* Touchdown set for 11:57 a.m. EST Wednesday in Florida
* Landing marks end of oldest shuttle's flying career
* Discovery's next mission: museum piece
By Irene Klotz
CAPE CANAVERAL, Fla., March 8 Astronauts aboard
the space shuttle Discovery prepared on Tuesday to bring NASA's
most-traveled spacecraft back to Earth, wrapping up its 39th
and final mission.
Touchdown at the Kennedy Space Center in Florida is
scheduled for 11:57 a.m. EST (1657 GMT) on Wednesday, with a
backup landing opportunity available at 1:34 p.m. (1834 GMT)Meteorologists expect the weather will be suitable for
Discovery blasted off on Feb. 24 to deliver supplies, a
storage room and an outdoor platform to hold spare parts for
the International Space Station, a $100 billion project of 16
nations that has been under construction 220 miles (350 km)
above Earth since 1998.
The mission completed the U.S. portion of the station, with
a final Russian laboratory due to arrive next year.
Two more shuttle flights are planned before NASA ends the
30-year-old shuttle program. On April 19, the shuttle Endeavour
is scheduled to launch with the station's highest-profile and
most expensive science experiment -- the $2 billion Alpha
Magnetic Spectrometer particle detector.
The last mission, a cargo run to the station aboard the
shuttle Atlantis, is slated for liftoff on June 28.
"It's bittersweet to see the last flight of an orbiter,"
said Johnson Space Center director Michael Coats, a former
astronaut who served as the pilot on Discovery's first mission
"You're sad to see an orbiter on its last mission that's
about to go into a museum. But it also makes you feel proud of
the team and what they've accomplished in the last 30 years,"
Coats said. "It's an amazing vehicle and I think we're going to
really miss it."
Two other shuttles were destroyed in accidents. Challenger
broke apart over the Atlantic Ocean shortly after takeoff on
Jan. 28, 1986, killing seven astronauts. Columbia disintegrated
as it re-entered Earth's atmosphere over Texas on Feb. 1, 2003,
killing seven more astronauts.
The United States is retiring its surviving three space
shuttles due to high operating costs and to free up funds for
work on a new launch system that can carry people and cargo to
destinations beyond the space station's orbit where the
shuttles cannot go.
Wrangling over the U.S. budget, however, has blocked NASA
from starting any new programs.
"It's always been our plan that at some point we would no
longer fly the shuttles. I feel very strongly that the agency
is about exploration and about getting beyond low-Earth orbit,"
said LeRoy Cain, head of NASA's shuttle mission management
team. "At some point, we need a system that can do those
missions, and the shuttle's frankly not that system."
"The hardest part of this for me is giving up the
capability, because if you really look at what this spacecraft
does, it can do everything except leave low-Earth orbit," added
Discovery commander Steven Lindsey, in an in-flight interview.
"I suspect that sitting on the runway, when it's time for
me to get out I don't think I'm going to want to leave my
seat," Lindsey said.
The United States will rely on the Russian government to
launch astronauts to the space station, though it hopes to
eventually buy rides from commercial companies, if any develop
Cargo runs will be handled by Russia, Europe and Japan, as
well as two U.S. firms, Space Exploration Technologies and
Orbital Sciences Corp ORB.N.
(Editing by Jane Sutton and Philip Barbara)