NASA's
shuttle Discovery and its seven-astronaut crew are cleared to launch toward the
International Space Station (ISS) on May 31 to deliver the high-flying laboratory's
largest orbital room, mission managers said Monday.
Discovery
is officially set to lift off from NASA's Kennedy Space Center in Cape
Canaveral, Fla., on a two-week mission to install Japan's
massive Kibo laboratory at the space station. The shuttle will launch at
5:02 p.m. EDT (2102 GMT) on May 31.
"It's a
challenging mission," said John Shannon, NASA's space shuttle program manager,
during a mission briefing today. "It's the largest international partner
laboratory flown."
Commanded
by veteran shuttle flyer Mark Kelly, Discovery's STS-124 astronauts plan to
perform three spacewalks during their 14-day mission to attach the 37-foot
(11-meter) segment of Japan's Kibo lab, relocate the tour bus-sized module's attic-like
storage compartment and perform other station maintenance.
They will
also replace American astronaut Garrett Reisman with fellow U.S. spaceflyer
Gregory Chamitoff during the spaceflight despite an ongoing investigation into the
Russian Soyuz spacecraft that serve as emergency lifeboats for station crews.
Soyuz
landing issues
NASA
shuttle and station officials considered delaying Discovery's mission due to an
ongoing investigation into last month's harrowing,
off-target landing of a Russian Soyuz spacecraft returning three astronauts
home from the ISS. Russian engineers are working to identify the exact cause of
the malfunction - the second in a row for Russia's Federal Space Agency.
The Soyuz
TMA-11 vehicle returned to Earth on April 19 with U.S. station commander Peggy Whitson
and two crewmates aboard. But the spacecraft experienced a module separation problem
and a glitch that sent it into a backup, ballistic
landing mode that reentered the Earth's atmosphere at a steeper-than-normal
angle that landed short and subjected the astronauts to extreme G-forces.
Another
Soyuz spacecraft currently docked at the station, however, is clear for use in
an emergency, leaving NASA officials confident that it is safe to replace Reisman
with Chamitoff during Discovery's STS-124 mission after next week's launch. Chamitoff
is due to return to Earth in November during a subsequent shuttle flight.
"We now know
that the Soyuz is acceptable for emergency return; it's acceptable to leave Greg
on orbit," said NASA's space operations chief Bill Gerstenmaier. "So that's our
basic plan, and that's the way we're heading."
Gerstenmaier
said that while Russian engineers hope to release their initial findings by the
end of the month, a final answer on whether Soyuz spacecraft are clear for
routine use is still pending.
"I don't
think they're near a final resolution," he added. "It's going to take a little
bit time for them to work through this to understand what they've got and what
the root cause is."
New fuel
tank to fly
Discovery's
May 31 launch will also include the first flight of an external shuttle fuel
tank built from scratch with all of the safety modifications stemming from the
2003 Columbia accident. A piece of fuel tank foam insulation popped free during
the shuttle Columbia's Feb. 1, 2003 launch and damaged the orbiter's heat
shield, leading to its destruction and the loss of seven astronauts during
reentry.
"This
essentially is the completed return-to-flight tank," Shannon said of Discovery's
fuel tank. "I expect this to be the best performing tank that we have had to
date."
Discovery's
STS-124 mission will mark NASA's third shuttle flight of the year to deliver a
new international room to the space station. The shuttle mission is the third
of up to five planned for 2008, is the 10th flight since the Columbia accident
and will leave 10 more to follow by 2010, when NASA retires its three-orbiter
fleet to make way for its Orion capsule successor.
The
remaining flights this year include NASA's last flight to overhaul
the Hubble Space Telescope, tentatively slated for an Oct. 8 launch, and a
planned Nov. 10 flight to deliver supplies and equipment to the ISS.
"This flight
of STS-124 is going to be something of a milestone in the space shuttle
program," Shannon said. "We're really hitting the halfway point here."
advertisement
