Watch a satellite spear space debris with a harpoon

By Loren Grush

University of Surrey

A British satellite in orbit around Earth has successfully tested out a particularly pointed method for cleaning up space debris: piercing objects with a harpoon. In a new video taken from the spacecraft, the satellite shoots its onboard harpoon to puncture a target panel that’s about five feet away.

The test was part of the University of Surrey’s RemoveDEBRIS mission, which is designed to try out various ways of getting rid of debris in orbit. Space debris has become a growing concern for the aerospace community over the last few decades, as it makes the space environment more dangerous for future satellites. These objects typically consist of defunct spacecraft and other uncontrollable objects circling around Earth at more than 17,000 miles per hour. Getting hit by even a small piece of this debris could be enough to take out a functioning satellite, and the collision could create even more dangerous pieces of junk in the process.

That’s why those in the aerospace industry are interested in figuring out ways to remove debris from the space environment to make Earth orbit cleaner and safer for future space travel. The RemoveDEBRIS satellite, which was deployed from the International Space Station in June 2018, is equipped with different tech that’s capable of ensnaring space junk. Before this harpoon test, the spacecraft successfully deployed a net for grabbing debris.

Now, those behind the RemoveDEBRIS mission say that harpoons could also be a good method of capture. “I think we have demonstrated the technology is viable,” Guglielmo Aglietti, principal investigator of the RemoveDEBRIS mission and director of the Surrey Space Centre at the University of Surrey, tells The Verge. “Although what we have done will have to be scaled up in order to touch really large pieces of debris, the method has been successfully tested.”

Aglietti says that the harpoon did not create any small, unexpected pieces of debris during the test; it just created a hole where it pierced the panel. He also noted that future space harpoons would need to have more taut tethers to keep the debris from moving around after it’s pierced. In the video, the targeted panel moves around quite a bit after it’s hit with the harpoon. “Once you have caught your piece of debris, then you have to tighten,” he says. Aglietti also notes that larger vehicles should not move around as much as the panel did once they’re harpooned.

The idea is that once a vehicle grabs hold of a piece of junk, it can then bring the debris down closer to Earth where it will burn up in the planet’s atmosphere. RemoveDEBRIS is going to test out this part of the removal process, too. The satellite will do one final experiment in March when it will inflate a giant “sail” that will help take the spacecraft out of orbit.

This sail is meant to increase the surface area of the vehicle, making it more susceptible to the air in Earth’s atmosphere. While objects in low Earth orbit are technically in space, there is still a very thin atmosphere at this height, and the tiny particles and gas within the atmosphere constantly push on spacecraft, dragging them down to the ground. This is why most objects in low Earth orbit fall to the planet eventually. A drag sail expedites this process by providing more surface for the gas to hit.

When the RemoveDEBRIS satellite tests out its sail, it will ultimately be destroyed during the process as it plunges into the air surrounding Earth. But if the sail is successful, it means the RemoveDEBRIS mission may have demonstrated some key technologies for cleaning up space.

In the future, similar satellites may be able to drag themselves down to Earth with a harpooned piece of debris in tow.