A pallet of used batteries from the International Space Station (ISS) is set to re-enter the Earth’s atmosphere in the coming days, with some parts expected to hit the ground. The pallet, which contains nine batteries, was released from the ISS on January 11, 2021. The European Space Agency’s (ESA) Space Debris Office predicts that the re-entry will occur at 1756 UTC on March 8, although there is an uncertainty of 0.4 days in the date and time, making it difficult to pinpoint the exact location of re-entry until closer to the event.
The re-entry area is estimated to be between -51.6 degrees South and 51.6 degrees North, which is quite a large region. This highlights the challenges involved in predicting a “natural” re-entry. Originally, the batteries were not intended to be jettisoned. From 2017 to 2020, the aging nickel-hydrogen power packs on the ISS were replaced with more powerful lithium-ion units. The old batteries were then mounted onto cargo pallets for the Japanese HTV freighters, which would make a controlled re-entry after departing from the ISS. This method allowed managers to dispose of the waste in an uninhabited area.
However, due to a Soyuz failure in 2018, plans had to be put on hold. NASA astronaut Tyler “Nick” Hague was onboard the Soyuz when it had to abort its launch mid-flight. Although Hague and Russian cosmonaut Alexey Ovchinin survived the incident, Hague’s involvement in the battery swaps had to be postponed. Consequently, when the HTV freighter brought the new batteries, it had to leave the station without taking the old ones back. This resulted in a leftover cargo pallet after the HTV program ended in 2020.
Astronomer Jonathan McDowell estimates that around half a ton of debris will reach the Earth’s surface. While the chances of the debris causing injuries are minimal, some countries, like Germany, have issued warnings to their citizens. However, even German authorities acknowledge that the probability of debris hitting their country is very low. Holger Krag, head of ESA’s Space Safety Program Office, reassures the public that the batteries used in space are no different from those used on Earth and do not pose any major danger. The main concern is the mechanical danger that comes from the falling object.
There is a possibility of witnessing luminous phenomena or hearing a sonic boom during the re-entry, which adds an element of excitement to the event. Hopefully, when the time comes to bring the entire ISS back down to Earth, the process will be more controlled.
