No matter how hard NASA and avid space observers try, they can’t always predict when an asteroid will zoom dangerously close to Earth. Some experts want the world to adopt a worldwide asteroid warning system—but in the event of a major looming impact, what could we do except hide under our beds? Researchers at the University of Strathclyde in Scotland are taking a more active approach to the asteroid threat with a proposal to attack the space rocks with solar-powered lasers.
The researchers, Massimiliano Vasile and Christie Maddock, are directing their energies towards one specific asteroid: Apophis. The rock might hit us in 2036 or 2037, but scientists don’t know for sure (as of 2009, researchers estimated a 1 in 250,000 chance). If it does hurtle straight towards us, Apophis could create a 510 megaton blast, killing millions of people.
In their paper, Maddock and Vasile propose using a number of small solar-powered lasers to destroy the asteroid—a technique known as laser ablation. The University of Strathclyde defines it as being "achieved by irradiating the surface of an asteroid by a laser light source. The resulting laser light is targeted onto the asteroid. This enables the surface rock to sublimate, transforming directly from a solid to a gas. Material subsequently expands into a debris cloud of gas, dust and ejecta."
Laser ablation is not a new technique, according to MIT Technology Review. But in the past, scientists have assumed it would need to be performed using a massive laser powered by nuclear energy. But small, solar-powered lasers may have a number of advantages: They require no outside fuel source, there’s more room for error if one of the lasers doesn’t do the job, and they’re cheaper to cool.
What about asteroids that are too far from the Sun for solar power to even work? The lasers could theoretically still pack enough punch to at least nudge the asteroids away from Earth. The researchers admit in their paper: "The efficiency of the laser and solar cells are at the upper limit of what is currently achievable in a lab environment. Although this is an optimistic assumption, current developments are progressing towards those limits independently of the deflection of asteroids."
And if the scheme fails, there’s always the idea proposed by scientists last year to use solar sail spacecraft to push an asteroid away from its course towards Earth.