The International Space Station has detached its large 2.9-ton pallet of 48 nickel-hydrogen batteries, which is now headed towards Earth. The array of discarded batteries was attached to a robotic arm that released it 265 miles above Earth’s surface and will spend around two to four years in the lower planet orbit (with other space junk) before burning up harmlessly in the atmosphere.
The move follows NASA’s up-gradation of ISS batteries in which the dated 48 nickel-hydrogen batteries were replaced with 24 lithium-ion units in 2016, with final swap occurring in 2020.
Leah Cheshier, NASA communications specialist, in a statement to Spaceflight Nowrevealed that discarded battery wasn’t to be left into the orbit to disintegrate, originally it was to return to Earth aboard Japanese H-II Transfer Vehicle (HTV). But, it had to be left behind due to a failed 2018 Soyuz launch in 2018 that altered spacewalk schedules.
He addedthis is the largest object, mass-wise, to ever be sent from ISS, almost twice the mass of Early Ammonia Serving tank jettisoned by spacewalker Clay Anderson during the STS-118 mission in 2007. The pallet is moving 4.8 miles per second and is believed to survive the intense heat after it enters Earth’s atmosphere. NASA’s ballistic officers ‘indicate no threat.’
The choice of lithium-ion batteries was made keeping in mind their success on Earth as they can withstand much intense heat and thermal events. “The greater energy density of lithium-ion technology reduces the number of needed batteries (and launch vehicles), translating into fewer cargo manifest spots required for the batteries,”read the statement.
The process of swapping batteries initiated in 2016 when NASA began sending the new batteries via the HTV cargo spacecraft, a process which took almost four years to complete and conducted by 13 astronauts and 14 spacewalks to complete.
This set of added 2.9 ton of garbage is in addition to almost 34,000 pieces of space junk along with millions of smaller objects already floating around Earth.