China Tests Gigantic Drag Sail for Removing Space Junk

China Tests Gigantic Drag Sail for Removing Space Junk
This kite-like space sail will help deorbit a rocket component within two years. (Image: Shanghai Academy of Spaceflight Technology)

Engineers in China have successfully deployed an ultra-thin sail attached to a rocket part to expedite its departure from low Earth orbit and reduce the amount of space junk aimlessly floating above our planet.

The 25-square-metre sail unfurled after launching from a Long March 2D rocket on June 24. Although the mission was not publicized beforehand, the Shanghai Academy of Spacecraft Technology (SAST) announced a few days later that the drag sail had been successfully deployed to assist with the deorbiting of the rocket component, which won’t happen for another two years or so.

When unfurled, the kite-shaped sail increases the atmospheric drag working against the object it’s attached to, thereby accelerating orbital decay. The rocket component will then meet its fate much sooner, deorbiting and burning up in Earth’s atmosphere on its way down. It’s a potential low-cost solution to the ever-growing problem of space debris.

The recently launched drag sail is made from super thin material, about the same thickness as one-tenth the diameter of a human hair. The component that it’s currently attached to, the payload adaptor of the rocket’s upper stage, weighs around 300 kilograms and is orbiting the Earth at an altitude of approximately 491 kilometres, according to SAST. The rocket is expected to get dragged down to lower altitudes with increased friction due to the sail and reenter Earth’s atmosphere in about two years.

China has been a bit reckless lately when deorbiting its rockets. In April, debris that was likely caused by a Chinese rocket that disintegrated on re-entry fell onto a western village in India. Similarly in May 2021, a Chinese Long March 5B rocket fell into the Indian Ocean after making an uncontrolled reentry through Earth’s atmosphere. A year earlier in May 2020, another incoming Long March 5B rocket caused pieces of debris to fall onto two villages in Cote d’Ivoire, damaging people’s homes.

The drag sail will help remove the rocket from Earth’s orbit sooner than it would have on its own, but it’s not clear whether China will account for where pieces of the rocket might fall in order to avoid populated areas.

It’s hoped that the new technology will aid in clearing orbiting space junk. The Department of Defence’s global Space Surveillance Network is currently tracking more than 27,000 pieces of orbital debris, and many more smaller pieces in the near-Earth environment, according to NASA. Ideally, as countries continue to expand their space programs, they will also figure out a way to deorbit their spacecraft not only more quickly, but also less harmfully.