Science with Richard Bleil
NASA astrophysicist Donald Kessler suggested that the density of low-level junk in orbit around the earth could reach a point that a cascading event could occur in which one collision would create enough debris to propagate the collision in 1978. Such a scenario wouldn’t mean the end of the world, but all satellites would effectively be destroyed. In 2009, he claimed that mathematical modeling supported the hypothesis.
I don’t believe it.
It seems like periodically scientists have their own ideas of Armageddon. My mother was friends with a man who periodically prophesied the end of the world based on his church’s predictions. I remember talking with my mom when she was particularly concerned one year by his prophecy, but I suggested that I was looking forward to it. Surprised, my mother asked why. “Think about it, mom,” I replied, “the dead rising from the graves, blood from the sky, everything we think we know about science would be proven completely wrong. What a cool thing to see!”
During the development of the atomic bomb, a nuclear physicist suggested that if we did create a nuclear fusion-based bomb (the hydrogen bomb), the heat would ignite the atmosphere and destroy the entire world. We know that this isn’t true because, although it was never used in wartime (Hiroshima and Nagasaki were atomic, or fission-based bombs, not fusion), our hydrogen bomb was tested above ground. Of course, it didn’t ignite the atmosphere. There are three things necessary for fire: fuel, heat and oxygen. In the upper atmosphere, there is oxygen, and there certainly was heat from the hydrogen bomb, but there was no fuel to burn. As such, there could be no global fire consuming the entire earth.
Kessler’s hypothesis sounds very much like the propagation of an atomic explosion. In Uranium or Plutonium, if you inject a neutron, it will collide with a nucleus which, in turn, will eject three more neutrons as the nucleus falls apart. There are three possible things that can then happen, these neutrons can either hit some impurity that won’t undergo fission absorbing the neutron harmlessly, or the neutron will exit the fuel if it’s too close to the edge. The third possibility is that the neutron will strike another nucleus which, in turn, will throw off three more neutrons. If the probability of hitting another nucleus is greater than the other two possibilities, a fission chain reaction will occur resulting in an explosion. This is why there is a “critical mass” (although today it’s “critical density”), when the mass of the fuel is large enough that the probability of propagation is enough to cause the fission explosion.
The problem with Kessler’s hypothesis is that a collision of space junk will create debris that flies in three dimensions. Most of the space junk is in a fairly narrow orbit around earth, thin enough, in fact, that it can be thought of as two-dimensional to a very good approximation. So when a collision creates debris, only that debris traveling along that two-dimensional (or nearly so) path could actually result in propagation of damage. From what I’ve read to date, it hasn’t been suggested that we already have sufficient space junk for this scenario to be likely, nor have I seen an estimate of exactly how much space junk is necessary or a projection of when that much junk has accumulated.
Sorry, Kessler; I’m not believing it.
There is, of course, a viable model that suggests one way that life on earth could end, and there is increasing evidence that it is legitimate. Interestingly, about the time that Kessler first proposed his doomsday scenario, it was also introduced along with a competing hypothesis. Of course, I’m talking about global warming, and global cooling. People don’t talk about global cooling anymore, but back in the ‘70’s the debate was if trapped greenhouse gases would create global warming and destroy us all, or if soot in the air caused by pollution would reflect light back into space before it can reach the surface leading to global cooling. Obviously, the hypothesis of global warming is the model that seems to be coming to pass although many people don’t want to believe it. Those same people are the ones who have made their money destroying the environment and giving rise to global warming who are now fighting to keep their money by not paying to fix the very problem they created. No, the nuclear bomb won’t ignite the atmosphere on fire, and Kessler’s model (in my opinion) won’t come to pass, but if we don’t start figuring out how to stop global warming, we’re in trouble.