The last nine batteries released from the International Space Station to crash on Earth this week are expected to reach the planet’s surface sometime Friday. They will naturally reenter Earth’s upper atmosphere, where they are expected to deteriorate and burn up. This is a safe procedure for the batteries, which have a mass of 2.6 metric tonnes. The reentry is forecast to occur within an area centered on 51.6 degrees South and 53 degrees North latitudes. The reentry area can change as the atmospheric conditions fluctuate.
In the meantime, space station residents spent Thursday focusing on space health studies and cargo activities. Flight Engineers Matthew Dominick, Mike Barratt, Jeanette Epps, and Alexander Moghbeli teamed up to learn how to use emergency equipment in the orbiting lab. They also studied the dynamic forces the ISS experiences as it flies around the planet.
Earlier in the day, Commander Sergey Prokopyev and Flight Engineer Dmitri Petelin worked inside two different Progress space freighters transferring cargo in and out of the vehicles. The crew members also updated the station’s inventory management system. Flight Engineer Anna Kikina configured and photographed electronics components and deployed radiation detectors throughout the orbiting laboratory.
Another task the astronauts took on Thursday involved cleaning cooling loops and checking water inside their Extravehicular Mobility Units (EVMUs). They also prepared for an upcoming battery replacement work on the far-outboard P-4 truss. The new lithium-ion batteries will replace the aging nickel-hydrogen units. Between January 2017 and last summer’s multi-spacewalk campaign, 11 EVAs have completed removing 48 old batteries from four trusses and fitting 24 new units in their place.
The ISS is powered by four aging nickel-hydrogen batteries, delivered to the station in March 2009 aboard SpaceX’s STS-134 mission. The batteries power the ISS during the “eclipse” portion of the station’s orbit when it is not in direct sunlight. The aging batteries are nearing the end of their useful life and must be replaced with new ones to continue the station’s operations.
In a typical scenario, the old batteries are placed inside an Uninhabited Transport Vehicle (UTV), jettisoned from the ISS during a spacewalk and sent falling to the Earth’s surface. The UTV is tracked by satellites, and the location of its reentry can be predicted with some accuracy. However, the recent failure of a Soyuz rocket, which forced NASA astronaut Nick Hague and Roscosmos cosmonaut Alexey Ovchinin to make an emergency landing in Kazakhstan, created a backlog for disposal activities. Canadarm2 will now toss the old batteries. It is estimated that about half a ton of the discarded batteries will reach the ground. The rest is expected to burn up in the upper atmosphere.
