Asteroid impact risks ‘underappreciated’

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A visualisation showing where sizeable asteroids have hit the Earth in recent years has been released by the B612 Foundation.

The US-based group, which includes a number of former Nasa astronauts, campaigns on the issue of space protection.

It hopes the visualisation will press home the idea that impacts are more common than we think.

The presentation leans on data collected by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO).

The CTBTO operates a network of sensors that listens out for clandestine atom bomb detonations.

Between 2000 and 2013, this infrasound system catalogued 26 major explosions on Earth.

None were caused by A-bombs; they were all the result of asteroid strikes.

They ranged in energy from one to 600 kilotons. By way of comparison, the bomb that destroyed the Japanese city of Hiroshima was a 15-kiloton device.

Fortunately, most of these space rocks disintegrated high up in the atmosphere and caused few problems on the ground.

A few, people will have heard about, such as the 20m-wide object that ripped across the sky above the Russian city of Chelyabinsk last year.

But many will have gone unseen because they occurred far out over the oceans.

And just one of the 26 events was detected in advance, and then by only a matter of hours.

The advocacy group uses the frequency and size range of the impacts to say something about the probability of larger strikes in the future.

Because although Chelyabinsk was a terrifying experience for those caught up in it, the event itself was quite small compared with some of the incomers recorded through Earth history.

The foundation says the CTBTO data would suggest that Earth is hit by a multi-megaton asteroid – large enough to destroy a major city if it occurred over such an area – about every 100 years.

Remembering the Tunguska event of 1908 – it was fortunate that that object, thought to be about 45m wide, struck a very remote part of the globe.

"This is a bit like earthquakes," explains Ed Lu, former shuttle astronaut and CEO of the B612 Foundation.

"In the cities that have a major danger – Tokyo, Los Angeles, San Francisco – they know the odds of big earthquakes by observing how many small earthquakes there are. Because there's a known distribution of earthquakes, meaning that earthquakes come in all sizes, small to large – if I can measure the small ones, I know how many big ones they're going to be. And you can do this with asteroids.

Written By: Jonathan Amos
continue to source article at bbc.com

41 COMMENTS

  1. I’m always conflicted about stuff like this. On the one hand I’m always for more space research (manned vs. unmanned is a different question but IMO clearly the US and world could benefit from more space exploration) and I agree it’s not an inconsequential thing to worry about given how devastating an asteroid hitting a major city would be.

    But it seems to me this kind of talk is almost irresponsible given the very real dangers we face from climate change. Climate change isn’t a very small probability of a disaster. Climate change is a very large probability of a disaster and a disaster that is more controllable than stopping an asteroid. I think this kind of fear mongering makes people think that scientists are always trying to scare people to justify their funding and that people who care about the planet should be putting all their energy into climate change right now, given how bad it is going to be and how little we are currently doing about it.

    The risks of doing nothing about asteroids in the next 20 years is very small. The risk of doing nothing about climate change in the next 20 years will be catastrophic.

    • In reply to #1 by Red Dog:

      I’m always conflicted about stuff like this. On the one hand I’m always for more space research (manned vs. unmanned is a different question but IMO clearly the US and world could benefit from more space exploration) and I agree it’s not an inconsequential thing to worry about given how devastating…

      I think this is a false dichotomy. This idea that somehow the money we invest in space exploration is robbed from other “more important” things. Plus, as the author suggests, time is of the essence when asteroids are concerned: if we wait in 20 years to begin producing and launching asteroid detecting technology, it will be way more expensive and we may be too late.

      For example, let’s consider the Sentinel project to be launched in 2018. First of all, it’s privately funded so right off the bat, the “less than judicious use of taxpayer money” argument goes right out the window. But even if it was taxpayer funded, at $250M US, it’s a bargain. Building a small bridge or a mere 50Km strip of freeway costs more than that.

      Of course, funding renewable energy, clean cars, etc.. is a HUGE priority, no argument here. But preventing catastrophic asteroid impacts is supremely important as well. So why can’t we do both? If cuts in the US budget are to be made, the space program is one of the worst choices. The military budget however would be a good place to start.

      • In reply to #2 by NearlyNakedApe:

        think this is a false dichotomy.

        It’s a false dichotomy if you are simply talking in abstract rational terms I agree. The problem is to do anything about this we have to start talking about our various national political systems and I live in the US and it’s far from rational. There are only so many things you can put in a budget and there are massive trade offs, deal making, etc. that go into the actual budget. The same (very limited few) rational people in the US Congress who understand climate change are for the most part the same people who would support this.

        I think for me though it really comes down to my own personal decisions about how to spend my time. I spend some time on politics, writing letters, phoning people to get them to vote, going to meetings, etc. Not a lot of time because frankly I don’t enjoy it a lot of the time but I think it’s something I should do. So for me it comes down to which issues I think are most important for me to spend my time on in political activism and in that analysis climate change is far more important. So I applaud all the people who also spend time advocating to do something about the Asteroids but I would ask them if they spend as much time advocating for climate change and if not then perhaps their priorities are a bit off.

        • In reply to #4 by Red Dog:

          So for me it comes down to which issues I think are most important for me to spend my time on in political activism and in that analysis climate change is far more important.

          Very commendable. I applaud your efforts, Crimson Canine. And again, I’m not underestimating how difficult the situation is with the US government. Most of Congress doesn’t even believe in climate change, so understanding the imminent threat it poses to humanity isn’t even part of the dialogue yet. It’s as if in 1941, when Japan bombed Pearl Harbor, the US Senate would have reacted by saying it’s a hoax.

          So I applaud all the people who also spend time advocating to do something about the Asteroids but I would ask them if they spend as much time advocating for climate change and if not then perhaps there priorities are a bit off.

          Well I wouldn’t be so quick to judge. What if nuclear physicists achieve controlled nuclear fusion in 5 years and clean fusion power plants start popping up within 10 years? What if there is an asteroid 15Km in diameter (or more) out there heading straight for us and due to hit us in 10 years from now? What would be the highest priority then?

          I think that different people advocate for different causes: every person have their own priorities and that’s OK. For example, Medecins Sans Frontieres advocates for better medical treatment in poor countries. They wouldn’t spend time advocating for climate change because like you, they have limited resources and time on their hands. If we all advocated for the same cause, a lot of important ones would be left unattended and would even go unnoticed by the rest of the world.

        • In reply to #4 by Red Dog:

          In reply to #2 by NearlyNakedApe:

          I think this is a false dichotomy.

          It’s a false dichotomy if you are simply talking in abstract rational terms I agree.

          It’s a false dichotomy if you talk in terms of the technology, or the science.

          So for me it comes down to which issues I think are most important for me to spend my time on in political activism and in that analysis climate change is far more important. So I applaud all the people who also spend time advocating to do something about the Asteroids but I would ask them if they spend as much time advocating for climate change and if not then perhaps their priorities are a bit off.

          Some of the same space technologies are used for monitoring Earth, other planets, and asteroids. Planetary climate mechanisms extend beyond Earth, and Earth’s climate is certainly largely determined by inputs from space.

          Earth’s climate history cannot be studied in isolation from the Solar-System. The very climate cycles climatologists study and use as a basis for their predictions, are derived from astronomical observations and geological records of astronomical events.

          Work is starting on studying the physical structures of asteroids:-

          http://www.richarddawkins.net/news-articles/2014/4/11/construction-to-begin-on-nasa-spacecraft-set-to-visit-asteroid-in-2018#

          http://www.richarddawkins.net/news-articles/2014/4/16/nasa-cassini-images-may-reveal-birth-of-new-saturn-moon#comment-box-4

          • In reply to #12 by Alan4discussion:

            In reply to #4 by Red Dog:

            In reply to #2 by NearlyNakedApe:

            I think this is a false dichotomy.

            It’s a false dichotomy if you are simply talking in abstract rational terms I agree.

            It’s a false dichotomy if you talk in terms of the technology, or the science.

            Looks like you’ve hit the nail on the head. So it’s not an either-or scenario. It’s anything but.

        • In reply to #4 by Red Dog:

          It’s a false dichotomy if you are simply talking in abstract rational terms I agree. The problem is to do anything about this we have to start talking about our various national political systems and I live in the US and it’s far f…

          Well, yes and no. A project like this one would cost only a small fraction of what it would cost to fight global warming (even though the price of not fighting global warming will be much higher in the end). We are talking about a few billion dollars, at most, in order to vastly improve our ability to deal with a potential threat of a deep impact. Compare that price tag with the estimated 3/4 trillion dollars given to the global fossil fuel industry in subsidiaries (in 2012). We are really talking about pocket change here.

          From a political point of view, you might unfortunately be right. These kinds of projects can be a distraction from other environmental issues. We know the public can only process so much information. From a cognitive perspective an asteroid impact is much easier to grasp than the very gradual and largely invisible threat of global warming. Also, this project would hardly be resisted by powerful lobby groups. I really can’t see who would benefit from fighting a project like this. At least not someone with deep enough pockets to actually make a change. This is the big problem in the current world we are living in. We spend trillions and trillions of dollar on seemingly meaningless things (meaningless for the great majority of the people on this earth), but when we are talking about the environment or potential disasters in the future few people seem willing to invest. The reason, of course, is that there are no short term profits to be made from these kinds of projects. That’s why capitalism is bound to fail. It can only sustain profitable projects. Unfortunately, the most important and noble of all enterprises aren’t profitable. At least not in the short term, and the profits tend to gain humanity as a whole and not only a small set of share holders. This goes against the very core of capitalism, and why human progress will not reach it’s full potential as long as we are slaves to a system like capitalism.

          • In reply to #15 by Nunbeliever:

            In reply to #4 by Red Dog:

            It’s a false dichotomy if you are simply talking in abstract rational terms I agree. The problem is to do anything about this we have to start talking about our various national political systems and I live in the US and it’s far f…

            Well, yes and no. A project like thi…

            The Apophis Asteroid is coming by in 2029. It would be a great chance to see if we can use these technologies.

          • In reply to #24 by alf1200:

            The Apophis Asteroid is coming by in 2029. It would be a great chance to see if we can use these technologies.

            Although Apophis will not hit earth in 2029. If I remember correctly there’s a tiny risk that it will enter some “gravitational keyhole” (a few hundred meters large) that might set it on a crash course in 2036.

          • In reply to #26 by Nunbeliever:

            In reply to #24 by alf1200:

            The Apophis Asteroid is coming by in 2029. It would be a great chance to see if we can use these technologies.

            Although Apophis will not hit earth in 2029. If I remember correctly there’s a tiny risk that it will enter some “gravitational keyhole” (a few hundred meters…

            Coming back to see us in 2039

          • In reply to #26 by Nunbeliever:

            In reply to #24 by alf1200:

            The Apophis Asteroid is coming by in 2029. It would be a great chance to see if we can use these technologies.

            Although Apophis will not hit earth in 2029. If I remember correctly there’s a tiny risk that it will enter some “gravitational keyhole” (a few hundred meters…

            We should know in plenty of time if it will come through the keyhole. Lasers or a standoff nuclear device should push just enough. I wish I were going to be here.
            We could also land a craft with thrusters. We have already done that.

          • In reply to #30 by alf1200:

            I wish I were going to be here. We could also land a craft with thrusters. We have already done that.

            Well, I’m definitely going to be there. Or most likely not THERE, but down here on earth watching. Unless I get hit by a truck of course ;)

          • In reply to #24 by alf1200:

            The Apophis Asteroid is coming by in 2029. It would be a great chance to see if we can use these technologies.

            It would be safer to avoid messing in early experiments, with the trajectories of asteroids which are near misses making relatively safe passes, – in case we accidentally put them on a future collision course.

            It would be better to calculate the future trajectory based on data collected after the first pass, rather than to use estimated projections.

            There are already plans to move a small asteriod.

            http://www.space.com/25235-nasa-asteroid-capture-mission-mars.html
            NASA’s wild plan to capture an asteroid and park it near the moon is only one step on the way to Mars, NASA chief Charles Bolden said Wednesday

    • In reply to #1 by Red Dog:

      The risks of doing nothing about asteroids in the next 20 years is very small. The risk of doing nothing about climate change in the next 20 years will be catastrophic.

      I don’t see why we need that comparison. We spend money on numerous trivia, and loads of silly political pet gimmicks, which could be better spent on asteroid detection, asteroid deflection, asteroid capture, and asteroid mining.

      There is actually a LOT of matter hitting Earth! Fortunately only a small proportion of it is big lumps!

      http://gizmodo.com/5882517/did-you-know-that-earth-is-getting-lighter-every-day

      • • Earth gains about 40,000 tonnes of dust every year, the remnants of the formation of the solar system, which are attracted by our gravity and become part of the matter in our planet. Our planet is actually made from all that starstuff.
      • • NASA says that Earth gains about 160 tonnes of matter a year because the global temperature is going up: “If we are adding energy to the system, the mass must go up.” Oh, those crazy thermodynamics.

      • • Earth’s core loses energy over time. It’s like a giant nuclear reactor that burns fuel. Less energy means less mass. 16 tonnes of that are gone every year. Not much.

      • • And here’s the big mass loss: about 95,000 tonnes of hydrogen and 1,600 tones of helium escape Earth every year. They are too light for gravity to keep them around, so they get lost. Gone into space.

  2. While Earth has more atmospheric protection, impacts on the Moon and Mars are quite common – indicating just how many rocks are flying around the inner Solar-System.

    Fresh impact crater spied on Mars – http://www.bbc.co.uk/news/science-environment-26067927

    A Nasa spacecraft in orbit around the Red Planet has spied a fresh impact crater on the Martian surface.

    The hole is about 30m (100ft) in diameter and surrounded by a blast zone of debris punched out of the ground by the meteorite impact.

    The explosion that generated this crater tossed out debris as far as 15km (9.3 mi).

    The image was taken by the Mars Reconnaissance Orbiter’s HiRise camera, one of six instruments on the probe.

    Researchers used HiRise to examine this site because the orbiter’s Context Camera had revealed a change in appearance in this Martian region between observations in July 2010 and May 2012.

    Scientists have carried before-and-after imaging to bracket the appearance dates of fresh craters on Mars.

    These studies indicate that impacts producing holes at least 3.9m (12.8ft) in diameter occur at a rate exceeding 200 per year across the planet.

      • In reply to #8 by Cairsley:

        In reply to #7 by Light Wave:

        Under apppreciated ? What possible difference could we make – even if we could see it coming….?

        Did you not read the article?

        Duh….we’ve still got – a snowball’s chance in Hell….to do anything about a big black lump coming at us from left field…Or behind the sun….whether I read the article or not ….which I did…

        • In reply to #16 by Light Wave:

          Duh….we’ve still got – a snowball’s chance in Hell….to do anything about a big black lump coming at us fro…

          What do you base that statement on? I think there is good evidence to suggest that we have the knowledge and technology to deal with even large asteroids if we can detect them in time. But, I agree. If we do nothing we don’t stand a chance. That is kind of obvious ;)

          • In reply to #17 by Nunbeliever:

            In reply to #16 by Light Wave:

            Duh….we’ve still got – a snowball’s chance in Hell….to do anything about a big black lump coming at us fro…

            What do you base that statement on? I think there is good evidence to suggest that we have the knowledge and technology to deal with even large asteroids…

            I base that statement on thoughts that circulate in my mind….calculating how long humanity has been on Earth and how many asteroids have hit Earth during that time….It seems doing nothing is actually okay….and so current humans may be slightly kidding themselves somehow….

          • In reply to #19 by Light Wave:

            It seems doing nothing is actually okay….and so current humans may be slightly kidding themselves somehow….

            Now you are changing the subject :) I asked you on what you base your statement that we can’t possibly deal with a large asteroid heading for earth?

          • In reply to #25 by Nunbeliever:

            In reply to #19 by Light Wave:

            It seems doing nothing is actually okay….and so current humans may be slightly kidding themselves somehow….

            Now you are changing the subject :) I asked you on what you base your statement that we can’t possibly deal with a large asteroid heading for earth?

            An overwhelming sense of doubt in our abilities to be so sure we can do this….the plans sound like grandiose theoretical computer graphics at the moment showing how things may be possible, but none are known to be practical or successful…….So the ‘total optimism’ is slightly misplaced in my mind……
            we’ve been on the Planet for millions of years and never once changed the course of an Asteroid…and we’re still here….

            Alan for Discussion – the weapons used for space and for Earth are different ….I was hugely generalising about military arming of space….however we’ll always try to do something about it if we can being human control freaks…. the more the threat is perceived as urgent…..But in the long history of the solar system I’m pretty sure who was here first and who will be here last…..
            Asteroids 1 – Humans 0

          • In reply to #33 by Light Wave:

            But in the long history of the solar system I’m pretty sure who was here first and who will be here last….. Asteroids 1 – Humans 0

            Well, I don’t really find these explanations so grandiose. To me, it seems like pretty basic physics + we have the technology to build everything we need to execute these different methods. I still, can’t see any rational reason for your immense pessimism with regard to these methods. Whether politicians are willing to spend money on these kinds of projects is a whole other issue. That said, I sincerely hope we will never have to find out whether these methods work or not.

          • In reply to #36 by Nunbeliever:

            In reply to #33 by Light Wave:

            But in the long history of the solar system I’m pretty sure who was here first and who will be here last….. Asteroids 1 – Humans 0

            Well, I don’t really find these explanations so grandiose. To me, it seems like pretty basic physics + we have the technology to build…

            Your over optimism is not so reassuring…I was commenting on the article and not your rationality….
            Maybe if there were any successful trials on known asteroids….that would be considered evidence that these theoretical methods actually work – but there’s always gonna be the element of surprise when the unexpected shadow looms fast toward us before we get anything built….so yeah….We have the technology – but we cant domesticate space…

        • In reply to #16 by Light Wave:

          In reply to #8 by Cairsley:

          In reply to #7 by Light Wave:

          Under apppreciated ? What possible difference could we make – even if we could see it coming….?

          Did you not read the article?

          Duh….we’ve still got – a snowball’s chance in Hell….to do anything about a big black lump coming at us fro…

          That is old technology now. They can use solar sails, lasers, standoff nuclear thrust. They have landed on asteroids.

    • In reply to #7 by Light Wave:

      Under apppreciated ? What possible difference could we make – even if we could see it coming….?

      http://www.planetary.org/explore/projects/laser-bees/

      What Are Laser Bees

      This technique involves many small spacecraft — each carrying a laser — swarming around a near-Earth asteroid. The spacecraft could precisely focus their powerful lasers pumped by sunlight onto a tiny spot on the asteroid, vaporizing the rock and metal, and creating a jet plume of super-heated gases and debris. The asteroid would become the fuel for its own rocket — and slowly, the asteroid would move into a new trajectory.

      • In reply to #11 by Alan4discussion:

        In reply to #7 by Light Wave:

        Under apppreciated ? What possible difference could we make – even if we could see it coming….?

        http://www.planetary.org/explore/projects/laser-bees/

        What Are Laser Bees

        This technique involves many small spacecraft — each carrying a laser — swarming around a ne…

        I have read of the conceptual and theoretical methods of changing the course of asteroids….but the one that struck russia shows us that we dont see them coming even with a million sky watchers on earth….
        This percieved threat….of needing technology to shoot down space objects sounds very convenient for the latest military arming and surveilance of and from space….china shooting down one of their own satellites sucessfully just to show that they can….made america sit up and take notice and then copied them…..this could be the new space arms race…

        • In reply to #20 by Light Wave:

          In reply to #11 by Alan4discussion:

          http://www.planetary.org/explore/projects/laser-bees/

          What Are Laser Bees?

          I have read of the conceptual and theoretical methods of changing the course of asteroids….but the one that struck russia shows us that we don’t see them coming even with a million sky watchers on earth….

          That is because politicians have refused to spend the money on the surveillance equipment to watch out for them. A million watchers without the right telescopes, or without a full view from an orbiting network of telescopes, are of little effect.

          This percieved threat….of needing technology to shoot down space objects sounds very convenient for the latest military arming and surveilance of and from space….

          That really is a misconception. Military surveillance of Earth and near Earth orbits, is a vast difference in distance and direction, from looking out into the Solar-System for Earth-crossing trajectories.

          china shooting down one of their own satellites sucessfully just to show that they can….made america sit up and take notice and then copied them…..this could be the new space arms race…

          This was a very silly decision made by politicians and the military, against the advice of astronomers. It has greatly increased the orbiting debris and greatly increased risks to astronauts and commercial satellites.

          However, You misunderstand the different nature of weapons in Low Earth Orbit, from that of systems like Laser bees, which are designed to operate millions of miles and months of travel, away from Earth, to change the orbital trajectories of asteroids or comets. The “shoot-’em-up” / “shoot-’em-down” approach, is poor-quality Hollywood science fiction.
          Asteroid deflection is about prolonged gentle pushing to alter trajectories and orbits.

          Lasers firing from orbit to Earth, already exist. http://www.richarddawkins.net/news-articles/2014/4/14/international-space-station-to-beam-video-via-laser-back-to-earth# as do high-powered lasers. Mirror/Laser Bees have nothing to do with developing weapons, which is probably why they have not secured the required funding for an effective asteroid detection and deflection system.

          @19 – I base that statement on thoughts that circulate in my mind….calculating how long humanity has been on Earth and how many asteroids have hit Earth during that time….

          Some interesting meteorite falls of the last two centuries – http://www.icq.eps.harvard.edu/meteorites.html

          It seems doing nothing is actually okay…

          …. Unless you were in Tunguska in 1908,

          http://history1900s.about.com/od/1900s/qt/Tunguska.htm

          The blast, centered in a desolate and forested area near the Podkamennaya Tunguska River in Russia, is estimated to have been a thousand times more powerful than the bomb dropped on Hiroshima. The explosion leveled an estimated 80 million trees over an 830 square-mile area in a radial pattern from the blast zone. Dust from the explosion hovered over Europe, reflecting light that was bright enough for Londoners to read at night by it.

          or Chelyabinsk 15 Feb. 2013.

          An extremely bright fireball (apparent brightness rivalling that of the apparent brightness of the sun) entered atmosphere over Alaska and moving westward toward Chelyabinsk, near its termination point shortly before sunrise, creating a huge airblast shock that damaged thousands of buildings in Chelyabinsk (mostly broken glass) and injuring more than 1000 people; apparently meteorites were found in water under a large circular broken ice feature found soon after the event.

          Doing nothing after being made aware of the risks, sounds like a Dinosaur Decision to me.

        • In reply to #20 by Light Wave:

          In reply to #11 by Alan4discussion:

          In reply to #7 by Light Wave:

          Under apppreciated ? What possible difference could we make – even if we could see it coming….?

          http://www.planetary.org/explore/projects/laser-bees/

          What Are Laser Bees

          This technique involves many small spacecraft — each car…

          We shot down our own satellite long ago with an F15. That isn’t tough.

          “Maj. Wilbert ‘Doug’ Pearson successfully launched an anti-satellite, or ASAT, missile from a highly modified F-15A on Sept. 13, 1985 in the Pacific Missile Test Range. He scored a direct hit on the Solwind P78-1 satellite orbiting 340 miles above”

          But that is worthless on an Asteroid.

        • In reply to #20 by Light Wave:

          …but the one that struck russia shows us that we dont see them coming even with a million sky watchers on earth

          Well, that’s why need eyes in space. Which is what this article is all about ;)

          This percieved threat….of needing technology to shoot down space objects sounds very convenient for the latest military arming and surveilance of and from space

          Well, technically you can’t shoot objects down in space. That said, I hardly think a missile based defense system is what scientists in general are opting for. First, we don’t have nukes big enough to actually pulverize a large asteroid. Even if we had, it would be a terrible idea to shoot a large asteroid into pieces. Instead of one projectile heading for earth we would suddenly have a dozen smaller but still very dangerous projectiles. You can of course change the trajectory of an asteroid with a strong explosive, but there are easier and less violent ways to do that. Which you ought to know, if you read the article. In fact a strong explosive is probably the last thing you want to use for these kinds of precision jobs. You have to know with surgical precision how much you want to change the course of an asteroid. It’s not enough to make it miss earth, you don’t want it to come back a few years later and finish the job. The solutions that were presented in this article and the ones that scientists deem as realistic and efficient are much more peaceful than the Hollywood scenario you are arguing against :) Although, if a large asteroid (or comet) hits the earth it will be anything but peaceful.

          • In reply to #27 by Nunbeliever:

            In reply to #20 by Light Wave:

            …but the one that struck russia shows us that we dont see them coming even with a million sky watchers on earth

            Well, that’s why need eyes in space. Which is what this article is all about ;)

            This percieved threat….of needing technology to shoot down space objec…

            Called the “Shotgun Effect”.

          • In reply to #27 by Nunbeliever:

            In reply to #20 by Light Wave:

            Well, technically you can’t shoot objects down in space. That said, I hardly think a missile based defense system is what scientists in general are opting for. First, we don’t have nukes big enough to actually pulverize a large asteroid. Even if we had, it would be a terrible idea to shoot a large asteroid into pieces. Instead of one projectile heading for earth we would suddenly have a dozen smaller but still very dangerous projectiles. You can of course change the trajectory of an asteroid with a strong explosive, but there are easier and less violent ways to do that. Which you ought to know, if you read the article. In fact a strong explosive is probably the last thing you want to use for these kinds of precision jobs. You have to know with surgical precision how much you want to change the course of an asteroid. It’s not enough to make it miss earth, you don’t want it to come back a few years later and finish the job.

            Indeed ! Studies in recent years have shown some asteroids to be “rubble-piles” loosely bound together by gravity. It would not take much to change them from a lump into a swarm.

            http://www.killerasteroids.org/rubble.php

            Think of what would happen if an asteroid were headed toward Earth and you try to push it or blow it up. It might work for a single, monolithic rock. But moving a rubble pile could be like kicking a pile of leaves. You’d need different strategies, and you’d probably have to do it very slowly, over long periods of time, to avoid breaking up the asteroid into a swarm of uncontrollable rocks.

            As alf1200 puts it @29, trying to blow up a rubble pile asteroid would create a “Shotgun Effect” out of a cannonball!

          • In reply to #31 by Alan4discussion:

            Indeed ! Studies in recent years have shown some asteroids to be “rubble-piles” loosely bound together by gravity. It would not take much to change them from a lump into a swarm.

            Is it possible to determine the density and other properties of asteroids (and comets) from a long distance? I know that we examine the properties of planets by studying electromagnetic radiation, using spectrometers and measuring the gravitational forces between different bodies. But, asteroids are so small and hard to observe in general. I mean, this would be of utter importance in order to successfully steer an asteroid away from earth.

          • In reply to #35 by Nunbeliever:

            In reply to #31 by Alan4discussion:

            Is it possible to determine the density and other properties of asteroids (and comets) from a long distance? I know that we examine the properties of planets by studying electromagnetic radiation, using spectrometers and measuring the gravitational forces between different bodies. But, asteroids are so small and hard to observe in general. I mean, this would be of utter importance in order to successfully steer an asteroid away from earth.

            I’m not sure about how big a distance could work, but telescopes are improving all the time. Measurements can certainly be made by telescopes and probes, with trajectory, effects of gravity indicating mass, and the volume estimated from images being used to make calculations of density.

            http://en.wikipedia.org/wiki/25143-Itokawa

            Itokawa is an S-type asteroid. Radar imaging by Goldstone in 2001 observed an ellipsoid 630 ± 60 m long and 250 ± 30 m wide.[5][6]

            The Hayabusa mission confirmed these findings and also suggested that Itokawa may be a contact binary formed by two or more smaller asteroids that have gravitated toward each other and stuck together.

            I think any asteroid on a suspicious orbit, would be thoroughly investigated to identify the type, mass, density etc. once people took the threat seriously.

            List of asteroids visited by spacecraft – wikipedia

          • In reply to #35 by Nunbeliever:

            In reply to #31 by Alan4discussion:

            Indeed ! Studies in recent years have shown some asteroids to be “rubble-piles” loosely bound together by gravity. It would not take much to change them from a lump into a swarm

            It seems to me we should be able to check mass by measuring it’s path as it moves close to another gravitational source.

          • In reply to #39 by alf1200:

            It seems to me we should be able to check mass by measuring it’s path as it moves close to another gravitational source.

            Assuming we have good enough telescopes to follow and detect these bodies in time of course.

  3. Space Guard was envisaged by Arthur C. Clarke, and it is something we’d be dumb as a dinosaur not to do as soon as we can. In the long run it may be the only significant point of difference between mammals and dinosaurs. There’s more than one scale of catastrophe.

  4. This is why we have to hurry up and fix the planet. Create sustainable and stable communities capable of generating the excess wealth needed for the insurance premiums we are currently skipping on.

    This is a threat, if all were mindful of it and could see as soluble with a spare few trillion dollars and the energy to back it up, that could have fantastically beneficial effects on cooperative working.

  5. The money that would be saved by stopping the endless roundabout of internecine wars would be enough to serve both purposes. Wars I might add that are largely related to whose version of quidditch is correct.

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