SpaceX F9 landing legsBack in November, following SpaceX’s first launch of a geostationary satellite, CEO Elon Musk said in a call with reporters that his company would attempt to bring back the first stage booster rocket on its next International Space Station supply mission.

SpaceX had successfully restarted the Falcon 9 first stage and steered the booster rocket through a controlled reentry into the atmosphere, an industry first. The rocket made it most of the way back to a soft landing in the Pacific Ocean, before instability caused by a lack of aerodynamic control caused it to crash, Musk said.

Controlled reentry, coupled with the kind of stabilized landings that SpaceX has demonstrated in flight tests closer to the ground, said Musk, would enable a successful safe return of the rocket in the next orbital test.

Reusable booster rockets are the Holy Grail of space flight. Currently booster rockets worth tens to hundreds of millions of dollars are simply discarded after launching their payloads. Imagine ditching an entire 747 after each transatlantic flight, and you’ll see why spaceflight is so expensive.

Musk and SpaceX flight want to change that equation with rockets that can be refueled and launched again. On his Twitter feed, he posted this picture of the Falcon 9 being fitting with landing legs for the ISS cargo delivery flight scheduled for March 16. He also tweeted that the rocket will land in the ocean following the flight, rather than on land as intended in the future.

“F9 will continue to land in the ocean until we prove precision control from hypersonic thru subsonic regimes”

Reusable booster rockets could change everything. Already SpaceX provides the lowest launch cost per pound to orbit, sending satellites to geostationary orbit for around 25% of competitors’ prices. A reusable vehicle could drop the price to as little as 10% of historical prices. It’s all in service of Musk’s ultimate vision: enabling the human settlement of Mars.