NASA is getting ready to launch a new space telescope that will scan the entire sky for the infrared glow of hidden asteroids and stars that are close to Earth but too dim to be easily seen.
Unlike telescopes that look for visible light, the Wide-field Infrared Survey Explorer, or WISE telescope, will pick up infrared light. All objects that have any heat give off infrared light — and that includes things we normally think of as being cold. WISE will be able to see objects at a wide range of temperatures, from as cold as liquid nitrogen to as hot as molten aluminum, according to NASA.
To make sure WISE isn't blinded by its own heat, it has to be kept supercold. It will work inside a giant thermos bottle called a cryostat, and hydrogen ice will keep the telescope at -438 degrees Fahrenheit. "We have now 40 pounds of solid hydrogen in our cryostat," says William Irace, WISE project manager at NASA's Jet Propulsion Lab in California. "Some people think it looks like R2D2 without wheels. It's kind of a funny-looking thing."
The funny-looking thing is about the size of a polar bear. A rocket will blast it into orbit around the Earth. NASA is targeting launch for Monday morning.
Once it reaches orbit, WISE will spend about six months taking over 1 million images that will be stitched together to create a panoramic, infrared view of the entire sky.
WISE should find many previously unseen asteroids, including ones that might be threatening to smack into Earth. Amy Mainzer, deputy project scientist for WISE, says a visible light telescope tends to see sunlight bouncing off of bright, shiny asteroids, but WISE will be able to detect dark asteroids that would go unnoticed — even if they're large. She says a dark asteroid may stand out more when WISE takes a look, "because what you're seeing is the heat that's being radiated from the asteroid."
In addition to dark asteroids, the telescope is also expected to pick up dim stars. Brown dwarfs, a kind of failed star, don't burn as hot as our sun — they have relatively feeble glow. So even though astronomers expect lots of brown dwarfs to be in the neighborhood around our sun, they've only detected a handful.
WISE should detect many nearby brown dwarfs — some of which might be closer than our closest known stellar neighbor.
"The closest star that we know of now is called Proxima Centauri. It's about four light-years away," says Peter Eisenhardt, NASA's project scientist for WISE. "And it's possible that one of these nearby brown dwarfs is even closer to the sun."
And the brown dwarfs may have planets around them, he says. So if WISE discovers that our nearest star neighbor is actually a brown dwarf, it may be that there are planets beyond our solar system closer to us than we ever thought.