NASA mission managers will wait until early
April to pick a new launch date for the space shuttle Atlantis pending additional
repairs and checks of its hail-battered
fuel tank, top agency officials said Wednesday.
The U.S.
space agency is eyeing April 10 as the decision day on whether to press ahead with
a possible mid-May launch for Atlantis or swap its damaged fuel tank with a new
one, which would push the planned space shot to June.
"Our
ultimate goal is to get the best tank that we can get ready to go fly," William
Gerstenmaier, NASA's associate administrator for space operations, told reporters
in a Wednesday teleconference. "It looks like by about April 10 or so, we
should have enough information."
A new shuttle
fuel tank, which would be used if mission managers go for the swap option, is
due to arrive at NASA's Kennedy Space Center (KSC) spaceport in Cape Canaveral,
Florida on April 10, Gerstenmaier added.
A freak
storm bombarded Atlantis at its Pad
39A launch site at KSC on Feb. 26, battering the orbiter and its fuel tank
with hail up to the size of golf balls, etching more than 2,500 dings into
Atlantis' external tank's vital foam insulation [image].
The resulting damage prompted mission managers to delay
the planned March 15 launch of the orbiter's STS-117
spaceflight to allow time for repairs.
NASA
currently has a window stretching from late April to around May 21 to launch
Atlantis' six-astronaut
STS-117 crew towards the International Space Station
(ISS). Commanded by veteran
shuttle flyer Rick Sturckow, the 11-day mission will deliver new
starboard solar arrays to the orbital laboratory.
Swapping
out the damaged fuel tank for a new one would push the launch to no earlier
than June 8, NASA has said.
NASA
shuttle program manager Wayne Hale said Atlantis' hail-spawned delay will likely
limit the space agency to launching four orbiter flights this year - as opposed
to the ambitious
five previously targeted - to continue assembly of the ISS. But that ripple
effect will likely dampen out by mid-2008, he added.
"We expect
that we will be able to get back on the prescribed [flight] manifest in about
12 months," Hale said of the impact. "It certainly does not affect our plan to
complete space station construction by 2010."
NASA plans
to complete at least 13 ISS-bound shuttle flights to complete assembly of the $100
billion orbital laboratory by September 2010, when its three-orbiter fleet is
due to retire to make way for its successor
Orion.
Damage
assessment continues
NASA has
paid close heed to the health of shuttle fuel tank foam since 2003, when a briefcase-sized
chunk popped free during the launch of Columbia and pierced heat shielding on
the orbiter's left wing.
The damage led to the orbiter's destruction,
and loss of its seven-astronaut crew, during as they reentered the atmosphere,
prompting NASA to devise a host
of fuel tank improvements to limit foam shedding during liftoff in the
future.
But statistically
speaking, hail storms the strength of the Feb. 26 tempest are expected to
affect a shuttle flight once every 10 years, NASA officials said, adding that
the last hail-related damage to shuttle hardware occurred 11 years ago.
NASA's
deputy external tank project manager John Honeycutt said Wednesday that most of
the damage to Atlantis' tank is concentrated near the nose cone [image],
where engineers plan to spray a new layer of foam and then sand it into the
proper shape to withstand the aerodynamic heating stresses that occur during
launch [image].
"The long
pole in the tent here is doing the testing and evaluation to make sure that we
can apply this spray foam in a way that it will be safe," Hale said, adding that he is confident the tank can be repaired to fly the STS-117 mission. "We have a
high degree of confidence that it will be, or else we wouldn't have picked this
route, but that work is still ahead of us."
If
everything goes well, and engineering studies of the spray foam repair method
and others bear out, Atlantis could be primed to launch in the mid-May
timeframe, Hale added.
But shuttle
officials stressed that the reason they are not choosing a new launch date for
Atlantis now is to allow the agency's engineering teams to complete their tank surveys
and repairs without any artificial schedule pressure.
"We're
going to fly this tank when it's safe to fly and not before," Hale said.
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