Above: Image © johan63, iStockphoto.com

Spotting a “No Littering” sign in your local park is pretty common. But would you expect to spot one in outer space? “Space littering” is a growing and increasingly dangerous problem. Let’s learn what this is, why it’s dangerous, and what scientists, engineers and politicians can do to solve it!

What is space junk?

Some things in space are supposed to be there, like working satellites and space stations. Other things are considered orbital debris, or space junk. It is hard to guess exactly how much space junk is in Earth’s orbit, but NASA estimated there was about 5,500 tonnes of it in 2008. That means if you added all of that junk together, it would equal around 24 Statues of Liberty!

NASA has been dealing with the space junk problem for years. In 2013, they kept track of over 500,000 pieces travelling up to speeds of 28,000 km/h! These floating, trackable objects range from small pieces the size of a marble to entire broken satellites!

So what exactly is this junk? Lots of different things! For example, there are rocket boosters that have detached during space shuttle launches. There are the leftovers of accidental or intentional explosions. There’s even an odd collection of equipment lost by astronauts: a glove, a camera, tools and garbage bags!

Did you know? One of the larger pieces of space junk currently in orbit is the broken-down Envisat satellite, which weighs 8 tonnes and could stay in orbit for up to 150 years!

The really dangerous stuff is often the tiny bits that NASA can’t keep track of. Most of the space junk scientists worry about is in a region called low Earth orbit. This is where the International Space Station and the majority of satellites are located. It’s the area that lies between an altitude of 180 and 2,000 km above the Earth’s surface.

In this environment, there’s very little air resistance to prevent objects from speeding up and causing serious damage. Something as innocent as a fleck of paint can leave a surprisingly large impact crater on a spacecraft’s surface! NASA has had to replace quite a few space shuttle windows because of these collisions.

But how bad can all this space junk really get?

Luckily for us on Earth, there’s a whole lot of space out in space!  On average, you would have to travel about 125 km in low Earth orbit before coming across a piece of space junk large enough to be tracked by NASA. That’s like driving from Toronto to Niagara Falls.

Did you know? On average, one piece of space junk has fallen back into Earth’s atmosphere every day for the last 50 years.

But that is not to say we have nothing to worry about! The 2013 sci-fi movie Gravity showed astronauts in the middle of a very possible scenario called the Kessler effect. That’s a critical point at which the space junk has gotten so dense that a collision could start a domino effect of more and more collisions, eventually destroying almost everything out there!

This would be a disaster, since here on Earth we have grown very dependent on orbiting satellites. They help humans with everything from communications to navigation. This is why everyone from NASA to tech companies to entire governments are researching ways to get rid of the space junk that’s already out there!

Did you know? There are currently no international laws or regulations that force companies or agencies to clean up their space junk. However, there are guidelines and lots of pressure for them to show how they plan to deal with newly launched satellites once their batteries run out or they are no longer needed.

How to get rid of space junk

One of the easiest ways to get rid of space junk is to change its orbit so it can fall and burn up in the Earth’s atmosphere. There are two possible ways to do this:

  1. With rockets. Small rockets on the broken junk satellites themselves can push them into a lower orbit. This can do one of two things. If the junk satellite is low enough, it’ll burn up right away. Otherwise, being in a lower orbit will speed up the wait time before it burns up in the atmosphere. For example, the French Spot-1 satellite actually changed its altitude from 830 km to 550 km in 2003 so it would get destroyed in the atmosphere in 15 years instead of 200!
  2. With lasers. Scientists can blast a laser at pieces of space junk to nudge them around. The laser could even be located on the Earth’s surface if it were built to be precise enough!

Right now, scientists are only using rockets to destroy space junk. They’re not using lasers yet because governments are worried about the dangers of lasers in space. After all, they could potentially damage things that aren’t space junk.

Some companies have proposed sending up a ship or giant net that could physically drag the space junk into falling orbits. That way, it could either burn up, or fall into a “graveyard orbit” far away from all the good, working satellites.

The latest idea from NASA is a brand new type of “space velcro” that could grab all the space junk. This idea was inspired by geckos! Their feet can grip onto walls using small flaps that create a static electric charge. This is just like when you rub a balloon against your hair to create an electric charge and then stick the balloon to the wall. Astronauts recently tested this inside the International Space Station, and will soon be testing it out in space.

What’s next?

As humans push the limits of space exploration and send more and more people beyond Earth, fixing the problem of space junk is getting really important. Luckily, some of the world’s best scientists and engineers are on the case. Who knows? We may one day see the start of a brand new industry: space junk removal!

Learn more!

About Space Junk

Warning of catastrophe from mass of ‘space junk’ (2008)
R. McKie & M. Day, The Guardian

Space Debris
European Space Agency

Orbital Debris Program Office
Astromaterials Research & Exploration Science, NASA

About How to Get Rid of Space Junk

Sticky ‘space Velcro’ developed by NASA to clear up junk in orbit (2017)
S. Knapton, The Telegraph

Space Junk Crisis: Time to Bring In The Lasers (2011)
A. Mann, Wired

De-orbitation of SPOT 1 (2003)
Centre nationales d’études spatiales

Nathalie Ouellette

I grew up in Montreal, where both my parents work as engineers. From a young age, space fascinated me, but light pollution in the city stopped me from seeing much of the sky. So I poured myself into as many science books as I could find! I did an undergraduate degree in physics at McGill University. Then I moved to Kingston, Ontario, to pursue a PhD in astrophysics at Queen’s University. I finished my PhD in 2016, and now work as a research associate and science communicator. In my free time, you’ll find me rock climbing with my husband, doing yoga, or petting my dog!


Je suis née à Montréal. Mes parents sont tous les deux ingénieurs, et j’ai développé un intérêt pour l’espace dès un très jeune âge. Par contre, la pollution lumineuse de la ville m’empêchait de voir les étoiles, alors je me suis jetée dans les livres! J’ai reçu un baccalauréat en physique à l’Université McGill avant de déménager à Kingston, en Ontario, pour poursuivre un doctorat en astrophysique à l’Université Queen’s. J’ai obtenu mon doctorat en 2016, et travaille maintenant comme associée de recherche et vulgarisatrice scientifique. Mes passe-temps incluent faire de l’escalade avec mon mari, pratiquer le yoga et jouer avec mon chien!







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