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Atlantis Set To Fly ; Little Debate On Go-Fly Decision

By | November 19, 2007

      Helium Valve Problem Still In Review; Space Station Crew Spacewalk Set Tomorrow

      Space Shuttle Atlantis is set to launch at 4:31 p.m. ET Dec. 6 from launch pad 39A at Kennedy Space Center, barring major snags that might force a liftoff postpone of a few days, or into January, NASA leaders told the news media.

      To help prepare for the Atlantis STS-122 Mission, Expedition 16 crew members aboard the International Space Station (ISS) will begin outfitting a large connecting room, the "Harmony" Node 2 module, that was installed on the space station.

      That module will be a connecting area to huge laboratories that space shuttle missions will bring to the artificial moon, including the �1.4 billion (US$2.049 billion) European Columbus laboratory module that Atlantis will bring to the space station. The module will have a 10-year life expectancy on orbit

      This space shuttle mission, if it lifts off next month, will be the fourth this year, despite Atlantis having suffered months of delay for repairs after its external fuel tank was slammed by hail during an errant thunderstorm last spring.

      NASA will need to, and will be able to, maintain that kind of four-a-year launch pace until the space shuttle fleet retires in less than three years, on Sept. 30, 2010, according to Wayne Hale, space shuttle program manager.

      "We don’t have any plans to keep flying past 2010," Hale said, the mandated deadline to cease shuttle operations. Further, NASA soon won’t be able to fly the shuttles on further missions after that date, because key suppliers of shuttle components will have ceased operations, he noted. When large welding equipment is removed from the Michoud Assembly Facility where workers build external fuel tanks for the shuttles, that will signal the end of shuttle flights, Hale said. That line in the sand when further shuttle flights would become improbable likely would be reached some time next summer, he said. Also, vendors supplying other parts will be going out of that business, he explained.

      Shuttle flights are needed, critically, because only the shuttles have the size and strength to hoist huge structural components into orbit to continue construction of the space station.

      To help ensure that the schedule will be met and that construction job 200-plus miles above Earth will be completed, NASA may keep Atlantis flying beyond its scheduled retirement Aug. 7, when it is to take astronauts to the Hubble Space Telescope to refurbish the astronomical asset.

      Continuing to fly Atlantis past that date is "one of the options to improve the schedule margin," Hale said. The decision will be made next year, probably in the spring, he added.

      Atlantis will fly Dec.6 despite having a helium valve stuck in the open, or operating, position, though NASA officials are hoping to fix the problem before launch.

      "The valve appears to be stuck open," which is the normal position during shuttle operations, but NASA would prefer the valve be operational, Hale said. In a pre-flight readiness review meeting, though, "some thought it would be acceptable to fly in that condition," Hale said. Tests are underway to determine whether the valve malfunction is caused by an electrical glitch, or some imperfection in the valve itself.

      Either the problem will be fixed before Atlantis lifts off, or the space shuttle will fly with the valve as is, Hale said.

      "We are working aggressively toward a launch date in early December," said Kenny Todd, ISS mission integration and operations manager.

      NASA experts also are reviewing problems with protective heat tiles on Space Shuttle Discovery, which recently flew to the ISS despite some cracking that was found in coatings on the reinforced carbon-carbon tiles on an orbiter vehicle wing.

      Hale said that experts have examined heat tiles minutely, employing everything from high-tech thermography sensors to eyeballing heat tiles with a jeweler’s loupe, Hale said.

      At this point, he said, results have been inconclusive in experiments with the tiles and coating, so officials aren’t certain whether the cracking phenomenon is something that should concern them, and there may be "a little bit of risk" in that lack of knowledge.

      "We would like to get to a root cause of the spalling mechanism," Hale said.

      Before Atlantis heads for the space station, however, there must be a 6-hour, 40-minute spacewalk by ISS Commander Peggy Whitson and Flight Engineer Dan Tani to begin external outfitting of the Harmony node in its new position in front of the U.S laboratory Destiny.

      The spacewalk is set to begin at 5 a.m. ET tomorrow from the U.S. airlock Quest. Whitson, the lead spacewalker, will wear the suit with the red stripes while Tani will be in the suit with the barber-pole stripes.

      After leaving the airlock and setting up tools and equipment, Whitson will remove, vent and stow an ammonia jumper, part of a temporary cooling loop. Removing it allows connection of the hookup of the permanent ammonia cooling loop on a fluid tray on the station’s exterior.

      Tani meanwhile will retrieve a bag of tools left outside on the station during the Nov. 9 spacewalk by Whitson and Flight Engineer Yuri Malenchenko. Then he’ll remove two fluid caps to prepare for connection of that permanent cooling loop.

      Next he will move on to reconfigure a circuit that was used for a Squib firing unit, a small pyrotechnical device that freed a radiator on the Port 1 truss for its deployment last week.

      Much of the spacewalk will be devoted to work with Harmony’s Loop A fluid tray. That 300-pound, 18.5-foot tray will be moved from its temporary position on the S0 truss, at the center of the station’s main truss, to Harmony, atop the starboard avionics tray.

      Tani will join Whitson at S0. They’ll release the fluid tray and then move it to Harmony. They’ll use a kind of relay technique, one moving ahead and attaching tethers to be ready to receive the tray, then the other moving farther forward to take the next handoff.

      Once they reach the installation point, they’ll bolt down the tray, then hook up its six fluid line connections, two at S0, two at the tray and two in between.

      Tani will move to his final task, on the port side of Harmony. There he will mate 11 avionics lines. Whitson, meanwhile, will configure heater cables, then mate electrical umbilicals by hooking up four electrical harnesses linking Pressurized Mating Adapter-2 at the outboard end of Harmony to station power.

      The two spacewalkers will do the standard cleanup process, then enter the airlock. The beginning of its repressurization will mark the official end of the spacewalk.

      Another spacewalk by Whitson and Tani to complete the exterior hookup of Harmony is scheduled for Saturday.

      It is unknown now just when further extravehicular activities, or EVAs, will be performed to inspect and repair a problematical mechanical part on the space station.

      That is the solar alpha rotary joint, or SARJ. Astronauts in an earlier spacewalk noticed filing or flaking bits on the surface of a race ring in the SARJ, and NASA engineers wonder whether that means there is some grinding or binding in the joint.

      It is a key part of the space station, because the SARJ points giant solar electrical generating panels at the correct angle to the sun, so they generate required electricity to power the fast-growing space station.

      "We are very uncertain as to what’s going on with the SARJ," Todd said. With hardware already prepositioned, that will help to support the starboard SARJ repair job when spacewalking astronauts get to perform it, perhaps early next year, he said. Another SARJ, on the port side, exhibited no such filings or particles on the race ring.

      Parts to fix the ailing SARJ, such as bearings and a drive lock assembly, are sufficiently heavy that some cargo will have to be left behind in an upcoming space shuttle mission, to avoid overloading the shuttle.

      Another problem that raised eyebrows occurred on the ground, when a smoky smell was detected inside a spacesuit during training.

      The crew member wearing the suit reported what seemed to be hot gas, and a slight smell of smoke, so the training session was suspended immediately, since there is a pure oxygen environment inside the suit that would feed any fire, according to Steve Doering, EVA manager.

      A mishap investigation board, however, found no degraded performance in the suit, and it "continues to perform nominally," he said.

      At this point, "we believe there was no combustion event," he said — that is, there was no fire inside the suit — because there was no residue in the suit of carbons or other substances that might have indicated a fire occurred, he said.

      All of these problems that are examined, analyzed and overcome with proper solutions are to be expected, and the process of reacting to problems is important to develop now, to use on longer missions to the moon, and immensely longer voyages to Mars, Hale said.

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