PDF version of COSPAR - Space Science Research in Canada Report

Dynacon Inc. of Mississauga, Ontario, is the prime contractor building thesatellite. It was also the lead contractor for the MOST satellite.Nevertheless, NEOSSat’s asteroid-tracking mission does have an internationalflavour; about half the science team is from outside Canada, mostly from the U.S,where researchers have been using Earth-based telescopes to search forasteroids for up to two decades. “We don’t have as much experience looking forasteroids in this country,” said Hildebrand.He noted that, while the data collected by NEOSSat will be used in assessing thethreat of collisions with Earth, the primary focus of the mission is to gatherscientific information on the population of near-Earth asteroids and to documenttheir movements and characteristics. “In terms of understanding the evolutionand distribution of the populations of asteroids, it’s going to be an excitingcontributor. We’re going to be able to make a contribution to this effort that isunique and valuable.”In 1998, the U.S. National Aeronautics and Space Administration set a 10-yeargoal of finding 90 percent of near-Earth asteroids with diameters of one kilometreor larger. The rate of discovery of these bodies exploded after that; the totalnumber jumped from less than 500 to more than 4600 by mid-2007, of whichmore than 700 are one kilometre or larger.Not all these “large” asteroids have been found yet; Hildebrand said thepopulation is estimated to be around 1100. He said it is not clear whether 90percent of them will be found by the target date of 2008 but a “respectablenumber” will be. “It’s a pretty good effort, compared to the near-total ignorance ashort time ago.”NEOSSat will be looking specifically for asteroids that have the most Earth-likeorbits and spend all or most of their time interior to Earth’s orbit. There are twotypes—Atens and IEO (interior to Earth orbit) asteroids. Atens asteroids crossEarth’s orbit and thus represent a potential collision threat. IEOs do not presentsuch a threat right now, but they could if their orbits are preturbed.Hildebrand said that NEOSSat is going to be a “terrific finder” of both types ofasteroids, which are difficult to detect from the Earth’s surface. Since IEOs staywholly inside Earth’s orbit, they are only rarely visible in the night sky to Earthbasedtelescopes. Putting a telescope in space eliminates this problem; outthere, the sky is always dark, even when looking close to the Sun, so theseasteroids can be more easily detected.48