2009 satellite collision

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Replica of an Iridium satellite
Digital painting of a Strela-2M satellite

The accidental 2009 satellite collision was the first time a hypervelocity collision occurred between two artificial satellites - until then, all accidental hypervelocity collisions happened between a satellite and a piece of space debris.[1] It occurred on February 10, 2009, 16:56 UTC, when Iridium 33 and Kosmos-2251 collided[2][3][4] at a speed of 11,700 m/s (26,000 mph; 42,000 km/h)[5][6] and an altitude of 789 kilometres (490 mi)[7] above the Taymyr Peninsula in Siberia.


Kosmos-2251 was a 950-kilogram (2,094 lb) Russian Strela military communications satellite.[8] It was launched on a Russian Cosmos-3M carrier rocket on June 16, 1993.[3] It had been deactivated prior to the collision, and remained in orbit as space debris. Iridium 33 was a 560-kilogram (1,235 lb) commercial US-built satellite and was part of the commercial satellite phone Iridium constellation of 66 communications satellites.[3] It was launched on September 14, 1997, atop a Russian Proton rocket.


Collision diagram

The collision destroyed both the Iridium 33 (owned by Iridium Communications Inc.) and Kosmos-2251 (owned by the Russian Space Forces). The Iridium satellite was operational at the time of the collision. Kosmos-2251 was launched on June 16, 1993, and went out of service two years later, in 1995, according to Gen. Yakushin.[9] It had no propulsion system,[10] and was no longer actively controlled.[11][12]

Several smaller collisions had occurred previously, during rendezvous attempts or the intentional destruction of a satellite, including the DART satellite colliding with MUBLCOM,[13] and three collisions involving the manned Mir space station, during docking attempts by Progress M-24, Progress M-34, and Soyuz TM-17,[14] but these were all low-velocity collisions. In 1996, the Cerise satellite collided with space debris.[15] There have been eight known high-speed collisions in all, most of which were only noticed long after they occurred.[16]


Flashes created by the tumbling main body of the Iridium 33 wreckage.
The collision resulted in significant debris in low Earth orbit

U.S. space agency NASA estimated that the satellite collision created approximately 1,000 pieces of debris larger than 10 centimeters (4 inches), in addition to many smaller ones.[17] By July 2011, the U.S. Space Surveillance Network had cataloged over 2000 large debris fragments.[18] NASA determined the risk to the International Space Station, which orbits about 430 kilometres (270 mi) below the collision course, to be low,[8][19] as was any threat to the shuttle launch (STS-119) then planned for late February 2009.[8] However, Chinese scientists have said that the debris does pose a threat to Chinese satellites in Sun-synchronous orbits,[20] and the ISS did have to perform an avoidance maneuver due to collision debris in March 2011.[18]

By December 2011, many pieces of debris were in a steady orbital decay towards Earth, and expected to burn up in the atmosphere within one or two years. By January 2014, 24% of the known debris had decayed.[citation needed] In 2016, Space News listed the collision as the fourth biggest fragmentation event in history, with Iridium 33 producing 628 pieces of cataloged debris, of which 364 pieces of tracked debris remain in orbit as of January 2016.[21]

A small piece of Cosmos 2251 satellite debris safely passed by the International Space Station at 2:38 a.m. EDT, Saturday, March 24, 2012. As a precaution, the six crew members on board the orbiting complex took refuge inside the two docked Soyuz rendezvous spacecraft until the debris had passed.[22]

A number of reports of phenomena in the US states of Texas, Kentucky, and New Mexico were attributed to debris from the collision in the days immediately following the first reports of the incident in 2009,[23] although NASA and the United States Strategic Command, which tracks satellites and orbital debris, did not announce any reentries of debris at the time[24] and reported that these phenomena were unrelated to the collision.[25] On February 13, 2009, witnesses in Kentucky heard sonic booms.[26] The National Weather Service issued an information statement alerting residents of sonic booms due to the falling satellite debris.[27] The Federal Aviation Administration also released a notice warning pilots of the re-entering debris.[28] Some reports include details that point to these phenomena being caused by a meteoroid shower.[24] A very bright meteor over Texas on February 15, 2009, was mistaken for reentering debris.[29]


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.[30]

Planning an avoidance maneuver with due consideration of the risk, the fuel consumption required for the maneuver, and its effects on 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.[16]

This collision and numerous near-misses have renewed calls for mandatory disposal of defunct satellites (typically by deorbiting them or at minimum sending them in graveyard orbit), but no such international law exists yet. Nevertheless, some countries have adopted such a law, such as France in December 2010.[31] The United States Federal Communications Commission (FCC) requires all geostationary satellites launched after March 18, 2002, to commit to moving to a graveyard orbit at the end of their operational life.[32]

See also[edit]


  1. ^ "Satellite Collision Leaves Significant Debris Clouds" (PDF). Orbital Debris Quarterly News. NASA Orbital Debris Program Office. 13 (2): 1–2. April 2009. Archived from the original (PDF) on 27 May 2010. Retrieved 20 May 2010.
  2. ^ McDowell, Jonathan (February 15, 2009). "Jonathan's Space Report No. 606". Retrieved 2009-02-17. Strela-2M satellites had lifetimes of around 3 years, and Gen. Yakushin of the Military Space Forces was quoted in Moscow Times as saying Kosmos-2251 went out of service in 1995.
  3. ^ a b c Iannotta, Becky (February 22, 2009). "U.S. Satellite Destroyed in Space Collision". Space.com. Archived from the original on 13 February 2009. Retrieved 12 February 2009.
  4. ^ Achenbach, Joel (February 11, 2009). "Debris From Satellites' Collision Said to Pose Small Risk to Space Station". The Washington Post. Retrieved 12 February 2009.
  5. ^ Marks, Paul (13 February 2009). "Satellite collision 'more powerful than China's ASAT test". New Scientist. Archived from the original on 15 February 2009. Retrieved 17 February 2009. (putting the collision speed at 42,120 kilometres per hour (11.7 km/s))
  6. ^ Matthews, Mark K. (2009-02-13). "Crash imperils satellites that monitor Earth". Orlando Sentinel. Archived from the original on 16 February 2009. Retrieved 2009-02-17. (reporting it as "what amounted to a 26,000 mph [(7.7 miles/sec)] collision")
  7. ^ "Collision between Iridium 33 and Cosmos 2251". N2YO. Archived from the original on 16 February 2009. Retrieved 17 February 2009.
  8. ^ a b c "Russian and US satellites collide". BBC. 2009-02-12. Archived from the original on 12 February 2009. Retrieved 2009-02-12.
  9. ^ "First Satellite Collision Called Threat in Space". Moscow Times. February 13, 2009. Archived from the original on January 13, 2013. Retrieved 19 February 2009.
  10. ^ Игорь Королев. Авария на $50 млн // Ведомости, № 26 (2296), 13 февраля 2009
  11. ^ "Russian and US satellites collide". BBC News. 2009-02-12. Archived from the original on 12 February 2009. Retrieved 2009-02-12. Russia has not commented on claims the satellite was out of control
  12. ^ Wolf, Jim (February 11, 2009). "U.S., Russian satellites collide in space". Reuters. Archived from the original on 15 February 2009. Retrieved 12 February 2009.
  13. ^ "DART Mishap Investigation Board Final Report" (PDF). NASA. 2007-01-04. Archived (PDF) from the original on 19 February 2009. Retrieved 2009-02-16.
  14. ^ Wade, Mark. "Soyuz". Encyclopedia Astronautica. Archived from the original on 2010-01-17. Retrieved 2009-02-12.
  15. ^ Stern, David (2004). "Is it possible for two orbiting satellites to collide?". NASA. Archived from the original on 20 January 2009. Retrieved 12 February 2009.
  16. ^ a b Weeden, Brian (2009-02-23). "Billiards in space". The Space Review. Archived from the original on 26 February 2009. Retrieved 24 February 2009.
  17. ^ Oleksyn, Veronika (February 19, 2009). "What a mess! Experts ponder space junk problem". Associated Press. Retrieved 20 May 2010.
  18. ^ a b "Orbital Debris Quarterly News, July 2011" (PDF). NASA Orbital Debris Program Office. Archived from the original (PDF) on 2011-10-20. Retrieved 2012-01-01.
  19. ^ Dunn, Marcia (February 12, 2009). "Big satellites collide 500 miles over Siberia". The Associated Press. Archived from the original on July 11, 2011. Retrieved 20 May 2010.
  20. ^ "China alert on U.S.-Russian satellite collision". Xinhua. February 12, 2009. Archived from the original on 13 February 2009. Retrieved 12 February 2009.
  21. ^ "10 breakups account for 1/3 of catalogued debris". Space News. April 25, 2016. Retrieved June 27, 2017.
  22. ^ Orbital Debris Safely Passes International Space Station (Web Broadcast). National Aeronautics and Space Association. 2012-03-23. Event occurs at 23 minutes 30 seconds. Retrieved 2012-03-23.
  23. ^ Byrne, Joe (2009-02-15). "Satellite wreckage falls on Kentucky, Texas, New Mexico". The Raw Story. Archived from the original on February 17, 2009. Retrieved 2009-02-16.
  24. ^ a b Phillips, Tony (2009-02-14). "Fireball Mania". National Aeronautics and Space Association. Retrieved 2011-12-14.
  25. ^ Berger, Eric; Carreau, Mark (2009-02-16). "Metallic meteorite likely sent fireball across Texas sky". Houston Chronicle. Retrieved 2009-02-16.
  26. ^ "Satellites Collide; Debris Seen Falling Over Kentucky". WYMT News. 2009-02-13. Archived from the original on 17 February 2009. Retrieved 2009-02-16.
  27. ^ "...POSSIBLE SATELLITE DEBRIS FALLING ACROSS THE REGION..." NOAA. 2009-02-13. Archived from the original on 17 February 2009. Retrieved 2009-02-16.
  28. ^ Harwood, William (2009-02-15). "FAA warns of possible falling satellite debris". CBS News Space Place. Archived from the original on 19 February 2009. Retrieved 2009-02-16.
  29. ^ Plait, Phil (February 15, 2009). "Texas Fireball: What's known so far". Bad Astronomy blog. Retrieved 17 February 2009.
  30. ^ "Iridium 33/Cosmos 2251 Collision". CelesTrak. Archived from the original on 17 March 2009. Retrieved 18 March 2009.
  31. ^ Reynolds, Glenn H (March 12, 2009). "Space Junk and the Law of Space Collisions". Popular Mechanics. Archived from the original on 16 March 2009. Retrieved 18 March 2009.
  32. ^ Peter de Selding (June 28, 2004). "FCC Enters Orbital Debris Debate". Space News. Archived from the original on 2004-07-01.

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