The collision of Iridium 33 and Cosmos 2251 was the most severe accidental fragmentation on record. More than 1800 debris approx. 10 cm and larger were produced. If solar activity returns to normal, half of the tracked debris will reenter within five years… Some debris from both satellites will remain in orbit through the end of the century.

The first-ever accidental in-orbit collision between two satellites occurred at 16:56 UTC, 10 February 2009, at 776 km altitude above Siberia. A privately owned American communication satellite, Iridium-33, and a Russian military satellite, Kosmos2251, collided at 11.7 km/s. Both were destroyed, and more than 2300 trackable fragments were generated, some of which have since reentered (that is, decayed and reentered the atmosphere, where they have burned up).

On 10 February 2009, Iridium 33 and Cosmos 2251 collided at an altitude of about 790 km. This on-orbit collision between two intact spacecraft created a significant amount of orbital debris. Less than 60 cataloged debris had reentered by 1 October 2009; some debris from both satellites will remain in orbit for decades to centuries.

COSMOS 2251 was a Russian communications satellite launched on 16 June 1993. It is reported to have ceased operations about two years after launch. On 10 February 2009, it collided with the operational Iridium 33 communications satellite in a nearly circular 780–800 km altitude orbit, destroying both spacecraft and creating a large amount of orbital debris.

The first ever accidental collision between two intact satellites, Iridium 33 and Cosmos 2251 (560 kg and 900 kg, respectively), highlighted the... More than 1500 large (>10 cm) debris from the collision have been identified by the US Space Surveillance Network. These debris are concentrated near 800 km altitude where a large number of spacecraft perform communications and Earth observation missions.

The collision between the active American Iridium 33 satellite and the retired Russian Cosmos 2251 satellite on 10 February 2009, is the first on-orbit collision between satellites. As of 1 December 2009, the U.S. space tracking system catalogued 1,632 fragments from the collision, many of which will stay in orbit for decades.

On 2009 February 10, Iridium 33 (an operational US communications satellite in low-Earth orbit) was struck and destroyed by Cosmos 2251 (a long-defunct Russian communications satellite). This is the first time since the dawn of the Space Age that two satellites have collided in orbit. As of 2009 August 26, the SSN has cataloged 406 pieces of debris (16 pieces of which have already decayed from orbit) associated with Iridium 33 and 960 pieces of debris (32 pieces of which have decayed) associated with Cosmos 2251.

Orbital debris is any human-made object in orbit about the Earth that no longer serves any useful purpose. ... The intentional destruction of the Fengyun-1C weather satellite by China in 2007 and the accidental collision of the American communications satellite, Iridium-33, and the retired Russian spacecraft, Cosmos-2251, in 2009 greatly increased the number of large debris in orbit and now represent one-third of all cataloged orbital debris. ... Debris left in orbits below 600 km normally fall back to Earth within several years. At altitudes of 800 km, the time for orbital decay is often measured in centuries.

On 2009 February 10, Iridium 33—an operational US communications satellite in low-Earth orbit—was struck and destroyed by Cosmos 2251—a long-defunct Russian communications satellite.[1] As of 2009 August 26, the SSN has cataloged 406 pieces of debris (16 pieces of which have already decayed from orbit) associated with Iridium 33 and 960 pieces of debris (32 pieces of which have decayed) associated with Cosmos 2251.[1] That left 209 of the 406 pieces of Iridium 33 debris and 553 of the 960 pieces of Cosmos 2251 debris (762 of the total 1,366 pieces of debris).[1]

Two big communications satellites – one American, the other Russian – collided in orbit on Tuesday at an altitude of about 491 miles (790 km) above northern Siberia, NASA officials said. The crash between the operational Iridium 33 satellite and the defunct Russian Cosmos 2251 spacecraft was the first major collision between two intact satellites. NASA said the collision created a cloud of debris made up of hundreds, and possibly more than 1,000, pieces of trackable size.

The incident involved an active commercial Iridium satellite and a defunct Russian Cosmos satellite at an altitude of approximately 800 km. The collision generated nearly 2,000 trackable pieces of orbital debris, along with thousands of smaller fragments, significantly increasing risks to satellites operating in low Earth orbit. Much of this debris is expected to remain in orbit for decades.

The collision on February 10, 2009 between the Iridium 33 satellite and the defunct Cosmos 2251 satellite at an altitude of 470 miles (770 km) significantly increases the amount of space debris in the region of space that is already the most crowded and has the greatest risk of collisions between orbiting objects. ... Prior to this collision, there were roughly some 3,000 objects larger than 10 cm in the region between 700 to 900 km altitude, so the additional 1,000–2,000 objects created by this collision (maybe half of which will stay in this altitude band) represent a significant increase.

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. NASA initially estimated ten days after the collision that the incident had created at least 1,000 pieces of debris larger than 10 cm, in addition to many smaller ones. By July 2011, the U.S. Space Surveillance Network had catalogued over 2000 large debris fragments from the collision.

The collision on February 10, 2009 between the Iridium 33 satellite and the defunct Cosmos 2251 satellite at an altitude of 470 miles (770 km) significantly increases the amount of space debris in the region of space that is already the most crowded. The two satellites were both orbiting the Earth at a speed of nearly 17,000 mph (7.5 km/s), and collided at a speed well over 22,000 mph (10 km/s). Because there is very little atmospheric drag at the high altitude where this collision occurred, a large fraction of the debris created will stay in orbit for several decades.

Two big communications satellites have collided in space, the first time such an event has occurred. A defunct Russian spacecraft, Cosmos 2251, and an Iridium commercial satellite hit each other at an altitude of about 800km. US space agency officials said the crash had created a cloud of at least 500 pieces of debris and that thousands of smaller fragments were also likely.

The defunct Russian communications satellite Cosmos-2251 slammed into the active US communications satellite Iridium 33 on 10 February at an altitude of about 790 kilometres. Early estimates by NASA and the US Space Surveillance Network suggested that the collision produced hundreds to more than 1,000 pieces of debris larger than 10 centimetres, and many more smaller fragments, some of which will remain in orbit for decades.

On February 10, 2009, a collision between the operational Iridium 33 and the derelict COSMOS 2251 promoted policy changes, ushering a new era of collision avoidance and space traffic management.[7] This later assessment paper discusses the long‑term evolution of the debris clouds produced by the collision and their implications for other spacecraft operating in similar altitude regimes.

On 10 February 2009, the operational Iridium 33 satellite and the inactive Russian satellite Cosmos 2251 collided in low Earth orbit at about 790–800 km altitude. The event generated a large number of debris objects; more than 2,000 fragments large enough to be tracked were eventually catalogued, and many of these pieces are expected to stay in orbit for many years or decades.

NASA officials said the smashup between the defunct Russian military Cosmos 2251 spacecraft and the operational Iridium 33 communications satellite occurred 490 miles (about 790 km) above northern Siberia. Early estimates suggested at least 1,000 pieces of debris larger than 4 inches (10 cm) were created, but later tracking by the U.S. Space Surveillance Network showed more than 2,000 fragments. Many of the fragments will remain in orbit for decades, NASA scientists said.

On Feb. 10, 2009, Iridium 33 and Cosmos 2251 collided at an altitude of roughly 790 km over northern Siberia, the first known accidental collision between two intact satellites. As of early 2024, approximately 1,128 trackable pieces of debris from the Iridium–Cosmos collision remained in orbit. The Iridium debris is in lower orbits and decays faster, while the Cosmos debris is at slightly higher altitudes and will persist for decades.

Fragments were assigned based on the originating object. For example, the Iridium 33 – COSMOS 2251 collision in 2009 yielded 157 Iridium fragments (tagged as commercial) and 773 COSMOS fragments (tagged as government). This paper analyzes data from NASA’s History of On-Orbit Satellite Fragmentations, 16th Edition and LeoLabs data as of January 31, 2025.

The Orbital Debris Quarterly News provides technical updates on debris environments and specific events. Issues following the February 2009 Iridium 33/Cosmos 2251 collision include the report "Small Debris Observations from the Iridium 33/Cosmos 2251 Collision", which discusses measurement of debris fragments smaller than 10 cm generated by this event and their persistence in low Earth orbit.

February 10, 2012 marks the third anniversary of the first ever collision between two intact satellites in orbit.[6] The collision, which occurred between Iridium 33 and Cosmos 2251 over Siberia, stunned the aerospace community and brought the realization that even though the heavens were vast, the orbital planes above the Earth are finite and there are few if any rules of the road when the traffic within that finite space becomes congested.[6] The article reviews how the resulting debris clouds posed long‑term risks to other satellites operating in similar orbits.

Iridium 33 was an operational U.S. commercial communications satellite that formed part of the Iridium constellation when it collided with Kosmos 2251 in 2009. Kosmos 2251 was a non-operational Russian communications satellite, often described as defunct or derelict, that had been launched in 1993 and was no longer under active control at the time of the collision.

On the 10th of February in 2009, the Iridium 33 communication satellite and Cosmos 2251, a Russian Strela 2M military communication satellite, had an unexpected meeting, colliding with each other at a speed of 11 km per second. They were in orbits at about 800 km where atmospheric drag is low. The US Space Surveillance Network cataloged 1,714 pieces of debris from Cosmos 2251 and a further 657 from Iridium 33 for a total of 2,371 tracked pieces of debris; in the 17 years since then, many of the pieces have reentered, leaving several hundred fragments still in orbit where they may remain for decades.