This week NASA sent a peculiar order to the astronauts on the International Space Station: release a load of space junk, the largest ever dropped. Nearly three tonnes of old batteries broke loose and will orbit the Earth for several years before finally burning up in the atmosphere.
It is the largest object to be jettisoned since the International Space Station, according to NASA. The pallet with the cargo came off after the International Space Station’s batteries were replaced last year. A cargo ship commanded by the Japan Space Agency arrived in May 2020 with six new lithium-ion batteries to replace the old ones.
The Japanese supply ship has delivered from 2017 to 2020 a total of four cargoes totalling 24 energy storage units. Previously, the International Space Station has been powered by 48 nickel-hydrogen batteries.
The battery replacement process has taken place outside the ISS. When the HTV cargo ship arrived, the robotic arm captured it and the astronauts went outside to collect batteries and anchor the old ones. The freighter would then return to Earth and disintegrate in the atmosphere, releasing the wreckage over the Pacific Ocean.
The last cargo, however, has run out of HTV cargo, and the gravitational pull will slowly move the pallet until it enters the atmosphere. NASA expects that to happen two to four years from now. Loaded with nickel-hydrogen batteries, the pallet weighs about 2.9 tonnes.
Space debris is one of the most controversial issues in space exploration. A huge number of satellites end up abandoned and orbiting the Earth’s atmosphere until they burn up in the Earth’s atmosphere. However, while they are still up there, they can collide with other spacecraft or satellites, as well as hindering astronomical observation.
Over the last few years, several initiatives have emerged to capture space debris, put an end to it or extend the life of satellites so that they do not end up being discarded so soon. However, it is also worrying how many satellites, such as Starlink, can still be a nuisance during their useful life.