CAPE CANAVERAL, Fla. -- SpaceX's new megarocket launched on its first test flight Tuesday from Florida's Kennedy Space Center as thousands jammed surrounding beaches.

Some details about the Falcon Heavy rocket, its cargo and what's ahead:

THE ROCKET

The Falcon Heavy has three first-stage boosters, strapped together with 27 engines in all. Stretching 40 feet (12 metres) at the base and standing 230 feet (70 metres) tall, the Heavy is a triple dose of the Falcon 9, the company's frequent flyer with just a single booster. At liftoff, the Heavy packs about 5 million pounds of thrust. That's more liftoff punch than any other rocket currently operating in the world -- by a factor of two -- but less than NASA's old space shuttles and Saturn V moon rockets. Two of the boosters-- recycled from previous Falcon 9 launches -- returned minutes later for simultaneous, side-by-side touchdowns at Cape Canaveral. There was no immediate word on whether the third booster made it onto the ocean platform.

THE CARGO

SpaceX's Elon Musk also runs the electric carmaker Tesla. So in a bit of cross-marketing, he put his own cherry-red Tesla Roadster on the Heavy's inaugural flight with a space-suited dummy at the wheel. No car has ever rocketed into space before, if you don't count NASA's Apollo-era moon buggies, still parked on the lunar surface. The Federal Aviation Administration had to sign off on the Heavy-Tesla combo. Usually, there are steel or concrete slabs or mundane experiments on test flights. The convertible was at the top of the rocket, enclosed for liftoff. The protective cover dropped away, allowing the car to travel on its way. Three cameras were mounted on the Roadster.

THE DESTINATION

SpaceX is targeting a long, oval orbit around the sun for the Roadster that will take the car as far out as Mars, and have it making laps for a billion years. First up, hours of deep-space coasting through the high-energy Van Allen radiation belts encircling Earth. If it weathers all this, the Roadster will reach the vicinity of Mars in six months. Musk said that the car could come fairly close to Mars and that there's an "extremely tiny" chance it could crash into the planet. Musk is intent on establishing a city on the red planet, with hordes of Earthlings and building materials flying there on a super-extra-mega SpaceX rocket that is still in development.

THE LAUNCH PAD

The Falcon Heavy lifted off from the same launch pad used by NASA to send astronauts to the moon. SpaceX leases Launch Complex 39A from NASA. Not only did LC-39A, as it's known, serve as the departure point for all the Apollo moonshots from 1968 to 1972, it was the scene for most of the space shuttle liftoffs. Its location at Kennedy Space Center keeps people at least three miles away, a distance determined by NASA in the 1960s to be safe just in case the Saturn V exploded on the pad.

THE FUTURE

SpaceX already has customers lined up for the Falcon Heavy. The rocket is designed to hoist supersize satellites as well as equipment to the moon, Mars or other far-flung points. The private company's online flight manifest shows the U.S. Air Force as already signed up. Other aerospace companies are developing rockets and NASA is sinking billions of dollars into a massive new rocket called the Space Launch System, or SLS, that's meant to return astronauts to the moon and also get them one day to Mars.