A SpaceX rocket failed to land properly on a barge in the open ocean, the fourth failed attempt and a frustrating development for Elon Musk in his pursuit of the ambitious project.

SpaceX has been trying to figure out how to consistently land a rocket safely after using it to launch a payload rather than simply dumping it into the sea, which could save space companies a huge amount of money and make space travel a lot cheaper and therefore more frequent.

The company has been successful after a few tries, but the latest crash shows that there’s still a long way to go before it can be done consistently. The SpaceX Falcon 9 rocket successfully delivered a commercial communications satellite known as SES-9 into orbit, and then work began to try to get it safely down onto a barge in the ocean. However, the rocket landed hard on the barge — too hard, it appears, according to a CNET report.

This was evident by the fact that a live feed from the barge suddenly cut out when the rocket’s thrusters became visible. Elon Musk later confirmed a Twitter that the rocket “landed hard on the droneship.” Not to worry, though, it’s not that big of a setback, he claimed: “Didn’t expect this one to work (v hot reentry), but next flight has a good chance.”

SpaceX has done four attempted landings on an ocean barge, and none of those four have worked out. It did successfully land a Falcon 9 rocket in December, but that was on land. Considering that many recoveries will have to be done at sea, that’s just not enough.

“That controlled descent was successful, but about 10 seconds before landing, a valve controlling the rocket’s engine power (thrust) temporarily stopped responding to commands as quickly as it should have,” a June 2015 SpaceX statement said describing a failure. “As a result, it throttled down a few seconds later than commanded, and—with the rocket weighing about 67,000 lbs and traveling nearly 200 mph at this point—a few seconds can be a very long time. With the throttle essentially stuck on “high” and the engine firing longer than it was supposed to, the vehicle temporarily lost control and was unable to recover in time for landing, eventually tipping over.”