HOUSTON (Reuters) - The shuttle crew being dispatched to work on the Hubble Space Telescope faces a higher-than-usual chance of disaster due to orbital debris, the shuttle program manager said on Monday.
NASA is preparing for a fifth and final servicing mission to the orbital observatory next month.
The environment where Hubble flies, about 350 miles (560 km) above the planet, is more littered with shards of exploded spacecraft and rockets than the area around the International Space Station, which orbits about 210 miles above Earth.
The odds of catastrophic damage from an orbital debris strike are 1 in 185 for the Hubble crew, compared with 1 in 300 for missions to the space station, John Shannon, the shuttle program manager, told reporters.
“It’s our biggest risk,” he said.
After the 2003 Columbia accident, NASA developed special cameras and a boom so shuttle crews could inspect their ships for damage after reaching orbit.
The shuttle Columbia was struck by a piece of falling debris during launch and broke up as it attempted to fly back through the atmosphere for landing, killing all seven crew members on board.
The investigation into the accident revealed the vulnerability of the shuttle’s thermal protection system, Shannon said, prompting NASA to reassess the relative risks of flying the shuttle.
Orbital debris impacts are the top danger, ahead of risks associated with launch, landing and all other phases of the flight, he said.
The orbital environment around Earth has also become more littered with junk, including thousands of shards from a satellite blasted by a Chinese missile in a controversial test and by a Russian spy satellite thought to have self-destructed this year.
The shuttles are scheduled to be retired in 2010, freeing funds for NASA to develop smaller, safer and less complicated ships called Orion.
Overall, NASA puts the chance of a catastrophic loss of the shuttle at 1 in 80, though Shannon said experience has shown the number actually to be about 1 in 60.
Editing by Jane Sutton and Todd Eastham
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