June 16, 2011
Shuttle Fueled Up For Testing
NASA workers at the Kennedy Space Center fueled up the space shuttle Atlantis on Wednesday in a key test ahead of its July 8 scheduled launch of the final shuttle flight.
Even though the shuttle launch is still weeks away, shuttle managers want to make sure that repairs to the external fuel tank are good and that no cracks pop up in any of the support brackets. The test was added after structural problems were discovered last year on a tank later used in the February launch of the shuttle Discovery.NASA reinforced metal supports inside both tanks, and preliminary checking indicated no cracking. But a valve for one of the three main engines recorded below-normal temperature readings during the fueling operation, indicating a possible hydrogen fuel leak. The engine was isolated and the test continued.
NASA officials said even if the valve needs replacement, they feel they can still make their planned launch date. The same kind of patches on the struts were used for Atlantis.
The struts, or brackets, are located in an area where there is no fuel, only instruments. The brackets were made from an aluminum alloy that was more brittle and, along with assembly issues, led to the cracking on Discovery's tank. Technicians plan to X-ray the brackets on Atlantis' tank starting this weekend to assure that the metal struts withstood the extreme temperatures generated by 500,000 gallons of liquid oxygen and liquid hydrogen inside the tank.
"It's very straight-forward," said launch director Mike Leinbach. "We fill it up, send the final inspection team out to the pad, they'll do their walk-down ... and then we'll get the 'go' for drain. That's it."
Wednesday's fueling operation was delayed several hours by thunderstorms that struck Cape Canaveral on Tuesday. Three lightning strikes were reported near the pad. NASA technicians and officials reported no damage from the strikes, although a power circuit went offline.
NASA will conduct a countdown rehearsal next week in preparation for the final flight.
NASA spokesman Allard Beutel told reporters that the agency is still analyzing a pair of issues from Endeavour's recent flight.
A glob of grease apparently caught fire around the main landing gear when Endeavour landed on June 1, but left no traces. The brief flash fire was caught on video, Beutel said Wednesday. Neither the crew nor shuttle was in any danger, he said.
Also, the loss of foam insulation from Endeavour's tank during liftoff on May 16 appears to be age related, said Beutel. The tank, a decade old, is the oldest tank ever flown.
Atlantis will be packed with supplies for the International Space Station (ISS) so that the orbiting outpost will be well-stocked until a private cargo carrier arrives. NASA expects the first supply run by a US company could take place by the end of the year.
Among the cargo for NASA's final mission will be an Italian-built shipping container holding 9,500 pounds of food, clothing, science gear and supplies for the ISS. The shuttle will also deliver an experiment to the station that will demonstrate how satellites can be robotically refueled in orbit.
The satellite refueling experiment could be a big game-changer in an industry worth more than $160 billion per year. Hundreds of communications, weather and other satellites are currently orbiting the Earth, but none are designed to be refueled. Once their fuel is spent, they can no longer reboot themselves or change position and maneuver, and they become expensive space debris.
The Robotic Refueling Mission will be a special assignment for Canadian-built robot Dextre. Dextre will be attached to the space station's 55-foot external crane and over the next two years, ground controllers will demonstrate how the robot can handle the various tasks associated with refueling the satellites and also handling minor repairs.
The July 8 Atlantis flight will mark NASA's 135th and final mission of the 30-year-old shuttle program. NASA's next-generation space program was halted by the Obama administration.
NASA will be retiring the shuttle program due to the high costs of operating and maintaining the spacecraft. It has hired two commercial companies, Space Exploration Technologies and Orbital Sciences Corp, to take over cargo deliveries to the ISS. NASA hopes the commercial venture will also be able to add human spaceflight within five years. Until then, the US will be paying Russia tens of millions of dollars per seat to hitch rides on its Soyuz crafts.
Image Caption: Space shuttle Atlantis stands on Launch Pad 39A at NASA's Kennedy Space Center in Florida, where it is set to liftoff on STS-135, the final shuttle mission. Image credit: NASA/Terry Zaperach
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