVladimir Putin as a counter to renewed US Strategic Defense efforts postAnti-Ballistic Missile Treaty. However, the status of these efforts, or indeed how they are being funded throughNational Reconnaissance Office projects of record, remains unclear. The US has begun working on a number of programs which could be foundational for a space-based ASAT. These programs include the Experimental Spacecraft System (USA-165), theNear Field Infrared Experiment (NFIRE), and the space-based interceptor (SBI).
After thecollapse of the Soviet Union, the MiG-31D project was put on hold due to reduced defence expenditures.[29] However, in August 2009,Alexander Zelin announced that theRussian Air Force had resumed this program.[30] TheSokol Eshelon is a prototype laser system based on anA-60 airplane which is reported to be restarting development in 2012.[31][needs update]
Three more launches were reportedly held in December 2016, on 26 March 2018, and on 23 December 2018—the latter two from a TEL.[32][33]
A new type of ASAT missile was seen carried by a MiG-31 in September 2018.[34][35]
On 15 April 2020,US officials said Russia conducted a direct ascent anti-satellite missile test that could take out spacecraft or satellites inlow Earth orbit.[36][37] A new test launch took place on 16 December 2020.[38]
In November 2021,Kosmos 1408 was successfully destroyed by a Russian anti-satellite missile in a test, causing a debris field that affected theInternational Space Station.[39]
In 2024, U.S. intelligence sources hinted that Russia was working on an anti-satellite weapon with some sort of nuclear technology, though it was unclear if it was a nuclear weapon or merely a nuclear-powered device.[40]
On 11 January 2007, the People's Republic of China successfully destroyed a defunct Chinese weather satellite,Fengyun-1C (FY-1C, COSPAR1999-025A). The destruction was reportedly carried out by an SC-19 ASAT missile with a kinetic killwarhead[41] similar in concept to the AmericanExoatmospheric Kill Vehicle. FY-1C was a weather satellite orbiting Earth in polar orbit at an altitude of about 865 km (537 mi), with a mass of about 750 kg (1650 lb). Launched in 1999, it was the fourth satellite in theFengyun series.[42]
The missile was launched from a mobile Transporter-Erector-Launcher (TEL) vehicle atXichang (28°14′49″N102°01′30″E / 28.247°N 102.025°E /28.247; 102.025 (Xichang Satellite Launch Center)) and the warhead destroyed the satellite in a head-on collision at an extremely high relative velocity. Evidence suggests that the same SC-19 system was also tested in 2005, 2006, 2010, and 2013.[43] In January 2007China demonstrated a satellite knock out whose detonation alone caused more than 40,000 new chunks of debris with a diameter larger than one centimeter and a sudden increase in the total amount of debris in orbit.[44][45]
In May 2013, the Chinese government announced the launch of a suborbital rocket carrying a scientific payload to study the upper ionosphere.[46] However, US government sources described it as the first test of a new ground-based ASAT system.[47] An open source analysis bySecure World Foundation, based in part on commercial satellite imagery, found that it may indeed have been a test of a new ASAT system that could potentially threaten US satellites ingeostationary Earth orbit.[48] Similarly on 5 February 2018, China tested an exoatmospheric ballistic missile with the potential to be used as an ASAT weapon, the Dong Neng-3, with state media reporting that the test was purely defensive and it achieved its desired objectives.[49]
TheHQ-29 (simplified Chinese:红旗-29;traditional Chinese:紅旗-29;pinyin:Hóng Qí-29;lit. 'Red Banner-29') is ananti-ballistic missile (ABM) and anti-satellite weapon (ASAT) system.[50]
In a televised press briefing during the 97th Indian Science Congress held in Thiruvananthapuram, theDefence Research and Development Organisation (DRDO) Director General Rupesh announced that India was developing the necessary technology that could be combined to produce a weapon to destroy enemy satellites in orbit. On 10 February 2010, DRDO Director-General and Scientific Advisor to the Defence Minister, Dr.Vijay Kumar Saraswat stated that India had "all the building blocks necessary" to integrate an anti-satellite weapon to neutralize hostile satellites inlow Earth andpolar orbits.[51]
In April 2012, DRDO's chairman V. K. Saraswat said that India possessed the critical technologies for an ASAT weapon from radars and interceptors developed forIndian Ballistic Missile Defence Programme.[52] In July 2012, Ajay Lele, anInstitute for Defence Studies and Analyses fellow, wrote that an ASAT test would bolster India's position if an international regime to control the proliferation of ASATs similar toNPT were to be established. He suggested that a low-orbit test against a purpose-launched satellite would not be seen as irresponsible.[53] The programme was sanctioned in 2017.[54]
On 27 March 2019, India successfully conducted an ASAT test calledMission Shakti.[55] The interceptor was able to strike a test satellite at a 300-kilometre (186 mi) altitude inlow earth orbit (LEO), thus successfully testing its ASAT missile. The interceptor was launched at around 05:40 UTC at the Integrated Test Range (ITR) inChandipur, Odisha and hit its targetMicrosat-R[56] after 168 seconds.[57][58] The operation was namedMission Shakti. The missile system was developed by theDefence Research and Development Organisation (DRDO)—a research wing of the Indian defence services.[59] With this test, India became the fourth nation with anti-satellite missile capabilities. India stated that this capability is a deterrent and is not directed against any nation.[60][61]
In a statement released after the test,Indian Ministry of External Affairs said that the test was conducted at low altitude to ensure that the resulting debris would "decay and fall back onto the Earth within weeks".[62][63] According toJonathan McDowell, an astrophysicist atHarvard–Smithsonian Center for Astrophysics, some debris might persist for a year, but most should burn up in the atmosphere within several weeks.[64] Brian Weeden of Secure World Foundation agreed, but warned about the possibility of some fragments getting boosted to higher orbits. USAir Force Space Command said that it was tracking 270 pieces ofdebris from the test.[65]
Following the test, actingUnited States Secretary of DefensePatrick Shanahan warned about the risks of space debris caused by ASAT tests, but later added that he did not expect debris from the Indian test to last.[66][67] TheUnited States Department of State acknowledgedMinistry of External Affairs' statement on space debris and reiterated its intention to pursue shared interests in space including on space security with India.[68] Russia acknowledged India's statement on the test not being targeted against any nation and invited India to join the Russian–Chinese proposal for atreaty against weaponisation of space.[69]
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The Arrow 3 or Hetz 3 is an anti-ballistic missile, currently in service. It provides exo-atmospheric interception of ballistic missiles. It is also believed (by experts such as Prof. Yitzhak Ben Yisrael, chairman of theIsrael Space Agency), that it will operate as an ASAT.[70]
In November 2023, Israel's Arrow 3 missile defense system successfully intercepted a missile above the Earths atmosphere launched by Houthi rebels in Yemen. While it was not a satellite, this was the first time a missile was intercepted in space during wartime; demonstrating the theoretical capabilities of such a system to intercept a satellite.[71][72]
| Date | Country | Anti-satellite weapon | Target | Altitude | Ref. |
|---|---|---|---|---|---|
| 1958–1962 |  United States | Varioushigh-altitude nuclear test missiles | None; various satellites unintentionally disabled | Seeartificial radiation belts | |
| 1968–1982 |  Soviet Union | Istrebitel Sputnikov co-orbital interceptors | Istrebitel Sputnikov targets | ~100–2,300 km | [13] |
| 13 September 1985 | United States | ASM-135 ASAT | Solwind P78-1 | 555 km | [19][73] |
| 11 January 2007 |  China | SC-19 | FY-1C | 865 km | [74] |
| 21 February 2008 | United States | RIM-161 Standard Missile 3 | USA-193 | 247 km | [75] |
| 27 March 2019 |  India | PDV Mark-II | Microsat-R | 283 km | [76] |
| 15 November 2021 |  Russia | A-235 PL-19 Nudol | Kosmos 1408 | ~465 km | [77] |
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While it has been suggested that a country intercepting the satellites of another country in the event of a conflict could seriously hinder the latter's military operations, the ease of shooting down orbiting satellites has been questioned. Although satellites have been successfully intercepted at low orbiting altitudes, the tracking of military satellites for a length of time could be complicated by defensive measures like inclination changes. Depending on the level of tracking capabilities, the interceptor would have to pre-determine the point of impact while compensating for the satellite's lateral movement and the time for the interceptor to climb and move.[78]
USintelligence, surveillance and reconnaissance (ISR) satellites orbit at about 800 km (500 mi) high and move at 7.5 km/s (4.7 mi/s), so if conflict was to break out between the United States and China, a ChineseIntermediate-range ballistic missile would need to compensate for 1350 km (840 mi) of movement in the three minutes it takes to boost to that altitude. However, even if the ISR satellite is knocked out, the US possesses an extensive array of crewed and uncrewed ISR aircraft that could perform missions at standoff ranges from Chinese land-based air defences.[78]
Global Positioning System and communications satellites orbit at higher altitudes of20200 km (12600 mi) and35800 km (22200 mi) respectively, and this puts them out of range of solid-fuelledintercontinental ballistic missiles. Liquid-fuelled space launch vehicles could reach those altitudes, but they are more time-consuming to launch and could be attacked on the ground before being able to launch in rapid succession. The constellation of 30 GPS satellites provides redundancy where at least four satellites can be received in six orbital planes at any one time, so an attacker would need to disable at least six satellites to disrupt the network.[78] However, even if the attack is successful, signal degradation only lasts for 95 minutes and backupinertial navigation systems (INS) would still be available for relatively accurate movement as well aslaser guidance for weapons targeting. For communications, the Naval Telecommunications System (NTS) used by theUS Navy uses three elements: tactical communications among a battle group; long-haul communications between shore-based forward Naval Communications Stations (NAVCOMSTAs) and deployed afloat units; and strategic communication connecting NAVCOMSTAs with National Command Authorities (NCA).[78] The first two elements use line-of-sight (25–30 km (13–16 nmi; 16–19 mi)) and extended line-of-sight (300–500 km (160–270 nmi; 190–310 mi)) radios respectively, so only strategic communications are dependent on satellites. China would prefer to cut off deployed units from each other and then negotiate with the NCA to have the battle group withdraw or stand down, but ASATs could only achieve the opposite. Moreover, even if somehow a communications satellite were hit, a battle group could still perform its missions in the absence of direct guidance from the NCA.[78]
On November 1, 2022, aUN working group adopted for the first time a resolution calling on countries to ban destructive anti-satellite missile tests. Although not legally binding, the resolution reflects an increase in international political support for a ban on these weapons. Other countries have noted that the United States has already tested its ASAT destruction capability and, therefore, this U.S.-backed resolution limits the progress of the other countries.[79]
That distinction in turn should help differentiate naval ASAT, as a tactical operation, from strategic-warning ASAT [...].
Zelin announced the decision to reinitiate the program to develop anti-space systems based on the heavy fighter interceptor MiG-31.
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