Physical Destruction

Satellite ground stations are large installations for high-capacity networks and their locations are obvious. They are very fragile, so can be readily destroyed by conventional forces, terrorist activity or missiles. Physical destruction of the space segment by direct physical attack is difficult but the US, Russia and China have a declared anti-satellite capability, with India and Israel announcing developments leading to such a capability. Anti-satellite weapons include kinetic-energy weapons (missiles) or directed-energy (laser) weapons. In addition to deliberate physical attack, accidental damage can be caused by collisions with other space objects.

Kinetic energy weapons

Ballistic missiles have apogees such that their warhead could be detonated to coincide with a LEO satellite. In 1985, the US fired an ASM-135 missile and destroyed the P78-1 Solwind satellite at an altitude of 525 km and, in 2008, a malfunctioning US satellite was destroyed by a missile fired from a US warship. ¹ In the early 1980s, the Soviet Union began development of an anti-satellite weapon launched from a modified MiG-31. In 2015 and 2016, Russia successfully tested its direct-ascent anti-satellite missile, PL-19 Nudol. ^2,3 In 2007, China destroyed with a missile a defunct Fengyun weather satellite in polar orbit at an altitude of 865 km, creating a vast cloud of debris that will pose a LEO threat for many years. ⁴ On 27 March 2019, India destroyed a Microsat-R satellite at an altitude of 283 km. ⁵

Both China and Russia have reportedly developed weapon systems that could threaten geostationary satellites. ^6,7,8 Russia has also developed a co-orbital anti-satellite interceptor capable of maneuvering alongside a satellite in polar orbit and firing its fragmentation weapon, reportedly testing the interceptor 20 times between October 1968 and June 1982. ^9,10

Directed energy weapons

Laser-based directed-energy weapons are more attractive than kinetic-energy weapons because they are delivered at the speed of light, can fire multiple times, and can be quickly redirected. They are, however, line-of-sight weapons that suffer from atmospheric attenuation which limits the locations from which they can be operated—nonetheless, satellites can be damaged or disrupted through laser-induced heating out to geostationary-orbit altitudes.

The Soviet Union began experimenting with ground-based lasers in the 1970s and 1980s, reportedly blinding a number of US spy satellites. In 1984, a laser weapon was reportedly used to disrupt operations on space shuttle Challenger. ¹¹ Reports in May 2010 indicated that Russia was developing a prototype laser based on an A-60 aircraft. ¹² The US Airborne Laser program aimed to develop a Boeing 747-mounted 1.2-megawatt laser designed to destroy missiles, but which could also target spacecraft. The aircraft successfully destroyed two test missiles in 2010 ¹³ but the program was cancelled in 2011 as a result of funding cuts. More recently, a number of countries are reported to be developing on-orbit anti-satellite weapons, both laser and kinetic. ^14,15,16

Accidental damage

Accidental damage to satellites can be caused by collisions with other spacecraft, space debris, or with natural space objects such as meteors. Perhaps surprisingly, there has been only one major collision between satellites, when Iridium 33 collided with a non-operational Russian satellite in December 2009. The threat from space debris is significant, however, and many agencies across the world have invested much effort in space situational awareness programs to assist in space domain management. Ultimately, as predicted by Kessler et al, the density of debris in LEO may become sufficient to cause cascading collisions. ¹⁷

The principal danger to satellites comes from micro-meteors under 0.05 mm in diameter. Although such particles have tiny mass, their high velocities mean they have considerable kinetic energy that can penetrate thin metal sheets and will sandblast solar panels, causing a significant degradation over time. Notable examples of meteor-caused damage include the Olympus 1 experimental satellite and Landsat 5, both of which suffered damage during annual Perseid meteor showers.

Perhaps surprisingly, there has been only one major collision between satellites. On 10 February 2009, Iridium 33 collided with a non-operational Russian satellite Cosmos 2251 at an altitude of 789 km above the Taymyr Peninsula in Siberia, creating about 2,000 pieces of debris, most of it from the Russian satellite. In April 2021, there was an alleged close approach between satellites from SpaceX and OneWeb, although there was not complete agreement on the cause or the result. On 28 Feb 2024, two non-manoeuvrable spacecraft (a derelict Russian satellite and an operational NASA satellite) passed at an altitude of 608 km by less than 20m with a relative velocity of 14 kms^-1—had COSMOS 2221 clipped TIMED, the total fragment count could have been ~2,500. ¹⁸

Most satellites can be maneuvered to avoid a possible collision, but a non-operational satellite cannot be controlled. Iridium suggests that close approaches (within 5 km) occur some 400 times each week for the entire Iridium constellation with a 1/50 million chance of collision per conjunction. ¹⁹

Space Debris

See Space Debris entry.