Russia Takes Aim at Asteroids
The dinosaurs never saw what hit them. We can do better..
http://online.wsj.com/article/SB10001424052748703580904574638230276797924.html
By MICHIO KAKU
Anatoly Perminov, head of the Russian Space Agency, caught scientists off guard when he called for a closed meeting of Russian scientists to counter a killer asteroid headed our way. He said that a potential impact from the asteroid Apothis around 2036 could kill hundreds of thousands of people. Immediately this conjured up images of Bruce Willis and his space cowboys riding the Space Shuttle to blow up a comet in the movie “Armageddon.” Scientists, realizing that the danger is slight but real, have in fact seriously proposed various ways in which to deflect the asteroid.
As asteroids go, Apophis is a whopper, measuring 1,000 feet across, about the size of the Rose Bowl. In 2029 it will make its first pass around the earth, so close that it will travel beneath our communication satellites. In fact, you might see it whiz by overhead with binoculars. Depending on how it whips around the earth, there is a slight chance it might actually hit the earth when it returns in 2036 (but the latest calculations only show a one in a hundred thousand chance of impact).
The Russians take such a threat seriously, since a “city buster” hit Tunguska, Siberia, in 1908, flattening about a thousand square miles of forest, destroying about 100 million trees, and leaving a huge scar in the Earth. The object that struck Siberia was probably only 100 feet across, yet it created a blast about 1,000 times greater than the Hiroshima bomb. The shock waves were so intense they were detected in Europe. It created a strange glow which spread over Asia and Europe so that you could read the London papers at night. If it had hit Moscow, it would have completely flattened that city and beyond. A city-buster like that happens once every 100-300 years, with most of them hitting the oceans.
A hit from Apothis, however, would be another story. It would be a “country buster,” capable of creating fire storms, shock waves, and a rain of fiery debris that would destroy an area almost the size of France, or perhaps the entire Northeast of the U.S. The energy of the impact would be roughly 100,000 times that of the Hiroshima bomb. If it hits the Pacific Ocean, it could also generate a huge tidal wave, a gigantic wall of water that could swamp most coastal cities in the Americas and Asia. An impact from an Apophis-like asteroid is estimated to happen once in a thousand years. (The worst case scenario, however, would be an impact from a “planet buster” as little as six miles across, like the one that hit Mexico and probably wiped out the dinosaurs 65 million years ago.)
Plans to counter such a hypothetical threat, however, are sketchy. A staple of science fiction is to send the Space Shuttle to blow it up. Bad idea.
First, this might only crack the asteroid, so you would have a swarm of deadly mini-asteroids headed your way. Second, the Space Shuttle can only circle the Earth; it is incapable of reaching deep space to intercept the asteroid. And it is going to be phased out this year anyway and a replacement won’t be ready for about five years.
Several proposals made by scientists are currently being studied. One likely scenario is to nudge the asteroid while it is still in deep space so that it eventually misses the Earth. This deflection might be done via rockets to push the asteroid years before it passes the Earth. Or, the gravity of the spacecraft itself may be used to gently tug on its trajectory. Yet another proposal is to use mirrors and even paint to increase the pressure of sunlight so that, over decades, its trajectory is modified.
At present, none of the hardware for such a mission exists, so we will be helpless for years if a real threat emerges. And any serious proposal will require tens of billions of dollars, for new booster rockets and the complex machinery to deflect the asteroid.
But given these hard economic times, money is scarce even to maintain the current space program. The Augustine Report on the future of space travel, commissioned by NASA and presented to President Obama in October, stated that manned missions to the moon and Mars were “unsustainable” without a new injection of funds. However, it did leave open the possibility of landing on an asteroid. So one real possibility is to land a probe on the asteroid in 2029 so that scientists can study its properties as well as get a free ride through the solar system. We know so little about Apothis that it might be a solid object or just a loose collection of rocky debris held together by gravity.
Some conspiracy theorists have raised the dark possibility that any nation that can deflect an asteroid could also send it hurtling toward its enemies. But such a weapon is simply too unstable and unreliable to be taken seriously.
Indeed, scientists are applauding the Russian Space Agency for addressing the issue, even if the danger from Apophis is very slight. Sooner or later, we will face a catastrophic threat from space. Of all the possible threats, only a gigantic asteroid hit can destroy the entire planet. If we prepare now, we better our odds of survival. The dinosaurs never knew what hit them.
Mr. Kaku, a professor of theoretical physics at City College of New York, is the author of “Physics of the Impossible” (Doubleday, 2008) and host of “Sci Fi Science: Physics of the Impossible,” on the Science Channel.