Sunday, January 29, 2012

ISS forced to fire thrusters to avoid 2007 Chinese anti-satellite missile test debris

It's not the stuff of science fiction, but the stuff of science fact: the Earth has thousands of pieces of debris orbiting it, and those objects pose a threat, at times, to other objects. That includes something as big as, and as costly as, the $100 billion International Space Station (ISS).

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On Saturday, Jan. 28, 2012, the ISS was forced to fire its thrusters to avoid orbital debris stemming from a 2007 Chinese anti-satellite missile test, which used a kinetic kill vehicle. That test, which took place slightly more than five years ago on Jan. 11, 2007, destroyed the Fengyun 1C satellite, leaving behind some 3,000 pieces of orbital debris.

This isn't the first time debris from that test endangered the ISS. In April 2011, the ISS was threatened in a similar incident.

At 6:50 p.m. EST on Saturday, rocket thrusters on the space station's Russian-built Zvezda service module were fired for 1-minute and four seconds, slightly raising the ISS' orbit, which should put it in a position to avoid future such incidents, NASA officials said, adding the ISS is not positioned "at the correct altitude and trajectory for future visiting vehicle activities and to avoid a repetitive coincidence of possible conjunctions with a piece of Chinese Fengyun 1C satellite debris."

"Conjunction" is the term used to describe instances in which space debris will fly close enough to a different object to cause concern.

Naturally pieces of the Fengyun 1C satellite aren't the only debris that threatens not just the ISS, but other vehicles and satellites. Over a half million pieces of "space junk" are currently tracked daily by NASA and the U.S. military's Space Surveillance Network in order to avoid collisions in orbit.

Earlier this month, the ISS had to fire its thrusters to avoid debris from a 2009 collision between a U.S. and a Russian satellite. That incident, between an Iridium 33 satellite and a Kosmos 2251 satellite, was the first accidental hypervelocity collision between two intact artificial satellites in Earth orbit.

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