The US shuttle Atlantis faces nearly twice the risk of being struck by debris on a mission next month to the Hubble telescope, due to the high levels of space litter floating at the altitude of Hubble's orbit, NASA said.
"It's a very challenging mission. We have hazards we don't typically have for an ISS (International Space Station) mission," NASA space shuttle programme manager John Shannon told a news conference on Monday.
"We have a one-in-180 chance of getting some type of catastrophic damage from micro-meteorites/orbiting debris (MMOD) compared to an ISS mission, which is typically a one-in-300 chance," he said.
Hubble is orbiting some 600 kilometers above earth, compared with 240 kilometers for the ISS.
When the risk faced by a shuttle mission is greater than one-in-200, the decision to go ahead with the flight has to come from the highest authorities in NASA, said Shannon.
But he expected they would give the green light for the Atlantis mission to lift off on what will be its final mission to conduct maintenance work on Hubble.
"Our risk has increased, but our ability to mitigate the risk has increased. So it makes us feel pretty good about it," said Shannon.
"MMOD is the biggest risk for all shuttle flights" and the risk grows the higher above the earth's surface the shuttle flies, he said.
Space has become more littered and dangerous in the past year due to mishaps, tests and aborted missions involving American, Chinese and Russian satellites and rockets, he said.
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