Nasa’s asteroid hunter goes back on duty
Explosion in skies of Russia this year gives sense of urgency to the search for near-earth objects

Nasa will reactivate a mothballed infrared space telescope for a three-year mission to search for potentially dangerous asteroids on a collision course with earth, officials said.
The Wide-field Infrared Survey Explorer, or WISE, telescope also will hunt for targets for a future mission to send a robotic spacecraft to rendezvous with a small asteroid and relocate all or part of it into a high orbit around the moon.
Astronauts would then visit the relocated asteroid during a test flight of Nasa's deep-space Orion capsule, scheduled for launch around 2021. Orion and a heavy-lift rocket called the Space Launch System are slated for an unmanned test flight in 2017.
Nasa is spending about US$3 billion a year for Orion and Space Launch System development.
Launched in December 2009, the WISE telescope spent 13 months scouting for telltale infrared signs of asteroids, stars, distant galaxies and other celestial objects, especially those too dim to radiate in visible light.