This story was updated at 8:41 a.m. EST.
Two astronauts will celebrate the International Space Station?s 10th birthday with some mundane, but much needed, spacewalk maintenance today.
Endeavour shuttle astronauts Heide Stefanyshyn-Piper and Shane Kimbrough are slated to float outside the station?s airlock at 1:45 p.m. EST (1845 GMT) for the second of four spacewalks aimed at cleaning and lubricating a jammed solar array gear.
But today?s spacewalk will be the $100 billion space station?s first of a new decade in Earth orbit. Its first element, the Russian-built Zarya control module, launched into space 10 years ago today.
?It?s hard to believe it?s been 10 years,? said Kirk Shireman, NASA?s deputy station program manager, who remembers it being a cold day on the steppes of Kazakhstan when Zarya roared spaceward from Baikonur Cosmodrome. ?This Thursday is a major milestone for the space station.?
Zarya was the first station?s first room. Since its 1998 launch, the outpost has grown from an orbiting studio apartment into a three-bedroom research laboratory with a Canadian robotic arm and modules from Russia, the U.S., Europe and Japan.
The space station has circled the Earth more than 57,309 times and traveled a distance of more than 1.3 billion miles (2 billion km). About 165 people from 15 different countries have visited the 313-ton orbiting laboratory.
Room for 6
Endeavour?s astronaut crew is delivering vital hardware to double the space station?s crew capacity up to six astronauts per mission next year. Chief among their cargo: a water recycling system that converts urine, sweat and wastewater back into drinking water and new gear to expand the station into a five-bedroom, two bath, two kitchen space research outpost.
Equally important are the four spacewalks planned for the mission, which are aimed at cleaning metal grit from a massive gear that turns the starboard solar arrays like a paddlewheel to always face the sun. The gear has been damaged for more than a year, with Stefanyshyn-Piper leading a spacewalking team on the arduous chore of replacing bearings, cleaning the mechanism and greasing it up to extend its performance.
?This is what you have to do to live and work in space 24-7, 365,? NASA chief Michael Griffin told SPACE.com, adding that making unexpected fixes are vital for the station and future trips back to the moon and on to Mars. ?It?s a pretty humble, workman-like task, and I?m sure there?s going to be some bobbles as we figure out how to do it, but this is the kind of stuff that you have to do.?
Today?s spacewalk will be the 116th trip outside the station for maintenance and construction. To date, astronauts have lived continuously aboard the station since 2000 and spent 725 hours and 40 minutes working in space to build the still un-finished orbiting laboratory.
NASA plans eight more shuttle missions to complete the space station, as well a ninth to overhaul the Hubble Space Telescope, before retiring its aging, three-orbiter fleet in September 2010.
Lost bag?s legacy
Stefanyshyn-Piper and Kimbrough are going into today?s spacewalk determined to keep careful track of all of their tools.
During a Tuesday spacewalk, a 30-pound (13-kg) bag of crucial tools for cleaning up the gear escaped from Stefanyshyn-Piper while she was trying to clean gobs of grease that had leaked all over her equipment.
"You have to learn from your mistakes. We're definitely not going to do it again, you?re not going to see us lose another bag,? she told the Associated Press Wednesday. ?We?re going to double and triple check everything from here on out.?
With the loss of Stefanyshyn-Piper?s bag and the grease guns, scrapers and wipes it included, she and Kimbrough will have to share their remaining gear in order to complete their cleaning tasks. They plan to improvise a makeshift lubrication tool by preparing some terry cloth-like wipes with the space grease ahead of time to avoid slowing each other down too much by having to share one set of tools, mission managers said.
The astronauts will also add a touch of grease to the space station?s Canadarm2 robotic arm. They?ll also reposition pair of carts on the outpost?s backbone-like truss to set the stage for the deliver of new starboard solar wings early next year.
But the solar array gear cleaning will take the bulk of their time and so far, the orbital tune-up job has gone well, NASA officials said.
?It?s going perfectly,? said space station flight director Ginger Kerrick on Wednesday. ?Just as expected.?
NASA is providing live coverage of Endeavour's STS-126 mission on NASA TV. Click here for SPACE.com's mission coverage and NASA TV feed.
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