Heading Out: ISS Astronauts to Make Spacewalk Today

Like sentinels guarding a door, two NASA spacesuits stand ready inside the International Space Station's Quest airlock where Expedition 13 astronauts Jeffrey Williams and Thomas Reiter will don them and step outside the outpost on Aug. 3, 2006. CREDIT: NASA.

Two astronauts are set to step outside the International Space Station (ISS) today with only spacesuits for protection against the harsh vacuum of their surroundings during more than six hours of orbital work.

NASA TV will broadcast today's spacewalk live beginning at 9:00 a.m. EDT. Click here.

ISS Expedition 13 flight engineers Jeffrey Williams and Thomas Reiter are expected to spend more than 6.5 hours attaching new equipment, experiments and making cooling system repairs on the station's exterior after leaving the orbital laboratory at 9:55 a.m. EDT (1355 GMT). [Click here for SPACE.com's live spacewalk coverage at 9:00 a.m. EDT (1300 GMT).]

"The contents of this EVA [extravehicular activity] will be to install a couple of systems outside the station," Reiter, the first long-duration astronaut from Germany and the European Space Agency (ESA) to serve aboard the ISS, told ESA officials during a recent space-to-ground phone call.

Expedition 13 commander Pavel Vinogradov will remain inside the ISS during today's planned spacewalk, marking a first time a human has stayed aboard while others worked outside since 2003. ISS crews were reduced to two-astronaut teams following NASA's loss of the shuttle Columbia and its crew in 2003, prompting two-person spacewalks that left the ISS empty and under control by mission controllers on Earth.

Vinogradov will not have to shut hatches or perform other precautionary work performed during the reduced crew spacewalks, NASA officials have said. He will, however, be able to help his spacewalking crewmates don their orbital work clothes, they added.

ISS Spotlight: New Tool Safeguards Astronauts Against Orbital Shocks

Once fully sealed inside their white NASA spacesuits - known as Extravehicular Mobility Units (EMUs) - Reiter and Williams will exit the station's U.S.-built Quest airlock and begin their first job of the day: installing what NASA calls the Floating Potential Measurement Unit (FPMU) on the end of the station's starboard truss.

"It will measure the electric potential that will accumulate from the solar arrays of the station," Reiter said of the new tool.

NASA tracks solar array electric potential because they can build up charge in flight and possibly spawn arcs that could shock nearby ISS equipment or a spacewalking astronaut. Earlier this year, Expedition 12 commander Bill McArthur tossed a device similar to the FPMU into space after other spacewalker photography found that its bolts were loosening their grip on the ISS.

Other major tasks include a series of repairs and maintenance to equipment supporting the station's cooling system, the set up of two new, suitcase-sized material exposure experiments on the orbital laboratory's hull, and a photography experiment using an infrared video camera. [Click here for a detailed look at the upcoming Expedition 13 spacewalk.]

"We've been working hard with this crew for the last year on preparing for this EVA," Paul Boehm, NASA's Expedition 13 lead spacewalk officer, said during a pre-EVA briefing. "[It] represents a true mix of ISS experiments and maintenance."

Boehm and fellow NASA station officials said the cooling system work Williams and Reiter will perform are the first tasks of an eight-spacewalk plan for ISS crews to aid future station construction between upcoming space shuttle visits.

Today's planned EVA will mark the third career spacewalk for both Williams, a NASA astronaut serving as science officer during Expedition 13, and Reiter.

Williams can be identified by the red stripe emblazoned on his NASA spacesuit and will lead the spacewalk as EV-1.

Reiter, in an all-white suit, is designated EV-2. His EMU spacesuit is the first to carry a German flag patch on its shoulder, NASA officials have said.

NASA will broadcast today's spacewalk live on NASA TV beginning at 9:00 a.m. EDT (1300 GMT). You are invited to follow the Expedition 13 spacewalk's progress using SPACE.com's NASA TV feed, which is available by clicking here.

• Space Station Astronauts Prepare for Aug. 3 Spacewalk
• Complete Coverage: ISS Expedition 13
• Great Space Quizzes: Life in Orbit
• Gallery: Building the International Space Station