Friday's launch represents the second formal resupply flight that SpaceX has undertaken under a $1.6 billion contract with NASA to ferry goods to and from the International Space Station.

A US cargo mission to the International Space Station has been placed safely on orbit, and after several hours of trouble-shooting, engineers appear to have gotten on top of a problem that could have put the rest of the mission in doubt.

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At 10:10 a.m., Eastern time, a Falcon 9 rocket and its Dragon cargo capsule launched from its pad at the Cape Canaveral Air Force Station in Florida.

Built and operated by Space Exploration Technologies Corp. (SpaceX) in Hawthorne, Calif., the Falcon 9's launch appeared to go flawlessly a welcome sign after one of the first stage's nine motors shut down prematurely during the company's first commercial launch last October.

The rocket delivered Dragon to its proper orbit, as planned. But shortly after the Dragon capsule separated from the rocket's second stage Friday morning, mission controllers reported that the flight-control system had prevented three of the capsule's four thruster pods from activating. The thrusters allow controllers to adjust the capsule's orbit, maneuver at the space station, and slow and orient the capsule properly for reentry.

The problem appears to have been traced to a balky oxidizer valve or clogged line. Initially, only one pod was functional. The craft needs at least two to put it on a trajectory to reach the space station.

By late afternoon, Elon Musk, the company's founder and chief technology officer, said that all four pods were working and that controllers were preparing to raise Dragon's orbit as it heads for the space station.

Initially, plans called for a rendezvous Saturday morning at 6:30, Eastern time. Now, that has been postponed, although NASA and SpaceX officials say the capsule could reach the station Sunday.

Read more:

SpaceX capsule hitch puts mission to space station in doubt