Fast Repair Puts Space Shuttle Countdown Back on Schedule

KENNEDY SPACE CENTER, Fla. --After first postponing the launching 24 hours, NASA reversed itself Sunday and said the space shuttle Atlantis would lift off on schedule Tuesday night for a flight to practice space station construction concepts.

Officials said a problem with a faulty hydraulic valve was resolved much more quickly than expected, and flight director Gene Thomas directed the launch team to pick up the countdown.

The launching, set for 4:29 p.m. PST Tuesday, will be only the second after-dark liftoff in 23 shuttle missions.

During a week in space, the crew of six men and a woman will deploy three commercial communications satellites, and space walkers Jerry Ross and Sherwood Spring will erect a 45-foot beam and a small pyramid to test techniques for assembling a space station in orbit.

Just 3 1/2 hours before the count was to start, the space agency announced the flight had been postponed until Wednesday night because of the need to replace a valve in the hydraulic system of engine No. 2.

Within hours, however, engineers had borrowed a replacement valve from the sister ship Discovery, installed it and tested it. National Aeronautics and Space Administration officials said the exercise was “exceedingly smooth” and had allowed for reverting to the original launching time.

The problem was with a valve that maintains pressure in the hydraulic fluid reservoirs.

The satellites will be released for the Mexican and Australian governments and for RCA American Communications. Mexico’s first astronaut, Rudolfo Neri, will be aboard to observe the release of the Mexican payload and to conduct several experiments.

The other crew members are commander Brewster Shaw, Bryan O’Connor, Mary Cleave and Charles Walker, a McDonnell Douglas engineer.

The Atlantis is to land at Edwards Air Force Base, Calif., on Dec. 4.