KENNEDY SPACE CENTER -- With fuel gauges still a possible problem, NASA is aiming for a Sunday launch of space shuttle Atlantis.
Senior managers have signed off on a plan to tighten flight rules and shoot for a slim one-minute window.
Managers believe the extra precautions will keep Atlantis and its seven-man crew as safe as possible.
Under the new rules, NASA will proceed with the countdown only if all 4 of the gauges in Atlantis' big hydrogen tank are working properly. 2 of them failed when the shuttle's tank was filled for liftoff on Thursday and a third one subsequently acted up.
Liftoff is set for Sunday at 3:21 p.m. Eastern time.
Atlantis is carrying a European lab intended for the international space station.