NASA engineers are preparing a linear aerospike engine for a third ignition test, possibly as early as Wednesday, at Stennis Space Center in Mississippi.

Steve Nunez, the X-33 project manager at Stennis Space Center, said the engine would be run up to 80 percent power to test the start sequence and capabilities of the engine.

"If the data looks good and the engine looks good, then we should have a quick turnaround," Nunez said.

He added if this week’s test is successful, full power tests could start within a few days.

Unlike conventional rocket engines that use a bell nozzle to constrict expanding gases, the aerospike shape is an inside-out and upside-down bell.

The aerospike’s design allows it to be efficient at all altitudes, unlike the conventional bell nozzle.

The X-33 is a test vehicle being built to demonstrate single-stage-to-space technology and is an almost half-scale version of a re-usable launch vehicle dubbed "Venture Star" by Lockheed Martin, its builder.