Last month, SpaceX finally stuck its landing. After launching a payload of satellites into orbit, the reusable portion of its Falcon 9 rocket—the first-stage booster—successfully landed in the middle of a pad at Cape Canaveral, Florida. SpaceX’s employees, watching from outside the glass-enclosed mission control room, were pretty stoked. (Seriously, you’d have thought they were watching a World Cup match, not a remote video feed of a rocket landing.)

But all that excitement that was just the undercard to this weekend’s main event. On Sunday, after SpaceX launches the Jason-3 ocean-monitoring satellite from Vandenberg Air Force Base in California, it’ll try another landing. But this one will continue the greatest matchup in modern times: Rocket vs. Robot Boat—Round 4!

So far, it’s boat, 2; rocket, zero. And one tie. SpaceX has tried to set the booster down on an autonomous barge three times. The first time, in January 2015, the Falcon booster ran out of the hydraulic fluid necessary to direct its descent. It crashed. Three months later, the booster came in too hot. It looked good at first, then leaned a little bit. And then it crashed.

And the third time … well, let’s just call that a draw. During a June resupply launch, a strut in Falcon 9’s liquid oxygen tanks broke, causing the rocket to explode just three minutes into its flight toward the International Space Station. The boat never got a chance to get a shot in.

But on Sunday, the Falcon might finally get its comeuppance.

You might wonder why, after a successful ground landing, SpaceX is still trying to land its reusable rocket on a target in the middle of the ocean that the company has never managed to hit. In the epic battle of rocket vs. drone barge, the barge has an unfair advantage: Its football field-sized surface is a tiny speck on the water, and unlike land, it moves.

The straightforward explanation is that SpaceX didn’t get environmental approval in time to land back at Vandenberg, so drone barge was the only option. Womp womp.

But in a larger sense, SpaceX is thinking way beyond ISS resupply missions. CEO Elon Musk has always been transparent about his long-term vision. He thinks humans need to get off the planet, and reusable rockets are a huge part of making that future cheap enough to happen. Luckily for him, NASA also wants reusable rockets in the near-term to keep the costs of satellite launches and ISS missions down—and for those missions within Earth’s orbit, ground landings are just fine.

Any missions that hope to get out of Earth’s orbit, though, will need to take off at a higher velocity—and therefore land at a higher velocity, too. If a booster is coming in fast, a drone barge will be a much safer place to land (and the ocean a much safer place to crash if something goes wrong).

It’ll be cheaper, too. A drone barge landing uses less fuel than a ground landing, since the rocket doesn’t have to change directions to head back toward the coast. Instead, it can take a parabolic path toward a barge waiting in exactly the right spot.

Not that fuel savings are on SpaceX’s mind right now. On Sunday, its employees will be waiting and watching to see if they have another first to flip out over. Check back here on Sunday to watch with them: NASA’s livestream of the launch starts at 12:45 pm Eastern time, and the launch itself is scheduled for 1:42 pm Eastern.


SpaceX Rocket vs. Robot Boat, Round 4! Tune in Live to the Grudge Fight