Eager Shuttle Crew Passes Spaceflight’s Halfway Mark

Behind shuttle astronauts (from left) Stephanie Wilson, Mark Kelly and Lisa Nowak are spacewalkers Piers Sellers and Mike Fossum. From the station's Destiny laboratory, they answered questions from reporters on Earth Tuesday morning. Photo CREDIT: NASA TV

HOUSTON - Now into their eight day in orbit, the six-astronaut crew of the shuttle Discovery has passed the midpoint of their spaceflight while one spaceflyer is just beginning his mission aboard the International Space Station (ISS).

NASA's STS-121 astronaut crew, commanded by veteran shuttle flyer Steven Lindsey, and newly arrived ISS crewmember Thomas Reiter are pushing ahead with tasks to transfer cargo between the station and Discovery as they prepare for one last spacewalk and one last heat shield inspection before heading home.

Many of Discovery's astronauts are confident that the performance of their spacecraft, the health of its heat shield and the success of its fuel tank changes are a signal that NASA can resume construction flights to the ISS.  

"I think my brother put it very well," Discovery pilot Mark Kelly told the Associated Press. Kelly's identical twin brother Scott is also an astronaut and commander of NASA's STS-118 shuttle flight next year. "I spoke to him on the IP phone and he said, 'We're back baby.'"

Discovery's STS-121 spaceflight is NASA's second shuttle test mission since the 2003 Columbia accident, and is aimed at completing many of the return to flight objective begun by last July's STS-114 flight aboard the orbiter. The spaceflight launched on July 4 and returned the ISS to its three-person capacity for the first time since the accident by transporting Reiter to the orbital lab. Kelly and some of his crewmates spoke with the Associated Press and USA Today during a space-to-ground link Tuesday.  

STS-121 mission specialist Lisa Nowak, who is making her first spaceflight aboard Discovery, said she hopes the mission will clear the shuttle for ISS assembly flights. Nowak and crewmate Stephanie Wilson will conduct a final round of heat shield inspections after undocking from the ISS on Saturday to scan for any damage from micrometeorites or debris.

"The shuttle, in a way, is always a test vehicle, every flight is a test flight," Nowak told USA Today. "After this flight, I think it will be ready to go."

Most of Discovery's STS-121 astronauts - as well as Reiter and his fellow ISS Expedition 13 crewmembers - are working to fill a cargo module full of trash, unneeded or unnecessary items for the return trip to Earth. The Italian-built module - dubbed Leonardo - rode inside Discovery's payload bay during the flight to resupply the ISS.

But two shuttle flyers - STS-121 mission specialists Piers Sellers and Michael Fossum - are gearing up for their third and final spacewalk of the flight. The two astronauts will step outside the space station's Quest airlock and spend more than six hours testing a heat shield crack repair method inside Discovery's payload bay.

"Piers and I and the rest of the crew have a lot invested in it," Fossum said of the test.

The crew also apparently has a bit of quick thinking to do each morning, when flight controllers wake the astronauts up with music carefully chosen for a specific astronaut.

"Sometimes we know ahead of times what the music is going to be, and sometimes it's a surprise," Kelly said with a smile. "And you have to scramble out of your bed to make some profound statement."

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