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SpaceX Successfully Tests Controlled Rocket Reentry

By Wesley Fenlon

SpaceX's Falcon 9 launched on Sunday was brought back into the atmosphere with a controlled reentry burn.

SpaceX sent its latest Falcon 9 launch vehicle to space on Sunday, delivering a payload of four satellites into Earth orbit. And then SpaceX did something new: it brought the Falcon 9's main stage back into the atmosphere with a controlled burn. Normally, the rocket explodes from the pressure of an uncontrolled reentry. This time, it made a successful reentry--but not a successful landing.

Ars Technica writes that Sunday's launch was the first Falcon 9 to travel to space with a new Merlin 1D engine--or, more specifically, nine of them, arranged in a circle around a central engine. The Merlin 1D is larger and provides more thrust than its predecessor. It's also cheaper to manufacture, but the Merlin 1D has a bigger part to play in SpaceX's plan to make launches cheaper. The Merlin 1Ds can come back.

Photo credit: SpaceX

After separating its second stage, powered by a single engine, the Falcon 9 began its descent to Earth. For the first time, SpaceX had the rocket reverse orientation and fire its engines to slow its reentry. SpaceX's goal was to have the rocket survive reentry, and it worked. When the engines fired again to slow the rocket further, though, it began to spin. Ars writes "According to Musk, this 'centrifuged the propellant'—spun it to the tank's walls and kept it from feeding into the engine. As a result, it hit the water hard, leaving the company's employees with pieces to recover. (This rocket didn't have landing gear anyway, and Musk said that the added hardware would act like fins to stabilize the spin.)"

This was the first test SpaceX had planned before attempting a complete recovery of a Falcon 9 in 2014. Controlled returns will present some drawbacks, namely a 15 to 30 percent reduction in available fuel for delivering a payload. But the Falcon 9 accounts for something like 75 percent of a launch's costs, meaning reusable rockets would dramatically lower the costs of regular launches. And that means more payloads making it to space, like the Canadian CASSIOPE weather satellite Sunday's launch delivered.

Part of the CASSIOPE satellite is a prototype called Cascade, which would deliver high-speed data uploads and downloads to the tune of 2100 Mbps. Instead of sending files across the Internet, companies or governments could use satellite dishes to beam them to Cascade in orbit. Currently, they'd have to wait and twiddle their thumbs as Cascade crawled along on its 90 minute orbit and found itself positioned over the receiving country. For huge transfers, that could still be much faster than a traditional Internet transfer, and multiple Cascade satellites would further speed up the service. With more SpaceX launches happening in the future, that's within the realm of possibility.