In late 2019, the giant Ocean Cleanup device—a huge floating barrier created to catch pieces of plastic trash floating in the sea that for years was the just a theoretical idea (and the subject of much press attention)—headed out for its first mission to the middle of the Pacific Ocean for a second time. The big question: Could the system actually work?

The answer was no. But after new tests at the patch this summer, new design tweaks seem to have solved the main problem, and the device is almost ready for a new mission—offering new hope for a chance to shrink the amount of plastic in our ocean.

The original design was fairly simple. A 2,000-foot-long tube, arranged in a U-shape, would float in the water with a screen hanging below it in the water, moving with the wind and the ocean currents. In theory, it would naturally move faster than the plastic floating in the water, creating an artificial shore where the plastic could be collected. The Great Pacific Gyre contains an estimated two trillion pieces of plastic, spread diffusely over an area twice the size of Texas; The Ocean Cleanup’s strategy is to concentrate that plastic into the device so it can be removed more easily.

“There were two main issues that we encountered, or ‘unscheduled learning opportunities,’ as we refer to them,” says Boyan Slat, the 25-year-old founder of the nonprofit. The first version, dubbed “Wilson,” fractured from the stress of being in the water. That was a problem, but not as difficult to solve as the second challenge: the device wasn’t actually moving at the right speeds to capture plastic. Sometimes it was too slow, sometimes too fast.

So in the June tests, the team tested two potential solutions—attaching huge inflatable buoys that would make it move faster, or a parachute that would slow it down. Both solutions helped, but the team now plans to move forward with the parachute, which allowed the device to consistently catch plastic in the tests. It concentrated the plastic by a factor of around 10,000, Slat says. “If we could do this to the whole patch, we’d take the plastic distribution down from twice the size of the state of Texas, to one-tenth the size of the city of Houston,” he wrote in a blog post.

The latest design still isn’t quite ready for deployment, as the fix for the fracture caused another problem (the engineers moved the screen forward to help eliminate the connection that caused the fracture—but that created another spot where plastic could escape). But it should be an easier problem to solve. Slat is still optimistic about the technology, despite skepticism from critics. And the issue remains vital: Out of all of the plastic ever made, only around 9% has been recycled. By next year, by one estimate, as much as 150 million metric tons of plastic may have ended up in the ocean. Even if the world suddenly stopped using less plastic—and even if all of it was recycled or thrown out correctly—we still have the problem of all of the trash that’s already in the water. In the Pacific, much of the waste is still in large pieces (whole bottles, toothbrushes, etc.), and cleaning it up now would be much easier than trying to deal with it after it breaks down into microplastic.

The Ocean Cleanup team plans to keep moving forward as quickly as it can. “The aim is to get to a proven technology—to a system that works,” says Slat. “We can then start working on something that can scale with which we can build a whole fleet to actually clean the whole patch. It’s all about that first crucial step.”