Two astronauts
will venture outside the International Space Station Tuesday to kick off their
mission's first spacewalk while their crewmates inside begin unpacking the tons
of cargo delivered by the shuttle Discovery.
Discovery
astronaut Danny Olivas and station crewmember Nicole Stott plan to don their
NASA-issue spacesuits and float outside at 5:49 p.m. EDT (2149 GMT) to begin a 6
1/2-hour maintenance call on the orbiting laboratory. Their main chore will
be the removal of an old, enormous ammonia coolant tank.
The ammonia
tank weighs about 1,800 pounds (816 kg). While it will float in microgravity
when removed, it will still carry the same mass as a small compact car so Stott
and Olivas will have to be careful, said Zeb Scoville, lead spacewalk officer
for Discovery's
mission.
"It's a
pretty complex task in terms of mass handling," said Scoville.
The old
tank is nearly empty and will be replaced with a new one to help keep the space
station's systems cool. It will take two spacewalks to make the swap, with the
second one scheduled for Thursday. Astronauts must also take care to avoid
contamination from toxic ammonia while working with the tank, mission managers
said.
Stott and
Olivas will also retrieve a suitcase-like material exposure experiment and a
European experiment from the end of the station's Columbus laboratory.
Tuesday's
spacewalk will mark the first for Stott and the third for Olivas, who is
leading all three of the spacewalks planned for Discovery's 13-day resupply
mission to the space station. The two astronauts camped out in the station's
airlock early Tuesday to purge their bodies of nitrogen in a protective measure
to avoid developing the bends during their spacewalk.
"I think it's
going to be really exciting," said Stott, who joined the station crew Sunday
after arriving aboard Discovery.
Delivery day at station
While
Olivas and Stott work outside the station, the
11 astronauts inside the outpost will begin unloading the nearly 8 tons of fresh
supplies and science gear from a cargo pod delivered by Discovery's crew late
Monday.
One of the
top items on Tuesday's move-in list is a treadmill named after TV
comedian Stephen Colbert, who won the naming rights for a new space station
room in an online NASA poll earlier this year, but got the exercise gear
instead.
NASA dubbed
the treadmill the Combined Operational Load Bearing External Resistance
Treadmill, or COLBERT, as a consolation prize after naming the new space
station room Tranquility in honor of the Apollo 11 moon base. The $5 million COLBERT
treadmill launched to the station in a
myriad of pieces to be assembled in space.
"It's in
many, many pieces," space station flight director Ron Spencer told reporters
late Monday. "I'm not sure when we plan on putting it together."
The
treadmill components are packed in several bags that will be stored aboard the
space station until mid-September, after Discovery leaves and a new unmanned
Japanese cargo ship arrives. Only then, mission managers said, will astronauts
have time for the 20 hours or so it will take to build the COLBERT treadmill.
Astronauts
will also move an air-scrubbing device, storage bin and new astronaut bedroom
the size of a large refrigerator into the space station on Tuesday.
"The crew
is going to be quite busy, even after [this] mission is over, for the next few
weeks," Spencer said of the station astronauts.
SPACE.com
is providing complete coverage of Discovery's STS-128 mission to the
International Space Station with Managing Editor Tariq Malik and Staff Writer
Clara Moskowitz in New York. Click
here for shuttle mission updates and a link to NASA TV.
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