Professor Matthew Colless is an astronomer who is Director of the Research School of Astronomy and Astrophysics at the Australian National University in Canberra. His main research is on understanding how galaxies and larger structures form in the universe. However, he also helps to build instruments for telescopes, and this has led him to get involved in a new research centre that is working on solutions to the problem of space junk.
Q. What is space trash?
A. Space trash is all the stuff orbiting the Earth that’s not meant to be there.
Q. Where does it come from?
A. Wherever people go they leave trash behind, and space is no different. Space trash includes all sorts of things: satellites that no longer work, debris from collisions between satellites, parts off old rockets, tools lost by astronauts, and even just flecks of paint off spacecraft.
Q. How much of it is there?
A. Lots! At present tens of thousands of pieces of space junk are being tracked, but it is estimated that there are several hundred thousand pieces of space junk orbiting the Earth.
Q. Why is it a problem?
A. Space trash is a problem because it can collide with valuable things like communications satellites or the International Space Station and cause serious damage. Even small pieces of space trash can do a lot of damage because things in orbit move so quickly. In low Earth orbit things are moving at about 7 km/s (16000 mph) – or about ten times faster than a bullet!
Q. What are space experts doing about it?
A. The first thing to do is to track the space trash so you know how much there is and where it is, so that satellites and the International Space Station can manoeuvre to avoid it. But some satellites can’t do that, so another option is move the space trash instead by pushing it with a laser beam. But if there’s too much space junk it won’t be possible to dodge or push it out of the way all the time. So we need to figure out ways to reduce the amount of junk in orbit. One way is to use lasers to slow the space junk down so it falls out of orbit and burns up harmlessly in the atmosphere.
Q. What is your project going to do?
A. We are working on all these things: we are trying to improve our ability to find and track space junk; we are figuring out how to predict the orbits more accurately so we know where it will be in future; and we are working on ways to push junk around with lasers. We are using a technique from astronomy called ‘adaptive optics’ which works a bit like noise-cancelling headphones to remove the blur caused by the atmosphere. That helps us see smaller, fainter, more distant bits of space junk, and to focus laser beams more precisely on things in orbit.
Q. How much is it going to cost?
A. Our program will spend tens of millions of dollars improving our ability to manage space junk, and will use facilities worth about a hundred million dollars (£55million). That’s a lot of money, but then the value of all the satellites and spacecraft in orbit is about 900 billion dollars (over £500million) and the value of the services they provide (like GPS, communications, weather forecasting and so on) is trillions of dollars – so it’s worth spending a lot to protect them!