Come 2013, the burliest rocket in the world may belong not to NASA, Boeing or any of the other traditional heavy-hitters in the aerospace field. It will belong to a relative newcomer, if start-up spaceflight firm SpaceX has its way.

PayPal co-founder Elon Musk, who heads up the Hawthorne, Calif., company, announced at an April 5 news conference that SpaceX is building a new rocket, called Falcon Heavy, with enough thrust to lift 53,000 kilograms into low Earth orbit. The heavy-lift rockets currently in use around the world, such as NASA's soon-to-be-retired space shuttle; the Delta 4, operated by Boeing and Lockheed Martin's United Launch Alliance; and the European Space Agency's Ariane 5 top out at a payload capacity of around 20,000 to 25,000 kilograms. (NASA's Saturn 5 booster of the Apollo era, with an orbital payload capacity of 118,000 kilograms, was far more powerful than anything in existence today.)

The announcement arrives at a troubled time for NASA's own efforts to build a new heavy-lift rocket for travel into deep space. Budgetary woes and a set of goals that do not always dovetail with those of Congress have made NASA's proposed heavy-lift Space Launch System a controversial subject. (In short, Congress has mandated a set of specs for the system, which NASA's chief has said are neither feasible nor necessary.) SpaceX says the Falcon Heavy rocket is designed to meet NASA's safety standards for human spaceflight, but it might take more than one launcher to send a manned mission to a near-Earth asteroid or some other deep-space destination.

The Falcon Heavy's first rocket stage will comprise three sets of nine Merlin engines, essentially tripling the booster array that SpaceX uses on its smaller Falcon 9 rocket. A finished Falcon Heavy should reach California's Vandenberg Air Force Base in late 2012 for a test flight in 2013, Musk announced during a news conference at the National Press Club in Washington, D.C. He said that both the U.S. government and the private sector had expressed "strong interest" in using the Falcon Heavy to launch spacecraft and satellites into orbit. (The appeal of larger rockets is their capacity to launch heavier spacecraft or multiple spacecraft at one time.)

The 69-meter-tall Falcon Heavy would cost about $100 million per launch, said Musk, who took a shot at the prices charged by the upstart company's competitors, presumably including United Launch Alliance, whose fees are not public. "Other providers kind of treat it like a rug bazaar," Musk said. "They'll charge what they think you can afford."

But there are some downsides to being the new kid on the block. Musk noted that SpaceX's potential customers were none too eager to go first with a new, unproved rocket, so the company is running the initial flight on its own dime as a demonstration.