MELBOURNE, Florida - Astronauts aboard the International Space Station planned to capture SpaceX's Dragon spacecraft early Sunday, a day later than planned after the commercial cargo carrier overcame propulsion system trouble early in its flight.
Station managers on Saturday cleared the Dragon to approach the orbiting research complex after SpaceX reported that all 18 thrusters, and other systems, were operating normally.
"SpaceX said it has high confidence there will be no repeat of the thruster problem during rendezvous, including its capability to perform an abort, should that be required," NASA said in a statement.
Station commander Kevin Ford and crewmate Tom Marshburn planned to snare the Dragon with a 58-foot robotic arm around 6 a.m. EST Sunday.
If successful, the capsule loaded with a ton of supplies, science experiments and hardware would be berthed to a station port about two hours later.
The Dragon had been expected to reach the outpost Saturday morning.
But shortly after it reached orbit Friday, minutes after a flawless launch from Cape Canaveral on a Falcon 9 rocket, SpaceX discovered three of the capsule's four thruster pods had not activated properly.
Engineers determined a line blockage or stuck valve had prevented several oxidizer tanks from pressurizing properly.
After repeatedly opening and closing a helium line valve, the obstruction cleared and all four thruster pods were up and running by late Friday afternoon.
By then, it was too late to complete the burns necessary to reach the station on time.
SpaceX CEO Elon Musk on Friday acknowledged the thruster problem was "a little frightening" at first, but by the end of the day a company press release called it "a minor issue" corrected within a few hours.
The resupply mission is SpaceX's second of 12 under a $1.6 billion NASA contract.
The upcoming station visit would be the third by a Dragon, the only privately designed and operated vehicle to reach the outpost. A demonstration flight and the first contracted mission were completed successfully last year.
Despite its late arrival, managers still expect the Dragon to return home March 25.
By James Dean, Florida Today