Twoastronauts aboard the International Space Station (ISS) are going through themotions of a spacewalk today in preparations for the real thing later thisweek.
ISSExpedition 13 commander PavelVinogradov and flight engineer JeffreyWilliams donned their Russian-built Orlan spacesuitsTuesday for a dress rehearsal of the nearly six-hour June 1 excursion to maintaintheir orbital spacecraft.
"The crewseems very comfortable and ready to go do the spacewalk," said Holly Ridings, NASA'slead flight director for the upcoming extravehicular activity (EVA), during a Tuesday press briefingat the Johnson Space Center in Houston, Texas.
While NASAISS flight controllers detailed the Expedition 13 crew's coming spacewalk, theastronauts themselves conducted final checks on the systems and mobility oftheir Orlan spacesuits, NASA officials said.
Vinogradovand Williams are expected to exit the space station's Russian-built Pirsdocking compartment at 6:40 p.m. EDT (2240 GMT) for a five-hour and 40-minutespacewalk to gather experiments and maintain the ISS. The spacewalk will markthe sixth career EVA for Vinogradov - who staged fiveothers from Russia's Mir space station - and the second for Williams.
"The equipmentthat we have is very good and the training that we've been provided by the teamon the ground is very good," Williams told reporters last week. "We will bevery prepared when the time comes to go out the door."
Among the twovital tasks for Thursday's spacewalk is the planned installation of a new vent forthe space station's primary oxygen generator - known as Elektron - to dumpwaste hydrogen into space.
The Elektrondevice, which separates water into much needed oxygen and waste hydrogen,has endured months of finicky activity largely due to a leaklast year that contaminated its original vent valve and rendered itunusable, said Kirk Shireman, NASA's ISS deputy program manager, during thepress briefing.
Since then,the Elektron has shared a vent with another ISS system, shutting down as thevent's original user required and undergoing shaky restarts. Vinogradov isexpected to install a new vent that would once again give the Elektron adedicated line to dump excess hydrogen.
"After thisEVA, you'll see very few blips in this Elektron system," Shireman said.
Vinogradovand Williams will also replace a faulty camera aboard the Mobile BaseTransporter, which slides the space station's robotic arm and other large ISScomponents along rails that run the length of the orbital laboratory's maintruss. While the camera itself isn't required for future ISS construction, the failureof another camera could cause serious delay, NASA officials said.
"If we didn'tdo this [camera replacement] and had an additional failure, we mightconceivably have to stop station assembly for awhile," Shireman said.
The nextISS construction mission - STS-115 slated to launch aboard the Atlantis shuttlein late August - will deliver a new solar array and truss to the ISS, he added.
TheExpedition 13 crew will also retrieve a series of experiments attached to theISS exterior, including one that studies the effects of Russian thrusters onthe station's hull and a Biorisk canister to determine how the spaceenvironment affects microorganisms. Vinogradov is due to photograph one antennaand remove slack from the cable of another at the aft end of the station'sZvezda module.
Missingamong the Expedition 13 crew's task roster is a golf shotfor which Vinogradov had trained to perform as part of a commercial stunt forthe Canadian golf equipment firm Element 21.
Scheduled underan agreement between Toronto-based Element 21 and Russia's Federal SpaceAgency, the golf shot called for Vinogradov to smack a radiotransmitter-equipped golf ball into orbit with a gold-plated six iron (bothmade by Canadian golfing firm). But the Canadian sporting good firm agreed to putoff the event until November when Russian ISS officials required more work timefor its spacewalks, company officials said.
"We figuredthat it was important for them and we could delay our space shot," Element 21'spresident and CEO Nataliya Hearn told SPACE.com, adding that Russianflight controllers said they needed more time to perform ISS repairs. "We're fairlyhappy, because it's obvious that the space shot is going ahead."
The golfshot is now slated for a Russian spacewalk during the next ISS mission - Expedition14 - with cosmonaut Mikhail Tyurin wielding the club.
NASAofficials said the final safety review documentation is still being finalizedto ensure that the golf stunt will not pose a debris hazard for the ISS or spaceshuttles.
Hearn said thatshe hopes that the golf shot - video of which will be used in a future Element21 commercial - could eventually lead to an orbital driving range of sorts forastronauts, or even space tourists, in coming years.
"The womenwould be aiming for Venus and the men will be aiming for Mars," Hearn said.
NASA willprovide live coverage of the Expedition 13 crew's spacewalk on NASATV beginning at 5:30 p.m. EDT (2130 GMT) on June 1. You are invited tofollow the crew's progress using SPACE.com's NASA TV feed by clicking here.