CAPE CANAVERAL, Fla. – A commercial craft carrying a ton of supplies for the International Space Station ran into thruster trouble shortly after liftoff Friday. Flight controllers managed to gain control, but were forced to delay its arrival at the orbiting lab.

The earliest the Dragon capsule could show up is Sunday, a full day late, said top officials for NASA and the private company SpaceX.

“We’re definitely not going to rush it,” said SpaceX’s billionaire founder Elon Musk. “We want to make sure first and foremost that things are safe before proceeding.”

The Dragon, owned and operated by SpaceX, holds considerable science experiments for the space station as well as food and spare parts.

Musk said six hours into the flight that all four sets of thrusters finally were working. “All systems green,” he reported via Twitter. The problem may have been caused by a stuck valve or a line blockage. The thrusters are small rockets used for maneuvering the capsule.

An hour later, the Dragon was raised with the thrusters to a safe altitude. “Dragon back on track,” he said in a tweet.

It was the first serious trouble to strike a Dragon in orbit. None of the four previous unmanned flights had any thruster issues, Musk told reporters by phone from company headquarters in Hawthorne, Calif.

He said it appeared to be a glitch versus a major concern.

SpaceX has a $1.6 billion contract with NASA to make a dozen deliveries to restock the space station. This is the third trip by a Dragon capsule to the station; the first Dragon flight, in 2010, was a solo test.

NASA space station program manager Mike Suffredini said at least three groups of thrusters on the Dragon need to work before the capsule can come close to the complex. That safety rule will not be waived, he said.

SpaceX is in charge of the flight until it gets near the space station. Then NASA calls the shots.