Earlier today, SpaceX fired up all 27 engines on its Falcon Heavy rocket for a test fire, the final crucial step before the rocket is allowed its maiden launch. Elon Musk took to Twitter shortly after to confirm that the launch was a success, and a launch can be expected in a week or so.

The maiden voyage has been a long time coming for SpaceX, with tests promised all the way back in 2013. SpaceX has commercial launches using the Falcon Heavy already planned, and the heavy-lift rocket is a key component in Elon Musk’s plan to send tourists to the Moon, and colonists to Mars.

The Falcon Heavy is the largest rocket SpaceX has ever built. It’s constructed by strapping three of SpaceX’s proven Falcon 9 rockets together, which provides around 5 million pounds of thrust at takeoff. That’s enough to get 140,000 pounds into Earth’s orbit, a little under three times the payload of a Falcon 9.

It’s also enough thrust to launch payloads to the Moon or Mars, so the Falcon Heavy is the key component in SpaceX’s bigger ambitions. Musk hopes to use the Falcon Heavy to send tourists around the Moon, and to send supplies to Mars for a manned mission.

For the test flight, however, SpaceX is going much crazier. Test flights do require a payload to make the math and aerodynamics work, but there’s also a good chance that the test flight might end in an explosion, so you don’t want to strap a billion-dollar communications satellite to the front.

Normally, that means sending a concrete mass into orbit, but Musk decided instead to send his original Tesla Roadster into an orbit around the Sun. The other mission parameters for the Falcon Heavy’s first flight are equally ambitious: All three Falcon 9 cores are expected to detatch from each other and land back on the launch pad or on a drone ship at sea.