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A FEW weeks ago, an asteroid almost 30 feet across and zipping along at 38,000 miles per hour flew 28,000 miles above Singapore. Why, you might reasonably ask, should non-astronomy buffs care about a near miss from such a tiny rock? Well, I can give you one very good reason: asteroids don’t always miss. If even a relatively little object was to strike a city, millions of people could be wiped out.
Thanks to telescopes that can see ever smaller objects at ever greater distances, we can now predict dangerous asteroid impacts decades ahead of time. We can even use current space technology and fairly simple spacecraft to alter an asteroid’s orbit enough to avoid a collision. We simply need to get this detection-and-deflection program up and running.
President Obama has already announced a goal of landing astronauts on an asteroid by 2025 as a precursor to a human mission to Mars. Asteroids are deep-space bodies, orbiting the Sun, not the Earth, and traveling to one would mean sending humans into solar orbit for the very first time. Facing those challenges of radiation, navigation and life support on a months-long trip millions of miles from home would be a perfect learning journey before a Mars trip.
Near-Earth objects like asteroids and comets — mineral-rich bodies bathed in a continuous flood of sunlight — may also be the ultimate resource depots for the long-term exploration of space. It is fantastic to think that one day we may be able to access fuel, materials and even water in space instead of digging deeper and deeper into our planet for what we need and then dragging it all up into orbit, against Earth’s gravity.
Most important, our asteroid efforts may be the key to the survival of millions, if not our species. That’s why planetary defense has occupied my work with two nonprofits over the past decade.
To be fair, no one has ever seen the sort of impact that would destroy a city. The most instructive incident took place in 1908 in the remote Tunguska region of Siberia, when a 120-foot-diameter asteroid exploded early one morning. It probably killed nothing except reindeer but it flattened 800 square miles of forest. Statistically, that kind of event occurs every 200 to 300 years.
Luckily, larger asteroids are even fewer and farther between — but they are much, much more destructive. Just think of the asteroid seven to eight miles across that annihilated the dinosaurs (and 75 percent of all species) 65 million years ago.
With a readily achievable detection and deflection system we can avoid their same fate. Professional (and a few amateur) telescopes and radar already function as a nascent early warning system, working every night to discover and track those planet-killers. Happily,none of the 903 we’ve found so far seriously threaten an impact in the next 100 years.
Although catastrophic hits are rare, enough of these objects appear to be or are heading our way to require us to make deflection decisions every decade or so. Certainly, when it comes to the far more numerous Tunguska-sized objects, to date we think we’ve discovered less than a half of 1 percent of the million or so that cross Earth’s orbit every year. We need to pinpoint many more of these objects and predict whether they will hit us before it’s too late to do anything other than evacuate ground zero and try to save as many lives as we can.
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