Asteroid-Zapping Space Mirrors

We’re all worried about the sudden destruction of planet Earth and every living thing upon it by a sudden, cataclysmic collision with a hurtling mass of space rock. Aren’t we? Well, New Scientist is taking a long, hard look in the mirror and telling us it’ll all be alright:

[R]esearchers led by Massimiliano Vasile of the University of Glasgow in Scotland have compared nine of the many methods proposed to ward off such objects, including blasting them with nuclear explosions.

The team assessed the methods according to three performance criteria: the amount of change each method would make to the asteroid’s orbit, the amount of warning time needed and the mass of the spacecraft needed for the mission.

The method that came out on top was a swarm of mirror-carrying spacecraft. The spacecraft would be launched from Earth to hover near the asteroid and concentrate sunlight onto a point on the asteroid’s surface.

In this way, they would heat the asteroid’s surface to more than 2100° C, enough to start vaporising it.

The bad news is, for a fair-to-middling sized asteroid, it’d take 5,000 ships working in concert for three year to save Earth. So, uh, we should probably start building our planet-saving mirror fleet NOW.