This story was updated at 2:00 p.m. EDT.
WASHINGTON - NASA is
hoping to launch the space shuttle Atlantis on the last service call to the
Hubble Space Telescope a day earlier than planned to avoid schedule conflicts
near its Florida launch site, agency officials said Thursday.
The long-delayed
Hubble repair flight, which mission managers have now found to be less
risky than initially thought, would lift off on May 11 at 2:01 p.m. EDT (1801
GMT) if the earlier target is approved next week.
"I feel
fairly confident that we can make a May 11 launch date," said LeRoy Cain,
NASA's deputy shuttle program manager, during a series of mission briefings.
Cain added that after further study, the risk
of damage to Atlantis from space debris has fallen within tolerable limits.
Top NASA
officials will decide whether Atlantis and its crew of seven astronauts will be
ready to launch early. The mission was previously
slated to launch on May 12 from NASA's Kennedy Space Center in Cape
Canaveral, Fla.
Launch
date shuffle
Veteran
shuttle commander Scott Altman and his Atlantis crew initially planned to
launch toward Hubble in October 2008, but NASA postponed the
flight after a serious glitch popped up aboard the space telescope. The astronauts plan to perform five
back-to-back spacewalks to install new instruments and make vital repairs to
Hubble, which celebrates its 19th birthday tomorrow. The upgrades are expected
to extend the space telescope's operational life through at least 2014.
Cain told
reporters that by targeting an earlier liftoff, Atlantis would have at least
two more chances to launch on May 12 and May 13 before standing down due to a
planned military operation at the nearby Cape Canaveral Air Force Station.
If Atlantis
cannot launch by May 13, NASA would have wait until May 22 to try again, Cain
said.
Preston
Burch, NASA's Hubble project manager, said engineers are working around the
clock to pack Atlantis with the new instruments, tools and other gear to
support the five spacewalks on tap to upgrade Hubble. But only time will tell
if they can finish in time for May 11, he added.
"Everything
really needs to go our way in terms of completing our installations and
hookups," Burch said. "Really, our primarily goal is to get it right, to make
sure we don't mess anything up."
Space
debris risk revealed
NASA
officials initially said that Atlantis and its crew would face a higher than
normal risk of damage from space debris, about a 1-in-185 chance, because the
shuttle must fly in a higher orbit than the International Space Station to
reach the Hubble Space Telescope. Hubble orbits the Earth at about 300 miles (482
km), while the space station flies about 220 miles (354 km) above the planet.
NASA
guidelines call for no more than a 1-in-200 chance of damage from debris. After
more study, Cain said Thursday that NASA believes the risk to Atlantis is
lower, about a 1-in-221 chance, and within acceptable limits. Atlantis will
also be moved to a lower orbit soon after its crew releases Hubble back into
space in a move to further reduce the risk, he added.
Atlantis
also has another backup, the space shuttle Endeavour, which is currently
perched atop a second launch pad and standing by to serve as a rescue ship if
needed.
Because
Hubble flies in a higher orbit and different orbital inclination than the
International Space Station, Atlantis astronauts will not be able to seek
refuge aboard the orbital laboratory like recent station-bound shuttle crews. Instead,
NASA has primed Endeavour and a skeleton astronaut crew to launch a
rescue flight and retrieve
Atlantis' crew within 25 days of an emergency.
Shuttle
flight director Tony Ceccacci told reporters that NASA is confident it will not
need any such rescue mission, but will keep Endeavour and its four-man crew on
standby "just in case."
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