The Wide-Field Infrared Survey Explorer

Faint objects in space are numerous, and a new space-based telescope from the National Aeronautics and Space Administration is designed to find them. The Wide-field Infrared Survey Explorer examines wide sections of space and detects objects emitting light at any of four infrared wavelengths. Scientists are looking for dim objects such as asteroids or comets that will be crossing Earth's path, distant galaxies, and faint stars that emit no more light than the planet Jupiter. The telescope will image the entire sky and return millions of photos.

By surveying the entire sky and detecting asteroids or comets that will be approaching Earth's path, WISE will provide information about how often a major collision with an asteroid or comet can be expected. The biggest collision of last century is believed to have happened at Tunguska in 1908 Russia, and it was more powerful than an atomic bomb. It is further believed that a collision with an asteroid or comet caused the extinction of the dinosaurs. By detecting specific objects that are on a collision path with Earth, scientists can inform political leaders so humans can act and change the object's path, which could save millions of lives.

The faint stars that the telescope is designed to detect are called "brown dwarfs" because they do not emit as much light as normal stars. Infrared telescopes are ideal for spotting brown dwarfs, and scientists expect to spot many in the galactic neighborhood of Earth. NASA speculates that a brown dwarf may be found closer to Earth than Alpha Centauri, the closest known star system (it is actually three stars). Alpha Centauri is about 4 ½ light years away.

In addition to asteroids, comets, and brown dwarfs, WISE will collect even more information about the universe. It will detect distant galaxies that are emitting tremendous light but cannot be seen with visible-light telescopes because of their distance from Earth. Scientists expect to find even more with WISE: rocks and dust orbiting stars; new stars; galaxy clusters beyond the range of visible-light telescopes; and more information about the Milky Way.

Infrared waves have a larger wavelength than visible light, and to detect these waves the telescope must be maintained at an extremely low temperature to avoid detecting the heat it generates during operation. Cryogen is used to lower the temperature to -429 Fahrenheit.