NASA has shuffled
landing options for two astronauts headed to International Space Station later
this year due to shuttle launch date uncertainties.
The U.S.
space agency announced a plan Tuesday to swap the return trips of Canadian
astronaut Robert Thirsk and American spaceflyer Nicole Stott this fall to
ensure that future shuttle mission delays don't extend Thirsk's mission beyond
the traditional six-month duration.
"It would
just put him, timeline-wise, on an earlier return," NASA spokesperson Nicole Cloutier-Lemasters
told SPACE.com from the agency's Johnson Space Center in Houston. "This
is just kind of a preemptive measure in case there is more slippage."
NASA has up
to six space shuttle missions on its 2009 schedule, with the first currently
slated to launch aboard Discovery no
earlier than March 12 on a construction flight to the International Space
Station. Discovery's STS-119 mission has been waylaid since Feb. 12 due to fuel
valve concerns, but NASA officials have said that if they launch shuttle by
around March 13 the delay should not affect launch targets for the rest of the
year.
If
Discovery is unable to launch in mid-March, NASA would have to stand down until
around April 7 – after a preplanned Russian Soyuz launch
of a new crew to the space station. Delaying the spaceflight to April could
cause a ripple delays for subsequent shuttle missions, some of which are
expected to include station astronaut crew swaps.
Thirsk is
currently slated to launch to the space station in late May aboard a Russian
Soyuz rocket as part of the space station's Expedition 20 – the
first six-person mission to the orbiting lab. He is Canada's first
long-duration astronaut and was slated to return home in November during NASA's
STS-129 shuttle mission.
Stott,
meanwhile, is currently scheduled to launch toward the station in August aboard
Discovery. She is also expected to join Expedition 20
and was due to return aboard the Russian Soyuz spacecraft that will launch
Thirsk.
But NASA's
announcement today will swap the return seats for Thirsk and Stott, with the
Canadian spaceflyer landing on the Soyuz and the American returning home on the
November shuttle flight.
NASA
officials said the swap ensures that Thirsk's mission won't exceed the typical six-month
duration for station astronauts, even if the November shuttle flight is
delayed. The longer astronauts fly in the weightless environment of space, the
more exposure they have to space radiation, muscle and bone loss, the space
agency has said.
"At this
point we prefer to keep them [in space] around six months," Cloutier-Lemasters
said.
advertisement
