Mission Control briefly awakened the crew of Discovery about 2 ½ hours early today after a malfunction of the telemetry and command system for the Technology Applications and Science-1 package left the Shuttle Laser Altimeter laser stuck in the "on" position.
At the time of the malfunction, the Shuttle Laser Altimeter, which is designed to make direct measurements of the height of clouds and acquire profiles of land and surface vegetation, was between targets over the South Atlantic Ocean.
Commander Curt Brown was asked to turn off the TAS-1 avionics and the SLA laser in an effort to regain the ability to command the experiment package from the ground. The laser was left in the "off" position so that the hitchhiker experiment packages in the payload bay could continue their observations without any threat of shining the laser on the co-orbiting CRISTA-SPAS atmospheric research satellite. CRISTA-SPAS investigators said they did not believe the laser would have harmed the satellite, but Mission Control opted to be conservative. There was no loss of CRISTA-SPAS data.
Scientists working with the Shuttle Laser Altimeter notified the flight team of the problem shortly before 8 p.m. CDT. The crew was awakened about 11:15 p.m. Brown successfully executed a procedure voiced up by Spacecraft Communicator Marc Garneau, and was allowed to return to sleep about 11:20 p.m. CDT.
Investigators for the TAS-1 reported at 11:22 p.m. CDT that full telemetry and command capability had been restored, which gave a green light for continued overnight experiment operations with TAS-1 and the International Extreme Ultraviolet Hitchhiker (IEH) and a return to the shuttle’s nominal attitude timeline.
Scientists gave a preliminary report that there was no significant data loss to the IEH or TAS-1, but began a detailed assessment of the malfunction’s impact on the mission’s objectives.
Discovery’s six person crew -- Brown, Pilot Kent Rominger, Mission Specialists Jan Davis, Robert Curbeam, and Steve Robinson and Payload Specialist Bjarni Tryggvason -- will be awakened at 1:41 a.m. Monday to begin its fifth day of on orbit activities.
The next mission status report will be issued at approximately 6 a.m. Monday morning.
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