SpaceX has pushed back an historic test of the Falcon Heavy, the world's largest rocket.

At Pad 39A, where Saturn V rockets and space shuttles launched, the first SpaceX Falcon 9 Heavy rocket is standing tall on the pad, where the commercial company's team was scheduled to perform a "static fire" test Thursday.

Just before 1 p.m., though, the company postponed the test fire. It could try again Friday.

SpaceX hasn't said why the static fire test was pushed back.

The rocket is the largest in the world right now, made up of three boosters and 27 engines.

Today's short firing test of those engines is part of the process ahead of the rocket's first demonstration flight, which is set at this point for late January.

SpaceX will fly the rocket on manned and unmanned Mars missions in the coming years.

The company has not said when exactly the rocket's engines will fire. Stay with Spectrum News for more coverage of this developing story.