Space Sail Could Bring Used Rockets Back to Earth

The risk to spacecraft from a collision with space debris could be reduced by equipping launchers with a gossamer-thin sail. The idea is to deploy the sail after the rocket has released its payload to amplify the drag of the last vestiges of the atmosphere, and so force the rocket out of orbit. Rocket stages are a particular risk to spacecraft because they often contain large amounts of unused fuel, which can explode when sunlight heats the tank. Leaking fuel can also act like a mini-thruster, pushing the rocket into an orbit where it may cause a collision. One way to tackle the problem is to vent unused fuel in a controlled way, and drain power from the battery, but this is unlikely to eliminate all collisions