HOUSTON - There was a lot riding on today's
spacewalk
outside the International
Space Station (ISS) and two shuttle astronauts did not disappoint, NASA
officials said Monday.
"It was a
big deal," Rick LaBrode, lead ISS flight director for NASA's STS-121
mission, told reporters. "To get it behind us is a great feeling."
STS-121
spacewalkers Piers
Sellers and Michael
Fossum spent almost seven hours outside the ISS to stow a spare cooling
system pump and replace a broken cable reel for the station's Mobile
Transporter. Both tasks will allow NASA to forge ahead with a precisely
choreographed series of 16 space shuttle missions - including STS-121 - to complete the
orbital laboratory and staff it with six full-time astronauts.
"The
assembly sequence is set to proceed fast and furious here, we're only six or
seven weeks away from the next mission," said Phil Engelauf, chief of NASA's
STS-121 mission operations representative, during a briefing here at NASA's
Johnson Space Center. "Seeing how everything has worked here, we have a green
flag to press ahead."
NASA's
first ISS construction mission since late 2002 - STS-115 aboard the Atlantis
orbiter - is slated to launch on Aug. 28 to deliver a pair of new solar panel
wings and their massive truss mast to the orbital laboratory. The space agency
hopes to launch STS-116 aboard Discovery in December to continue the orbital
ISS construction effort.
But much of
that work hinged on restoring the backup power and data cable system for the
station's Mobile Transporter, which will be used to haul large ISS components
into position along the outpost's main truss. Today's spare pump module
installation was also originally slated for the STS-116 crew, but was pushed
earlier to get ahead on the many tasks needed to support the ISS.
Discovery's
STS-121 mission is NASA's second orbiter flight since the 2003 Columbia accident and is at
the midpoint of a 13-day flight to the ISS. Sellers, Fossum and their shuttle
crewmates launched
toward the ISS on July 4 carrying tons of supplies,
a new
station astronaut and a mission to complete NASA's orbiter inspection and
repair tests before the flight is through.
"The
mission is going great," Engelauf said. "The health
of the vehicle is great and we're not really working any particular
problems."
A tough
spacewalk
There may
be no major problems but Discovery spacewalkers Sellers and Fossum certainly
had their share of frustrating moments during their Monday spacewalk, which
marked the second of three planned for their STS-121 mission.
"We
definitely knew it wasn't going to be simple," LaBrode said, adding that the
spacewalk included many complicated tasks.
The
astronauts had to work through stuck bolts (the solution: twist the screw
harder), a stubborn spring that prevented initial attempts to install the new
cable reel in place, and a lot of bumping that ultimately knocked Sellers' emergency
thruster system loose.
Sellers was
connected to Discovery or the ISS with two tethers at all times, and not in
danger of drifting free, but spacewalk planners were concerned the Simplified
Aid for EVA Rescue (SAFER) thruster system could separate from his spacesuit and pose a debris
hazard for the orbiter or station. Fossum later reengaged the latches to lock
Sellers' SAFER system into its fittings.
"I wasn't
worried about the crew at all," said Tomas Gonzalez-Torres, lead spacewalk
officer for the STS-121 mission.
Gonzalez-Torres
said his STS-121 spacewalking astronauts and ground crew performed above the
bar during the orbital repair, and were on schedule - and ahead at some times -
through the six-hour and 47-minute activity.
"I couldn't
have asked for a better crew," Gonzalez-Torres said. "These guys were
fantastic.
advertisement
