Nasa is considering re-activating a mothballed space telescope to help find asteroids that could be on a collision course with Earth, according to a senior US space agency official.
Launched in December 2009, the Wide-field Infrared Survey Explorer (Wise) telescope spent about a year taking pictures for an all-sky map. With its infrared detectors, Wise was able to peer through thick layers of dust and see even relatively dim objects such as cool brown dwarf stars in great detail.
Nasa then put Wise to work on another mission looking for asteroids and comets in the solar system. Of particular interest were objects in orbits that pass relatively close to Earth.
Wise found about 150 near-Earth asteroids, including 20 that were potentially hazardous, before funding for the project ran out. The telescope was put into hibernation in February 2011.
Nasa is now reviewing options to enhance its asteroid-hunting efforts including bringing Wise out of hibernation, Lindley Johnson, who oversees the agency's Near-Earth Objects observations programme, said this week.
This follows February's explosion of a small asteroid in the skies above Russia and the near-Earth passage of a larger one the same day.
More than 1,500 people were hurt by flying glass and debris after that small asteroid exploded above Chelyabinsk, Russia. The larger asteroid then zipped past Earth closer than the networks of communication satellites that ring the planet.
Together, those events served as a celestial alarm clock, prompting congressional hearings and fresh calls for Nasa and other agencies to step up asteroid detection initiatives.
Nasa says it already has found about 95% of the asteroids that are 1km or larger in diametre.
"If an object of that size were to impact the Earth, it would have global consequences," Lindley said during a Nasa advisory committee meeting in Washington. "One as much as 100 metres in size would have regional effects and could cause a great many casualties," Lindley added.
The Obama administration has requested funding from Congress to double Nasa's $20m Near-Earth Objects detection programmes for the 2014 fiscal year beginning October 1.
Costs for Wise's potential re-activation and operation were not released, but Johnson said it may be possible within the programme's current $20m annual budget and would easily fit within the proposed $40m spending plan.
Nasa's human exploration programme also has been developing an initiative to send a robotic spacecraft to a small nearby asteroid and redirect it into a high orbit around the moon, officials said.
Astronauts would then visit the asteroid as part of an initial foray to send humans beyond the International Space Station, which flies about 400km above Earth.
Another $85m in Obama's $17.7 bn 2014 spending plan for Nasa would start technology developments and planning for the robotic portion of the asteroid encounter.
Nasa is about halfway through a 15-year effort to find 90% of all near-Earth objects that are as small as about 140m in diametre.
Scientists say one of the quickest ways to speed up the effort is to re-activate Wise. "We think it can be operated for three years and get much more data," Johnson said.
Time is of the essence as Wise is expected to slip from its optimal viewing orbit around Earth by early 2017.
