Launch of a SpaceX Dragon cargo ship like this one, shown during final approach to the International Space Station last September, has been delayed from Friday to Jan. 6 because of technical issues, holiday launch opportunities and orbital temperature constraints. SpaceX

SpaceX has delayed the launch of its fifth operational space station resupply mission from Friday to Jan. 6 because of problems encountered during an engine test firing Tuesday, limited options for additional launch attempts over the holidays and unrelated issues concerning the space station's orbit, the company and NASA confirmed Thursday.

SpaceX spokesman John Taylor said the hot fire test, in which the nine Merlin 1D engines in the Falcon 9 rocket's first stage were briefly ignited Tuesday evening to make sure ground and flight systems were ready for launch, was cut short, but he did not provide any details.

He said it would have been possible to press ahead for launch either Friday or Saturday, but mission managers decided to err on the side of caution and to delay the flight to early January.

"While the recent static fire test accomplished nearly all of our goals, the test did not run the full duration," he said via email. "The data suggests we could push forward without a second attempt, but out of an abundance of caution, we are opting to execute a second static fire test prior to launch."

"Given the extra time needed for data review and testing, coupled with the limited launch date availability due to the holidays and other restrictions, our earliest launch opportunity is now Jan. 6 with Jan. 7 as a backup."

The "other restrictions" refer to so-called "beta angle cutouts," periods when the angle between the sun and the plane of the space station's orbit results in near continuous sunlight and higher-than-normal temperatures that increase the demand on the lab's cooling systems.

The next cutout, extending from Dec. 28 to Jan. 7, would not have any impact on the Falcon 9's launch, but the arrival of the SpaceX Dragon cargo ship could cause problems. For a launch on Jan. 6, the Dragon would reach the station on Jan. 8, after the beta constraint eases.

The upcoming launch will kick off the first U.S. station resupply flight since an Orbital Sciences Antares rocket carrying a station-bound Cygnus cargo ship exploded seconds after liftoff Oct. 28.

In the wake of the space shuttle's retirement, NASA is relying on Orbital and SpaceX to deliver critical U.S. supplies and equipment to the lab complex, augmenting cargo carried up aboard Russian Progress supply ships and occasional Japanese freighters.

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SpaceX delays space station resupply flight