Space Junk

American spacecraft had to dodge space debris four times in 2008, NASA revealed Tuesday, a fact that highlights both the extent of the space junk problem and the primary mitigation option open to NASA.

By tracking pieces of debris larger than around four inches, space engineers can identify some dangerous space junk and meteoroids. If a satellite or spacecraft is in danger of getting hit, they simply move it out of harm’s way. The International Space Station, for example, had to make an evasive maneuver back in August 2008, to avoid a piece of an old Russian craft.

“On average, Shuttle and ISS have conducted several collision avoidance maneuvers over the past ten years on the order of about one per year,” said Nicholas Johnson, chief scientist at NASA’s Orbital Debris Program Office, in a teleconference with reporters ahead of a House subcommittee on space and aeronautics meeting about space debris.

Space debris is an increasing problem. Johnson noted that from the 1960s until the past year, orbital debris had increased linearly, despite advances in decreasing the amount of debris left behind per trip to space. But recently, a Chinese missile test on a satellite and the collision of two satellites in orbit, sent the amount of space debris up considerably. The satellite collision alone increased the risk to the upcoming May shuttle mission to the Hubble Space Telescope by 8 percent.

That complicated an already unusual mission. The Hubble Space Telescope, orbiting at 340 miles above Earth’s surface, has a far more densely crowded space debris environment than the ISS. The orbits near 560 miles are the most crowded with junk.

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