Space Station Astronauts Ready for Mission's First Spacewalk
ISS Expedition 12 flight engineer Valery Tokarev, left, and commander Bill McArthur work Thursday in the station's Quest airlock.
Credit: NASA TV.

For the first time in more than two years, the astronauts aboard the International Space Station (ISS) will step outside their spacecraft clad in U.S. spacesuits during their mission's first spacewalk, NASA officials said Thursday.

ISS Expedition 12 commander Bill McArthur and flight engineer Valery Tokarev are scheduled to exit the station at 9:30 a.m. EST (1430 GMT) on Nov. 7 for a 5.5-hour spacewalk to revamp tools on the outpost's exterior.

"It's pretty exciting," Tokarev told ABC News Wednesday of the spacewalk, which will be a career for the Russian Federal Space Agency cosmonaut. "I've been asking Bill a lot about his experience."

McArthur has conducted two spacewalks - both during the shuttle Discovery's STS-92 mission to the ISS in 2000 - to support the station. He and Tokarev will leave the ISS empty while they toil in space, leaving station control in the hands of flight controllers on Earth.

"It is the first time we've done a U.S. EVA without anyone inside," said Pete Hasbrook, NASA's Expedition 12 increment manager, Thursday during a press conference at the agency's Johnson Space Center in Houston, Texas. "We've been able to use a lot of the lessons that we've learned from our preparations for the Russian EVAs...[but] it certainly has not become routine for us."

The spacewalk will also mark the first time since April 2003 that ISS astronauts left the station from its U.S.-built Quest airlock and worn U.S. spacesuits. In the interim, ISS crews were limited to two astronauts per flight after the Columbia accident and spacewalkers relied on Russian-built Orlan spacesuits for two-person EVAs.

Contamination to both the airlock and the station's U.S. spacesuits - dubbed Extravehicular Mobility Units (EMUs) by NASA - prevented the equipment from being used earlier, though the portal has since been repaired and new spacesuits delivered to the orbital platform.

Straightforward tasks

McArthur and Tokarev have two primary tasks to complete for their spacewalk, though flight controllers do have some bonus chores waiting for them if there's time.

"The tasks themselves are not overly challenging," explained Anna Jarvis, Expedition 12 EVA director, during the press conference. "We have not trained them in this exact sequence, but they [require] very generic skills."

After leaving the ISS airlock, McArthur and Tokarev will pull themselves hand-over-hand to the leftmost edge of the space station - the tip of its P1 truss - to install a camera, lights and stand. The camera, which McArthur said would weigh a couple of hundred pounds on Earth, will provide ISS views during future station assembly spacewalks.

"As we say on the farm, it would take two men and a boy to carry this around," McArthur told CBS News Wednesday while Tokarev appeared to effortlessly tote the camera equipment in microgravity.

The Expedition 12 crew will then retrace their steps across about 60 feet (18 meters) to the Quest airlock, retrieve tools then climb another 60 feet (18 meters) or so the pinnacle of the space station - a solar array tower dubbed the P6 truss, Jarvis said.

Once there, McArthur will remove a device called the Floating Potential Probe, which monitors the electric potential of the station as it flies through Earth's magnetic field, and cast it into space.

The probe has failed and appears to be backing out of its berth in photographs, so McArthur will jettison it aft and above the ISS to prevent it from breaking free on its own, Hasbrook said, adding that the probe will burn up after 100 days or so.

If the Expedition 12 crew has extra time after completing those tasks, they may also retrieve a broken radiator rotary joint motor controller and replace a faulty circuit breaker attached to station's railcar-like mobile transporter.

A scientific beginning

After a full month aboard the ISS - McArthur and Tokarev boarded the orbital lab on Oct. 3 - the two astronauts are just beginning their six-month science program.

In addition to repairs and other science studies, McArthur has worked with the station's Human Research Facility rack 2 (HRF-2) and performed the first of three kidney stone experiment measurements alongside Tokarev. The kidney stone experiment studies how spaceflight increases the risk of kidney stones, NASA's Expedition 12 lead scientist Julie Robinson said.

More than 9,400 students on the Earth tapped into an Earth-watching camera - conveniently named EarthKam - to observe their home planet remotely, while meteorologists are using the Expedition 12 crew's photographs of Hurricane Wilma to better understand the massive storms, NASA officials said. Meanwhile McArthur awaits additional science experiment equipment slated to launch toward the ISS aboard an unmanned Russian cargo ship on Dec. 21, the added.

"We're really just getting started on the research for this expedition," Robinson said.