Tuesday, November 25, 2008

840a 11/25 Update: SARJ tested; urine processor up and running

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CBS NEWS STS-126 STATUS REPORT: 68
Posted: 8:40 AM, 11/25/08

By William Harwood
CBS News Space Analyst

Changes and additions:

   SR-65 (11/24/08): Starboard SARJ work complete; port SARJ lubrication now half done
   SR-66 (11/24/08): Spacewalk ends
   SR-67 (11/24/08): Urine processor appears to run normally in extended test; additional test runs planned overnight; engineers hopeful
   SR-68 (11/25/08): SARJ tested; urine processor tests continue

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08:40, 11/25/08, Update: SARJ tested; urine processor tests continue

Engineers began testing the space station's right-side solar array rotary joint today to find out if the damaged 10-foot-wide drive gear at the heart of the mechanism is rolling with less vibration and friction after spacewalking work by the Endeavour astronauts to install new bearings and lubrication. While engineers will spend weeks evaluating the test data, officials said telemetry showed lower motor currents, indicating reduced friction and smoother operation.

The space station is equipped with two SARJ mechanisms on either side of its main solar power truss. The joints are designed to rotate outboard solar arrays to keep them face-on to the sun as the station goes around the planet.

Engineers first noticed problems with the starboard SARJ last year when sensors measured increased vibration levels and power usage in the drive motor. Inspections by spacewalking astronauts later showed one of the gear's three bearing races was heavily damaged, apparently because of a lubrication breakdown that generated extensive metallic contamination.

One of the 12 trundle bearings that grip the gear was replaced last June to help engineers troubleshoot the problem. During parts of four spacewalks, the Endeavour astronauts replaced the other 11 bearing assemblies, cleaned off the metallic debris and re-lubricated all three races.

Going into the flight, station managers said the outer canted bearing race was too damaged to permit resumption of around-the-clock auto-track operations. But engineers hoped the cleaning and re-lubrication would lower vibration and friction levels enough to permit periodic operations to boost power when needed.

Officials said a realtime assessment of telemetry showed the joint was, in fact, operating more smoothly than it did before the repair work, indicating the spacewalks may have accomplished the objective. But it will take several weeks of data analysis before engineers develop a plan for using the starboard SARJ on a more regular basis.

Inside the station, meanwhile, the newly installed urine processor assembly continues to operate after work Monday to mount the unit's centrifuge and distillation assembly more firmly to its mounting rack. Flight controllers ran the unit for more than five hours late Monday and after a three-hour cool-down period, restarted it again today. The plan is to let the processor operate all day to collect additional performance data and process additional samples.

The astronauts also plan to hook up and activate a new potable water dispenser later today that is tied into the Destiny lab module's potable water bus. Engineers want to bring down samples from the water recovery system racks and from the dispenser to test water quality. More than three months of tests are required before NASA wll be clear to boost station crew size from three to six next year.

Additional details about the SARJ operation and the water recycling system troubleshooting are expected at today's mission status briefing at 3:30 p.m.

Here is an updated timeline of today's activity (in EST and mission elapsed time; includes revision K of the NASA television schedule):

EST........DD...HH...MM...EVENT

11/25/08
08:55 AM...10...13...00...Crew wakeup
10:25 AM...10...14...30...ISS daily planning conference
11:10 AM...10...15...15...Potable water bus vent/fill
11:10 AM...10...15...15...Water recovery rack UPA troubleshooting
12:20 PM...10...16...25...Post-EVA spacesuit transfer and reconfig
12:35 PM...10...16...40...Potable water dispenser activation
03:30 PM...10...19...35...Mission status briefing on NASA TV
04:05 PM...10...20...10...Joint crew meal
05:05 PM...10...21...10...PAO event
05:25 PM...10...21...30...Node 2 CBM/CPA install
08:10 PM...11...00...15...Configure MPLM racks
09:00 PM...11...01...05...Evening planning conference
11:25 PM...11...03...30...ISS crew sleep begins
11:55 PM...11...04...00...STS crew sleep begins

11/26/08
12:00 AM...11...04...05...Flight day 12 highlights
07:30 AM...11...11...35...Flight director update
07:55 AM...11...12...00...Crew wakeup

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Quick-Launch Web Links:

CBS News STS-126 Status Reports:
http://www.cbsnews.com/network/news/space/current.html

CBS News STS-126 Quick-Look Page:
http://www.cbsnews.com/network/news/space/currentglance.html

NASA ISS Expeditions Page:
http://www.nasa.gov/mission_pages/station/expeditions/index.html

NASA Shuttle Web: http://spaceflight.nasa.gov/shuttle/index.html
NASA Station Web: http://spaceflight.nasa.gov/station/index.html
Spaceflight Now: http://spaceflightnow.com/index.html
GoogleSatTrack: http://www.lizard-tail.com/isana/tracking/

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