With ferocious flames and smoke in the barren Utah hills north of Salt Lake City, the National Aeronautics and Space Administration on Thursday successfully test fired the first stage of a new rocket that might soon be canceled.

The firing was the first demonstration of a major component of the Ares I rocket that NASA has been developing for the past four years to replace the space shuttles, which are scheduled to be retired next year.

The first effort at the test firing, on Aug. 30, was halted with 20 seconds left in the countdown because of a glitch with a power unit that steers the nozzle.

On Thursday, the countdown proceeded smoothly, and the motor, the largest and most powerful in the world, ignited at 1 p.m., Mountain time. Securely fixed in a horizontal position, the motor did not go anywhere, shooting its 4,500-degree exhaust at a speed three times that of sound into a pile of sand and turning it to glass.

Just over two minutes later, after reaching a maximum thrust of 3.6 million pounds, the motor exhausted the fuel and fell quiet.

The motor is essentially a stretched version of the solid rocket boosters used by the shuttles, and NASA chose the design in 2005 claiming that the simplicity of the design — a single solid fuel motor in the first stage without the complicated plumbing of liquid fuel engines — would make the Ares I safer than any other rocket for astronauts. The reusable casings of the motor tested Thursday were in fact used on shuttle launchings; one flew on the first shuttle flight, in 1981.

Although the test went smoothly — engineers will now spend weeks analyzing the data gathered — it may mark the beginning of the end for Ares I. A blue-ribbon panel reviewing the human spaceflight program included the Ares I in only one of the options it is presenting to the Obama administration. The same rocket motor could be used for the planned larger Ares V rocket, but that option is also in flux.