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When Satellites Collide: Iridium 33 Meets Kosmos 2251

Satellite Technology

Satellite Technology Feature Article

February 12, 2009

When Satellites Collide: Iridium 33 Meets Kosmos 2251

By Richard Grigonis, Executive Editor, IP Communications Group

Iridium started out as Motorola’s (News - Alert) amazingly ambitious satellite project “to bring personal communications to every square inch of the earth.” The idea was that you could use an Iridium phone pretty much anywhere — so long as you were outside and could “see” one of the Iridium satellites. (It’s called Iridium after the element iridium, which has 77 electrons, which was originally the number of satellites needed. In 1994, they realized they could do the job with 66 satellites. But the name stuck.)

According to Motorola, “for the first time, anyone, anywhere, at any time can communicate via voice, fax, or data.” Iridium started launching satellites in November of 1997 and started service sometime in 1999, after many delays and several launches of new satellites to replace those that had failed. This advanced satellite/phone pager network uses TDMA in the 2 GHz band for inter-satellite links so as to maintain coverage worldwide.
And now, Iridium, of Bethesda, Maryland, has announced that it “lost an operational satellite” (one of the original 1,234 lb Iridium 33 satellites launched in 1997) after it was struck on Tuesday, February 11, 2009 by in a collision with a defunct 2,094 lb Russian Kosmos 2251 military satellite that had been launched in 1993 and ceased functioning two years later.
Iridium said that some of its client could experience brief outages until it had temporarily fixed the problem by Friday by calling into service an in-orbit “spare” satellite sometime over the next 30 days.
Americans are now following the debris path spewed forth from the collision. Although most of it should fall to Earth and burn up in the atmosphere up re-entry, there is however a small possibility (“very small and within acceptable limits” according to NASA) that some bits of debris from the impact may endanger the International Space Station (ISS) which orbits Earth about 435km below where the collision occurred.
Orbital debris expert Nicholas Johnson of the Johnson Space Center in Houston, was quoted by the Associated Press as saying that the Hubble Space Telescope and Earth-observing satellites which operate at higher orbits (and thus closer to the impact site) were at greater risk of damage from the debris cloud.

Richard Grigonis is Executive Editor of TMC (News - Alert)’s IP Communications Group. To read more of Richard’s articles, please visit his columnist page.

Edited by Jessica Kostek

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