Just as sat-nav did away with the need to argue over the best route home, scientists from the University of Surrey have developed a new method to find the optimal routes for future space missions without the need to waste fuel. The paper is published in the journal Astrodynamics.

The new method uses mathematics to reveal all possible routes from one orbit to another without guesswork or using enormous computer power.

Danny Owen, who developed the technique at the Surrey Space Center, said, "Previously, when the likes of NASA wanted to plot a route, their calculations relied on either brute force or guesswork.

"Our new technique neatly reveals all possible routes a spacecraft could take from A to B, as long as both orbits share a common energy level.

"This makes the task of planning missions much simpler. We think of it as a tube map for space."

In recent decades, space missions have increasingly relied on the ability to change the course of a satellite's path through space without using fuel.

A piece of space junk recently crashed through the roof and floor of a man's home in Florida. Nasa later confirmed that the object had come from unwanted hardware released from the international space station.

The 700g, 10cm-long piece of hardware was expected to burn up, Nasa said. Even a relatively small piece of junk can cause considerable damage when falling from space.

This raises several important questions. Who is liable for damages caused by human-made objects that fall from the sky? Can anything be done to prevent this happening? Luckily, international treaties provide some answers to the first question, while recent developments help with the second.