The era of the Space Shuttle is ending. And SpaceX plans to take over.

Elon Musk, the millionaire founder of private space company Space Exploration Technologies Corp (SpaceX for short) said the long planned Falcon Heavy vehicle would be ready for liftoff at the end of 2012. The rocket, which he called the most powerful in the world, would be capable of taking men to the International Space Station, dropping vehicles and astronauts on the moon -- and maybe even cruising to Mars and back.

"This is a rocket of truly huge scale," Musk said at a press conference unveiling the rocket. "With Falcon Heavy, we'll be able to put well over 100,000 pounds into orbit," he said, and possibly as much as 120,000 pounds.

"That's more than a fully loaded Boeing 737 -- with passengers and fuel" and even luggage, Musk said.

The Falcon Heavy consists of a standard Falcon 9 rocket with two additional Falcon 9 first-stage rockets acting as liquid strap-on boosters. The upgraded Merlin engines that power the rocket will generate 3.8 million pounds of thrust at liftoff -- the equivalent of 15 Boeing 747s, he said.

It is intended primarily to carry satellites and other such payloads into space, though it will meet NASA's requirements for carrying humans as well.

"It can launch people if need be, and do so safely," he said.

NASA spokesman Michael J. Braukus was cautiously optimistic that the ship would help U.S. interests in space, though he declined to comment on whether Falcon Heavy would be useful for human transport.

"The addition of a third [heavy lift] vehicle to the commercial rocket inventory should help bring down launch costs for unmanned missions," Braukus told FoxNews.com.

But for cargo transport, it will clearly have a role: Musk said this version of the spacecraft would have twice the capability of the space shuttle.

The Falcon Heavy will also dramatically surpass the Delta IV Heavy's 25-ton capacity and the yet-to-be-built Atlas 5 Heavy's 32 tons. It will be assembled at California's Vanderburg Air Force Base, but Musk said it would be able to take off from Cape Canaveral as well.

Musk also claimed the Falcon Heavy would cost a third per flight than the Delta IV rocket, and sets a new world record for the cost per pound to orbit of around $1,000. A launch is estimated at $80 million, the company said, while an Atlas 5 costs as much as $100 million more.

We can realistically contemplate a mission to Mars with this craft, Musk said, because the tremendous capacity of the vehicle would allow it to carry enough fuel to return to Earth successfully.

"Falcon Heavy would be capable of launching people as soon as we've proven it out with a few launches," Musk said. "It opens up a wide range of possibilities, such as a mission to the moon or conceivably even Mars," he said.

"First launch from our Cape Canaveral launch complex is planned for late 2013 or 2014,” Musk said.