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– Last Thursday was apparently garbage day on the International Space Station, which disposed of a 2.9-ton pallet of used nickel-hydrogen batteries. It is the largest mass of space debris the ISS has ever unleashed, and NASA wrote that the platform “is moving safely away from the station and will orbit Earth for two to four years before burning harmlessly in the atmosphere.” As for how large, a NASA representative tells Gizmodo that the chunk is “more than double the mass of the Early Ammonia Servicing System tank that was dropped by spacewalker Clay Anderson during the STS-118 mission in 2007.” Syfy explains that this was not the original plan. Japanese disposable H-II Transfer Vehicle (HTV) vehicles were dedicated to replacing those old batteries with lithium-ion batteries, and each HTV would return to Earth with a pallet of batteries on board. The items would be burned during re-entry, and any remainder would fall into the South Pacific.
As for why this pallet was scrapped from the ISS, blame the “domino” effect of an emergency landing in 2018 that interfered with the ISS removal schedule, Syfy reports. Spaceflight Now explains that astronaut Nick Hague was supposed to take part in the battery changes, but his inability to reach the ISS at the time ultimately resulted in there being a pallet of batteries 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 tweeted Thursday, “This seems to me (haha, a pun under the circumstances) as dangerous. It looks large and dense, so it is unlikely to burn completely. Astronomer Jonathan McDowell agreed in one answer, tweeting, “Yes. On the other hand, for example, Tiangong-1 weighed 7,500 kg, much larger. But I would say that given how dense the EP9 is, it is worrying, albeit on the lower end of worrying.” The US Space Command will keep an eye on things. (Read more stories from the International Space Station).