Shuttle Discovery and six astronauts got a green light today for the planned launch Wednesday of the fleet leader's final flight, an International Space Station outfitting mission.
The 18-story spaceship and its crew remain scheduled to blast off from Kennedy Space Center's launch pad 39A at 3:52 p.m. Wednesday, the middle of a 10-minute opportunity to set sail for the international outpost.
"Right now we're not tracking any issues that would prevent launch," said NASA Shuttle Launch Director Mike Leinbach. "Nothing that's going to hold us up."
The weather forecast for Wednesday looks good. Kathy Winters, shuttle weather officer with the U.S. Air Force's 45th Space Wing Weather Squadron, said there is a 70 percent chance conditions will be acceptable for launch. The only concerns are the possibility of low-level clouds or rain showers within 20 nautical miles of the Shuttle Landing Facility.
The weather on Thursday is expected degrade on Thursday. A cold front is expected to sweep over the Florida peninsula, bringing a chance of low-level clouds, showers and possibly isolated thunderstorms into the Cape Canaveral area.
NASA flight rules prohibit launching when low-level clouds might obscure the view of the three-mile shuttle runway in the unlikely event of an emergency landing. Rain showers could damage the orbiter's fragile heat-shield tiles, and thunderstorms could trigger destructive bolts of lightning in flight.
The front is expected to pass through the area Thursday evening and the weather for Friday is expected to be better. There is a 70 percent chance of acceptable weather on Friday.
NASA must launch the shuttle by Nov. 7 or delay the flight until a short opportunity in early December. A new NASA analysis shows the agency might be able to make an attempt on Nov. 8. But as it stands, the sun angle on the station between Nov. 8 and Nov. 23 will be such that the outpost could not generate enough electricity or dispel enough heat to support a docked shuttle. Then a Soyuz crew is scheduled to depart the station on Nov. 29, leaving just three people onboard the outpost.
So the next opportunity would be Dec. 1 through Dec. 5. However, the Discovery mission includes several sortie science experiments that are to be performed on the station and then returned to Earth on Discovery. With only three station crewmates onboard the outpost, it's questionable whether the experiments could be carried out.
Traffic at the station then picks up with the arrivals of two Russian progress cargo carriers and space freighters from Europe and Japan. The next shuttle launch opportunity, as a result, would be Feb. 27, currently the launch date for the last flight of Endeavour.
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