Two spacewalking astronauts on Monday replaced broken hardware deemed crucial for the completion of the International Space Station, a new success for Nasa in the six-day-old Discovery shuttle mission.
In their second of three planned spacewalks, astronauts Mike Fossum and Piers Sellers, who arrived aboard the shuttle last week with five colleagues, replaced a broken cable reel of the orbiting laboratory’s construction equipment transporter.
Failure could have scuttled Nasa’s Atlantis shuttle launch planned for August 28, since the next mission will focus on resuming construction of the unfinished ISS, a US space agency official said.
”Phew, man, do I feel better,” Rick LaBrode, the lead ISS flight director for the current mission, told reporters.
”If we didn’t get this successfully changed and checked out, then we couldn’t proceed with the next mission, which is right on our heels,” LaBrode said.
The spacewalk ”was a big deal, and to get it behind us successfully is just a great feeling,” he said.
Fossum and Sellers performed some space acrobatics during their excursion, as one astronaut hanged horizontally at one point while the other held the large old and new cable reels for a tricky handoff.
The pair also installed a spare pump module to an external stowage platform during their nearly seven-hour spacewalk.
”Good job guys, slightly ahead of time. It’s a pleasure to watch,” mission control capsule commentator Julie Payette said from Houston after they placed the pump.
The astronauts also took a moment to admire the view about 350km above Earth.
”It’s like standing in an all-around Imax. It’s just beautiful,” Sellers said.
Fossum and Sellers will venture out of the ISS again on Wednesday to try out new shuttle repair techniques.
In their first spacewalk on Saturday, Sellers and Fossum tested a boom extension on the shuttle’s robotic arm as a possible work platform for future repairs. Nasa described the test as a success.
The key repair came a day after Discovery was declared free of damage that could have required in-orbit repairs before its return to Earth on July 17.
The mission, just the second flight since the 2003 Columbia tragedy, is a final test of Nasa’s efforts to dramatically improve safety in order to resume regular shuttle launches and complete the ISS.
”Everything has been working great on this mission,” Phil Engelauf, the chief of Nasa’s flight director office, told reporters at the Johnson Space Centre in Houston, Texas following the spacewalk.
Nasa administrator Michael Griffin wants to conduct 16 more flights to complete the ISS by 2010, when the 25-year-old shuttle fleet is scheduled to be retired.
In addition to testing in-orbit repair techniques, Nasa has made several modifications to foam insulation on the shuttle’s external fuel tank to prevent debris from striking the spacecraft during liftoff.
Columbia‘s demise was caused by foam insulation that peeled off its external fuel tank and pierced its heat shield during liftoff, dooming its return to Earth on February 1 2003.
A large piece of foam shed from Discovery‘s fuel tank last year in the first post-Columbia flight without hitting the shuttle. Nasa grounded the fleet until now to make further modifications to the orange-hued reservoir.
Officials were pleased with the performance of Discovery‘s fuel tank during last week’s lift-off, saying it shed small pieces of debris as expected but too late into ascent to cause concern. – AFP
