HOUSTON - After
eight days docked at the International Space Station (ISS), the shuttle
Discovery cast off from the orbital laboratory Saturday and began the trip back
to Earth.
Discovery's
seven STS-114 astronauts exchanged hugs and handshakes with the space station's
two-man Expedition 11 crew then closed the hatches between their spacecraft at
about 1:14 a.m. EDT (0514 GMT).
"We thank
them for being such great hosts and we're so happy to have spent time up here
with them," STS-114 commander Eileen Collins told the station's Expedition 11
crew before closing the hatches. "These are memories that we will have forever."
Discovery is
scheduled to land Monday at 4:46 a.m. EDT (0746 GMT) at Kennedy Space Center (KSC)
in Cape Canaveral, Florida.
Shuttle
pilot James Kelly flew Discovery during today's undocking, which occurred on
time at 3:24 EDT (0724 GMT), then guided the orbiter on a fly-around maneuver
that circled the space station at a distance of about 400 feet. His fellow
STS-114 crewmembers photographed the station during the maneuver.
"We have
physical separation," Collins said, as the two spacecraft undocked.
Collins and
her six fellow STS-114 astronauts are the first shuttle astronauts to visit the
ISS since the Endeavour orbiter left the station in December
2002. Their mission, NASA's first shuttle flight since the 2003 Columbia
tragedy, delivered tons of fresh supplies
to the station and is carrying tons more trash and broken or unneeded
equipment back to Earth.
The STS-114
crew spent eight days, 19 hours and 54 minutes at the ISS after docking
at the station on July 28.
"We're not
glad to see you go," Expedition 11 flight engineer John Phillips told the
STS-114 crew. "Great flight, soft landing, and we look forward to seeing you
back in Houston in a few months."
While
Discovery will land Monday, the Expedition
11 astronauts must wait until October - and the end of their six-month stay
aboard the ISS - to return to Earth.
During
their flight, Collins and her crew staged three spacewalks and tested out heat
shield repair techniques and an orbital inspection boom tipped with laser and
camera sensors to scan for cracks and other damage. Those measures were part of
NASA's effort to enhance shuttle flight safety in response to the loss of seven
STS-107
astronauts aboard the Columbia orbiter, which suffered foam debris damage
to its heat shield during launch and subsequently broke apart over Texas during
reentry on Feb. 1, 2003.
In addition
to replacing a vital gyroscope
used to maintain the station's attitude control, STS-114 astronauts swapped out
experiment packages and installed a spare
parts platform - with spare parts included - to ISS' exterior.
STS-114
spacewalker Stephen Robinson also performed the first-ever in-flight repair
of a shuttle's heat shield when used the fingers on his right hand to remove
two strips of space-filling material from between the tiles lining Discovery's
belly.
"It's
really been such a fantastic experience," Collins told Sen. Kay Bailey Hutchinson
(R-Texas) Friday during an Earth-to-space phone call. "I'm looking forward to
seeing my family again."
There may
be an extended gap between Discovery's ISS mission and the next shuttle mission.
NASA officials said Friday that the agency's second return-to-flight mission,
Atlantis' STS-121 spaceflight, will launch no earlier than Sept. 22
- pushed back from Sept. 9 - to allow engineers to study and fix an external
tank foam insulation shedding problem seen during Discovery's launch.
As
Discovery shot into space, a nearly 1-pound piece of foam fell from its
external tank - it did not hit the orbiter - in a similar manner to the foam
loss that crippled Columbia's heat shield. NASA officials said they will not
launch another shuttle until the foam debris issue is resolved.
"Space
exploration isn't easy," Collins said told Congressman Tom DeLay (R-Texas) in
the Friday phone call. "Not everything is going to be 100 percent successful,
but the important thing is we're learning."
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