Space Junk

It's a huge problem - in 2013, NASA was tracking 500,000 pieces of debris. The big fear is what's known as "Kessler syndrome" - a chain reaction of satellite destruction that could interdict us from large parts of Earth's orbit.

A smaller issue is that people have, yes, been hit by space debris. Lottie Williams, for example, was hit by part of a propellant tank in 1997 (she was uninjured).

Part of the solution is that we now care a lot more about what happens to obsolete and defunct satellites. GEO satellites, for example, are obliged to carry enough fuel to move them to an out of the way "graveyard" orbit. Other satellites are designed to de-orbit - to burn up intentionally in the atmosphere.

But in the long term, we need to do something about the hazards to navigation. The most common concept is a "space janitor" - a robot satellite that is designed to collect pieces of space junk.

Emilien Fabicher has an interesting - and exciting - proposal. His robot would use a strong magnetic beam to chase down defunct satellites and alter their orbit, either sending them into the atmosphere or into a better parking orbit.

The magnetic beam would grab satellites at a range of 10 to 15 meters and then shift their orbit.

We science fiction fans have a word for this.

It's called a tractor beam.