Discover 12/10/2021
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.
Which is why NASA and other space agencies are attempting to map the population of Near Earth Asteroids. Today, just 40 per cent of these have been spotted. But the goal is to build a complete picture of the threats from asteroids down to a few tens of meters in size, within the next few decades.
That raises an obvious question: if we find an asteroid heading our way, what should we do next? Last month, NASA launched the Double Asteroid Redirection Test (DART) mission to test one idea. This involves crashing the spacecraft into an asteroid to change its course. Other options include attaching thrusters to the asteroid to push it off course or even ablating the rocky surface with a nuclear explosion.
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.
Force of LightThis thrust would be tiny. But Katz points out that once a small asteroid has been identified, its trajectory can be determined centuries in advance, particularly if transponders are placed on its surface to track it more accurately.
More:
https://www.discovermagazine.com/the-sciences/spray-painting-killer-asteroids-could-redirect-them-away-from-earth
