One of the world’s largest impact craters (see below) lies under Mexico’s Yucatan peninsula, evidently a major player in the demise of the dinosaurs. Chicxulub is 180 kilometers in diameter, the subject of continuing research by the man who identified it, Alan Hildebrand (University of Calgary). So you could say Hildebrand has an idea what massive impacts from asteroids can do to the Earth’s surface, having studied the environmental effects caused by this one and mapping the crater’s structure to identify mineral, oil and gas resources. That interest has led Hildebrand into an ongoing asteroid hunt, and explains his current plans to build and launch a space-based observatory designed to look for near-Earth objects.
The scientist currently uses use a retrofitted satellite tracking telescope in NEO work here on Earth. The instrument, based at the University of Calgary’s Rothney Astrophysical Observatory (some 75 kilometers southwest of the city) is an extensive re-build, a Cold War era instrument whose motors were replaced, its mount and optics modified and its electronics brought up to speed several years ago at the cost of $500,000. The telescope has been in asteroid-spotting use ever since.
Image: What we’re all hoping to avoid, an artist’s conception of a near-Earth object heating up as it encounters the upper atmosphere. Credit: Melinda Wenner/Wired Magazine.
Taking the asteroid search into space in the form of the Near Earth Object Surveillance Satellite (NEOSSat), an event that could occur within two years, would create the first space-based asteroid telescope, one to be used not only for identifying potential threats but also for helping us firm up our inventory of asteroids near enough to the Earth for manned missions. Nor is the suitcase-sized microsatellite a costly investment, totalling $10 million. Its position in space should allow the observatory to block sunlight to look for objects between the Earth and the Sun that are otherwise difficult to see.
Because some of these asteroids come close to matching Earth’s orbital speed, a robotic or manned asteroid mission becomes a distinct possibility. That would offer not only useful information about the early Solar System — such asteroids being remnants of same — but would also help us take the measure of the kind of objects we might one day need to push out of Earth-impacting trajectories. Would nukes work? Gravitational tugs? Sooner or later we’ll fly a NEO mission because we need to understand the nature of these asteroids as we assess the various strategies for dealing with them.
NEOSSat has the potential of cataloguing at least 50 percent of the one-kilometer or larger NEOs that orbit largely between Earth and the Sun, as New Scientist reports. Interestingly, the magazine cites Timothy Spahr (Harvard-Smithsonian Center for Astrophysics) as saying that an even better idea (though obviously far more expensive) would be to place a NEO-watching observatory in orbit around Venus, where the inventory of inner system objects could be even more definitively compiled.
Addendum: Although I had original identified Chixculub as the world’s largest impact crater, reader James Davis Nicoll quickly corrected me. Both Vredefort (300 km) and Sudbury (250 km) are larger.