Asteroid Impact Inevitable/Likely

Asteroid Impact by 2036

AMERICANS who read the papers or watch Jay Leno have been aware for some time now that there is a slim but real possibility — about 1 in 45,000 — that an 850-foot-long asteroid called Apophis could strike Earth with catastrophic consequences on April 13, 2036. What few probably realize is that there are thousands of other space objects that could hit us in the next century that could cause severe damage, if not total destruction. Last week two events in Washington — a conference on “planetary defense” held by the American Institute of Aeronautics and Astronautics, and the release by NASA of a report titled “Near-Earth Object Survey and Deflection Analysis of Alternatives” — gave us good news and bad on this front. On the promising side, scientists have a good grasp of the risks of a cosmic fender-bender, and have several ideas that could potentially stave off disaster. Unfortunately, the government doesn’t seem to have any clear plan to put this expertise into action. In 1998, Congress gave NASA’s Spaceguard Survey program a mandate of “discovering, tracking, cataloging and characterizing” 90 percent of the near-Earth objects larger than one kilometer (3,200 feet) wide by 2008. An object that size could devastate a small country and would probably destroy civilization. The consensus at the conference was that the initial survey is doing fairly well although it will probably not quite meet the 2008 goal. Realizing that there are many smaller but still terribly destructive asteroids out there, Congress has modified the Spaceguard goal to identify 90 percent of even smaller objects — 460 feet and larger — by 2020. This revised survey, giving us decades of early warning, will go a long way toward protecting life on the planet in the future.

Maybe. Scientists calculate that if Apophis passes at a distance of exactly 18,893 miles, it will go through a "gravitational keyhole." This small region in space--only about a half mile wide, or twice the diameter of the asteroid itself--is where Earth's gravity would perturb Apophis in just the wrong way, causing it to enter an orbit seven-sixths as long as Earth's. In other words, the planet will be squarely in the crosshairs for a potentially catastrophic asteroid impact precisely seven years later, on April 13, 2036. Radar and optical tracking during Apophis's fly-by last summer put the odds of the asteroid passing through the keyhole at about 45,000-to-1. "People have a hard time reasoning with low-probability/high-consequence risks," says Michael DeKay of the Center for Risk Perception and Communication at Carnegie Mellon University. "Some people say, 'Why bother, it's not really going to happen.' But others say that when the potential consequences are so serious, even a tiny risk is unacceptable." Former astronaut Rusty Schweickart, now 71, knows a thing or two about objects flying through space, having been one himself during a spacewalk on the Apollo 9 mission in 1969. Through the B612 Foundation, which he co-founded in 2001, Schweickart has been prodding NASA to do something about Apophis--and soon. "We need to act," he says. "If we blow this, it'll be criminal." If the dice do land the wrong way in 2029, Apophis would have to be deflected by some 5000 miles to miss the Earth in 2036. Hollywood notwithstanding, that's a feat far beyond any current human technology. The fanciful mission in the 1998 movie Armageddon--to drill a hole more than 800 ft. into an asteroid and detonate a nuclear bomb inside it--is about as technically feasible as time travel. In reality, after April 13, 2029, there would be little we could do but plot the precise impact point and start evacuating people