HOUSTON - Flight
controllers are watching the weather for Discovery's return to Earth Monday and
are planning alternate landing sites should rain storms in Florida prevent the
early-morning touchdown, mission managers said Saturday.
The shuttle undocked from the International Space
Station (ISS) earlier today and flew around the orbital platform before heading
back to Earth.
"The undocking and
fly-around both went by the book," said Paul Hill, lead shuttle flight
director for the orbiter's STS-114 mission. "We couldn't be happier with
the operational success of STS-114."
Discovery's only landing
target Monday is NASA's Kennedy Space Center (KSC) in Cape Canaveral, Florida,
where it launched spaceward on July 26. While the
orbiter is slated to land at 4:46 a.m. EDT (0746 GMT) on Aug. 8, it could also
land 5:21 a.m. EDT (0921 GMT) if weather prevents the initial attempt.
Both KSC and a contingency runway at Edwards Air Force Base in
Southern California will be on call Tuesday if needed, shuttle officials said,
adding that a third airstrip in White Sands, New Mexico is also a landing
option.
Current weather predictions
at KSC call for light and variable winds, a few scattered clouds and a slight
chance of rain during the predawn hours of Discovery's landing opportunities,
they added.
"That's about as good
a forecast as you're going to get in Florida, but I have high hopes," said
Wayne Hale, NASA's deputy shuttle program manager, during a press briefing here
at Johnson Space Center. "You don't commit until
it's time to de-orbit."
By a chance of orbital
mechanics, most of Discovery's Monday landing approach will be over water -
though it will pass over parts of Central America and Cuba before reaching
south Florida and homing in on the at the Shuttle Landing Facility runaway at
KSC. That ground track poses little risk to the populations the shuttle flies
over, a new consideration for NASA since the Columbia orbiter broke apart over
Texas in 2003, scattering debris across the region, shuttle officials said.
"These ground tracks
are low risks in terms of public overflight
hazards," Hale said. "This is a new topic for us, [and] it's not a
concern for our primary landing site at the Kennedy Space Center."
Should Discovery and its
STS-114 crew, commanded by veteran astronaut Eileen Collins, be forced to land
at Edwards Air Force Base, flight controllers have tweaked two trajectories to
shift them away from passing over major population areas in the Los Angeles
Basin, Hale said.
Limiting flight over
populated areas is largely tied to whether Discovery is suffering from any
hazard concerns. This is not the case for the STS-114 flight, shuttle officials
said, citing data from sensors inside the orbiter's wing leading
edges that confirm no impacts from micrometeorites at all thus far in the
13-day mission.
"We thought the
batteries were going to run down after 36 hours," Hale said of the
sensors, which were primarily designed to monitor wing impacts and temperatures
during launch. "This vehicle is in extremely clean shape."
Discovery's STS-114 flight
is NASA's first shuttle mission since the 2003 Columbia accident, which claimed
the lives of seven astronauts and destroyed their spacecraft. Investigators
later found that a chunk of foam insulation fell from Columbia's external tank
and pierced the shuttle's heat shield during launch, critically wounding the
orbiter. The resulting damaged allowed hot gases to enter the orbiter's wing
during reentry and destroy the vehicle on Feb. 1, 2003.
Hale said there are about
47 in-flight anomalies that shuttle engineers will have to address from the
STS-114 flight before they launch the space shuttle Atlantis on NASA's second
return-to-flight mission. The Sept. 22 launch target for Atlantis' STS-121
spaceflight discussed Friday by NASA officials remains tenuous due to the work
required, he added.
Discovery must be turned
around and prepared to serve as a rescue shuttle for Atlantis' STS-121 mission,
and there work still remains to prepare Atlantis itself for launch, Hale said.
There is also the challenge of addressing the foam debris shedding seen during Discovery's launch,
which shuttle officials have pledged to understand and fix before Atlantis or
any other orbiter flies.
"I would not call that
a serious launch date at this point," Hale said
of Atlantis' Sept. 22 target. "It's just a date for people to start
thinking about, is there something we can do by then or not."
Meanwhile, all eyes will be
on Discovery and its STS-114 crew during Monday's planned reentry, shuttle
officials said.
"I'm looking forward
to watching the crew walk off the orbiter in Florida," Hill said.
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