HOUSTON - Atlantis astronauts will
prime their spacecraft for a planned Friday landing as they enter the
homestretch of NASA's last-ever visit to the Hubble Space Telescope.
Shuttle commander Scott Altman and
his seven-astronaut crew will check Atlantis' systems today and convert the
spacecraft into a 100-ton glider for landing after giving the 19-year-old
Hubble a new lease on life.
"It's hard to believe that we're
coming to an end here," Altman radioed Mission Control Wednesday.
The astronauts are nearing the end
of an 11-day mission Hubble and received a congratulatory call from U.S.
President Barack Obama late Wednesday lauding their work to overhaul the iconic
observatory for the last time.
"Like a lot of Americans, I've been
watching with amazement the gorgeous images you've been sending back, and the incredible
repair mission you've been making in space," President Obama said, adding
that the space telescope is an inspiration to the American public. "By allowing
Hubble to continue on its journey, you've really allowed all of us to continue
on our journey of growth and exploration."
The Atlantis crew is also expected
today to testify from space briefing during a NASA budget hearing by Senate
Commerce, Justice and Science Appropriations Subcommittee. They are due to
discuss their mission with reporters after test firing the shuttle's thrusters
and checking its flight control surfaces in a standard systems check.
Hubble's last visit
The shuttle astronauts steamed
through a five-spacewalk marathon to outfit Hubble with state-of-the-art
instruments and extend its life through at least 2014. It is NASA's fifth, and
final, mission to the space telescope before the agency retires its three-shuttle
fleet next year.
During their flight, the Atlantis
crew added a new wide-field camera and super-sensitive spectrograph, as well as
replaced vital gear like batteries, gyroscopes and insulation. They also repaired
two long-dead instruments - an advanced camera and older spectrograph - that
were never designed to be fixed in space.
They completed their work on Tuesday
and released
Hubble back into space. They are slated to land tomorrow at 10:01 a.m. EDT (1401 GMT)
on a runway at NASA's Kennedy Space Center in Florida.
"We've been training for this flight
for a few years now, so I know we're all proud about what we've accomplished,"
astronaut Megan McArthur told reporters Wednesday. "But we're also looking
forward to taking a little break."
Homeward bound
NASA is hoping for a break in the
weather for the astronauts' Friday return. The Spaceflight Meteorology Group
here at NASA's Johnson Space Center has warned that the potential for rains and
thunderstorms could delay the shuttle landing.
Mission Control ordered the Atlantis
crew to shut down some unneeded systems and backup computers in order to
conserve power in case weather keep the astronauts aloft for
another day or two. NASA will only target the Kennedy Space Center, Atlantis'
home port and launch site, for landing on Friday, but could call up a back up
site in California if required.
Today, while the rest of their
crewmates prepare Atlantis for re-entry, Altman and shuttle pilot Gregory H.
Johnson will use a computer simulator to rehearse their approach and landing.
It has been nearly two weeks since they practiced landing Atlantis in a
modified NASA aircraft, so the simulator is vital, Altman said.
"This program refreshes us on that
and gives us a chance to practice before we put it all on the line on landing
day," Altman said. "I think it's a great rehearsal but the proof's going to be
in the pudding when we get back, and I'm looking forward to getting her back
down soon."
SPACE.com is providing continuous
coverage of NASA's last mission to the Hubble Space Telescope with senior
editor Tariq Malik in Houston and reporter Clara Moskowitz in New York. Click here for mission
updates and SPACE.com's live NASA TV video feed.
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