An estimated 1.2 million pieces of debris larger than 1 cm (0.4 in) are floating in Earth’s orbit, each of which could cause serious damage if it struck functional space equipment. This problem has inspired scientists to come up with some pretty strange cleaning solutions. Sticky satellites Most space debris was not designed to be collected, so docking it in space is a big challenge. A team of researchers in Germany is working on a solution inspired by the sticky paws of geckos. Gecko legs stick to walls due to van der Waals forces: weak interactions between the electrical charges of atoms. The plan is to launch a satellite with a surface coated in a gecko-inspired synthetic material that will stick to passing debris. Geckos’ feet are covered in millions of microscopic hairs that allow them to adhere to almost any dry surface. Credit: Getty Alternatively, the sticky material could be tied to a string and thrown, capturing debris like a chameleon’s tongue catches insects. The satellite could then drag the object back into Earth’s atmosphere, where it would burn up upon re-entry. Robotic Tentacles Several groups have proposed using robotic arms, claws or tentacles to grab space junk in orbit. For example, the European Space Agency is developing a 500 kg (1,100 lb) craft equipped with four tentacle-shaped robotic arms. Its mission (to capture the defunct PROBA-1 satellite) is scheduled to launch in 2029. Space harpoons An alternative proposal involves equipping a satellite with a harpoon, which can be fired at 20 meters per second (66 feet per second), piercing space debris with a barbed lance. A test of the system, led by researchers at the University of Surrey, successfully harpooned a test target in orbit. Despite this, space harpoons have yet to be deployed to capture actual space debris. Laser cannons Instead of going to the trouble of docking space junk, why not deorbit it? In 2015, researchers in Japan proposed mounting a 500,000-watt laser on a satellite to patrol low-Earth orbit and explode debris into smaller pieces, which would return to Earth more quickly. An alternative solution, investigated by NASA in 2011, would use a laser on Earth to remove space debris from the path of operating satellites. Space Ties Engineers didn’t have cleanliness in mind when they built satellites in orbit today, but that could all change in the future. The Japanese Space Agency has been developing a space tether, also known as an electrodynamic tether, that could connect to new satellites before launch. The 700 m (nearly 2,300 ft) lead cable would uncoil at the end of the satellite’s life and be trapped by Earth’s magnetic field, dragging the craft to a fiery end upon re-entry. This article is an answer to the question (asked by Alfie Hughes, Stoke-on-Trent) “How can we clean up space junk?” To submit your questions, email us at questions@sciencefocus.com or message our Facebook, X, or Instagram pages (don’t forget to include your name and location). Check out our fun facts page for more mind-blowing science. Read more:
