Mir Back on Track, but Shuttle Rendezvous Is Still in Question

The troublesome motion-control system aboard the Russian space station Mir was working again Monday, one day before the planned launch of the U.S. shuttle Discovery on NASA’s last mission to the space outpost, officials said.

The Russian space outpost had been adrift in orbit since its motion-control system shut down Saturday, threatening to delay the launch of Discovery. NASA’s strict flight rules forbid a shuttle to dock if Mir is not under full control.

Mir’s crew replaced the computer at the heart of the motion-control system Sunday and got the computer to work Monday morning, only to discover that the problem seemed to lie elsewhere.

The cosmonauts finally reactivated the motion-control system by connecting it to another rate sensor--a device that records the station’s movement.

Despite the loss of the crucial system, Mir did not spin out of control and its crew was never in danger, NASA officials said. A fortunate alignment with the sun meant Mir was never short of electrical power. NASA managers planned to meet before the shuttle is fueled today to assess the condition of the station and decide whether to proceed with the launch.