The dress rehearsal, which is a routine training exercise before every U.S. shuttle launch, went without a hitch and ended with four seconds left on the countdown clocks.
”I’ve never been so close to a shuttle that’s going to launch,” Sweden’s first astronaut and Discovery crewmember Christer Fuglesang told reporters during a break earlier in the week. ”It feels fantastic.”
The seven-member crew has been in Florida since Monday to learn about launch pad emergency escape procedures and to participate in other tests before lift-off scheduled for 9:36p.m. EST (0236 GMT) on Dec. 7.
Fuglesang, who like the others wore a bulky, bright orange pressurized suit for Thursday’s practice countdown, is one of five rookie astronauts due to fly on Discovery’s mission to the International Space Station.
It will be NASA’s first night-time launch since the 2003 Columbia accident.
The first three missions after the Columbia disaster were launched during daylight hours so cameras would have clear views of the shuttle’s fuel tank to spot any falling debris.
During Columbia’s launch, the tank shed a large piece of foam insulation that hit and critically damaged the shuttle’s wing. The shuttle was torn apart as it attempted to return to Earth for landing and all seven astronauts aboard were killed.
NASA has spent hundreds of millions of dollars on two redesigns of the tank, and also introduced extensive in-flight inspections to check for heat shield damage.
But to finish building the International Space Station before the shuttle fleet is retired in four years, the agency needs the flexibility to launch at night. At least 14 more construction missions are required to complete the half-built $100 billion outpost.
NASA plans to use radar to spot any debris during night launches. Engineers also expect backlighting from the shuttle’s booster rockets to provide adequate illumination for cameras.
Discovery commander Mark Polansky said launching at night was really no different for the crew than flying by day. The difference, he said, is how much information engineers are able to gather, which might be important for future flights.
During their 12-day flight, Polansky and his crewmates plan to deliver and install a new piece of the station’s external metal structure and to rewire the station’s power system.