SpaceX has been running out of room in its facilities in Florida as it lands rockets by sea and ground, so it would like to begin reusing some of these first-stage Falcon boosters as soon as possible. The first step was finding a customer, and now SpaceX has done that. The Luxembourg-based satellite operator SES said Tuesday that it intends to launch a geostationary satellite, SES-10, on a reusable rocket in the fourth quarter of this year.

“Having been the first commercial satellite operator to launch with SpaceX back in 2013, we are excited to once again be the first customer to launch on SpaceX's first ever mission using a flight-proven rocket," said Martin Halliwell, Chief Technology Officer at SES. "We believe reusable rockets will open up a new era of spaceflight and make access to space more efficient in terms of cost and manifest management."

SpaceX has not yet specified how much it will charge for launch services on one of its flown boosters, but industry officials anticipate about a 30 percent discount on SpaceX's regular price of $62 million for a Falcon 9 launch. The company has not shared how much it is spending to refurbish and reuse a Falcon 9 stage, nor has it offered much public information about the extent to which the vehicle's engines have had to be tested and prepared for a second flight.

To make good on its goal of low-cost, reusable launch services, however, it is not enough for SpaceX to make spectacular landings at sea and on land. The company must now take the critical step of showing that rockets that have flown into space and made high-energy returns to Earth are capable of being turned around in reasonably short order, and at a low cost, to make reusable rocketry practical. Launching by the end of 2016—at a discount—would begin to deliver on that promise.