NASA astronauts Edward Lu and Stanley Love first proposed using a robotic spacecraft to nudge space rocks away from Earth using the gentle force of gravity a few years ago. Now a European aerospace giant has begun seriously investigating the concept.

The 11-ton "gravity tractor" would have to launch 15 years before a predicted collision between an asteroid and Earth, according to the BBC. But the company, EADS Astrium, noted that no spacecraft prototype has emerged just yet.

Any defense against asteroids smacking the Earth currently relies upon a loose surveillance network of ground-based telescopes and volunteer observers to keep track of potential dangers. The National Research Council released a report earlier this month on how NASA lacks the funding to meet its goals for detecting nearby space rocks.....