Speaking at the National Press Club, Musk, who also founded PayPal, Inc. and Tesla Motors, said that he concluded over the past 12 months that it was possible to develop and deploy a fully reusable launch vehicle capable of returning to Earth intact.

It's just a very tough engineering problem," Musk said. I am not saying we're certain of success here, but we're going to try to do it, and we have a design that on paper, doing the calculations, doing the simulations, it does work.

SpaceX released an animated video on Sept. 29 illustrating the launch and recovery of their proposed reusable spacecraft, a heavily modified two-stage derivative of the company’s Falcon 9 rocket. Although the simulation is mostly accurate, Musk cautioned that it is not technically correct, because of timing constraints and SpaceX “keeping a few technical things under (its) hat.”

According to the simulation, the first stage separates from the upper stage and turns back towards earth. Then, the first stage’s engines reignite to boost it back towards the launch pad. At a certain altitude, small rockets fire to slow the first stage’s descent and help it land upright on its landing legs. After unloading its payload, the upper stage initiates a de-orbit burn and begins its reentry into the atmosphere.  The upper stage uses its powerful heat shield to withstand the forces of atmospheric reentry. After penetrating the atmosphere, the upper stage uses small rockets to maneuver, slow its descent, and land upright on its landing legs.

The simulation also suggests that SpaceX’s Dragon capsule, which currently carries cargo and will eventually be able to carry a crew, uses its heat shield to re-enter the atmosphere. After reentry, the capsule uses special rockets to slow its descent and land softly on its landing legs. Several engineers and writers, including Aviation Week’s Frank Morring Jr., have suggested that the unwinged capsule’s flight profile is one of the simulation’s technical inaccuracies.

If all goes as planned, the two stages and capsule would land vertically at the same facility from which they were launched. The rocket’s stages and capsules would then be serviced, reassembled, refueled, and rapidly relaunched.

“If it does work, it’ll be pretty huge,” Musk said. “If we can reuse the rocket, say, a thousand times, then that would make the capital cost of the rocket per launch only about $50,000.”

A rapidly reusable orbit class rocket is essential to Musk’s goal of eventually achieving multi-planetary life.

“I think a fully and rapidly reusable system is fundamentally required for life to become multi-planetary and for us to establish life on Mars,” Musk said.

Without a reusable platform, the cost of making life multi-planetary would be prohibitive as it would constitute 100 percent of the U.S. gross domestic product, Musk said.

Musk’s plans are not without technical challenges or controversy.

Musk openly admitted that a reusable rocket faces unique engineering challenges not the least of which is maintaining the delicate balance between vehicular weight and orbital payload. This balance is further complicated by the need to reinforce a reusable rocket’s thermal protection and strength to withstand the atmospheric forces of reentry. These improvements add significant weight to the vehicle and degrade its payload and range capabilities.

Henry Hertzfeld, a research professor at the Space Policy Institute at The George Washington University’s Elliot School for International Affairs, questioned the maturity and reliability of SpaceX’s reusable rocket technology.

“A truly reusable vehicle is still years away,” Hertzfeld said. “People in the past have tried to land spacecraft on all fours and none have succeeded on a routine basis.”

Hertzfeld also questioned some of SpaceX’s efficiency claims.

“Bringing something back in parts is not quite as efficient as one might assume and (SpaceX’s two-stage rocket) is definitely not an ‘airplane-like’ vehicle,” Hertzfeld said.

In the meantime, SpaceX must convince its customers of its technical success and the reliability of its still unproven technologies, Hertzfeld said.

Additionally, some question SpaceX’s business model, which focuses heavily on launching satellites and resupplying the International Space Station on behalf of the U.S. government.

Forty percent of SpaceX’s outstanding orders are from the U.S. government, which Musk said is in line with other government contractors. SpaceX is projecting its fifth consecutive year of profits and has $3 billion under contract over the next five years.

Musk said that SpaceX’s development of a reusable rocket will “be a parallel effort” and will not affect any of its resupply missions, satellite launch operations, or development programs.