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The space telescope will be no bigger than a hefty suitcase and weigh just 65 kilograms, but the Canadian scientists behind the project say when the device is launched two years from now, it may well go on to save the world.

The $12-million Near Earth Object Surveillance Satellite, dubbed NEOSSat, is considered a world's first - designed specifically as an early warning system to pinpoint asteroids on a collision course with Earth. It will also detect space junk in the path of other orbiting satellites to prevent crashes that could shut down telecommunications - television, telephone, GPS and banking systems - around the globe.

"These hazards are very real and potentially devastating to life on Earth," Rose Goldstein, vice-president of research at the University of Calgary, said yesterday in announcing the project.

Scientists gathered at the university's Rothney Astrophysical Observatory southwest of Calgary, where the country's only telescope to search the night sky for asteroids is based. Only a handful of other ground-based telescopes around the world are looking for potential dangers, and all are hampered by unfavourable weather conditions and the light of the sun.

NEOSSat, fitted with a baffle to block the sunlight, aims to overcome such limitations by being positioned far above the Earth where its 15-centimetre diameter telescope can work around the clock beaming back images from deep space.

"This is the cutting edge of technology," said William Harvey, a project manager with the Canadian Space Agency, a partner in the mission.

Mississauga, Ont.-based Dynacon Inc., which has built another "microsatellite" now in orbit studying the structure of stars, is already working on the blueprints. When complete, NEOSSat will piggyback on a rocket to orbit about 600 to 800 kilometres above the Earth for at least five years running on less power than a 60-watt light bulb.

Fittingly, the project was announced just a few days before the 100th anniversary of the Tunguska event, when a meteorite blasted into the Earth's atmosphere over a Siberian forest, scorching and knocking down millions of trees over 2,000 square kilometres.

Scientists had estimated that the June 30, 1908, impact had the force equivalent to a 10-to 20-megatonne bomb, but simulations conducted last year suggested the impact was more likely one-quarter to one-third that size.

Events like Tunguska are rare, but every year, about 7,000 meteorites touch the ground, many just small fragments of space rock that cause little damage.

Experts have catalogued about 9,100 near-Earth asteroids floating around out there, but officials figure that 95,000 space rocks at least 140 metres in diameter - all larger than the one that hit Tunguska - are still in orbit.

U.S. Congress has mandated NASA to find 90 per cent of them by 2020, and researchers said yesterday NEOSSat will be key in accomplishing that mission by spotting asteroids as far away as 150 million kilometres.

At the same time, Lauchie Scott, one of the researchers on the project with Defence Research and Development Canada, said about 12,000 pieces of space junk are circling the planet, but only 4 per cent of them are active satellites, and more and more objects are sent into space every year.

NEOSSat should be able to detect objects of space junk that are 15,000 to 50,000 kilometres away, predict collision paths and warn operators to move their satellites, or foresee if any will fall to Earth, he said.

"Space is getting more congested," Mr. Scott added.

But what happens once one of these potentially civilization-ending asteroids is spotted heading toward our atmosphere? Do we have the kind of blow-them-up and deflect-them technology that Hollywood likes to muse about?

Professor Alan Hildebrand of the University of Calgary, who leads the Near Earth Space Surveillance asteroid-search program, said asteroid hunting could give society time to plan an evacuation or allow scientists to attempt to divert the danger.

In 2005, scientists managed to fire a probe from a spacecraft named Deep Impact - so-dubbed for the 1998 doomsday film - into the belly of a comet, creating a celestial fireworks display and leaving a crater to study.

"Armageddon was a good movie," added Prof. Hildebrand, referring to another doomsday blockbuster, as he gazed out over the prairie sky from atop the observatory, "but the science was ludicrous."

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Asteroid hunting

Canada's latest micro-satellite, NEOSSat (Near Earth Object Surveillance Satellite), has been designed to pinpoint debris whose orbits cross the Earth's, including asteroids that could pose a threat to the planet.

-The Tunguska Event, which happened 100 years ago Monday, was most likely caused by the air burst of an asteroid 5-10 km above the Earth's surface.

NEOSSat

Telescope: Able to look for objects near the sun - a task virtually impossible to do from Earth.

Extends 30 centimetres.

Weight: 65 kilograms

Power: 45 watts with favourable orientation of solar panels

Propulsion: Solar-powered magnetic "fingers" push against the Earth's magnetic field. It will never run out of propellant.

Orbit: Sun synchronous, 800 km above the Earth, orbiting pole to pole

SOURCES: UNIVERSITY OF CALGARY; CANADIAN SPACE AGENCY, NASA, GOOGLE EARTH.