Everyone’s attention may be taken up by the recent spacewalk but astronauts weren’t the only things that exited the International Space Station last week.
The ISS jettisoned its largest piece of space junk ever on March 11. The external pallet, containing old Nickel-Hydrogen batteries, weighed about 2.9 tonnes. This makes it the biggest object to be dropped from the ISS since 2007.
EP9, the external pallet from the HTV-9 cargo ship, was jettisoned from the ISS by the Canadarm-2 robot arm today, Mar 11 (possibly around 1100 UTC? Does anyone have the correct time?). With 9 old batteries attached, it has a mass of about 2430 kg.
— Jonathan McDowell (@planet4589) March 11, 2021
The exposed pallet was delivered by Japan’s final HTV supply ship to the ISS last May. It carried six lithium-ion battery orbital replacement units which astronauts connected last year. The old nickel-hydrogen batteries were then moved and placed onto the pallet to be jettisoned.
The pallet was removed by the 17 meter-long Canada robotic arm, which NASA’s ground teams controlled from the Johnson Space Centre. The whole event was streamed live for viewers on the ISS website.
NASA said that the pallet will orbit Earth for approximately 2-4 years before it is predicted to re-enter Earth’s atmosphere.
— Mike Hopkins (@Astro_illini) March 11, 2021
Cloudy with a chance of space junk
So should we be worried about a 2-tonne pallet of space rubbish dropping on us one day? According to Spaceflight Now, a statement from NASA claims it expects the pallet will burn up harmlessly in our atmosphere.
There is also apparently no chance that the pallet will orbit Earth and impact the ISS as it was jettisoned on a trajectory a safe distance away.
That being said, space debris trajectories aren’t an exact science and have been a bit of a problem in the past. Last year, a hunk of a Chinese rocket became the largest piece of uncontrolled space debris after it didn’t break up in Earth’s atmosphere. Thankfully, it crashed into the Atlantic Ocean.
New methods for removing space debris are always being considered as the quantity of junk grows. The European Space Agency recently signed a $140 million contract to use a space net to remove a payload adapter. The adapter could potentially cause problems with functioning satellites and the ISS, hence there’s an expensive plan to remove it.
If that fails, there’s always the old space harpoon option.