The term ‘space junk’ sounds like a euphemism for Captain Kirk’s nether regions, but we assure you, it’s real and it’s not sexy. Ever since Sputnik was launched in 1957, we’ve been hurling things into orbit. There’s even a manhole cover up there (supposedly) - it was launched into space during an underground nuclear test in the 50s. The pressure from the bomb hurled the cap into space and possibly out of Earth’s orbit.
Hopefully it left our solar system because we have enough crap flying around our planet as it is. In 2020, NASA recorded roughly 8,000 tonnes of debris in Earth’s orbit. And it may surprise you that space junk isn’t just made up of defunct satellites. Roughly 23,000 pieces are larger than 10cms, and over 100 million are bigger than 1mm. Small, but dangerous. Here are some other types of debris you can find whizzing about up there:
Junk from human activities, such as a wrench that got ‘dropped’ during a spacewalk, or human waste ejected from the ISS.
Fragments from spacecrafts caused by wear and tear, like peeling paint.
Rocket stages that became ‘useless’ after they’ve launched a satellite.
Fragments of equipment caused by collisions in orbit (yikes).
Launch hardware like bolts and payload covers.
So what do we do about all this rubbish? Well, we can control how we ‘retire’ certain pieces of equipment, like satellites. In general, agencies have three options:
Drop them into low-Earth orbit (1,200 miles from Earth), and let them burn up in the atmosphere. This is typically used for small pieces of junk.
Carefully hurl them into the ‘spacecraft cemetery’ (a specific part of the South Pacific Ocean). This way, any debris that doesn’t burn up in the atmosphere lands far from people’s heads.
Fire them into the ‘graveyard orbit’, roughly 22,400 miles from Earth.
Great, seems like they’ve got it under control. Not really. Space junk can cause dangerous collisions and explosions, especially if fuel is present. In 1978, NASA scientist, Don Kessler predicted a nasty outcome, which became known as the Kessler Syndrome. As explained on the ESA website: “Once past a certain critical mass, the total amount of space debris will keep on increasing: collisions give rise to more debris and lead to more collisions, in a chain reaction.” The European Space Agency (ESA) releases an Annual Space Environment Report to document the debris, and space scientists across the world are working to reduce the amount of detritus we throw up there.
And it’s not just equipment that’s taking a hit. The junk can have devastating impacts on the people who currently live in space. About once a year, astronauts on the ISS have to maneuver the space station away from oncoming debris. Imagine if the Kessler Syndrome became a reality - the ISS would be pummeled to smithereens and the movie Gravity would be a documentary.
Image by ESA