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A depleted battery pack from the International Space Station orbited Earth for nearly three years before deorbiting and plunging back into the atmosphere on Friday. Most of the trash probably burned up during re-entry, but some fragments may have reached the Earth’s surface intact.
Larger pieces of space debris regularly fall to Earth on unguided trajectories, but they are usually abandoned satellites or spent rocket stages. It was a space station battery pallet with a mass of more than 2.6 metric tons (5,800 pounds). NASA intentionally sent space debris on a path toward unguided reentry.
Natural self-cleaning
Sandra Jones, a NASA spokeswoman, said the agency “conducted a thorough evaluation of the platform’s debris analysis and determined that it will safely re-enter Earth’s atmosphere.” This was by far the most massive object ever thrown overboard from the International Space Station.
The batteries re-entered the atmosphere at 2:29 pm EST (1929 UTC), according to the United States Space Command. At that time, the pallet would be flying between Mexico and Cuba. “We don’t expect any part to have survived re-entry,” Jones told Ars.
The European Space Agency (ESA) also followed the trajectory of the battery platform. In a statement this weekAccording to the ESA, the risk of a person being hit by a piece of the pallet is “very low”, but “some parts may reach the ground”. Jonathan McDowell, an astrophysicist who closely follows spaceflight activity, estimated that about 500 kilograms (1,100 pounds) of debris would hit the Earth’s surface.
“The general rule is that between 20 and 40 percent of the mass of a large object will reach the ground, although it depends on the design of the object.” the Aerospace Corporation says.
A dead ESA satellite re-entered the atmosphere in a similar uncontrolled manner on February 21. At 2.3 metric tons, this satellite had a similar mass to the discarded battery platform. ESA, which has positioned itself as a world leader in space sustainability, created a website that provided daily monitoring updates on the deterioration of the satellite’s orbit.
As NASA and ESA officials have said, the risk of injury or death from spacecraft reentry is quite low. Falling space debris has never killed anyone. According to ESA, the risk of a person being struck by a piece of space debris is approximately 65,000 times lower than the risk of being struck by lightning.
This circumstance is unique in the type and origin of space debris, which is why NASA intentionally dumped it on an uncontrolled trajectory back to Earth.
The space station’s robotic arm released the battery charging pad on March 11, 2021. Since then, the batteries have been drifting in orbit, circling the planet about every 90 minutes. Over a period of months and years, low-Earth orbit cleans itself through the influence of aerodynamic drag. Drag from rarefied air molecules in low-Earth orbit gradually slowed the platform until gravity finally pulled it back into the atmosphere on Friday.
The cargo platform, which launched inside a Japanese HTV cargo ship in 2020, carried six new lithium-ion batteries to the International Space Station. The station’s two-armed Dextre robot, assisted by astronauts on spacewalks, swapped out old nickel-hydrogen batteries for improved units. Nine of the old batteries were installed on the HTV’s charging pad prior to its release from the station’s robotic arm.