NASA has officially declared the heat shield tiles and thermal blankets on Discovery safe for landing.
Those account for about 90% of the surface area of Discovery, says shuttle deputy program manager Wayne Hale. The only areas remaining to be cleared are the Reinforced Carbon-Carbon (RCC) panels on the wings and nose-cone and two gap fillers that are sticking out from between tiles.
Concerns had been raised after photographs and video footage of the shuttle鈥檚 launch had shown damage in various areas. But careful analysis of the material, assisted by close inspections 鈥� enabled by a special extension to the shuttle鈥檚 robot arm 鈥� has allayed fears.
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Shuttles have always sustained some damage during launch, but the issue became critical after Columbia was lost due to a breach in its wing. Discovery was the most closely scrutinised shuttle launch ever.
Laptops and water
Also on Saturday, NASA confirmed Discovery will spend an extra day in space to transfer more supplies to the International Space Station. That moves landing one day back, to 8 August.
The additional time has been granted because it remains uncertain when the next shuttle will visit the station. The fleet is grounded until NASA has fixed a problem with foam coming off the external tank during launch. The crews will spend the extra day hauling more supplies from the shuttle to the station and help with the maintenance of the station.
Fifteen tonnes of supplies were already scheduled to be transferred to the station from the shuttle鈥檚 cargo module, but the shuttle crew will now also move laptop computers, office supplies, an ohmmeter and 20 days worth of water (86 litres).
鈥淭here鈥檚 nothing really big that we鈥檙e transferring, and I think that鈥檚 kind of a tribute to the teams on how well they did planning,鈥� says Bill Gerstenmaier, NASA鈥檚 space station program manager.
Two Russian Progress cargo ships are scheduled to launch to the station later in 2005. 鈥淲e鈥檙e fine from a consumables standpoint all the way through the end of the year, so again, we鈥檙e in very good shape,鈥� Gerstenmaier says.
鈥淲hat a view!鈥�
Soichi Noguchi and Steve Robinson completed the first of the mission鈥檚 three spacewalks without a hitch on Saturday.
鈥淭oday, let鈥檚 go spacewalk,鈥� Noguchi told ground control after they played his wake-up music 鈥� his own children singing in a choir. Then, as he opened the door to space to begin the 6 hour, 50 minute spacewalk, he exclaimed: 鈥淲hat a view!鈥�
Noguchi and Robinson tested two potential tools to repair a damaged heat shield, making this the first spacewalk where liquid materials were exposed to space. The pair were careful to wipe any of fluid off their gloves after finishing, to prevent any material getting back inside the sensitive environment of the space station.
Noguchi tested a tile repair technique known as emittance wash 鈥� essentially painting over problem areas. Robinson tried filling gouges and cracks in RCC panels with non-oxide adhesive (NOAX). 鈥淚t鈥檚 like licorice-flavoured pizza dough,鈥� Robinson said.
The test were performed on deliberately damaged tiles and RCC segments carried into space specifically for the tests. The effectiveness of the repairs will be analysed back on Earth. Robinson did not have time to do extra samples that could be placed in an arc jet, so his work will just be tested for holes. (Read more on the tests here.)
Broken gyros
The duo also rerouted power to a failed gyroscope. The four gyros keep the station oriented in the right direction, meaning precious fuel does not have to be used firing thrusters.
On their next spacewalk, they will attempt to replace a second inoperable gyroscope. A third gyro was showing current spikes while the shuttle was docked, so once the other two are working, it will be given a rest.
Noguchi and Robinson also replaced a Global Positioning System antenna and retrieved several experiments that have been attached to the exterior of the space station.
Other crew members were also busy on Saturday, with Discovery pilot Jim Kelly performing another robotic arm inspection of seven areas on the front edge of Discovery鈥檚 left wing to check for any cracks or damage.
