SpaceX has carried out its first commercial launch with its Falcon Heavy rocket tasked with placing a Saudi satellite in orbit.

The bright white rocket rose and spewed thick gray smoke on the ground as it made its way up into clear blue skies over Cape Canaveral, Florida. It trailed a long stream of bright orange fire.

Boisterous spectators chanted along with the launch announcer who counted down the final ten seconds before liftoff.

The rocket exerts 5.1 million pounds of thrust - that of more than a dozen jetliners, SpaceX said.

The rocket is to carry a Saudi Arabian satellite operated by Arabsat, a year after sending founder Elon Musk's red Tesla roadster into orbit as a test.

The Falcon Heavy had been scheduled to lift off from the Kennedy Space Center on Wednesday but was delayed because of fierce winds in the upper atmosphere.

The job is to place the six-tonne Arabsat-6A satellite into geostationary orbit about 36,000km above the Earth.

Roughly three minutes after clearing the pad, the rocket’s two side boosters separated from the core rocket for a synchronized landing at the Cape Canaveral Air Force Station, sparking boisterous cheers from SpaceX headquarters.

The middle booster, after pushing the payload into space, returned nearly ten minutes later for a successful landing on SpaceX's seafaring drone ship 645km off the Florida coast.

"Three for three boosters today," a SpaceX webcast commentator said.

It was a key demonstration for Mr Musk's space company in the race to grasp lucrative military launch contracts.

"The Falcons have landed" he wrote on Twitter, inaugurating the first successful recovery of all three rocket boosters, which will be refurbished and re-fly in another Falcon Heavy mission this summer to carry a swarm of military and science satellites for the Air Force.

In a 2018 test mission, the rocket's core booster missed the vessel and crashed into the Atlantic Ocean.

The US Air Force tapped SpaceX in 2018 to launch for $130 million a classified military satellite, and in February added three more missions in a $297 million contract.

SpaceX and Boeing Co are vying to send humans to space from US soil for the first time in nearly a decade under NASA’s Commercial Crew Program.

SpaceX’s Crew Dragon capsule, atop a Falcon 9 rocket, cleared its first unmanned test flight in March ahead of its crewed mission planned for July, while the first unmanned test for Boeing’s Starliner capsule is slated for August on ULA’s Atlas 5 rocket.

Falcon Heavy carried a communications satellite forSaudi-based telecom firm Arabsat, which will beam internet and television services over Africa, Europe and the Middle East.