A satellite or artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. Satellites have a variety of uses, including communication relay, weather forecasting, navigation (GPS), broadcasting, scientific research, and Earth observation. Additional military uses are reconnaissance, early warning, signals intelligence and, potentially, weapon delivery. Other satellites include the final rocket stages that place satellites in orbit and formerly useful satellites that later become defunct.
Anti-satellite weapons (ASAT) are space weapons designed to incapacitate or destroy satellites for strategic or tactical purposes. Although no ASAT system has yet been utilized in warfare, a few countries 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.
Space debris are defunct human-made objects in space – principally in Earth orbit – which no longer serve a useful function. These include derelict spacecraft, mission-related debris, and particularly-numerous in-Earth orbit fragmentation debris from the breakup of derelict rocket bodies and spacecraft. In addition to derelict human-made objects left in orbit, space debris includes fragments from disintegration, erosion, or collisions; solidified liquids expelled from spacecraft; unburned particles from solid rocket motors; and even paint flecks. Space debris represents a risk to spacecraft.
Kosmos is a designation given to many satellites operated by the Soviet Union and subsequently Russia. Kosmos 1, the first spacecraft to be given a Kosmos designation, was launched on 16 March 1962.
Space warfare is combat in which one or more belligerents are situated in outer space. The scope of space warfare therefore includes ground-to-space warfare, such as attacking satellites from the Earth; space-to-space warfare, such as satellites attacking satellites; and space-to-ground warfare, such as satellites attacking Earth-based targets. Space warfare in fiction is thus sub-genre and theme of science fiction, where it is portrayed with a range of realism and plausibility. In the real world, international treaties are in place that attempt to regulate conflicts in space and limit the installation of space weapon systems, especially nuclear weapons.
Hypervelocity is very high velocity, approximately over 3,000 meters per second. In particular, hypervelocity is velocity so high that the strength of materials upon impact is very small compared to inertial stresses. Thus, metals and fluids behave alike under hypervelocity impact. An impact under extreme hypervelocity results in vaporization of the impactor and target. For structural metals, hypervelocity is generally considered to be over 2,500 m/s. Meteorite craters are also examples of hypervelocity impacts.
The Kessler syndrome, proposed by NASA scientist Donald J. Kessler in 1978, is a scenario in which the density of objects in low Earth orbit (LEO) due to space pollution is numerous enough that collisions between objects could cause a cascade in which each collision generates space debris that increases the likelihood of further collisions. In 2009, Kessler wrote that modeling results had concluded that the debris environment was already unstable, "such that any attempt to achieve a growth-free small debris environment by eliminating sources of past debris will likely fail because fragments from future collisions will be generated faster than atmospheric drag will remove them". One implication is that the distribution of debris in orbit could render space activities and the use of satellites in specific orbital ranges difficult for many generations.
Space policy is the political decision-making process for, and application of, public policy of a state regarding spaceflight and uses of outer space, both for civilian and military purposes. International treaties, such as the 1967 Outer Space Treaty, attempt to maximize the peaceful uses of space and restrict the militarization of space.
USA-193, also known as NRO Launch 21, was a United States military reconnaissance satellite launched on 14 December 2006. It was the first launch conducted by the United Launch Alliance (ULA). Owned by the National Reconnaissance Office (NRO), the craft's precise function and purpose were classified. On 21 February 2008, it was destroyed as a result of Operation Burnt Frost.
Spacecraft collision avoidance is the implementation and study of processes minimizing the chance of orbiting spacecraft inadvertently colliding with other orbiting objects. The most common subject of spacecraft collision avoidance research and development is for human-made satellites in geocentric orbits. The subject includes procedures designed to prevent the accumulation of space debris in orbit, analytical methods for predicting likely collisions, and avoidance procedures to maneuver offending spacecraft away from danger.
The Jules Verne ATV, or Automated Transfer Vehicle 001 (ATV-001), was a robotic cargo spacecraft launched by the European Space Agency (ESA). The ATV was named after the 19th-century French science-fiction author Jules Verne. It was launched on 9 March 2008 on a mission to supply the International Space Station (ISS) with propellant, water, air, and dry cargo. Jules Verne was the first of five ATVs to be launched.
On February 10, 2009, two communications satellites—the active commercial Iridium 33 and the derelict Russian military Kosmos 2251—accidentally collided at a speed of 11.7 km/s (26,000 mph) and an altitude of 789 kilometres (490 mi) above the Taymyr Peninsula in Siberia. It was the first time a hypervelocity collision occurred between two satellites; previous incidents had involved a satellite and a piece of space debris.
Operation Burnt Frost was a military operation to intercept and destroy non-functioning U.S. National Reconnaissance Office (NRO) satellite USA-193. The mission was described by the Missile Defense Agency as a "mission of safeguarding human life against the uncontrolled re-entry of a 5,000-pound satellite containing over 1,000 pounds of hazardous hydrazine propellant". The launch occurred on 21 February 2008 at approximately 10:26 p.m. EST from the USS Lake Erie, using a heavily modified Standard Missile-3 (SM-3) to shoot down the satellite. A few minutes after launch, the SM-3 intercepted its target and successfully completed its mission. The operation received scrutiny from other countries, mainly China and Russia.
Kosmos 2499 was a Russian satellite orbiting the Earth, before breaking up on January 4, 2023.
The Space Safety Programme, formerly the Space Situational Awareness (SSA) programme, is the European Space Agency's (ESA) initiative to monitor hazards from space, determine their risk, make this data available to the appropriate authorities and where possible, mitigate the threat.
These are tables of space probes which have been deliberately destroyed at their objects of study, typically by hard landings or crash landings at the end of their respective missions and/or functionality. This list only includes spacecraft specifically commanded to crash into the surface of an extraterrestrial celestial body, thus precluding unintentionally crashed spacecraft, derelict spacecraft, or spacecraft designed as landers. Intentionally crashing spacecraft not only precludes the hazards of orbital space debris and planetary contamination, but also provides the opportunity in some cases for terminal science given that the transient light released by the kinetic energy may be available for spectroscopy; the physical ejecta remains in place for further study. Even after soft landings had been mastered, NASA used crash landings to test whether Moon craters contained ice by crashing space probes into craters and testing the debris that got thrown out.
Space sustainability aims to maintain the safety and health of the space environment.
Kosmos-1408 was an electronic signals intelligence (ELINT) satellite operated by the Soviet Union. It was launched into low Earth orbit on 16 September 1982 at 14:55 UTC, replacing Kosmos-1378. It operated for around two years before becoming inactive and left in orbit.
