The latest set of observations from NASA's Near Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission suggests that there are fewer asteroids in our solar system which are large enough to destroy the planet (should collision occur) than originally thought.

NEOWISE is part the Wide-field Infrared Survey Explorer (WISE) mission, which was commissioned in December 2009. It was designed to search for small bodies, asteroids and comets, using infrared light. To date it has managed to find 20 comets, 124 Near-Earth Objects (NEOs) and more than 33,000 asteroids, in the main belt between Mars and Jupiter.

“NEOWISE allowed us to take a look at a more representative slice of the near-Earth asteroid numbers and make better estimates about the whole population, Amy Mainzer, the lead author of the new study and principal investigator for the NEOWISE project at NASA's Jet Propulsion Laboratory, said.

The technology has enabled the research team to capture far more accurate data than its previous attempts, largely because the infrared detectors could distinguish between both dark and light objects.

In total WISE surveyed the entire celestial sphere, through infrared light, twice in the period from January 2010 to February 2011. The survey, according to NASA, found significantly fewer near-Earth asteroids in the mid-size range than previous estimates suggested.

The report also suggests that more than 90 per cent of the near-Earth asteroids - like those, for example, big enough to have wiped out the dinosaurs - have been found.

The risk of a really large asteroid impacting the Earth before we find and warn of it has been substantially reduced, Tim Spahr, the Director of the Minor Planet Center at the Harvard Smithsonian Center for Astrophysics in Cambridge, Massachusetts said.

The NASA report also suggests that none of the larger asteroids represent any sort of serious threat to the planet, at least over the next few centuries.

The spacecraft that provided all of this data webt into what NASA calls hibernation mode in February this year and is in polar orbit around the Earth. However, NASA did also say that it could be re-called in the future, should the ocassion demand it.