SpaceX unveiled its latest rocket, called the Falcon Heavy, the most powerful launcher ever built by a private company.

At a press conference today, SpaceX CEO Elon Musk said he expects to be carrying the first commercial payloads in 2013, and that they will be at the launch pad at Vandenberg Air Force Base by the end of the year.

The Falcon Heavy can carry 53,000 kilograms (117,000 pounds) to orbit, nearly double the capacity of the Space Shuttle and making it second only to the Saturn V, which was retired in 1973.

The design is a variation on the Falcon 9, which sent the first privately-launched orbital vehicle into orbit on a test flight earlier this year. Where the Falcon 9 is a single core of engines, the Falcon Heavy has a first stage made up of what amounts to three Falcon 9s.

SpaceX says the Falcon 9 can lift twice the payload of the Delta IV Heavy, but do so at one-third the cost. A typical launch, the company says, can be done for $80-125 million.

At the press conference, Musk said the Falcon Heavy can deliver payloads to orbit for about $1,000 per pound. Most analysts put the magic number at about $1,000 per pound to low earth orbit to make commercial space flight viable. Musk said the Falcon 9 can address about half of the launch market and the Falcon Heavy will be able to address the heavy lift part of the launch market and also open up new opportunities. Eventually, Musk said, SpaceX hopes to get below the $1,000 per pound mark.

Getting the costs of launching spacecraft down, Musk said, Is critical to humans becoming a spacefaring civilization.

The rocket is designed to meet NASA's human space flight standards. Both the Falcon 9 and Falcon Heavy are designed to carry the Dragon crew vehicle, which was tested on the Falcon 9 launch.

There's no changes we are aware of that we would make to Falcon Heavy to launch people, he said. The Falcon 9 can take people to low earth orbit, which means to the International Space Station. The Falcon Heavy has the ability to go much farther, Musk said.

With about half the capacity of the Saturn V, the Falcon Heavy could, in two launches, return astronauts to the Moon. Musk said the rocket had enough lift to take 30,000 pounds to an orbit that would allow for a Mars mission, which would allow for not only a trip to Mars but a sample return.

The capacity of the Falcon Heavy makes interplanetary missions simpler as well, because more equipment can be brought to orbit at once than with current rockets.

Initial launches, Musk said, would be from Vandenberg Air Force Base but later it would be launched from Cape Canaveral.

Musk added that SpaceX is shooting for 10 launches per year. That's not an impossible number, he said. Musk said the company is in discussions with possible customers for the Falcon Heavy.

A first launch will be a demonstration flight, to show that it can carry the advertised payloads to orbit.

SpaceX is one of several companies, including Boeing, that are designing launch vehicles to replace the Space Shuttle, which will make its last flight this year.Currently the U.S. space program has no heavy-lift launchers, and after the Space Shuttle retires theonly way to get American astronauts to orbit will be to ride on Russian rockets.