Astronomer suggests a cheap way to protect Earth from killer impacts by turning asteroids into 'interplanetary disco balls' and allowing reflected light to change their orbit.
Asteroids represent an existential threat to humankind. A collision with a 10 kilometer-sized asteroid led to the demise of the dinosaurs some 65 million years ago. Astronomers expect other collisions with asteroids about 1 kilometer across every 500,000 years or so.
Now Jonathan Katz at Washington University in St Louis, Missouri, says there is a simpler and more efficient way to redirect asteroids—by painting them with a metallic coating. The idea is that the coating changes the amount of sunlight the asteroid reflects, its albedo, creating a thrust that redirects it. “Changing an asteroid’s albedo changes the force of Solar radiation on it, and hence its orbit,” he says.This thrust would be tiny.
He points out that asteroids are generally dark. So coating one with lithium or sodium metal would dramatically increase its reflectivity, turning it into an interplanetary disco ball. He calculates that about 1 kilogram of metal could coat an entire asteroid with a micrometer-thick layer that would turn the asteroid silver.
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