Recent E-Waste from Dead Satellites and Space Junk

🌱 How did the waste come to be?

On 21 February 2024, the “Earth Remote Sensing” satellite, ERS-2 from the European Space Agency (ESA) burned in Earth’s atmosphere. The ERS-2 satellite was originally used to help scientists study Earth’s atmosphere, land, and oceans. It was decommissioned after 16 years of operation. On 8 March 2024, a cargo pallet called “Exposed Pallet 9 (EP9)” from the International Space Station (ISS) reentered Earth’s atmosphere. The pallet contained batteries that were originally used to store energy collected by the solar arrays of the ISS and no longer needed. SpaceX recently announced plans to bring down 100 of its satellites to avoid future problems. The company said it discovered a fault which “could increase the probability of failure in the future”.

🌱 What is done with the waste?

So-called “dead-satellite falls” like the one of the ERS-2 happen regularly. The ERS-2 satellite’s mission was ended by the ESA in 2011. The ESA then decided to deorbit the satellite to reduce “the risk of collision with other satellites or pieces of space debris”. Disposing “used or unnecessary equipment” by tossing them overboard from the ISS is a common practice. That said, the uncontrolled reentry of large-scale objects, like the EP9 pallet, from space to Earth’s atmosphere is not a common occurrence. A set of used batteries from the ISS needed to be removed, as they had been replaced with newer and more efficient lithium-ion batteries. The original plan was to dispose of the old batteries properly on a Japanese cargo ship. Yet, due to a “backlog” in equipment disposal, NASA decided to place them on a cargo pallet and use the robotic arm of the ISS to toss the pallet towards Earth for an uncontrolled reentry.

🌱 What resources are there in the waste?

According to the ESA, “[i]n the 67 years of spaceflight, thousands of tons of artificial space objects have reentered the atmosphere”. The ERS-2 satellite was “roughly the size of a school bus” and weighed over 2 tonnes. It contained an array of measurement equipment and a battery system. The EP9 pallet had “the approximate mass of a large SUV”. It was “the largest object ever thrown out from the ISS” and weighed a total of 2.9 tonnes. The pallet contained 9 old nickel-hydrogen batteries, with a combined mass of 2.6 metric tonnes. Typically, “[a]n object of similar size falls into Earth's atmosphere every few weeks”.

🌱 What happens upon reentry into Earth’s atmosphere?

Most objects that reenter through Earth’s atmosphere burn up entirely. The ERS-2 burnt up completely in the atmosphere. While most of the EP9 pallet burned when it reentered the Earth’s atmosphere, it is unknown if it burned entirely. It is possible that parts from the pallet survived the heat.