Spaceflight Now STS-102

Countdown rolls on for Thursday's shuttle launch

Posted: March 6, 2001

  Pad 39B
Space shuttle Discovery poised on the launch pad. Photo: Spaceflight Now/NASA TV
Space shuttle Discovery's electricity-generating fuel cells are being loaded with super-cold liquid oxygen and liquid hydrogen cryogenic reactants today as the countdown continues smoothly for Thursday's launch.

"We are working right on the timeline with no issues," NASA Test Director Pete Nickolenko told reporters at this morning's countdown status briefing. "Our flight and ground hardware and personnel are performing exceptionally well."

Technicians have completed activation and checkout of the shuttle's onboard computer and display systems, and the payload bay doors have been closed for launch. Overnight the work began to load the three fuel cells, which are located beneath Discovery's payload bay. The cryogenic reactants are combined within the fuel cells to produce electricity for the shuttle's systems and the astronauts' drinking water during the mission.

Officials expect the fuel cells to be filled by 1 p.m. EST today, with launch pad 39B being reopened to workers later this afternoon once the hazardous operation is completed. The focus will then shift to final main engine checks and securing the pad structures and facilities for liftoff. See our chart showing all countdown events leading up to liftoff.

The weather forecast continues to show a 30 percent chance cold weather could pose a problem for Thursday's targeted 6:42 a.m. EST launch. NASA's temperature limits for shuttle launches ensure that ice does not form on the external fuel tank, which could break away for liftoff and damage the vehicle. The temperature criteria is based on a calculation of the air temperature, humidity and winds.

Meteorologists are currently predicting a temperature of 44 degrees F, relative humidity of over 80 percent and winds 8 to 12 knots. Those conditions would be within limits for launch.

Priselac shows reporters his cold weather chart. Photo: Spaceflight Now/NASA TV
Shuttle Weather Officer Ed Priselac says there is some uncertainty with his forecast and the temperature could dip as low as 41 degrees F. If that happens, the winds would have to be above 3 knots to satisfy the launch rules.

The only other issue managers are dealing with is the Atlantic Ocean. Scheduled to depart port Wednesday, the Freedom Star and Liberty Star solid rocket booster recovery ships could face high seas with waves of 16 feet during their trek to a point 140 miles northeast of Kennedy Space Center, off the coast of Jacksonville, Florida.

"Because the seas are pretty rough today and again tomorrow, there is some concern about when they will get underway," Priselac said.

The ships were supposed to leave around 7:30 a.m. EST Wednesday, but that could be delayed a few hours or more to wait for a calmer sea. Such rough conditions would be hard on the people and equipment aboard the ship, Priselac explained.

Twice before NASA has launched a shuttle without the ships standing by in the Atlantic to pluck the spent solid rocket boosters from the ocean for later refurbishment and reuse. There is no rule that requires the ships be deployed prior to liftoff, so this issue should not hamper Discovery's chances of an on-time blastoff.

Status Summary

See the Status Center for full play-by-play coverage.