Satellite collision more destructive than Chinas missile test in 2007

February 14th, 2009 - 12:26 pm ICT by ANI  

London, Feb 14 (ANI): A leading space scientist has said that the collision between two satellites on February 10, which created a lot of debris in space, expended a great deal more destructive energy than Chinas infamous anti-satellite missile test did in January 2007.

The collision happened between an Iridium communications satellite and the defunct Soviet-era Cosmos 2251 spacecraft.

In 2003, space debris expert Hugh Lewis and colleagues at the University of Southampton in the UK ran predictions on the debris field that would be created in a hypothetical Iridium satellite break-up owing to a collision with just 1 kilogram of space junk.

Now, according to a report in New Scientist, he has fed Cosmos 2251s orbital data, mass and velocity into that computer model.

To be completely obliterated, a spacecraft must be hit with an energy of 40 joules for every gram of its mass.

In Chinas anti-satellite (ASAT) test, a defunct weather satellite called Fengyun-1C was destroyed by a missile that imparted an estimated 350 joules per gram of its mass.

But, the Iridium and Cosmos satellites collided at 42,120 kilometers per hour, Lewis calculates, imparting 50,000 joules per gram of their mass.

The resulting unprecedented debris field, according to Lewis, is still being analyzed by space agencies.

But, he expects it to create an extra 10,000 tennis-ball-sized debris shards - more than triple the number created in the ASAT test.

There was more energy here than in the Chinese ASAT test so well see more debris, Lewis said.

According to Nicholas Johnson, chief scientist for orbital debris at NASAs Johnson Space Center in Houston, Texas, the exact amount of debris generated in the collision depends on the geometry of the smashup, which is not yet known.

If they collided main body to main body, that would create the maximum amount of debris, Johnson told New Scientist. It is possible that one satellite hit an appendage of the other or only a small portion of the other, he added.

Worryingly, the new debris will raise the collision risk for other Iridium satellites.

Thats because the 65 remaining satellites in the Iridium network move in circular orbits that cross each other at the Earths poles.

The debris cloud that is forming will create a torus (doughnut) of high-density debris that Iridium satellites will now need to pass through, warned Richard Crowther of the British National Space Centre. (ANI)

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