Posted July 16, 2015

Cleanup of space is about to start

Experts have warned about the pollution of outer space for more than 30 years. Countless pieces of junk are circling the Earth, endangering satellites and astronauts. Now three different missions are in preparation to demonstrate cleanup technology.

As early as 1982 NASA held a workshop on the subject of space debris. Sources of junk were mostly regular satellite launches. For instance, second stages of rockets used to end up in orbit, with leftover fuel in their tanks. Explosions were a possibility, multiplying the number of useless objects flying around. Also in the closing years of the Cold War some satellites were blown up on purpose, as the superpowers were testing space weapons.

Fun fact: in 1986 I wrote about the problem in a Dutch newspaper. At the time there were slightly over 5000 trackable objects larger than 10 cm in orbit. There was already a finite chance that a large structure such as a space station (then in the planning phase) would be hit within its lifetime. The number of tiny paint chips whizzing around at about 10 kms per second was estimated to be billions. They left visible marks even then as they impacted windows of the Space Shuttles.

Now the number of trackable objects has grown fourfold. Thanks to some precautionary measures satellite launches don't add to the mess the way they used to. But the autonomous multiplication of junk by objects colliding with one another has begun: in 2009 two satellites, one active and one defunct, collided, causing a spike of thousands of extra objects for space agencies and companies to worry about. There have been a couple more high speed collisions as well.

You can't clean up space the way some people are trying to clean up the oceans. Metal junk at several kms per second can't be caught. Some of it will disappear over time, from the lower orbits at least, due to friction.

What you can do is pick up discarded satellites and physically remove them from orbit. This will prevent the creation of new debris. There are many intitatives in this direction. The École Polytechnique Fédérale de Lausanne (EPFL) has designed a grabbing mechanism that has been compared to Pac-man. It could be launched in 2018 to pick up EPFL's own aging Swisscube satellite. ESA has their e.DeOrbit programme, which aims to catch old satellites using a robot arm or a net. An e.DeOrbit mission will not fly before 2021. ESA is still interested in your ideas to clean up space debris.

And then there is Astroscale from Singapore. Their idea is to launch a 'Mother' satellite carrying up to six 'Boys.' Each Boy can glue itself to a stray satellite and decelerate it by 100 m/s, wich in many cases will be enough to make it plunge back to Earth and burn up. A prototype Mother with one Boy is due to be launched in 2017.

One thing is for sure: getting rid of space junk is going to be hard and expensive. Better not create it in the first place.


About Herbert Blankesteijn

Herbert Blankesteijn is a technology journalist from the Netherlands who has written for many prominent Dutch newspapers. He presented and directed television and radio programmes and has 10 books to his name. Herbert is interested in nascent fields such as 3D printing, drones, robotics and the private space business.