Gravity's tug could be used to tow asteroids

Dangerous asteroids can be towed out of harm's way using the pull of gravity, say two astronauts from the Nasa Johnson Space Centre in Houston, Texas.

Edward Lu and Stanley Love devised the idea of hovering a spacecraft over an asteroid and using the gravitational tug to tow it away from any collision course with Earth.

They calculate that this method could be used on the 320 metre-wide asteroid 99942 Apophis, that is due to swing close to the Earth on Friday, April 13 2029. By nudging it off its trajectory that year they hope to prevent its likely return to strike the Earth in 2035 or 2036.