Mission managers today also decided to extend Discovery's mission by one day to spend more time docked with the International Space Station. Astronauts are busy transferring more water and supplies to the ISS in case the next Shuttle mission is delayed. An additional 10 gallons of water was transferred along with a pair of laptop computers and other supplies.
Astronauts Steve Robinson and Soichi Noguchi of the Japan Aerospace Exploration Agency wrapped up a successful 6-hour, 50-minute spacewalk at 11:36 a.m. Saturday, completing a demonstration of Shuttle thermal protection repair techniques and enhancements to the Station's attitude control system.
For the repair demonstration, they worked with tiles and reinforced carbon-carbon intentionally damaged on the ground and brought into space in Discovery's cargo bay. They tested an Emittance Wash Applicator for tile repair and Non-Oxide Adhesive eXperimental (NOAX) for the reinforced carbon-carbon samples.
Helped by Astronaut Andy Thomas, who served as a coach and monitor from Shuttle's aft flight deck, they also installed a base and cabling for a stowage platform and rerouted power to Control Moment Gyroscope-2 (CMG-2), one of four 600-pound gyroscopes that control the orientation of the Station in orbit.
CMG-2 has been healthy, but a faulty circuit breaker interrupted its power supply in March. Since that time the Station had operated successfully on two CMGs. About 9:20 a.m. Mission Control told the astronauts they saw power again flowing to CMG-2. Plans call for it to be spun up to its 6,600 rpm operating speed over the next several hours and subsequently put back into the attitude control mix. Another gyroscope, CMG-1 which failed in 2002, is to be replaced Monday on the second of three spacewalks. They also replaced a faulty global positioning system antenna on the Station.
The spacewalk began at 4:46 a.m., after deliberate preparations delayed the planned start. The Station crew, Commander Sergei Krikalev and NASA Science Officer John Phillips, had moved the orbiting laboratory's Canadarm2 into position to help Noguchi and Robinson's work. Discovery Pilot Jim Kelly and Mission Specialist Wendy Lawrence ran the arm, helping the spacewalkers install the stowage platform base.
The spacewalkers had time for some get-ahead tasks near the end of their spacewalk, bringing in two experiments that exposed a variety of materials samples to the harsh vacuum and extreme temperatures of space. Noguchi also photographed some insulation on the port side of Discovery's cabin.
Hatches between the Station and Discovery had been closed in preparation for the spacewalk. Once hatches were reopened, remaining crewmembers, Eileen Collins and Mission Specialist Charlie Camarda, went about other tasks, including transfer of cargo from the Shuttle to the Station.
Among those tasks was another survey of parts of Discovery's thermal protection system by the Shuttle's robotic arm and the Orbiter Boom Sensor System. Kelly and Camarda, operating the arm, focused their attention on seven areas of interest along the leading edge of Discovery's port wing.
After analysis of many images taken of Discovery during and after its launch, including information from previous surveys like the one done Saturday, no damage that would threaten a safe landing by the Shuttle has been identified. About 25 dings have been seen on Discovery, compared to a mission average of 145 in missions before Columbia's loss.