SpaceX was founded in 2002 by Elon Musk, a co-founder of the online payment service, PayPal. Mr. Musk's team has developed rockets aimed at driving down the cost of launching payloads and people into space.

In 2008, after three failures, the company's two-stage Falcon 1 rocket became the first privately financed rocket to reach orbit. It lofted its first satellite in 2009.

The company's next model, the Falcon 9, is designed to be the workhorse for space-station resupply missions and for launching commercial satellites. As a resupply ship, it's topped by a capsule (called Dragon) designed to carry cargo and – in the future – space-station crew members. So far, NASA has spent $75 million on the company's efforts to develop the human-transportation portion of its efforts.

Falcon 9 aced its first test launch in June 2010, topped with a dummy capsule. A second launch six months later put the company into the record books as the first privately financed rocket maker to orbit and recovery a capsule.

As early as the end of this year, SpaceX plans to test its next rocket, the Falcon Heavy, in a launch from Vandenberg Air Force Base in California. It's designed to loft up to 53 metric tons of cargo to low-Earth orbit, more than twice the capacity of the space shuttle. It would be the most powerful rocket in the US stable since NASA's Saturn V first launched astronauts to the moon's surface in 1969.