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– Last Thursday was apparently the day of garbage at the International Space Station, which got rid of a pallet of 2.9 tons of used nickel-hydrogen batteries. It is the largest mass of space debris that the ISS has unleashed, and NASA wrote that the spacecraft “is safely moving away from the station and will orbit the Earth for two to four years before burning harmlessly in the atmosphere.” As for how big it is, a NASA representative tells Gizmodo that the hunk is “more than double the mass of the Early Ammonia Servicing System tank thrown by Spacewalker Clay Anderson during the 2007 STS-118 mission.” Syfy explains that this was not the original plan. Japanese single-use H-II Transfer Vehicle (HTV) cars have been hired to replace those old batteries with lithium-ion ones, and each HTV would fall back to Earth with a battery pallet on board. The objects burned during re-entry, with debris falling into the South Pacific.
As for the reason why this pallet was removed from the ISS, blame the “ripple” effect of an emergency landing in 2018, which confused the ISS removal program, reports Syfy. Spaceflight Now explains that astronaut Nick Hague was supposed to take part in the battery exchange, but his failure to reach the ISS at that time eventually led to the existence of a battery pack that was not recovered by an HTV. However, Bad Astronomy blogger Phil Plait is not convinced of the long-term success of this plan, and posted on Twitter Thursday, “This seems dangerous to me (haha, given a pun given the circumstances). It looks big and dense, so it’s unlikely to burn completely.” Astronomer Jonathan McDowell agreed with an answer, tweeting“Yes. On the other hand, for example, Tiangong-1 weighed 7,500 kg, much higher. But I would say that given how dense EP9 is, it’s worrying, albeit at the lower end of the concern.” The US space command will follow things. (Read more articles about the International Space Station.)