London, June 18 : NASA has unveiled an elaborate contingency plan to rescue the shuttle Atlantis should it get into trouble while on its way to repair the beleaguered Hubble Space Telescope.
According to a report in Nature News, though NASA had long planned to send a shuttle to repair the Hubble Space Telescope, after the Columbia shuttle disaster in 2003, the mission was cancelled amid concerns about how the crew would be rescued if the shuttle were damaged.
However, in 2006, the repair mission was reinstated and scheduled for this year, with NASA intending to send the shuttle Atlantis out to Hubble.
The agency has now unveiled an elaborate rescue plan to be put into action if Atlantis should get into trouble.
"The rescue scenario will come into play if Atlantis is irreparably damaged during launch - such as by taking a knock to its thermal tiles - and is unable to bring the crew back to Earth," said Don Savage, NASA's Hubble mission spokesman.
Although the odds of such damage occurring are estimated at only 1 in 400, NASA will have a second shuttle, Endeavour, waiting on a neighbouring launch pad, ready to blast into action and retrieve the crew if necessary.
The crippled Atlantis will only be able to survive in orbit with extreme power conservation for between 17 and 25 days, so Endeavour must reach it within that time.
Endeavour will be primed to launch within four days of Atlantis, and the rescue mission is scheduled to take eight days from launch to landing.
Endeavour would rendezvous with Atlantis within a day, but would then be faced with the tricky task of transferring the stranded crew to the rescue shuttle.
To do this, the two shuttles must line up their payload bays at a 90-degree angle to one another, and Endeavour's robotic arm will then reach out to grab the orbital boom system on Atlantis.
Once secure, astronauts from Endeavour will retrieve their colleagues during a series of three spacewalks between the shuttles. The Atlantis shuttle would then be released and sent crashing into the ocean. f all goes well, the Atlantis astronauts will replace Hubble's gyroscopes and batteries, fix its broken camera and spectrograph, and add two new, more advanced pieces of monitoring equipment and an outer insulating blanket.
"We're doing this because Hubble is deemed to be a national treasure that has helped to rewrite astronomy textbooks," said Savage. "This will make Hubble more powerful than it has ever been," he added.