In my post last week, I argued that taking steps to avoid possibly extreme disruptions created by climate change is justified by their potential seriousness even if that outcome is considered unlikely. A friend of mine, who didn’t agree, asked why the same argument would not apply to preparing for dangerous asteroids and comets that might strike the Earth? After all, a comet flattened a forest area the size of Manhattan in Tanguska, Russia in 1908. And, we have recently had a meteor display that dramatically exploded in the atmosphere over Chelubinsk, also in Russia. The question is, what if one of those struck Manhattan or one the size of the planet killer that took out most life on Earth 65 million years struck again? I think he was trying to point out the absurdity of my argument about preparing for the worst impacts of global warming. Instead, he was actually right about the likelihood of major asteroid or comet strikes, but wrong if he thought that concerns with global warming or deadly visitors from outer space did not warrant action.
And, guess what? We have been concerned about deadly visitors from outer space for some time. Since 1998, the US government has been funding, and NASA has been running, a program at the Jet Propulsion Laboratory to track what are called “Near Earth Objects” or NEO’s. The program identifies objects that will come close to the earth and estimates their risk of collision with the earth to identify “Potentially Dangerous Objects,” of which, there are about 1000 so far.
Also, after the near-miss at Chelubinsk, according to ibtimes, UN officials “announced plans to establish an International Asteroid Warning Group to intercept and divert dangerous asteroids.”
Two Upcoming Near Misses and What’s Next
In fact, NASA has already identified an asteroid – XF-11 – that will pass close to the earth (about 2.5 times the distance to the moon) in 2028. And, in 2040, earth will be just missed by Asteroid 2011 AG5 that was only discovered in 2011 (see here).
But what do we do if it does appear that a very large asteroid is actually likely to hit us? Clearly, we are not talking about sending Bruce Willis and Ben Affleck into space to blow it up. After all, in the movie, they actually blew the asteroid into pieces, some of which hit the earth anyway and created a Tsunami that killed two of the movie’s stars. No, we’re talking about something entirely different.
In fact, the problem of a potential collision has long been an issue. A 1994 review article in Nature by Clark Chapman and David Morrison has a long bibliography of prior research articles. And, in 1999, the American Astronomical Society and American Institute of Aeronautics and Astronautics held a joint conference on close approaches and related topics. In a conference paper, “Predicting Close Approaches and Estimating Impact Probabilities. . . “ Paul Chodas and Donald Yeomans presented their own work as well as citing other work through the ‘90’s and earlier. And, in 2013, NASA issued a “Grand Challenge” asking for proposals to improve the identification of asteroids on a collision course with Earth and ways to divert it. In any case, proposals had already out there and more are coming. So, the recognition that asteroids and comets could be problem has long been recognized.
What are our options if Bruce Willis isn’t available? In fact, almost all involve diverting the asteroid or comet. The likelihood is that we will know in enough time to take action to move the object into a non-collision path. One interesting suggestion is to attach a long tether with a ballast to the outer edge to the asteroid, changing its center of mass and causing its orbit to shift. And there are others: Robert Lamb lists 10, including painting the asteroid or strapping solar sails on it. Sorry, to see why these and other methods would work you have to go to the article.
The point of all this is that when there are problems with the potential for very serious, possibly catastrophic damage even if the odds are low, the prudent course is to figure out ways to avoid them at a doable cost, not to make fun of or ignore them. That’s why I argued that attending to the potentially disastrous results of climate change is a conservative approach.