Elon Musk says SpaceX has a 50 percent chance of landing a rocket on floating platform

Sending a rocket to space is hard enough, but landing it back on Earth is even harder. It's the problem that is plaguing private space flight because one-time-use rockets are tremendously expensive. But SpaceX founder Elon Musk says his company is close to being able to land and reuse a rocket.

Mr. Musk says SpaceX has a 50 percent chance of landing a Falcon 9 rocket booster on the next attempt. At the Massachusetts Institute of Technology's Aeronautics and Astronautics Centennial Symposium, Musk said he wants to land rockets so that they can be reused, which will dramatically decrease the cost of sending cargo and people to space, making the prospects of regular spaceflight attainable.

"There are a lot of launches that will occur over the next year," Musk says. "I think it's quite likely that in one of those flights, we'll be able to land and re-fly. I think we're quite close."

SpaceX will attempt to land the rocket on an ocean platform that is currently being built in a Louisiana shipyard. The platform is 300 feet by 170 feet and the rocket's landing legs span 60 feet. The unanchored platform will be positioned in the Atlantic Ocean, and will be equipped with a GPS and engines to keep it in place. Because of the size and waves, Musk says landing on the platform will be "tricky."

"We're going to try to land on [the floating landing platform] on the next flight," Musk says. "If we land on that flight, I think we'll be able to re-fly that booster."

SpaceX has already brought two Falcon 9 rocket boosters from space and been able to perform soft landings in the Atlantic Ocean, but there were complications.

"Unfortunately, [one rocket] sort of sat there for several seconds, then tipped over and exploded," Musk says. "When a 14-story building falls over, it's quite a belly flop."

When Space X is able to successfully land a rocket multiple times, the company will attempt to touch down on land. Musk says the next launch has a 50 percent chance of landing, but he said there is a 90 percent probability that one of the launches planned over the next year will be landed. 

Landing a rocket is crucial for SpaceX's mission of putting a sustainable human colony on Mars, something Musk said is like "life insurance for the human race."  Musk says, unlike Earth, wings and landing gears don't work on Mars. He could use a parachute, but then the rockets wouldn't be reusable. 

"You have to get good at propulsive landing if you want to go someplace other than Earth," Musk says.

SpaceX's next launch will be the fifth official robotic cargo mission to the International Space Station, which is planned no earlier than Dec. 9.