A year ago, on February 15, 2013, a stony asteroid 20 meters wide weighing 12,500 metric tons entered the Earth’s atmosphere at 69,000 kilometers an hour (42,900 MPH). (Size and mass values are estimates based on the size of the explosion when it hit, but the velocity figures are pretty accurate.) The asteroid entered the atmosphere over Chelyabinsk, Russia at about 9:30 AM local time on a shallow angle. It started burning due to atmospheric friction, becoming brighter than the sun. It then blew apart due to the stresses associated with the rapid deceleration. The explosion was estimated to be larger than 500 kilotonnes of TNT, making it larger than many nuclear weapons. The resulting shock wave blew out windows for hundreds of kilometers.
Its entry was captured on hundreds of video cameras (Russian motorists often have them mounted on their dashboards due to the terrible traffic conditions) and security cameras. Go to YouTube to find many of them, such as this one or this one. Within seconds of its passing, even more people ran out with cellphones and cameras to view the meteor’s trail, only to film the blast of the shock wave arriving (here). I guess if you speak Russian you should be warned, there are a lot of very stunned, surprised, and scared citizens of the Chelyabinsk region shouting what I can only assume is Russian profanity.
The Russian government says that 1,491 people received injuries from the blast, most from flying glass and debris as windows broke, walls fell, and roofs collapsed over a wide area. Over 100 people had injuries serious enough to require hospitalization. The total damages to property was over one billion rubles (about $33-million USD).
This was a near miss. We (as in “we” inhabitants of Planet Earth, not as in “we” citizens of Chelyabinsk) dodged a bullet. A bullet the size of a building traveling over sixty times the speed of sound.
Over the past twenty or thirty years, as optics and computers have gotten faster and cheaper, there have been a growing number of more and more powerful searches for asteroids, particularly asteroids that might have the potential to come close to us at some point (“near-Earth” asteroids). We’ve found a LOT of them, almost 10,000. About 10% of those are over 1 km in size — that’s on the order of 100 to 500 times the size of the Chelyabinsk rock.
As we’ve gotten better at searching, we haven’t found all of the potential killer asteroids. What we’ve really found is that there are far, far more “smaller” asteroids (50 to 500 meters) than we previously believed. The more we find, the more we realize how many we haven’t yet found.
The Chelyabinsk asteroid wasn’t seen in advance because it was “tiny” and coming almost straight out of the sun at us. We have blind spots like that where we can’t see asteroids. We also can’t see the really small ones until they’re really close, so we often have less than 48 hours’ warning before they arrive. Since the Chelyabinsk meteor, with the additional attention given to the search for similar objects, we have seen similar sized objects that passed closer to Earth than our geosynchronous satellites, but were discovered only days before their closest passage.
Having a Chelyabinsk-sized rock come in at a sharper angle and either slamming into the ground or exploding a few kilometers up instead of thirty kilometers up would be far more destructive than Chelyabinsk. If it happened over a more heavily populated area (the US, Europe, India, China, Japan) or a major city, it could result in thousands to hundreds of thousands of casualties and trillions of dollars in damage. If a rock or comet ten times larger hit, it could wipe out an area thousands of miles across with millions of casualties. If a rock or comet one hundred times larger hit, it could cause enough damage to cripple the entire world, bringing civilization to its knees.
Of course, even larger objects exist, and they have hit the Earth in the past. Ask a dinosaur. Oh, wait…
This is the only natural disaster that has the potential to wipe out the human race. Tornadoes, floods, drought, flooding, earthquakes, tsunamis, fires — they can kill hundreds of thousand and lay waste to huge areas, but they can’t eliminate the entire human race and wipe away all of human society. A large comet or asteroid collision can.
But the most important realization in this discussion is that this is also the only natural disaster that is 100% preventable. Forget about stupid movies (even if they have Bruce Willis or Robert Duvall to save us all), in real life we have the technology available today to detect any incoming threat and to divert it before it gets here.
100% preventable.
But do we have the will to do it? Will we spend the money, or will the politicians ignore the dangers and the solutions. It’s very easy to assume that it won’t really happen. After all, it hasn’t happened in millions of years. Sure, there is Meteor Crater in Arizona, and this Chelyabinsk thing, and the Tunguska event of 1908, and all of the other “small” rocks that we’re now seeing. But what are the odds of it happening and why should we care and why should we spend the money?
The odds of it happening tomorrow are very, very small. The odds of it happening in the next hundred years are very small. The odds of it happening in the next thousand years are small. The odds of it happening in the next 100,000 years or 500,000 years approach 100% pretty quickly.
And let’s not forget the other factor in the risk management equation — the risk. The odds may be low, but the potential risk is astronomically huge. Potentially it could be the death of every human being on the planet. Even if it’s not the ultimate worst-case scenario, it could still be the immediate death of more people than were killed in all of World War II. Those kinds of monstrously huge risks balance out the small odds.
Do we all have insurance on our cars and houses? If we’re smart we do. What are the odds that our house will burn down tomorrow? What are the odds that our car will be damaged in a crash tomorrow? In the next week? In the next month? In the next year? In the next twenty years? You’re now talking about a high-probability scenario. So we pay for the insurance all the time, now and next year and beyond. We don’t know if we’re going to have that personal disaster tomorrow, or in ten years, or ever — but it’s still smart to have the insurance just in case, rather than being wiped out.
Compared to the potential cost of a major strike by a comet or asteroid, the “insurance” of a space-based detection and deflection system is pretty cheap.
Politicians are not known for their long-term strategies, vision, and ability to understand math and science issues. Rest assured, if we found something large on a collision course that will wipe us out in five years, we would spend trillions and trillions of dollars a year for those five years to try to save ourselves. With no actual threat identified, basing our arguments on science, probability, and the growing body of evidence we have, politicians won’t give us the time of day.
Fortunately, even before Chelyabinsk, private groups and individuals are stepping up and showing some leadership regarding this problem. Primary among them is the B612 Foundation, which is a non-profit organization dedicated to first finding these threats, then being able to protect against them. Their Sentinel Program is aimed at launching and operating a satellite (or satellites) with the sole purpose of mapping our skies to find as many threatening objects as they can, giving us as much warning as possible about any objects on potential collision courses. They’re also working on research into techniques for moving threatening objects out of their collision courses.
Advance warning is the key. It’s pretty hard to actually hit something in the solar system — look at how hard we have to work to put space probes on, near, or in orbit around other planets, or even our own moon. If something is found that is going to hit us in a year, we need a massive amount of power very quickly to move it into an orbit that misses us. (Forget about blowing it up like they did in those movies — there are so many reasons that’s really unlikely to work.) But if we find it ten years before it hits us, then a little bit of a nudge over months and years will easily do the same thing.
We have the technology to build space-based telescopes that can find 99.9% of these hazards, and keep an eye on them. We have the technology to gently nudge an incoming object over a long period. We aren’t even close to having the technology to save ourselves if we only have a couple of years (or less) before impact.
So, go look at those YouTube videos. Listen to the blasts, breaking glass, and cussing Russians. Think about the potential consequences of a bigger or much bigger collision. Then, if you’re a multimillionaire, maybe you could lob a few hundred thousand dollars in the direction of the B612 Foundation. Even if you’re not a multimillionaire, the next time you’ve got a couple of extra bucks and you’re looking for a tax deduction, keep the B612 Foundation in mind.
We dodged a building-sized, hypersonic bullet a year ago. Let’s learn from the experience and help find the next one before it finds us.
We Love The Stars Too Fondly 