The Wide-field Infrared Survey Explorer mission will survey the entire sky in infrared light, revealing, among other objects, hundreds of thousands of asteroids. Some of the asteroids will be ones we already know about, and others will be new to us. And some will have orbits that pass close to Earth. Infrared observations are ideal for finding the darkest, hidden asteroids, and for estimating asteroid sizes and compositions. Knowing how big an asteroid is, and how dense, will help determine how often Earth can expect hazardous impacts. The mission's survey began in mid-January and is expected to end nine months later, when the coolant it needs to see infrared light runs out.
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