Iridium 33


Iridium 33
Iridium satellite.jpg
A mockup of an Iridium satellite
Mission typeCommunication
OperatorIridium Satellite LLC
COSPAR ID1997-051C
SATCAT no.24946
Spacecraft properties
ManufacturerLockheed Martin
Launch mass700 kg
Start of mission
Launch date14 September 1997, 01:36 UTC
RocketProton-K / DM2
Launch siteBaikonur, Site 81/23
via International Launch Services
End of mission
Destroyed10 February 2009, 16:56 UTC
Collision with Kosmos 2251
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Perigee altitude779.6 km [1]
Apogee altitude793.9 km
Period100.4 minutes
Epoch10 February 2009

Iridium 33 was a communications satellite launched by Russia for Iridium Communications. It was launched into low Earth orbit from Site 81/23 at the Baikonur Cosmodrome at 01:36 UTC on 14 September 1997, by a Proton-K rocket with a Block DM2 upper stage.[2][3] The launch was arranged by International Launch Services (ILS). It was operated in Plane 3 of the Iridium satellite constellation, with an ascending node of 230.9°.[2]


Iridium 33 was part of a commercial communications network consisting of a constellation of 66 LEO spacecraft. The system uses L-Band to provide global communications services through portable handsets. Commercial service began in 1998. The system employs ground stations with a master control complex in Landsdowne, Virginia, a backup in Italy, and a third engineering center in Chandler, Arizona.[4]


The spacecraft was 3-axis stabilized, with a hydrazine propulsion system. It had 2 solar panels with 1-axis articulation. The system employed L-Band using FDMA/TDMA to provide voice at 4.8 kbps and data at 2400 bps with a 16 dB margin. Each satellite had 48 spot beams for Earth coverage and used Ka-Band for crosslinks and ground commanding.[4]


On 10 February 2009, at 16:56 UTC, at about 800 km altitude, Kosmos 2251 (1993-036A) (a derelict Strela satellite) and Iridium 33 collided, resulting in the destruction of both spacecraft.[5] NASA reported that a large amount of space debris was produced by the collision, i.e. 1347 debris for Kosmos 2251 and 528 for Iridium 33.[6][7][8][9]


  1. ^ "Iridium 33 tracking details". Retrieved 2019-02-04.
  2. ^ a b Wade, Mark. "Iridium". Encyclopedia Astronautica. Archived from the original on 2009-02-16. Retrieved 2009-02-12.
  3. ^ Wade, Mark. "Proton". Encyclopedia Astronautica. Retrieved 2009-02-12.
  4. ^ a b "Iridium 33: Display 1997". NASA. 14 May 2020. Retrieved 5 June 2020. Public Domain This article incorporates text from this source, which is in the public domain.
  5. ^ Iannotta, Becky (2009-02-11). "U.S. Satellite Destroyed in Space Collision". Retrieved 2009-02-11.
  6. ^ "2 orbiting satellites collide 500 miles up". Associated Press. 2009-02-11. Retrieved 2009-02-11.
  7. ^ "Google Earth KMZ file of the debris". John Burns. 2009-03-05. Retrieved 2010-11-25.
  8. ^ "U.S. Space debris environment and operational updates" (PDF). NASA. 2011-02-18. Retrieved 5 June 2020. Public Domain This article incorporates text from this source, which is in the public domain.
  9. ^ "Javascript visualisation of Iridium 33 debris".