CAPE CANAVERAL, Fla. – An electrical problem forced NASA to postpone yesterday's liftoff of the space shuttle Atlantis yet again, and engineers faced with a tight launch schedule struggled to understand the problem.
About 11 hours before the scheduled midday launch, engineers discovered that a coolant pump that chills one of the shuttle's three electricity-generating fuel cells was giving an erratic reading.
NASA rules say all three fuel cells must be working to launch, and if one fails in orbit, the shuttle must come home promptly.
Space agency officials met for hours during the afternoon trying to figure out whether they could fix the problem, whether they could safely ignore it, or whether they would have to put the flight on hold for perhaps weeks.
Managers, who were divided on the issue, ruled out a launch attempt today but said tomorrow was still a possibility.
Mission managers will meet at 1 p.m. EDT today to assess the issue. If the team decides to “go” for launch tomorrow, liftoff would be at 11:41 a.m. EDT.
Officials wanted more time to analyze the coolant pump because “there's something funny going on in that fuel cell,” said Wayne Hale, space shuttle program manager.
NASA officials said they were going “above and beyond” the agency's safety requirements because flying with the pump problem wouldn't violate any rules.
The space agency's options are to replace the fuel cell or to fly Atlantis as is. Changing the fuel cell would take several weeks, ruling out a launch tomorrow.
There was also a 30 percent chance that bad weather would prohibit liftoff tomorrow.
The space agency might have to wait until late October – or relax daylight launching rules instituted after the 2003 Columbia accident and try again at the end of September.
NASA rules say shuttles have to be launched in daylight so that the big external fuel tank can be photographed for evidence of any broken-off pieces of foam of the sort that doomed Columbia.
Atlantis and its six astronauts plan to haul 17½ tons of girders and solar panels into orbit and resume construction of the international space station, which has been on hold since the Columbia disaster 3½ years ago.
Astronauts are to make three spacewalks to put the pieces together.
The shuttle was supposed to lift off on Aug. 27 but was delayed, first by a lightning bolt that hit the launch pad, then by Tropical Storm Ernesto.
NASA is caught in a schedule squeeze. The space agency made an agreement with the Russians not to attempt a launch after tomorrow because Russia is sending a three-person Soyuz capsule to the space station Sept. 18. If Atlantis blasts off after tomorrow, there would be a traffic jam at the space station.
Once the Soyuz comes back, NASA may attempt a launch in late September even though it would be in the dark, spokesman Allard Beutel said.
If NASA doesn't ease its rules, the next launch attempt after tomorrow would be Oct. 26 or Oct. 27.
NASA has to squeeze 15 shuttle launches into the next four years to finish the construction of the space station.
