What’s heavy as a truck and races through space at 4.8 miles per second? No, SpaceX hasn’t launched a Cybertruck into orbit — at least, not that we know of. But the International Space Station has just jettisoned a nearly 3-ton slab of spent technology that’s reportedly big enough to qualify it as the single largest piece of space junk left behind in the station’s 20-year operational history.
NASA mission controllers helped take out the ISS’s oversized space trash from the ground on March 11, successfully instructing the station’s 57.7-foot Canadarm 2 robotic arm to release “a pallet loaded with old nickel-hydrogen batteries into Earth orbit,” according to NASA. At 2.9 tons, it may not be the fastest hunk of human-created junk in the galaxy, but it’s definitely among the biggest: NASA spokesperson Leah Cheshier told Gizmodo that the pallet is “the largest object — mass-wise — ever jettisoned from the International Space Station…more than twice the mass of the Early Ammonia Servicing System tank jettisoned by spacewalker Clay Anderson during the STS-118 mission in 2007.”
With the debris “safely moving away from the station” and expected to orbit for 2-4 years before gravitational decay finally draws back into the Earth’s atmosphere, NASA says it expects the batteries to “harmlessly” burn up completely on re-entry. But some longtime space watchers have a wary eye turned toward the skies to see if NASA’s assurance pans out.
Bigger human-made objects, like the remnant’s of China’s Tiangong-1 space station prototype, have certainly made the burn after falling out of orbit. But, as our own Phil Plait tweeted last week, the atypical density of the ISS’ recently-departed space junk makes the idea of a complete burn a little bit of a mystery: “It seems big and dense so unlikely to burn up completely,” he observed.
Earth’s newest piece of orbital garbage wasn’t originally destined to be released directly from the ISS in such a tight bundle. As a relic of the ISS’s recent transition from nickel-hydrogen batteries to lithium-ion, it was meant to be jettisoned from one of the Japanese H-II Transfer Vehicle (HTV) disposable crafts that had been conducting the battery-replacement missions. But the failed Soyuz launch that NASA’s Nick Hague and Russia’s Alexy Ovchinin had to (safely) abort in 2018 created a ripple in the ISS’ disposal schedule, leaving the extra pallet of batteries behind.
NASA’s Cheshier told Gizmodo that U.S. Space Command will keep its tracking eyes on the pallet through the duration of its orbital decay, to ensure it’s not on a collision course with other human-made space objects that aren’t trash (and, of course, to monitor the moment of its re-entry). So if you see a streaking object speeding your way from the skies sometime in the next 2 to 4 years, there’s no need to call the cops: it’s not a Cybertruck, and it’s already on NASA’s radar.