Launch Countdown Underway for NASA's Shuttle Discovery

The countdown is underway to launch NASA's space shuttle Discovery on the STS-116 construction flight to the International Space Station (ISS). CREDIT: NASA TV.

CAPE CANAVERAL, Fla. - The clock is ticking for NASA's shuttle Discovery as launch controllers began counting down towards the spacecraft's planned Dec. 7 launch late Monday.

NASA controllers reported to their consoles in Firing Room 4 at the Launch Control Center here at the Kennedy Space Center (KSC) at 10:30 p.m. EST (0330 Dec. 5 GMT) today and countdown clock began ticking towards liftoff 30 minutes later.

"Five, four, three, two, one, and the clock is rolling," said NASA commentator Bruce Buckingham. "Countdown has begun for NASA's first night time launch in four years."

Discovery is slated to blast off on Thursday, Dec. 7 at 9:35:47 p.m. EST (0235:47 Dec. 8 GMT). The T-43 hour countdown includes 27 hours, 36 minutes of built-in hold time.

Current weather forecasts predict a 80 percent chance that launch will proceed as scheduled, although there are some concerns of low clouds and isolated showers.

The five-man, two-woman STS-116 crew flew into KSC from Houston yesterday afternoon. In these final days leading up to the launch, they will be performing final inspection of the hardware and tools they will use during their 12-day construction mission on the International Space Station (ISS).

Discovery commander Mark Polansky and pilot William Oefelein are also practicing shuttle landing, said NASA spokesperson Kylie Clem.

"The rest of the time is studying the mission and free time," Clem told SPACE.com.

Riding with Polansky and Oefelein will be mission specialists Nicholas Patrick, Robert Curbeam, Joan Higginbotham, Sunita Williams and Christer Fuglesang, a European Space Agency (ESA) astronaut who is also the first Swede to fly in space.

The STS-116 crew is tasked with rewiring the electrical grid of the ISS and delivering a new $11 million portside piece of the orbital laboratory. Williams will also relieve ESA astronaut Thomas Reiter who has been aboard the station since July.

ISS flight controllers also successfully performed a 23-minute rocket burn to boost the orbital laboratory to a higher orbit Monday afternoon in preparation for docking with the shuttle on Dec. 9. Attempts to do so last week were cut short due to an unexpected shift in the station's orientation caused by the installation of new ISS components in September.

A failure to raise the station's orbit would have cut into the shuttle's launch window, which currently runs from Dec. 7 to 17 and possibly later if shuttle mission managers approve Discovery for flight over the end-of-year rollover.

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