After a six-month delay, the final preparations are now underway for the last mission to service the Hubble Space Telescope. If all goes well, the space shuttle Atlantis will launch on the mission a day early, on 11 May.
Ground crews finished installing the last equipment, which includes 180 tools needed to manipulate parts of the telescope, into the shuttle's payload bay on Wednesday, according to Tracy Young of NASA's Kennedy Space Center.
Now mission managers are looking to see how much time can be shaved off final preparations and are hoping to launch a day before the current launch target of 12 May.
They want to provide as many days as possible to launch the shuttle before 14 May, when there's a black-out window for shuttle launches that will last until 22 May. During that time, an Air Force facility needed to track shuttle launches will be used for military operations instead.
During a press briefing on Thursday, NASA officials discussed some of the safety concerns for the mission. Despite initial worries, they said the debris from an unprecedented collision between two satellites in February should not pose a significant risk to the shuttle, even though it will fly at a higher orbit – which lies closer to the debris – than typical shuttle missions to the International Space Station.
Initial estimates put the risk of a catastrophic impact with orbital debris at 1 in 185. But further analysis suggests the mean risk is now 1 in 221, deputy space shuttle programme manager LeRoy Cain told reporters. That risk level is lower than a limit of 1 in 200, above which special approval for the mission would be required by top officials.
The shuttle Atlantis will drop down to a lower orbit after the spacewalks, which will reduce the risk of a collision with orbital debris. The shuttle will also spend as much time as possible flying with its tail forward and its payload bay pointed at Earth, an orientation that protects vulnerable parts, like the shuttle's nose cap.
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