The space shuttle Columbia is expected to make its third flight in Earth orbit during the week of March 22, a flight that will last more than twice as long as either of the first two flights.

"We expect to roll the shuttle into the vehicle assembly building on Feb. 5 and out to the pad about Feb. 21," orbiter project engineer James A. Thomas said yesterday at the Kennedy Space Center in Florida. "Everything points at a launch the week of March 22."

The third flight is planned to last seven days and take astronauts Jack Lousma and Charles G. Fullerton on an orbital path that will let the sun bake critical parts of the spacecraft the entire time Columbia is in sunlight. The spacecraft payload bay door will soak up 26 hours of sunshine, the tail 30 hours and the nose 80 hours.

"This is a thermal mission," Thomas said. "We're targeting toward the sun to get measurements of how Columbia reacts to the heat of the sun at certain flight angles."

Thomas said that exhaustive testing of the fuel cell that failed on the last flight and cut the mission from five to three days showed that the failure was "not generic" to all three fuel cells that power the spacecraft in orbital flight.

"We discovered that the failed cell had a small metal sliver in a pump that aspirates water out of the fuel cell, a device much like the aspirator a dentist puts in your mouth to remove excess water," Thomas said. "The sliver clogged the pump, which then was unable to aspirate water. The water then backed up into the fuel cell and flooded the cell. We don't anticipate this happening again."

By late Thursday, Thomas said, technicians had replaced 400 of the 449 silica fiberglass tiles that cover the shuttle's fuselage to protect it from heat of reentry and that had been removed after the second flight.