This story
was updated at 6:29 p.m. EDT.
HOUSTON - Space
shuttle Discovery returned to Earth on Saturday, ending a successful 13-day
mission that completed the International Space Station's backbone and brought
the outpost to full power and symmetry with the addition of two final solar
array wings.
Discovery's
STS-119 commander Lee Archambault piloted NASA's oldest orbiter to
a safe touchdown at 3:13:17 p.m. EDT (1913:17 GMT) on Runway 15 at the
Kennedy Space Center's Shuttle Landing Facility in Cape Canaveral, Florida. The
return was delayed by one orbit to provide time for clouds and gusting
crosswinds to clear from the vicinity of the landing strip.
"Welcome
home Discovery after a great mission to bring the International Space Station
to full power," astronaut George Zamka told the crew from Mission Control
here.
"Thank you
very much, it is good to be back home," Archambault replied.
Returning with
Archambault and Antonelli on Discovery were mission specialist John Phillips,
lead spacewalker Steven Swanson, educator astronauts Joseph Acaba and Richard
Arnold II, and Sandra Magnus, who was returning
from the space station after 134 days in orbit. She traded places with Japan's
first long-duration crew member, Koichi Wakata, who launched with to the
station with the STS-119 crew.
"I'm looking
forward to being home and seeing everyone today, hopefully," Magnus said
early Saturday.
Space
station at full power
The STS-119
crew launched on March 15, bringing the 30,000-pound (13,607-kg) Starboard 6,
or S6, truss segment, a 45-foot (13.7-meter) long girder tipped with two
115-foot (35-meter) solar
wings to the space station.
Swanson and
Arnold bolted the truss segment to its adjoining piece on the right edge of the
station during the mission's first spacewalk, completing the station's 356-foot
(108-meter) backbone. Two subsequent spacewalks by Swanson, Arnold and Acaba
worked on configuring the outpost's outside equipment for future shuttle
missions, as well as the arrival of Japan's first unmanned cargo craft, the
HTV.
With the S6
truss installed, the astronauts deployed the segment's solar arrays, nearly
doubling the available power to the station. With all eight wings extended, the
station - now symmetrical in appearance - generates enough electricity to power
42 average-size homes. It is now about 81 percent complete.
"This is really
an amazing time and an amazing mission," said NASA space operations chief William
Gerstenmaier after Discovery landed.
Gerstenmaier
said he was awestruck at the first images of the space station with its
complete power grid, which astronauts beamed down Wednesday after undocking.
"That's
probably the most amazing image that you can ever imagine," he said.
Discovery also
delivered a replacement distillation unit for the station's malfunctioning
urine processing assembly, part of a water recovery system that will be used to
recycle the crew's waste into potable water. After some initial trouble that
required the replacement of filters, space station commander Michael Fincke was
able to get the recycler to
process urine,
and samples of the resulting water were brought back to Earth on Discovery to
be tested.
The addition of
the solar arrays and the installation of the water recovery system was
necessary before the space station could increase its crew compliment from
three to six residents.
With both
accomplished, the orbiting lab was ready for
the arrival
of the Russian Soyuz TMA-14 spacecraft at 9:06 a.m. EDT (1306 GMT) Saturday,
just a few hours before Discovery landed, delivering the station's next
increment crew and American billionaire Charles Simonyi, the world's first
repeat space tourist. The Expedition 19 astronauts will continue to ready the
outpost before helping to form the first six-person crew in May.
Tripping the
boundary
While
Discovery's heat shield received a clean bill of health with respect to launch
and orbital debris, mission managers were still expecting the shuttle to "trip the boundary layer"
early as a part of an experiment designed to improve engineers' understanding
of how spacecraft re-enter the atmosphere.
Engineers added
a slight protuberance, or "speed bump," to one of the thousands of heat shield
tile on the spacecraft's underbelly to disturb the hypersonic airflow
surrounding the orbiter, creating turbulence that, in turn, should result in
increased heating downstream of the specially-fabricated tile's position near
the rear of the left wing. The bump posed no risk to the shuttle or its crew,
mission managers said.
"Obviously the
shuttle is one of a kind, it's a winged vehicle flying at these very high Mach
numbers, and that boundary layer transition [test] will allow us to collect
some very good heating data," entry flight director Richard Jones Friday here
at the Johnson Space Center.
The bump should
have its effect as the orbiter travel Mach 15, or 15 times the speed of sound.
In addition to sensors installed under and around the tile, a U.S. Navy
aircraft will fly under Discovery's path, recording infrared imagery of the
orbiter's belly as it trips the boundary.
The results of
this test may help NASA create a better heat shield for its next generation
crew exploration vehicle, Orion, being designed to take astronauts to and from the
space station, as well as return humans to the Moon.
Other than that
intentional protuberance, Jones said that the shuttle was safe for reentry.
"This mission has just been exceptionally clean, Discovery and her crew have
been performing just flawlessly," he commented.
Discovery's
mission marked the 125th for NASA's space shuttle program and the 36th flown by
the orbiter. NASA plans to launch up to eight more shuttle missions by 2010 to complete
station construction and one more - set to launch May 12 - to overhaul the
Hubble Space Telescope one last time.
The mission was
also the 100th flight since the loss of space shuttle Challenger in January
1986, which was highlighted by the delivery of the 100th bouquet of flowers to
Mission Control by the Shelton family of Texas. Space enthusiasts Mark, Terry
and their daughter MacKenzie Shelton have been sending the roses - one for each
space shuttle crew member and a white rose for those lost in flight - for every
shuttle flight over the last 21 years.
"They represent
many families out there that are looking at NASA and are appreciative of the
work that we hope we are doing for everyone out there," said Jones.
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