WISE Opens Eyes
NASA engineers and scientists said Dec. 29 the recently launched WISE
(Wide-Field Infrared Survey Explorer) has successfully dropped its
protective lens cover and opened
its eyes to the starry sky. NASA is now busy adjusting the rate of the
spacecraft to match the rate of a scanning mirror.
WISE launched on Dec. 14 from Vandenberg Air Force Base in California.
The spacecraft is an unmanned satellite carrying an infrared-sensitive telescope that will image the entire sky. The spacecraft will circle Earth over the poles, scanning the entire sky one-and-a-half times in nine months. NASA hopes the mission will uncover hidden cosmic objects, including the coolest stars, dark asteroids and the most luminous galaxies.
The lens cover served as the top to a Thermos-like bottle that chilled the instrument -- a 16-inch telescope and four infrared detector arrays with one million pixels each. The instrument must be maintained at extremely low temperatures (minus 447 degrees Fahrenheit) to prevent it from picking up its own heat -- or infrared -- glow.
The cover kept everything cool on the ground by sealing a vacuum space into the instrument chamber. Now, space itself will provide the instrument with an even better vacuum than before.
Powered by solar panels and orbiting several hundred miles above the dividing line between night and day on Earth, the telescope will look out at right angles to the sun and will always point away from Earth. As WISE orbits from the North pole to the equator to the South pole and then back up to the North pole, the telescope will sweep out a circle in the sky.
As the Earth moves around the sun, this circle will move around the sky, and after six months WISE will have observed the whole sky.Each picture will cover an area of the sky three times larger than the full moon. After six months WISE will have taken nearly 1.5 million pictures covering the entire sky. Each picture will have one megapixel at each of four different wavelengths that range from 5-to-35 times longer than the longest waves the human eye can see.