When the ice in your glass of iced tea melts, the tea gets warm and watery. When the ice in your cooler melts, the potato salad goes bad. And when the ice in your spacecraft melts, the craft goes blind.
That's what's happening now to a mission known as WISE -- the Wide-field Infrared Survey Explorer.
Launched late last year, WISE has surveyed the entire sky at infrared wavelengths. The infrared reveals some of the coolest astronomical objects: asteroids and comets in our solar system, cocoons of dust around newborn stars, and the "failed" stars known as brown dwarfs.
During its first six months, WISE took more than a million pictures. They revealed hundreds of thousands of infrared objects -- more than all the other infrared telescopes before it combined.
But infrared is basically heat. So any heat from the instruments themselves would produce enough infrared energy to overpower the view of the sky. So WISE's telescope and its four infrared detectors were encased in a giant Thermos bottle ringed with two blocks of frozen hydrogen. The heat from the instruments vaporized some of the hydrogen. The hydrogen gas was then released into space, carrying away the heat.
WISE finished one of the rings of hydrogen in August, blinding two of its detectors. The other ring is expected to run out this month -- bringing a cool mission to a hot conclusion.
Script by Damond Benningfield, Copyright 2010
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