Elon Musk’s SpaceX is preparing to launch Falcon Heavy—its massive, heavy-lift rocket—for its first paying customer, more than a year after its debut demonstration mission in February 2018. Last year’s initial Falcon Heavy launch was a spectacle thanks in part to its test payload: Musk’s cherry-red Tesla Roadster with a mannequin passenger, dubbed Starman, sitting in the driver’s seat. This time SpaceX will be carrying a payload for Saudi Arabia’s Arabsat, a satellite services provider.

Falcon Heavy will rumble aloft as soon as Thursday from NASA’s Kennedy Space Center in Florida, after wind scuttled an attempt to fly on Wednesday. Scores of fans and tourists have flocked to the Florida Space Coast for the event, which will be broadcast live on SpaceX’s website.

The Falcon Heavy has three boosters with 27 Merlin liquid-propellant engines in total, giving it more than 5 million pounds of thrust—the most for a launch since the Saturn V rocket last used for Apollo moon missions in the early 1970s. It’s been made even more powerful since last year’s demo flight through upgrades that SpaceX refers to as Block 5, which were applied to the company’s smaller Falcon 9 rocket starting in May.

For SpaceX, the addition of the large and reusable Falcon Heavy to its launch business gives the company the ability to bid on heavier payloads than it can with the smaller Falcon 9 rocket, opening up the market for big commercial satellites launches and national security missions. A standard Falcon Heavy launch costs $90 million, according to the company’s website, compared to $62 million for the Falcon 9.

SpaceX has several paying customers committed to flying on Falcon Heavy, including Inmarsat, Viastat and Arabsat, according to its launch manifest. The U.S. Air Force also chose Falcon Heavy for STP-2, its Space Test Program 2 mission.

Following the launch, SpaceX will attempt to simultaneously return the two side boosters to landing pads and land the center core on a drone ship. Last year, SpaceX recovered two Falcon Heavy boosters on land but narrowly missed landing the third on a drone ship in the Atlantic Ocean.

SpaceX, based in Hawthorne, California, set a company record last year with 21 launches for customers. This year the big focus is on human flight: SpaceX has a contract with NASA to send U.S. astronauts to the International Space Station as part of what’s known as the Commercial Crew program.

In early March, SpaceX pulled off a key test by sending an unmanned Crew Dragon spacecraft to the ISS, then recovering it after a flawless splashdown. Proving that SpaceX can safely fly humans is key to Musk’s ambitions for space tourism and creating a human colony on Mars.