Let’s face it, we’re sitting ducks. The planet has a huge bullseye painted on it just waiting for a giant asteroid to hit the target. But rather than get a breeding population of people and a library of all our history and achievements the hell off the planet, we have apparently decided that manned space missions are unnecessary and too expensive, and instead pick our noses and look at pictures taken by unmanned go-carts on Mars.
But when the Big One comes, it will wipe out not only the nose pickers, but also Buddha, Plato, Shakespeare, Caravaggio, the Beatles, and French supermodel Laetitia Casta — the whole exercise of human existence will have been for naught.
Even those who so foolishly disregard the threat posed by asteroids to both human existence and history may wish to reflect on the subject as we approach the hundredth anniversary of the Tunguska event that occurred on June 30th, 1908, at 7:14 am. Obviously, the Tunguska asteroid was not the Big One, or you would not be reading this. It was a relatively small one which detonated in the atmosphere with a force, some theorized, of 10 to 15 megatons of TNT, flattening over 2000 square kilometres of Siberian forest.
The Tunguska asteroid managed to produce this devastation without ever striking the earth. Nor did the huge fireball produced by its detonation at an altitude of approximately 10 kms. cause the incredible damage, petering out as it did at a height of about 4 km. Instead, the the fireball forced a shock wave at the earth that wrought the destruction, which continued mercilessly even after the sky was no longer lit by flames.
Now, an article on the Planetary Society website suggests that the blast may have been much smaller than previously thought — perhaps only three to five megatons. As author Amir Alexander writes, “According to some estimates, asteroids big enough to cause a 3 to 5 megaton explosion in the atmosphere may strike Earth as frequently as once every few centuries. This suggests that we or our descendants may well have another Tunguska-like event in store for us, and while the 1908 impactor merely flattened trees in a Taiga forest, the next sizable asteroid to take aim at our planet is just as likely to strike in the heart of New York, Paris, or Beijing.”
At Tunguska, nature is reclaiming the blasted landscape, and it won’t be long before even stumps torn up by the blast have returned to the earth leaving no sign that the Tunguska event ever happened.
Meanwhile, since these things don’t strike according to clockwork, no one can say when exactly the next will hit. It could be streaking towards us as you read these words.
But even if earth is in the cross-hairs, humanity doesn’t have to be. The Mars Society exists to “further the goal of the exploration and settlement of the Red Planet”. If you don’t want to see us wiped out by a giant asteroid, you might consider joining. Of course, our annihilation could also come from nukes (though full scale nuclear war doesn’t seem that likely at the moment), or from super bugs that escape from a research lab, or self-reproducing nanobots which get out of control and reduce the earth to a grey dust. In any such eventuality, it would be nice if there were humans on Mars saying “Wow, glad I’m not on earth right now.”