A SpaceX cargo ship loaded with more than a ton of spare parts, science equipment and crew supplies bound for the International Space Station thundered into orbit Friday, but trouble with the capsule's thrusters forced flight controllers to delay solar array deployment and replan an already complex rendezvous.
"It appears that although it achieved Earth orbit, Dragon is experiencing some kind of problem right now," John Insprucker, SpaceX's Falcon 9 product manager, said during a company webcast. "We'll have to learn about the nature of what happened. According to procedure, we expect a press conference to be held a few hours from now. At that time, further info may be available."
A few minutes later, SpaceX founder and chief designer Elon Musk said in a tweet from company headquarters in Hawthorne, Calif., that three of four maneuvering rockets were being inhibited by the on-board avionics and that company flight controllers were "about to command inhibit override."
He then tweeted that solar array deploy was being held up until at least two thruster pods were successfully activated. The Dragon cargo ship can only function for about 15 hours on battery power alone, not long enough to carry out a successful space station rendezvous.
But SpaceX flight controllers were able to get a second thruster pod back on line and shortly before noon ET, Musk tweeted that both solar panels had been successfully deployed.
The Dragon cargo ship's Falcon 9 rocket, also built by Space Exploration Technologies, roared to life at 10:10 a.m. ET and majestically climbed away from launch complex 40 at the Cape Canaveral Air Force Station.
Trailing a torrent of flame from its nine Merlin 1C engines, the 157-foot-tall rocket launched almost directly into the plane of the space station's orbit, accelerating through low clouds on a trajectory paralleling the East Coast of the United States.
During the first operational SpaceX resupply flight last October, one of the booster's first stage engines suffered a combustion chamber rupture, prompting an early-but-safe shutdown. The other engines fired longer than planned to make up for the shortfall and the Dragon cargo ship was released into the intended orbit.
This time around, all nine engines appeared to work normally and the first stage fell away on time about three minutes after liftoff. The second stage, powered by a single Merlin engine, then continued the climb to space.
Live television views from a camera mounted at the base of the second stage showed the engine nozzle glowing cherry red against the limb of the Earth as the rocket climbed toward orbit.
The second stage appeared to operate normally and another television camera showed the Dragon capsule as it was released from its booster about nine minutes and 46 seconds after liftoff.
The capsule's two solar arrays were expected to deploy about two minutes later, but that ended up being delayed almost a full orbit.
The Dragon spacecraft was released into an initially elliptical orbit with a high point of around 200 miles and a low point of around 120 miles. Assuming the thruster issue can be resolved to NASA's satisfaction, the spacecraft should be able to execute a complex series of rendezvous rocket firings to catch up with the space station for a normal rendezvous.
But flight controllers may have to replan a series of rendezvous rocket firings, which could affect how long it might take to catch up with the station.
At the moment of liftoff, the International Space Station was 253 miles above the Atlantic Ocean just east of New England. The flight plan called for the Dragon to pull up to within about 30 feet of the huge lab complex Saturday morning and then to stand by for capture.
At that point, station commander Kevin Ford, working at a robotics work station in the multi-window Cupola compartment, planned to use the lab's robot arm to grapple Dragon capsule around 6:30 a.m. Saturday.
The astronauts typically handle berthing chores, carrying out complex multi-joint maneuvers to move the captured spacecraft to its docking port on the Earth-facing side of the station's forward Harmony module.
But this time around, ground controllers at the Johnson Space Center in Houston were expected to take over, sending commands to remotely operate the arm through berthing to demonstrate their ability to carry out complex arm procedures and to give the astronauts a bit of a break during a very busy day.
The Dragon capsule is packed with some 2,300 pounds of equipment and provisions, including 178 pounds of crew supplies; 300 pounds of space station hardware, including replacement components for the lab's carbon dioxide removal system; and more than 700 pounds of science gear, including a pair of Glacier freezers and experiment components.
A spacewalk equipment handling fixture called a grapple bar is mounted in the Dragon capsule's unpressurized trunk section. The station's robot arm, again operated by flight controllers in Houston, will be used a few days after berthing to extract the grapple bar assembly and stow it on the station's exterior for future use.
Assuming a successful berthing, Ford and his crewmates plan to re-pack the capsule with 1.5 tons of no-longer needed gear, components that need refurbishment or failure analysis and experiment samples that are needed by scientists back on Earth.
The return manifest includes 209 pounds of crew equipment; 1,455 pounds of science gear, including a Glacier freezer and cold bags loaded with experiment samples; and 884 pounds of space station hardware.
The SpaceX Dragon capsule is the only space station cargo craft designed to bring cargo back to Earth, a critical capability that was lost when NASA's space shuttle fleet was retired in 2011.
The manned Russian Soyuz spacecraft that carry three-person crews to and from the space station can only bring back a few hundred pounds of cargo. All other station vehicles -- unmanned Russian Progress supply ships and European and Japanese cargo craft -- burn up during re-entry.