"coondoggie writes 'Canadian scientists are developing a 143-lb microsatellite to detect and track near-earth asteroids and comets, as well as satellites and space junk. The suitcase-sized Near Earth Object Surveillance Satellite includes a 6-inch diameter telescope, smaller than most amateur astronomers' scopes, that by being located 435 miles above the Earth's atmosphere will be able to detect moving asteroids delivering as few as 50 photons of light in a 100-second exposure. The NEOSSat will twist and turn hundreds of times each day, orbiting from pole to pole every 50 minutes almost always in sunlight. The telescope has a sunshade that allows searching the sky to within 45 degrees of the Sun, in order to detect near-Earth asteroids whose orbits are entirely inside Earth's.' The probe was announced a few days before the 100th anniversary of the Tunguska blast.