2009 satellite collision
Encyclopedia
Hypervelocity
The term hypervelocity usually refers to a very high velocity, approximately over 3,000 meters per second . In particular, it refers to velocities so high that the strength of materials upon impact is very small compared to inertial stresses. Thus, even metals behave like fluids under hypervelocity...
collision between two intact artificial satellites
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
in Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
. The collision occurred at 16:56 UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
on February 10, 2009, at 789 kilometres (490.3 mi) above the Taymyr Peninsula
Taymyr Peninsula
The Taymyr Peninsula is a peninsula in the Far North of Russia, in the Siberian Federal District, that forms the northernmost part of mainland Eurasia and Asia...
in Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
, when Iridium 33
Iridium 33
Iridium 33 was a U.S. Iridium communications satellite. It was launched into low Earth orbit from Site 81/23 at the Baikonur Cosmodrome at 01:36 GMT on 14 September 1997, by a Proton-K carrier rocket with a Block DM2 upper stage...
and Kosmos-2251
Kosmos-2251
Kosmos-2251, , was a Russian Strela-2M communications satellite. It was launched into Low Earth orbit from Site 132/1 at the Plesetsk Cosmodrome at 04:17 GMT on 16 June 1993, by a Kosmos-3M carrier rocket.-Destruction:...
collided. The satellites collided at a speed of 11.7 km/s, or approximately 42120 kilometres per hour (26,172.2 mph), faster than escape velocity
Escape velocity
In physics, escape velocity is the speed at which the kinetic energy plus the gravitational potential energy of an object is zero gravitational potential energy is negative since gravity is an attractive force and the potential is defined to be zero at infinity...
on Earth.
Collision
The collision destroyed both Iridium 33 (owned by Iridium Communications Inc.) and Kosmos 2251 (owned by the Russian Space Forces). While the Iridium satellite was operational at the time of the collision, the Russian satellite had been out of service since at least 1995 and was no longer actively controlled. Kosmos-2251 was launched on June 16, 1993, and went out of service two years later, in 1995, according to Gen. Yakushin.U.S. space agency NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
reported that a large amount of debris
Space debris
Space debris, also known as orbital debris, space junk, and space waste, is the collection of objects in orbit around Earth that were created by humans but no longer serve any useful purpose. These objects consist of everything from spent rocket stages and defunct satellites to erosion, explosion...
was produced by the collision. As of March 2010, the U.S. Space Surveillance Network
United States Space Surveillance Network
The United States Space Surveillance Network is a critical part of United States Strategic Command's mission and involves detecting, tracking, cataloging and identifying artificial objects orbiting Earth, i.e. active/inactive satellites, spent rocket bodies, or fragmentation debris...
has cataloged 1740 pieces of debris from the collision, with about 400 additional pieces awaiting cataloging. NASA says the risk to the International Space Station
International Space Station
The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...
, which orbits about 430 kilometres (267.2 mi) below the collision course, is low, as is any threat to a shuttle launch (STS-119
STS-119
-Crew notes:This mission was originally scheduled to bring the Expedition 9 crew to the ISS. This crew would have consisted of:-Mission parameters:* Mass:* Orbiter liftoff: * Orbiter landing: * Perigee: * Apogee:...
) then planned for later February 2009. However, Chinese
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
scientists have said that the debris does pose a threat to Chinese satellites in Sun-synchronous orbit
Sun-synchronous orbit
A Sun-synchronous orbit is a geocentric orbit which combines altitude and inclination in such a way that an object on that orbit ascends or descends over any given point of the Earth's surface at the same local mean solar time. The surface illumination angle will be nearly the same every time...
s.
Several smaller collisions had occurred previously, often during rendezvous attempts or the intentional destruction of a satellite, including the DART
DART (spacecraft)
DART, or Demonstration for Autonomous Rendezvous Technology, is a NASA sponsored project. The goal was to develop and demonstrate an automated navigation and rendezvous capability in a NASA spacecraft. Currently, only the Russian Space Agency, JAXA and ESA have autonomous space craft navigation...
satellite colliding with MUBLCOM
MUBLCOM
The Multiple Paths, Beyond-Line-of-Sight Communications satellite, built for the Pentagon's Defense Advanced Research Projects Agency, was launched in May 1999 by a Pegasus rocket...
, and three collisions involving the manned Mir
Mir
Mir was a space station operated in low Earth orbit from 1986 to 2001, at first by the Soviet Union and then by Russia. Assembled in orbit from 1986 to 1996, Mir was the first modular space station and had a greater mass than that of any previous spacecraft, holding the record for the...
space station, during docking attempts by Progress M-24, Progress M-34, and Soyuz TM-17
Soyuz TM-17
Soyuz TM-17 was a Russian mission to the space station Mir, launched on July 1, 1993. It lasted 196 days and 17 hours, making more than 3,000 orbits of the planet Earth.-Crew:-Mission highlights:...
. In 1996, the Cerise
Cerise (satellite)
Cerise was a French military reconnaissance satellite. Its main purpose was to intercept HF radio signals for French intelligence services. With a mass of 50 kg, it was launched by an Ariane rocket from Kourou in French Guiana at 17:23 UT, 7 July 1995...
satellite collided with space debris. There have been eight known high-speed collisions in all, most of which were only noticed well after the fact.
Spacecraft
Kosmos-2251 was a 950 kilograms (2,094 lb) StrelaStrela (satellite)
Strela is a Russian military communications satellite constellation operating in low Earth orbit.-History:The first three satellites, Kosmos 38 , Kosmos 39 and Kosmos 40 , were launched on 18 August 1964...
communications satellite
Communications satellite
A communications satellite is an artificial satellite stationed in space for the purpose of telecommunications...
. It was launched on a Kosmos-3M carrier rocket on June 16, 1993. It had been deactivated prior to the collision, and remained in orbit as space debris
Space debris
Space debris, also known as orbital debris, space junk, and space waste, is the collection of objects in orbit around Earth that were created by humans but no longer serve any useful purpose. These objects consist of everything from spent rocket stages and defunct satellites to erosion, explosion...
. Iridium 33, a 560 kilograms (1,235 lb) satellite that was part of the Iridium satellite constellation
Iridium satellite constellation
The Iridium satellite constellation is a large group of satellites providing voice and data coverage to satellite phones, pagers and integrated transceivers over Earth's entire surface. Iridium Communications Inc...
of 66 communications satellites, was launched on September 14, 1997 atop a Proton rocket.
Fallout
On February 13, witnesses in KentuckyKentucky
The Commonwealth of Kentucky is a state located in the East Central United States of America. As classified by the United States Census Bureau, Kentucky is a Southern state, more specifically in the East South Central region. Kentucky is one of four U.S. states constituted as a commonwealth...
began hearing sonic boom
Sonic boom
A sonic boom is the sound associated with the shock waves created by an object traveling through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding much like an explosion...
s. The National Weather Service
National Weather Service
The National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...
issued an information statement alerting residents of "explosions and or earthquakes" due to the falling satellite debris. Similar reports from as far west as New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
were all attributed to falling debris from the collided satellites. The Federal Aviation Administration
Federal Aviation Administration
The Federal Aviation Administration is the national aviation authority of the United States. An agency of the United States Department of Transportation, it has authority to regulate and oversee all aspects of civil aviation in the U.S...
also released a notice warning pilots of the re-entering debris.
A bolide ("fireball") over Texas on February 15 was mistaken for reentering debris.
The United States Strategic Command
United States Strategic Command
United States Strategic Command is one of nine Unified Combatant Commands of the United States Department of Defense . The Command, including components, employs more than 2,700 people, representing all four services, including DoD civilians and contractors, who oversee the command's operationally...
, which tracks satellites and orbital debris, reported that the booms and flashes of light in the sky were unrelated to the satellite collision.
Nicholas L. Johnson, NASA's chief scientist for orbital debris, estimated that the satellite collision created approximately 1,000 pieces of debris larger than 10 centimeters (4 inches), in addition to many smaller ones.
Cause
Events where two satellites approach within several kilometers of each other occur numerous times each day. Sorting through the large number of potential collisions to identify those that are high risk presents a challenge. Precise, up-to-date information regarding current satellite positions is difficult to obtain. Calculations made by CelesTrak had expected these two satellites to miss by 584 meters.Planning an avoidance maneuver with due consideration of the risk, the fuel consumption required for the maneuver, and affects the satellite's normal functioning can also be challenging. John Campbell of Iridium spoke at a June 2007 forum discussing these tradeoffs and the difficulty of handling all the notifications they were getting regarding close approaches, which numbered 400 per week (for approaches within 5 km) for the entire Iridium constellation. He estimated the risk of collision per conjunction as one in 50 million.
This collision and numerous near-misses have renewed calls for mandatory disposal of defunct satellites (typically by deorbiting them), but no such international law exists as of yet.