Atlantis Releases Hubble, Heads Home
CAPE CANAVERAL, Fla. - Space shuttle astronauts rescued it from infamy and repeatedly helped polish its legacy.
On Tuesday, a crew let go of the Hubble Space Telescope for the last time, leaving it in the best condition of its 19-year existence but also at the whim of electronic circuits and space junk, with no hope for another comeback.
Atlantis' astronauts gingerly dropped the Hubble Space Telescope overboard, sending the restored observatory off on a new voyage of discovery and bidding it farewell on behalf of the planet. Hubble — considered better than new following five days of repairs and upgrades — will never be seen up close by humans again. This was NASA's last service call.
Atlantis mission specialist Megan McArthur relaxed a robotic arm's grip on the 12.5-ton observatory just before 9 a.m. and the shuttle quietly eased away, 350 miles above Africa.
"Hubble has been released," mission commander Scott Altman radioed several minutes later. "Now Hubble can continue on its own, exploring the cosmos and bringing them to us, as we head for home in a few days."
The Atlantis crew soon turned its attention to a final inspection of shuttle heat shields in preparation for a planned landing Friday that would end a hugely successful 11-day mission - the fifth and last to service Hubble.
Eight more shuttle flights remain before NASA retires the fleet, all to the International Space Station. No other spacecraft can carry the combination of people and hardware needed to fix Hubble again.
Despite that sad reality, scientists are frothing at the chance to grab control of Hubble's new and improved instruments.
"It's show time for us now," said Eric Smith, Hubble program scientist at NASA Headquarters in Washington, D.C. "We got everything we asked for. We're going to have a great mission for years to come."
While Atlantis held Hubble for seven days, two teams of spacewalkers installed a state-of-the-art camera and high-powered spectrograph, and resuscitated two older instruments that had failed.
With new batteries, gyroscopes, pointing sensors and thermal blankets also added, NASA conservatively expects Hubble to survive another five years, and possibly beyond 2020.
Not bad results for a mission that was cancelled in 2004, the year after the shuttle Columbia was lost, because it was considered too dangerous.
The Atlantis crew on Tuesday continued with precautions instituted since then to ensure its safety.
Altman and pilot Greg Johnson fired the shuttle's rear orbital engines to adjust their trajectory, dropping more of their flight path into a lower altitude that is less cluttered by space debris.
The mission was at a greater risk of a catastrophic hit from debris than missions to the space station: 1 in 229 compared to about 1 in 300.
The move also gave Atlantis a chance to land at Kennedy Space Center earlier than originally planned, just after 10 a.m. Friday, to improve the chance of catching good weather.
Atlantis then began its heat shield inspections. Analysts at Johnson Space Center in Houston reviewed digital images of the shuttle's heat shields overnight.
Managers are expected to announce Wednesday whether Atlantis is cleared to re-enter Earth's atmosphere, or whether potential debris damage needs a closer look.
The possibility of irreparable damage, though unlikely, hasn't yet been ruled out. So technicians at KSC this week have continued to ready shuttle Endeavour for what would be an unprecedented rescue mission.