A long article at The New Scientist about our current state of preparedness against an extraterrestrial hit. Bottom line: we could be doing a lot better. And it wouldn’t have to cost a lot of money. In fact, we could probably save money while enhancing planetary security, if we took a less insane approach to human spaceflight.
17 thoughts on “Seventy-Two Hours”
Comments are closed.
I wonder how one would apply the “precautionary principle” to this topic, if one were so inclined. I am not….
Very interesting article, thanx for the link.
I dunno. I can’t say I’m hugely impressed. The article estimates the probability of a 30 to 50 meter object impact as 1/500 per year, or 9.5% over a half century. But this is hardly the important statistic: after all, how many people did the Tunguska event kill? Essentially zero, for the obvious reason that hardly anyone lived in Siberia in 1908. Hardly anyone lives there now, too. You could set off a 10-megaton nuke in about 80% of Russia and (fallout aside) it wouldn’t really do much consequential damage.
The important statistic is how often one might expect their nightmare scenario: a 50-meter object heading for Washington D.C. Now, as it turns out, urbanized areas, in which roughly half the world’s population lives, total only about 173,000 square miles or 0.088% (1/1140) of the Earth’s surface. So the probability of a 50-meter rock hitting a major city — instead of, say, the Sudanese desert or Siberia or the mid-Pacific — is more like 1/500 times 1/1140 = 1 out of 570,000 per year, or less than one chance in ten thousand over the next half century.
I’m not saying that as a technological culture we mature, we shouldn’t keep a wary eye on the sky. We should. But this should not become the Doomsday Scenario du Siecle, as irrationally excessively feared as global climate catastrophe.
In short, I do not like the tone of this article. A thoughtful advocacy of some seed money in asteroid detection schemes rather than breathless OMFG!! Rocks from the sky! Al Gorism would usefully feed public cynicism less. But I guess it sells fewer magazines, alas.
There are, unfortunately, significantly nonlinear geopolitical effects to impacts. An event two orders of magnitude smaller than Tunguska almost anywhere in south or southwest Asia could very easily start a nuclear war. No need for a direct hit on a city.
Important problem, but human spaceflight has little or nothing to do with this. So what “less insane approach to human spaceflight” bears on this issue?
Another issue I’ve heard discussed is infrastructure. If a Tunguska-type blast hit mid-US, there are gas lines and big powerlines that could be affected. I don’t know the details, but thought it was an interesting point. This article (http://www.centauri-dreams.org/?p=1146) seems to touch on it, and the map included shows areas near major cities (especially those near the coast) where an impact would still be bad.
…”nightmare”…?
I would think a Tunguska-size object impacting (I know the current theory is it didn’t impact) almost anywhere in an ocean would create a significant tsunami. I would welcome any pointers to specific data.
Curt, the article itself says this is unlikely. I would tend to agree. Tsunamis are very long wavelength waves, so they must be made by very long wavelength events, like undersea landslides, earthquakes, et cetera. An meteorite impact, while very fierce — a lot of energy — would be pretty short wavelength, tens to hundreds of meters only. It would likely generate spectacularly high but short wavelength waves. Those waves would lose coherence and spread their energy into general heating and mixing of the sea fairly shortly, I would think. Tsunamis are dangerous because their very long wavelength makes them very slow to dissipate in the open ocean.
Another way to put it is that there have been plenty of events that release as much energy as an undersea quake over the ocean (e.g. hurricanes, the 1950s Pacific atoll nuke tests), but they do not produce tsunamis, more or less because the transmitting “antenna” of the event is the wrong wavelength to excite them.
I hadn’t thought of that. A lot of energy there but no significant long-range wave action, good point.
You could set off a 10-megaton nuke in about 80% of Russia and (fallout aside) it wouldn’t really do much consequential damage.
You’re assuming that Russia would not decide to retaliate against someone. Orbiting sensors and ICBMs did not exist in 1908, so the Tunguska event does not fully account for the range of possible results.
Also, you assume an impact on land. Much more likely is an impact in the ocean, and tsunamis will not be confined to the immediate area of the impact.
Tsunamis are very long wavelength waves, so they must be made by very long wavelength events, like undersea landslides, earthquakes, et cetera. An meteorite impact, while very fierce — a lot of energy — would be pretty short wavelength
Researchers at Los Alamos, Sandia, Lawrence Livermore, UC Santa Cruz, etc. disagree with you. So, possibly, does the historical record.
http://currents.ucsc.edu/02-03/06-02/tsunami.html
http://es.ucsc.edu/~ward/papers/W+A.pdf
http://www.eurekalert.org/pub_releases/2002-06/danl-nws060402.php
http://idisk.mac.com/mpaineau-Public/paine_tsunami_asteroid99.pdf
http://dsc.discovery.com/news/2008/11/20/asteroid-tsunami.html
You’re assuming that Russia would not decide to retaliate against someone
I was kind of assuming the Russians would be doing it themselves. They did, you know, for testing purposes, including the famous 50 megaton Tsar monster that you can find on Youtube. Besides, my point is physical damage and loss of life, not interesting geopolitical consequences. I’m just pointing out most of the planet is uninhabited.
Also, you assume an impact on land. Much more likely is an impact in the ocean, and tsunamis will not be confined to the immediate area of the impact.
Not I, no. And, as I said, the professionals quoted in the article and I both think that a modest (30 to 50 meter) meteor strike would not actually generate tsunamis, because the energy is not delivered to the ocean at the correct wavelength (very long). It’s sort of like the fact that when bullets impact they do not generate much in the way of radio noise. The event doesn’t have the right-size “broadcast antenna” to inject energy into that particular mode.
Ed, we were talking about a small rock, 30 to 50 meters in diameter, because the point of the original article is that such rocks are (1) hard to detect until nearly too late, and (2) fairly common.
Certainly a big kilometer-scale rock, such as was used in the UCSC simulation to which you point, something akin to the suggested KT extinction event object, could quite easily generate tsunamis. But, on the other hand, such objects are far easier to detect, and hit the Earth enormously more rarely.
I was kind of assuming the Russians would be doing it themselves…. Besides, my point is physical damage and loss of life, not interesting geopolitical consequences.
If Russia is hit by an asteroid, I think it will be safe to say “the Russians” did not do it themselves. What makes you so sure that the geopolitical consequences of a sudden, unexpected multimegaton blast would not result in physical damage or loss of life?
the professionals quoted in the article and I both think that a modest (30 to 50 meter) meteor strike would not actually generate tsunamis
I don’t see anyone quoted as saying that. I do see this: While our atmosphere is likely to protect us from asteroids smaller than 100 metres across, anything larger hitting the ocean – including chunks of Innoculatus’s rubble pile – would cause a giant splash that could smash coastal buildings with high-speed volleys of water.
If a body smaller than 100 meters does not make it through the atmosphere, then, obviously, it will not cause a tsunami — but not for the reasons you stated.
Ed, we were talking about a small rock, 30 to 50 meters in diameter,
You seem to have missed part of the article: The asteroid consisted of two parts: a pile of rubble 270 metres across which was destined to splash down in the Atlantic Ocean off the west coast of Africa, and a 50-metre-wide rock heading, in true Hollywood style, directly for Washington DC.
Only one of those qualifies as “30 to 50 meters in diameter.”
Oy, Ed, I really think you’re missing the point here, so let me summarize, and then if you think you disagree, let me know:
(1) No one doubts that a K-T extinction event would be terrible. But these things happen roughly every 20-50 million years. It’s not reasonable to think that we have less than a few million years to prepare for this one, and we’re very likely to see it coming a long way off.
(2) Strikes by objects in the kilometer range would indeed cause a lot of damage, even if they hit in remote places, from dust and crap in the air to, yes, tsunamis. But these don’t happen very often, either, and, again, we are probably going to see it coming for a long time. It would certainly suck to know that in 6 months’ time a 50-foot wave is going to sweep the East Coast, and certainly a lot of people will die. But not as many as were killed in, say, the Second World War, and the Republic will probably survive just fine. This isn’t civilization-ending stuff.
(3) Strikes by objects in the meter range are relatively common; we can expect them every century or so. Plus they are hard to detect early. And if they hit a major city square on, they would probably do as much damage as a big nuke. Ugh! But (and this was my point) they are also very likely to hit in uninhabited or very lightly inhabited areas, where they will do minimal damage. And if they hit in the ocean, they won’t generate tsunamis, because while they dispose of a lot of energy, it’s not of the right wavelength to generate them.
I don’t like the tone of the article in part because they mix up the consequences of a big strike with the probability of a small strike, to give the vague impression that we should be really really worried. It’s as if someone preaching health care reform said OMG! Imagine how expensive and devastating it would be to get sick with cancer! And people get sick (with flu and colds) practically every year! Aieee!
As I said, I personally advocate keeping an increasing watch on the sky, as well as many other possible sources of widespread destruction, such as interesting new viruses out of Africa, or solar output irregularities, yadda yadda. All good arguments for spreading the species off planet.
But I don’t think alarmism is useful, either in global warming or in meteor strikes, Y2K, “Silent Spring,” and so on.