Astronaut Heidemarie Stefanysyn-Piper deploys solar array on truss segment of the International Space Station.
Credit: NASA
HOUSTON, Texas, 16 September 2006: Two U.S. astronauts have put the finishing touches on the installation of a solar power system for the International Space Station in the third and final spacewalk of the Atlantis mission.
Astronauts Joe Tanner and Heidemarie Stefanyshyn-Piper finished the installation of a set of solar arrays on the orbiting ISS during nearly seven hours in space. The pair deployed a radiator on the solar structure and repaired wireless television antennas.
They also made preparations for future spacewalks by fellow astronauts and cosmonauts as the Atlantis mission marks the resumption of construction of the station after the 2003 space shuttle Columbia disaster. The extra-vehicular activity - or spacewalk - will complete the series of three spacewalks for the 11-day mission that began a week ago.
The spacewalk began at 10:00 GMT (8pm on Friday night, Sydney time) after a 45-minute delay due to a problem that affected the depressurisation pump in the chamber where the two astronauts had slept breathing pure oxygen to prepare their bodies for the effects of space. It concluded six hours and 42 minutes later at 15:42 GMT (1:42am Saturday, Sydney time), the U.S. space agency NASA said.
"We have to say what a wonderful job you both did today, especially you, Joe, with a legendary performance," said Pam Melroy at the Johnson Space Centre's Mission Control Centre in Houston, Texas.
Tanner and Stefanyshyn-Piper, the only woman in the Atlantis six-member crew, removed the restraints on a radiator and deployed it on the station. The radiator will be used to prevent the overheating of the new solar array system.
The two astronauts had performed the mission's first spacewalk four days ago, using a robotic arm to attach a new 16-tonne structure bearing the solar arrays that Atlantis delivered to the ISS. Tne next day,
two Atlantis astronauts went on a seven-hour spacewalk to remove launch restraints on the solar arrays that prevented damage when Atlantis lifted off from Cape Canaveral, Florida.
Two days ago, astronauts stretched out the new set of solar arrays measuring 73 meters on the space station. It will ultimately provide a quarter of ISS power needs once the orbiting laboratory is completed in 2010.
The additional electricity furnished by the second set of solar arrays is expected to be sufficient to power the European Columbus laboratory and the Japanese Kibo laboratory, which are to be installed in later missions.
The new solar power system will not be activated until the next scheduled shuttle mission, by Discovery, in December.
At the end of ISS construction in 2010, once the four sets of double arrays are in place, they will generate a combined 110 kilowatts of electricity, equivalent to the consumption of 55 average households.
Today will bring a half-day of free time for the six astronauts.
Atlantis, whose protective thermal shield was declared in perfect shape for re-entry, is scheduled to land on September 20 at the Kennedy Space Centre in Cape Canaveral, Florida. The last ISS assembly work was in November 2002 after the Columbia accident forced NASA to work on improving flight safety.
Columbia was doomed by foam insulation that peeled off its external fuel tank during liftoff and pierced its ceramic heat shields, causing it to disintegrate as it returned to Earth in February 2003.
