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Hazardous Asteroids

29 Comments

…may be more common than we thought:

The scientific orthodoxy said that a Chelyabinsk-size event ought to happen every 140 years or so, but Brown saw several such events in the historical record.

Famously, a large object exploded over the Tunguska region of Siberia in 1908. But there have been less-heralded impacts, including one on Aug. 3, 1963, when an asteroid created a powerful airburst off the coast of South Africa.

“Any one of these taken separately I think you can dismiss as a one-off. But now when we look at it as a whole, over a hundred years, we see these large impactors more frequently than we would expect,” said Brown, whose paper appeared in Nature.

But our response, and actions to become a space-faring civilization, remains pathetic.

29 thoughts on “Hazardous Asteroids”

  1. Seems likely to me that most Chelyabinsk-size events before the space age went unobserved, striking over the ocean or uninhabited regions. So estimating frequency by known events is likely to underestimate by large margin.

  2. If we underestimate the little ones, we are also underestimating the big ones. How many calderas are the result of an asteroid hit that isn’t considered one?

  4. Yeah, yeah, asteroid hazard.

    I read that the USGS had 5 things to worry about that have nothing to do with asteroid impacts.

    1. The Big One that slides Southern California into the Pacific Ocean.

    2. The Big One that slides Seattle into Puget Sound.

    3. The Big One that slides Memphis into the Mississippi River.

    I am thinking that #3 could happen in my lifetime, and this disaster for Memphis will be a Northridge-level event for Wisconsin. I can’t get my wife to agree to “California” latches on the cabinets. An epic disaster in Memphis will be an expensive mess in the upper Midwest, but there is still

    4. The Yellowstone volcano that will bury all of us east of the Rockies in 10s of feet of ash,

    and finally

    5. The Canary Island seismic landslide-induced tsunami that will wipe out the entire East Coast U.S..

    1. All the more reason to develop space. A nice Bishop Ring should be safer than Earth in a lot of ways. No geology, controlled weather. And being in space means you harvest asteroids, not get hit by them. The only thing to really worry about at that point is gamma ray bursts or a nearby supernova.

    2. Paul,
      There are three major differences between the NEO hazard and the geological hazards you discuss.

      First, except for a possible Yellowstone event it is not possible to predict the others with any useful level of accuracy. (i.e. time to get out of town…) Yellowstone would be the exception as you would likely see increased seismic activity and ground movements before the event. And its unlikely any additional investment in seismic research will help significantly in improving the prediction abilities in the near future as earthquakes are triggered by the stress reaching a “breaking point”. You are able to measure now the increasing level of strain, but its predicting the “breaking point” that is the issue.

      By contrast a modest investment greatly increases the probability of both identifying the NEO that are hazardous and predicting the impact points years, perhaps decades in advance. Its off the shelf technology for the most part, just add money to build the systems needed.

      Second, unlike earthquakes and volcanoes, the theoretical models to deflect NEOs exist. Again, its just a matter of investing in the R&D needed to determine which methods work best for which types of NEOs. Simulations are good, but you really need to go out there and test a few systems to make sure they will work when needed. In short, the science is known, just add money to translate it into systems that will work.

      Third, although investments in earthquake and volcano mitigation may yield benefits when an event happens, you don’t need to prevent a NEO impact to reap the benefits of NEO mitigation research. The exact same systems that would be used to identify and deflect them could with very little modifications be used to mine them for their wealth.

      That is why its a pity NASA has been wasting its time looking for life on Mars when its talent and resources could be better used to protect life on Earth. When a NEO takes out a populated area folks will indeed hold NASA to account for not properly focusing its resources these last forty years.

  5. The first two are fiction. I don’t know about Memphis. Yellowstone does go off regularly and is overdue. Tsunamis happen.

    All are limited events that will not wipe out humanity. One asteroid could. Multiple asteroids hit our atmosphere every day. The big one already has us targeted. It is coming.

    1. For Southern California west of Needles to slide into the Pacific in one earthquake is fiction as in the Christopher Reeves Superman movie. At a research university located just northeast of L.A., the grad students hailing from much less seismically hazardous lands joked about “California falling into the ocean”, although we knew better. A geology professor prominent in both the Plate Tectonic and Impact Hypotheses informed us, however, that Southern California separating from the Mainland was only a matter of a few million years time owing to the plate movements.

      But the seismic hazard on the San Andreas, in Cascadia, and from the New Madrid fault, all of these are very real and are documented by geologic evidence. Large portions of California, Seattle, and Memphis are indeed at risk for the Big One.

      Major earthquakes in those three places may be more localized catastrophe’s, although there is something about the ground that makes the New Madrid quakes carry further. These are perhaps one in every couple hundred year affairs.

      The Yellowstone “super volcano” is a once every couple million years deal, although there is concern regarding the magma chamber being active and the ground shifting. When that thing “blows”, it affects half a continent.

      The other thing is that for the Yellowstone volcano or the San Andreas fault or the Cascade range being “overdue” for an event may be a statistical fallacy. If the statistics are truly “Poisson”, that the Yellowstone volcano blew up a million years ago to the date and it is known to blow up every million years, that doesn’t make a blowup imminent. On the other hand, the filling of the magma chamber may follow a natural cycle, and if there is some regularity to the blowups, maybe there is a bigger risk.

      Another consideration is observational. Impact crater features on the Earth may not be rare, but they are occult, either on account of erosion or on account of the plate tectonic process and molding of the earth result from plate tectonics, such as volcanos, covering them up. This evidence suggests that geo-catastrophes are more probable and asteroid-collision catastrophes.

      As to asteroid impacts in the global extinction category, for which there is stronger evidence for the Cretaceous-Tertiary extinction and more speculative evidence for the Permian-Triassic event, these happen every 50-100 million years? Yeah, yeah, I heard your chances in dying in an extinction event are the same as dying in a plane crash when you crunch the numbers.

      But the geo hazards are very real — such as Naples’ proximity to Vesuvius and many other places where a lot of people live close to an active, explosive volcano.

      1. … Southern California separating from the Mainland was only a matter of a few million years time owing to the plate movements.

        Southernmost (Baja) California, of course, has already long since separated from the mainland, and the long Red Sea-like bay resulting from that split would extend far up into American California, except that the delta of the Colorado River has filled it up the gap and blocked it with a natural levee near the present border.

        I certainly agree that a continuation and opening up of that split — beyond what is now San Francisco — is what’s likely happen, not some absurd falling into the sea.

      2. Seismic hazard and fall into the ocean are too very different things.

        In AZ we joke about all our sand becoming beach front, but it ain’t gonna happen.

        BTW, I was in Silverdale when that last earthquake hit WA in the early aughts. Having just moved our company from CA the talk was of magnitudes as light poles were wildly swinging down the street (none of our windows broke but some of the older brick buildings developed some impressive cracks.)

  6. The Yellowstone “super volcano” is a once every couple million years deal.

    Make that about once every 700,000 years, given the frequency of the last three (super) eruptions. Note that lesser (but still substantial) eruptions occur much more frequently at Yellowstone — but those wouldn’t endanger half the continent. One such might be what a filling of the magma chamber foretells, and not a super eruption — the next of which might well be tens of thousands of years away.

    1. Rickl,

      Yes, an August 13, 1930 event .

      http://adsabs.harvard.edu/full/1995Obs…115..250B

      But unlike Siberia the rainforest hides such events quickly.

      It also appears there was one in British Guyana in 1935 and possibly a second one in Brazil in 1995.

      http://www.science-frontiers.com/sf103/sf103g08.htm

      The problem is folks forget how empty the Earth is of human population. Most is ocean, ice and forests or tundra. However the rate from the last 30 years or so should be able to be estimated from the USAF systems (VELA) designed to monitor for nuclear explosions.

      1. The Vela program ended a long time ago and primarily monitored gamma rays and x-rays. The DSP satellites and newer SBIRS birds use IR sensors and routinely track things entering the Earth’s atmosphere.

  8. There was also a fairly large strike in northern Norway in 2006 and a kiloton-range event in Namibia in the 1990s or 2000s; I can’t find the reference for the latter.

    I’m sorry to say, however, that the one easiest to prevent and least likely actually to be prevented is #6; the Big One that vapourises half of Manhattan Island.

  9. If believing an E.L.E. asteroid will never hit is like believing the house numbers will never hit on a roulette wheel then the ratio of house to regular numbers has just gone up. (Realizing we start with a whole bunch of regular numbers… having only 36 we would not be around to imagine it.)

  10. I was going to compile a list based on the comments here, but Wikipedia has saved me the trouble:

    List of meteor air bursts

    Including events in 1859 and 1919, both over the United States, I count 15 multi-kiloton events in the last 154 years, an average of one per decade.

    I had never heard of the 1859 and 1919 airbursts before. No estimated yields are given, but the descriptions of effects felt on the ground sound an awful lot like Chelyabinsk in both cases.

    1. Agreed, but for small impactors it doesn’t really matter whether those are included or not. The only reason those might be said to really matter is in calculations of the likelihood of events that have planetary or continental-scale effects. To make such calculations, one has to extrapolate the frequency vs. size upwards, which is fraught with possible errors. But there is a direct measure of the frequency of large events, because those leave craters that can persist for hundreds of millions of years.

      During the period in which there has been multicellular life on Earth (about 600 million years) there have been about 60 impacts with impact energy of 10,000,000 MT or more (leaving a 60-mile crater and having major effects on the entire ecosphere) which means that the risk of such an impact in an average lifetime is of the order of one in 150,000. Since such an event would kill damn near everyone even at the bottom end of the range, and destroy civilisation for sure, such a risk (although low in absolute terms) is significant.

      The planetary budget for detection of potential impactors (never mind doing something about it) is somewhat smaller than the amount spent by Americans on lipstick. There is definitely something wrong with humanity’s priorities.

      1. There’s nothing wrong with their priorities. They spend money on lipstick because they perceive an immediate benefit. Looking good today is more important than maybe saving the world 867 years from now.

        If you change the equation, make investment in space companies attractive to pension funds, then those longer term investments become more important to people.

      2. Flecther

        You are comparing apples and oranges.

        Lipstick exists because there is a commercial market for it. In a free market economy suppliers produce what the market wants as long as the market is willing to pay enough to exceed the cost of production. In plain language some one is able to make money on it.

        By contrast there is no commercial market for NEO mitigation. So efforts to address the problem depend on government funding and/or charity, where it completes with all the other activities that folks think are good to have but don’t turn a profit.

        But the risks of NEOs will eventually be addressed by one of three things happening.

        First, one will hit large enough to wipe out civilization. Very low probably but it will solve the problem 🙂

        Second, one takes out a populated region. Now it will be recognized as a problem and dealt with after much finger pointing at why it wasn’t dealt with earlier.

        Third, most likely and desirable, folks find a way to get rich mining NEOs, in which case any NEO sighted on a Earth intercept course will be quickly processed and disappear as goods sold in the commercial market, either on Earth or in space. Yes, that iron NEO will impact Earth, but in the form of a million Ford trucks not as an impact event…

        The latter model incidentally is why large predators, which really endangered primitive humans, are no longer a hazard to the vast majority of the population. When a market developed for their pelts they were soon hunted nearly out of existence. The same will happen to most of the NEO on the hazardous object list once NEO mining becomes a way to get rich just as those folks who design a new brand of lipstick get rich. And yes, I am sure astronomers will be crying about the lost of so many asteroids they never had a chance to study…

        1. Yeah. Maybe we’ll get lucky, and the first strike in history to hit an inhabited area will hit a certain town on the Arabian peninsula – or the lower end of Manhattan, or the City of London. Thus rubbing humanity’s nose in its vulnerability and cutting out a parasitic infestation at the same time.

          And BTW, my earlier comment wasn’t a sideswipe at the lipstick industry in particular – just the amount of money involved.

  12. Indeed not, Mr. Anthony. Which is one very good reason indeed for the Western democracies, perhaps in combination, to be the first to develop this technology.

    It might be very easy indeed to give a rock a little nudge in just the right (or wrong) direction. Unfortunately for that idea, precise targeting would involve course correction rather closer to Earth. There are small effects (unbalanced radiation pressure, outgassing…) that might make targeting problematic if no corrections are made less than a few hundred million miles away.

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