1230p 11/11 Update: Shuttle crew arrival, countdown on tap; weather 60 percent 'go' for Friday launch

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CBS NEWS STS-126 STATUS REPORT: 06
Posted: 12:30 PM, 11/11/08

By William Harwood
CBS News Space Analyst

Changes and additions:

   SR-04 (10/23/08): Endeavour hauled from pad 39B to 39A
   SR-05 (10/30/08): Endeavour cleared for 11/14 launch; Hubble mission delayed to at least May
   SR-06 (11/11/08): Shuttle countdown on tap; weather 60 percent 'go' for Friday launch

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12:30 PM, 11/11/08, Update: Shuttle countdown on tap; weather 60 percent 'go' for Friday launch

The shuttle Endeavour is on track for launch Friday evening, weather permitting, to kick off a space station resupply and servicing mission, the fourth and final shuttle flight this year. Liftoff is targeted for 7:55:34 p.m. Friday, with forecasters predicting a 60 percent chance of acceptable weather.

Endeavour's seven-member crew - commander Chris Ferguson, pilot Eric Boe, Don Pettit, space station flight engineer Sandra Magnus and spacewalkers Heidemarie Stefanyshyn-Piper, Stephen Bowen and Robert "Shane" Kimbrough - planned to fly to the Kennedy Space Center from Houston later today to prepare for launch. Endeavour's countdown was scheduled to begin at 10 p.m. this evening.

The primary goals of the four-spacewalk mission are to service the station's degraded right-side solar array rotary joint mechanism and to install water processing equipment, a new toilet and galley that will permit the urine and waste water recycling needed to expand the lab's crew from three to six next year. Magnus will join Expedition 18 commander Michael Fincke and flight engineer Yury Lonchakov as a long-duration crew member while Gregory Chamitoff, launched to the station last June, will return to Earth aboard Endeavour.

Kathy Winters, the shuttle weather officer, told reporters today the timing of a frontal system moving toward Florida will play a major role in whether Endeavour gets off Friday. As of today, the forecast called for a 40 percent chance of clouds and rain showers ahead of the front that could delay launch. The odds worsen to 60 percent "no go" Saturday and improve to 70 percent go on Sunday.

"Our main concern for weather when it comes to launch is the front that's going to be moving into the area at the end of the week," Winters said. "It's going to be moving into the southeast U.S. as we move into Friday and Saturday. I think mainly the frontal passage will be moving through on Saturday, but there will be a lot of clouds and a chance for some showers ahead of the front."

NASA flight rules forbid a launch in the event of thick clouds along the shuttle's flight path at an altitude where the temperature is 32 degrees or lower because of the possibility of rocket-triggered lightning. Another issue is rain showers over the pad or within 20 nautical miles of the shuttle's emergency runway where Endeavour could be forced to land due to an engine failure in the first few minutes of flight.

Whether those conditions actually develop will depend on when the frontal system moves into central Florida.

"The timing of the front will be critical," Winters said.

Another wild card is the planned launch of an unmanned Russian Progress supply ship from the Baikonur Cosmodrome in Kazakhstan. Launch is targeted for 7:38 a.m. on Nov. 26 with docking on tap Nov. 30. If Endeavour's launch is delayed past Nov. 16, the Russians would have to delay the Progress docking to ensure at least 24 hours between the shuttle's undocking and the supply ship's arrival. It is not clear as of this writing how long the Progress could loiter if Endeavour's launch slips toward the end of its window.

The shuttle launch window closes Nov. 26. Between then and mid December, the angle between the sun and the plane of the space station's orbit - the beta angle - will be such that temperature constraints for the docked shuttle-station complex would be violated. Shuttle managers have said they would delay the flight to early next year if Endeavour does not get off this month.

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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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