NASA will use space-based telescope to hunt near-Earth asteroids
Yesterday, NASA announced that it intends to bring an infrared survey telescope out of hibernation in order to hunt for near-Earth asteroids. Today, the agency followed up with animations that depict a mission to an asteroid, one that a separate retrieval mission will first have to place in a near-Earth orbit. These and other developments indicate that NASA is attempting to build support for the Obama administration's plan to send humans to an asteroid later this century.
The telescope in question is the Wide-field Infrared Survey Explorer (WISE). The space-based telescope spent two years scanning the entire sky for infrared light sources, which ranged from distant galaxies to asteroids and comets in our own Solar System. In contrast to a high-resolution telescope like the Spitzer, WISE only has a relatively small aperture (40 cm) but a very wide field of view. Its full-sky survey was done while the instruments were cooled using solid hydrogen carried on board. When that ran out, the telescope ended its large-scale survey and was repurposed to search for near-Earth objects, a mission that picked up the nickname NEO-WISE.
The hardware proved so successful at identifying small bodies within the Solar System that NEO-WISE identified roughly a quarter of the 600,000 rocky bodies we know of. But the mission was eventually declared complete, and the telescope's electronics were placed into a hibernation mode. The new plan requires the hardware to be reactivated and checked out again, but assuming it comes back to life successfully, the telescope will provide a powerful tool for sighting nearby bodies.
The move makes sense in two ways. Although we've probably identified all of the large ones, we don't have a full catalog of small near-Earth objects that could pose threats to Earth's inhabitants. WISE's hardware was suited to this purpose (asteroids absorb sunlight and then radiate it back in infrared), and it has a proven track record. If the money is available and the hardware starts up without a hitch, reactivating WISE doesn't seem like a bad idea.
http://arstechnica.com/science/2013/08/nasa-will-use-space-based-telescope-to-hunt-near-earth-asteroids/