The International Space Station is to be moved into a different orbit to avoid the possibility of a collision with a piece of space junk.
The problem of 'space junk' is growing. There are fears that old rockets and probes orbiting the Earth could collide with the satellites used for navigation, communications and weather forecasting.
The BBC's science editor says various solutions are being proposed including spearing the junk.
A harpoon would be fired from close range. A propulsion pack tethered to the projectile would then pull the junk downwards, to burn up in the atmosphere.
The research is in its very early stages. A barbed spear about 30cm in length is proposed. It would be mounted on a "chaser satellite" that would edge to within 100m of a junk object.
Pictures sent to the ground would be used to assess the target, before the chaser was moved to within perhaps 20m to take a shot.
Lot of junk up there
The BBC reports more than 50 years of space activity have left a huge quantity of redundant hardware in orbit.
This includes not just satellites and the upper-stages of the rockets used to put them there, but also debris from fuel tank explosions.
It is said more than 22,000 objects are actively being tracked.