After a
series of hurricane-related delays,
a space shuttle fuel tank is finally on heading back to its New Orleans
factory.
The external
tank, one of several to be returned to NASA's New Orleans-based Michoud
Assembly Facility from Kennedy Space Center (KSC) in Florida, rode a barge out
to sea Monday to begin the five-day trip.
"It's just
a signal that everything is getting back to normal," NASA KSC spokesperson
Jessica Rye told SPACE.com.
The
delivery of External Tank-119 (ET-119) to Michoud is vital for NASA's return to
flight effort - which is aimed at launching the space shuttle Discovery and its
STS-121 crew to the International Space Station next year. The ET-119 fuel tank
is currently slated to help launch the STS-121
mission, NASA's second planned orbiter flight since the Columbia disaster.
But first,
engineers must determine how to reduce the chances of potentially harmful
pieces of insulating foam from popping free from protective ramps, known as a protuberance air load (PAL) ramps, on the tank's exterior during launch. Engineers have been studying the
problem at Michoud between hurricanes and hope to pick apart ET-119 for a
closer look.
"The first
step is the non-destructive evaluation on both the hydrogen and oxygen PAL
ramps," explained Martin Jensen, a NASA spokesperson and Marshall Space Flight
Center in Alabama where the agency's External Tank Project Office is based.
"Then we'll do some dissection of those PAL ramps and cut into them. That's the
near-term plan."
Foam debris
shedding doomed the space shuttle Columbia in 2003 when a
1.67-pound chunk of foam fell from its tank during liftoff and pierced the
orbiter's heat shield along its left wing leading edge. The resulting damage
allowed hot gases to enter the wing during atmospheric reentry, which ripped
apart the vehicle and killed its seven-astronaut STS-107 crew.
After two
and half years of study and safety modifications, NASA launched
Discovery on STS-114,
its first return to flight mission, on July 26, only to find unacceptably
large pieces of foam fall from the PAL ramp - previously thought safe - and
other locations during launch. While none of those pieces caused significant
damage to the orbiter, NASA pledged to address the shedding problem once more
before the shuttle's next space shot.
The need
for more study forced NASA to abandon
plans to launch the STS-121 mission aboard Atlantis this year, and instead target
March 2006 for the next shuttle mission.
Last week,
NASA chief Michael Griffin told the Washington Post that the space
agency will likely target May 2006 for its next shuttle flight in order to
recover time lost from facility closures caused by Hurricane
Katrina. That storm - and its successor Hurricane Rita -
damaged Michoud
and Mississippi's Stennis
Space Center during Katrina and Johnson
Space Center (JSC) during Rita.
"But
nothing has been decided," NASA's Dean Acosta, Griffin's spokesperson, told SPACE.com,
adding that any definite launch target change would be made in an official
announcement.
Jensen said
it should take ET-119 and its barge Pegasus until Sunday to reach Michoud in New Orleans, with engineers currently expected to unload it on Monday.
NASA
officials said that the next fuel tank to make the trip from KSC to Michoud
will be ET-120. That shipment should leave Florida in the next few weeks, they
added.
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