WASHINGTON — Space Exploration Technologies (SpaceX) cut short a static test firing of its Falcon 9 rocket Dec. 3 at Cape Canaveral Air Force Station, Fla., four days before the company is slated to conduct the maiden launch if its Dragon space capsule atop the medium-class launcher.

A SpaceX source said computer systems shut down the first-stage engines before the test was complete, but added that engineers are analyzing the data and that a second attempt is likely to occur Dec. 4.

The first-stage firing was part of a dress rehearsal conducted in preparation for the planned Dec. 7 launch, the first of three increasingly complicated flight demonstrations of Falcon 9 and Dragon under the company’s Commercial Orbital Transportation Services (COTS) agreement with NASA. The $278 million deal calls for Hawthorne, Calif.-based SpaceX to develop and demonstrate hardware capable of ferrying cargo to and from the international space station.

SpaceX holds a separate contract valued at $1.6 billion to make regular resupply runs to the space station using the vehicles developed under COTS. Those flights were supposed to begin this December, but SpaceX has fallen behind schedule and now is not expected to begin resupplying the orbital outpost before next fall.

In a Dec. 2 news release, SpaceX said the static firing was designed to “exercise the countdown processes and end after the engines fire at full power for two seconds, with only the hold-down system restraining the rocket from flight.”

During the upcoming flight test Falcon 9 and Dragon are expected to launch from the Cape at a due-east trajectory over the horizon. The first stage will separate for a planned recovery off Florida’s coast. Dragon is designed to separate from the second stage following insertion in low Earth orbit, where it is expected to demonstrate communications, navigation and maneuvering during as many as four Earth orbits before splashing down in the Pacific Ocean for recovery. The entire mission is expected to last four hours.