HOUSTON – The
vital heat shield protecting NASA's space shuttle Endeavour appears in good
shape after launch despite three apparent debris hits, mission managers said Thursday.
Cameras mounted
to Endeavour's external tank caught nine pieces of foam insulation break off
during liftoff, three of which appeared to strike the orbiter, said John
Shannon, STS-118 mission management chairman, during a briefing here at the
Johnson Space Center. None of the impacts are believed to have caused
significant damage, he added.
Shannon
said one fragment popped free about 24 seconds after Endeavour's
Wednesday launch and appeared to hit the end of the shuttle's aft-mounted
body flap.
A second
piece separated about 58 seconds into the flight and appeared to cause a spray
of material on Endeavour's starboard wing. The third fragment separated near
the three-minute mark, much too late to cause significant damage.
But the
foam incidents did not appear to be severe in images relayed to Earth by
Endeavour's fuel tank camera, Shannon said.
"I
would tell you that the picture was extremely underwhelming," Shannon said
of the apparent starboard wing hit. "The report initially was that you got
a spray of debris from this area and of course that brings up images of
Columbia...this was not even remotely of the same magnitude."
A
briefcase-sized piece of foam fell from the shuttle Columbia's fuel tank during its 2003 launch,
piercing the heat shield and leading to the loss of the orbiter and its
seven-astronaut crew.
During
Endeavour's rendezvous with the International Space Station (ISS) at 1:53 p.m.
EDT (1753 GMT) tomorrow, astronauts aboard the orbital laboratory will take
detailed photographs of the three impact points before the orbiter docks. The
images, as well as data taken from the shuttle crew's heat
shield inspection today, will be analyzed by engineers on Earth.
Commanded
by veteran astronaut Scott Kelly, the STS-118 crew's major
tasks include attaching a starboard (S5) truss spacer to the ISS,
delivering fresh cargo and shuffling space station components to make way for
further construction.
Minor
alarm
Endeavour's
crew awoke to an alarm last night, which turned out to be the failure of
an oxygen tank pressure sensor. Liquid oxygen is used in Endeavour's fuel cells
to help generate electricity for the shuttle, but must gently boiled into gas
by heaters when power is needed.
"With
the failure we're going to have to use manual heater control. The automatic
heater control is not functional on that tank," said Matt Abbott, NASA's STS-118
lead shuttle flight director.
Because of
the faulty sensor, the astronauts will need to turn on the heaters via flight
deck controls about once every hour to keep feeding the shuttle's electricity-generating
fuel cells.
"It's
just a matter of flipping the switch on, flipping the switch off," Abbott
said of the procedure, which should not impact the crew's busy ISS construction
schedule during their 11-to-14-day mission. "It will require some
babysitting."
Endeavour's
STS-118 mission marks the first time in space for three mission specialists,
including teacher-astronaut Barbara
Morgan as well as Alvin Drew and Tracy Caldwell. Shuttle pilot Charlie
Hobaugh and mission specialists Dave Williams and Rick Mastracchio round out
the crew.
The astronauts awoke early Thursday
to the song "Where My Heart Will Take Me" by Russell Watson, the
theme to "Star Trek: Enterprise," chosen for Mastracchio.
"They're
having a great time," Abbott said of the rookies, adding that every one of
the crew members looks like "they're having a ball."
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