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Space Shuttle Atlantis Launch Postponed Again; Liftoff Now Set For Jan. 10, If Glitch Resolved

By | December 17, 2007

      NASA Experts Still Seek Cause Of Sensor Data Snafu

      Tests Set For Tomorrow, May Unearth Problem In Sensors; Simultaneous Space Station Spacewalk To Examine SARJ

      NASA again postponed the launch of Space Shuttle Atlantis on its STS-122 mission to the International Space Station (ISS), with flight now set for Jan. 10, more than a month beyond the initially planned Dec. 6.

      Meanwhile, the space agency early tomorrow will conduct tests on the spacecraft in an attempt to resolve a problem that forced the launch postponement.

      While the countdown leading up to Dec. 6 went brilliantly well for days, a problem arose just hours before the then-scheduled launch when sensor data from fuel gauges in the external fuel tank went awry.

      As engineers and others grappled with the failure, the launch was put off a day, then two days, then three days. At that point, an attempt to fly again ended in a cancellation as crews began loading liquid hydrogen into the external fuel tank, and the maddening sensor-data malfunction reappeared. Because the problem is intermittent, and can’t be commanded to recur, it is enormously difficult to analyze.

      The Dec. 9 recurrence of the difficulty prompted NASA to delay the Atlantis launch until Jan. 2, or later, to provide time for engineers and scientists to make a frontal assault on the problem, and attempt to divine its root cause. A malfunction in the sensor could mean Atlantis engines would fail to cut off if the fuel ran low, and a catastrophic explosion could ensue.

      Then, last week, NASA decided to set a Jan. 10 launch date, both to provide more time for the sleuthing to continue, and to provide a holiday-season break for NASA personnel.

      Wayne Hale, the space shuttle program director, earlier had expressed concern that crews were putting in long hours and working furiously to overcome the sensor data problem, and said then that he hoped they could get some time off to be with their families in the holidays.

      When the decision finally was made to postpone the launch yet again, to Jan. 10, Hale reprised those thoughts.

      "The workforce has stepped up to and met every challenge this year," Hale said. "Moving the next launch attempt of Atlantis to Jan. 10 will allow as many people as possible to have time with family and friends at the time of year when it means the most. A lot has been asked of them this year and a lot will be asked of them in 2008."

      Even the Jan. 10 liftoff isn’t a guaranteed sure bet, because the cause of the sensor data problem still is an unknown. Liftoff then depends on resolution of the problem.

      Suspicion centers chiefly not on the fuel-gauge sensors themselves, but on wiring and connectors that carry data from the sensors along a roughly 100-foot path.

      If and when Atlantis finally flies, it will continue the job of building the space station, carrying into orbit a huge European space laboratory called Columbus. It will provide scientists around the world the ability to conduct a variety of life, physical and materials science experiments.

      That Atlantis mission and assembly job is slated to be followed little more than a month later by a similar journey to the space station.

      On Feb. 14, Space Shuttle Endeavour is slated to lift off for the STS-123 Mission to carry the Japanese laboratory Kibo into orbit and attach it to the "Harmony" Node 2 module on the space station at a point near where Columbus is to dock.

      It is important that these additions to the ISS be installed more or less on schedule, because only the space shuttles have the size and power to haul the huge, building-sized components to the ISS, and the shuttles are to retire in 2010.

      To complete the space station, NASA needs to get an average of four shuttle flights per year off the launch pad. The space agency would have attained that pace this year, had it not been for Atlantis being hit by a damaging hail storm last spring, and Atlantis having the engine cutoff (ECO) fuel sensor woes currently blocking the mission.

      NASA will consider whether to retire Atlantis as now planned after missions next year, or whether to keep the shuttle flying to help reduce risk of falling behind schedule.

      Spacewalk Tomorrow

      Even as ground crews are filling the Atlantis external fuel tank in a hunt for the sensor data problem, another drama will unfold hundreds of miles overhead.

      The Expedition 16 crew on the space station will perform an extravehicular activity to examine the solar array rotary joint, or SARJ.

      Spacewalkers on a prior mission noted that the SARJ is covered with metal filings or debris, so the spacewalkers tomorrow will exit the space station to examine the SARJ, determine the source of the debris and attempt to determine what corrective actions may be required.

      The rotary joint positions a giant solar array toward the sun so that the array reaches maximum electrical generating capacity to power the rapidly-expanding space station.

      Both the tank-filling test of the Atlantis sensor system and the space station spacewalk will be covered on NASA TV.

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