This story
was updated at 9:30 p.m. EDT.
CAPE CANAVERAL, Fla. – The space shuttle Discovery is
back at the launch pad as workers prepare the spaceplane for NASA’s
second orbiter mission since the 2003 Columbia accident.
A massive crawler carrier hauled Discovery and its mobile
launch platform up to Pad 39B at the Kennedy Space Center (KSC) here more than
seven hours after leaving the shelter of NASA’s Vehicle Assembly Building
(VAB) at about 12:45 p.m. EDT (1645 GMT).
“It’s a fabulous feeling to see that we’re
rolling Discovery back to the launch pad for our next launch attempt,”
NASA’s shuttle program manager Wayne Hale told reporters after riding
with the orbiter as it left the VAB. “I think we’re on a really
good path to make that July 1 window opening day.”
The orbiter's move marked a major milestone for NASA's STS-121
mission – the agency's second shuttle test flight since the 2003 Columbia accident.
Discovery is currently slated to launch its astronaut crew, commanded by
shuttle veteran Steven
Lindsey, on a mission to test shuttle fuel tank modifications, orbiter
repair techniques and resupply the International Space Station (ISS) between
July 1 and July 19.
Hale said that preliminary results of wind tunnel tests to
check changes to Discovery’s external fuel tank – primarily the removal
of a foam ramp that guarded pressure lines – are positive, but
won’t be final for about three weeks. While wind tunnel tests have
concluded, a detailed analysis of their data is still underway, he added.
“We have to wait until we get to the bottom line,”
Hale said. “We could be smarter tomorrow and somebody could find out
something we need to deal with.”
Today’s rollout allowed Discovery to join its payload
– a cargo pod dubbed Leonardo, spare space station parts and other items
– at Pad 39B. The Leonardo module and equipment palettes will be loaded
into Discovery’s cargo bay after engineers shroud the spacecraft with its
protective Rotating Service Structure, an activity currently slated to occur
Sunday, NASA officials said.
Meanwhile, Hale said he is confident that Discovery’s
planned July launch will be the first of three shuttle flights this year.
Additional launch opportunities arise on Aug. 28 and Dec. 14, he added.
“Now it will be tight…it depends a lot on the
tank,” Hale said of the third shuttle flight’s external tank
– External Tank 123 – which engineers are working to complete early
to support a possible rescue flight should anything go awry during the planned
August space shot. “Given that, we have a good shot at making three
shuttle flights this year.”
Preparing Discovery
Engineers at KSC spent the last week mating Discovery to the external
tank and solid rocket boosters – known as the launch stack – that
will push the 100-ton spaceplane into orbit. During that time, shuttle workers
also took detailed photographs of the orbiter's heat shield to be compared to
images from in-orbit inspections during the STS-121 mission, integration
engineers told SPACE.com,
adding that they took similar photos while preparing Discovery for NASA's first
post-Columbia mission STS-114.
"Everyone was excited for STS-114 and they're doubly so
for STS-121 because it's our opportunity to get into regular launch mode
again," said Tim Riley, the shuttle's integrated operations chief for NASA
contractor United Space Alliance, in a recent interview. "Hopefully, we'll
get a couple more [shuttle flights] in this year.
Discovery's STS-121 mission is the last of two post-Columbia
accident test flights to shakedown new shuttle safety and repair methods before
NASA can resume
construction of the ISS later this year. While NASA is currently targeting
July 1 to launch Discovery's STS-121 mission, the orbiter has a flight
window that extends through July 19. Additional shuttle launch opportunities
open in late August and mid-December.
NASA's 5.5 million-pound (2.5 million-kilogram) crawler
vehicles have transported NASA spacecraft to and from their launch pads since
they first became operations in 1966. The entire assembly – including
Discovery, its fuel tank and boosters, mobile launch platform and crawler
vehicle – weight about 17.5 million pounds (7.9 million kilograms) and
move at a top speed of about one mile per hour (1.6 kilometers per hour).
“It was great,” said Hale, who rode the immense
crawler as hefted Discovery toward the launch pad. “It’s better
than going on a cruise ship.”
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