** There is a common misconception, that has been mentioned in this thread a few times already, that breaking up a meteor into pieces will simply cause it to burn up and not be a worry. While half true, this doesn't lower the risk by any large amount. A pile of gravel hitting the earth would be about as bad as a solid rock of the same size hitting the earth. Why? Just think about it in terms of energy. Sure, the gravel will burn up. But, hey, its burning up in our atmosphere. Isn't that kinda... hot? Yes, yes it is. Notably, the Tungesta event is an example of something that caused widespread damage, but did not actually hit the ground. This pile of gravel would burn up (a bunch would probably still reach the ground, depending on the average size of its constituent particles), but this big mass of stuff burning up could cause the air to become rapidly heated, which would cause a shock wave, which would knock shit over. Plus this would add large amounts of dust directly into the atmosphere, possibly altering global climate.
It depends on how it breaks up and how much spread there is. If I break it into two fragments that hug each other...that's bad. If I can get it to litterally gravel with a wide spread...then no. And while the effects you discribe are bad, they aren't world/civilization ending. It would be a climate change but not so radical that the system that is Earth won't compensate for them. It's the dust/heat effect of Krakatoa without the tidal waves.
Um. Wouldn't the amount of money to comprehensively track NEOs be trivial?
Trivial relative to what?
Amount of money wasted on Iraq? Probably.
Current education budget? Probably not.
We spend upwards of 400 billion tax dollars on education every year in this country.
What would it cost for an astronomy staff funded by the U.N. to chart the course of all the larger NEOs? two billion per year out of the world economy?
God damnit you morons stop spouting off about how it would take all the resources of the world working together for decades to divert a large asteroid. It wouldn't. You don't have to blow it up or move it to the next solar system. A tiny course adjustment is enough.
It would probably take less effort than one of the moon landings to get a missle up there with enough power to nudge the rock a bit. Especially considering it would be unmanned and there doesn't have to be a return trip.
Not a trivial task but well within current technology and the scale of project that have been pulled off multiple times in the past by the US.
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SmasherStarting to get dizzyRegistered Userregular
About breaking an asteroid up into smaller pieces, I've read that this might actually be a very bad idea for the larger, potentially civilization-ending ones. By breaking it up you ensure that all the energy will be absorbed by the atmosphere, while if it still was in one piece the earths mantle would absorb the major part of the energy. So, shooting nukes at it would probably be counterproductive as the atmosphere is much more fragile than the planet itself. You want the rock in one piece of you are certain that it is going to hit.
As for the actual odds of a major impact, does anyone have any links to actual studies about this? According to what I have been able to find, Tunguska-class events happen at a rate of about once every century. This event had an energy of about 10-20 megatons, so about a fifth of the largest H-bomb ever detonated. Somewhat smaller ones, but still capable of causing casualties in the hundreds of thousands if they hit a city occur at a rate of about 5 every century. Since 3/4 of the earth is water, we can expect at least one to hit land every century. If I remember correctly, about 1 % of the land-area of earth is considered urban, so... that would mean that there is a chance of 1 to 10000 every year that we will have a major meteorite-related catastrophy?!?
Hm, I don't know what to make of those odds... as a scientist, I'm all for more spending on things that expand our knowledge, but from a pure cost-benefit perspective? I have no idea how that risk corresponds to other things.
About breaking an asteroid up into smaller pieces, I've read that this might actually be a very bad idea for the larger, potentially civilization-ending ones. By breaking it up you ensure that all the energy will be absorbed by the atmosphere, while if it still was in one piece the earths mantle would absorb the major part of the energy. So, shooting nukes at it would probably be counterproductive as the atmosphere is much more fragile than the planet itself. You want the rock in one piece of you are certain that it is going to hit.
As for the actual odds of a major impact, does anyone have any links to actual studies about this? According to what I have been able to find, Tunguska-class events happen at a rate of about once every century. This event had an energy of about 10-20 megatons, so about a fifth of the largest H-bomb ever detonated. Somewhat smaller ones, but still capable of causing casualties in the hundreds of thousands if they hit a city occur at a rate of about 5 every century. Since 3/4 of the earth is water, we can expect at least one to hit land every century. If I remember correctly, about 1 % of the land-area of earth is considered urban, so... that would mean that there is a chance of 1 to 10000 every year that we will have a major meteorite-related catastrophy?!?
Hm, I don't know what to make of those odds... as a scientist, I'm all for more spending on things that expand our knowledge, but from a pure cost-benefit perspective? I have no idea how that risk corresponds to other things.
You don't shoot missles at an asteroid to blow it up. That's both stupid and for the larger ones not possible. You use the explosion to adjust its course by a couple tenths of a percent which is more than enough to turn a hit into a miss.
Current education ain't going to be worth shit if we get smacked with a big fucking rock.
Look, the thing is, even if we see the thing coming, we don't have any feasible technology to stop it from hitting us anyway.
The chances of a big rock hitting Earth and causing global calamity are incredibly low to the point of "virtually non-existent". The worst case scenario that has any meaningful possibility of happening is a local disaster, as in the case of Apophis. In such a case, I don't see why our money should not be spent toward averting other local disasters, such as floods, storms, or even things like epidemics. Proactively trying to prevent such disasters not only costs much less, it saves more lives (because such disasters occur on a much more frequent basis than killer meteors), it is also actually feasible.
You are calling the possible impact of Apophis a "local distaster"? A quick wikipedia check shows that the thing is 2x10^10kg. That is not a local disaster right there. NASA estimated a release of energy around 800 megatons if that thing hit Earth. There are not many places on the planet where that thing could land and not cause big problems for someone, or the entire world.
Hardly an "end of the world" scenario. Yes, it would still suck, but definitely not worth this "omg we can all die tomorrow!" scaremongering.
Simply put, risk is calculated by the formula: potential damage x likelihood
Potential damage is fairly high, but it is basically neutralized by the super-low likelihood.
And even then, when we calculate in detail the potential damage we have to take into account the fact that only 1/8th surface area of Earth is populated with humans. The rest consists of seas, mountains, and other impassible terrain. Furthermore, the majority of that 1/8th surface area is made of rural regions with low population density. Urban areas - places where the only considerable amount of damage to humans would occur - make only 1.5% of Earth's total surface.
Therefore potential damage ends up to be fairly small as well.
Considering this extremely low amount of risk, you gotta ask yourself if the cost would be worth mitigating the risk. And I'm saying "mitigating" because we can't completely eliminate it; even if we see the thing coming the best we can do is attempt to evacuate the area.
God damnit you morons stop spouting off about how it would take all the resources of the world working together for decades to divert a large asteroid. It wouldn't. You don't have to blow it up or move it to the next solar system. A tiny course adjustment is enough.
It would probably take less effort than one of the moon landings to get a missle up there with enough power to nudge the rock a bit. Especially considering it would be unmanned and there doesn't have to be a return trip.
The tiny course adjustment would be meaningful only over long distances. Which means that we have to hit the thing - in the right spot - while it is still insanely far from the Earth. The possibility of success for such a mission is quite small, considering the asteroid is going to be unevenly shaped, will be rotating, and hitting it in the right spot at just the right time.... yeah. It's composition will be uneven as well; an explosion on an iron surface will not have the same effect as an explosion on a granite surface.
It's not simply a matter of "let's make a rocket, load it up with a shit ton of explosives, and hit the damn thing!"
You've already said in this thead that you don't know shit about astrophysics. Thanks for once again hammering that point home. A tiny course adjustment is all it takes. Do you have any idea how fast the Earth is moving and what a small target it is? Slowing down or speeding up an object (by knocking it off course by a couple tenths of a degree) enough so that it arrives seven minutes later / earlier than expected would result in a clean miss. Such a project would be nowhere near as complex as landing several humans on the moon and returning them, or the recent probe that intercepted a commet or even putting rovers on mars.
The only technological challenge here is building the detectors and improving the anyalysis of the data they provide. Even a kilometer sized iron asteroid could me nudged off course with present technology.
If asteroid impacts had a cyclical pattern of frequency, you would be right.
I see what you're doing. You claim impact frequency proves there's no issue, then when I claim that if we use frequency, it means we're due. Then you come back and acknowledge that we don't know the chances, as though you made some substantial point. Then you expect me to not notice that you acknowledged that we don't know, proving the value of investing in tech to better prepare.
I would say you're very dumb, but you probably plan these things way in advance. It's not dumb, it's sad.
The tiny course adjustment would be meaningful only over long distances. Which means that we have to hit the thing - in the right spot - while it is still insanely far from the Earth. The possibility of success for such a mission is quite small, considering the asteroid is going to be unevenly shaped, will be rotating, and hitting it in the right spot at just the right time.... yeah. It's composition will be uneven as well; an explosion on an iron surface will not have the same effect as an explosion on a granite surface.
It's not simply a matter of "let's make a rocket, load it up with a shit ton of explosives, and hit the damn thing!"
It's been a while since I took physics, and I don't know anything about astrophysics, so someone needs to check my math on this.
But.
Assume the keyhole width of roughly 400m and the asteroid velocity of roughly 31 km/s. At a distance of, let's say, the Moon, call it 400,000km for simplicity's sake, you have about 13,000 seconds (about three and a half hours) to move it.
To move it the full 400m (actually the most would be half that, but assume the full 400m) in that time would require shifting its velocity by about 0.03m/s. Note that's meters, not kilometers.
Now, and this is stretching my mechanics knowledge, I believe to move an object massing 2x10^10kg at 0.03m/s would take approximately 9,000,000 joules of energy.
Nine million joules probably sounds like a lot; for comparison's sake, one kilogram of TNT is equivalent to about 4,000,000 joules.
This isn't to say necessarily that you could shunt the asteroid with just a couple pounds of explosives, of course. But (again, if my calculations are correct) if you consider 400,000km to be "insanely far from the Earth", well... the sixties called. Just wanted to, you know, touch base.
The tiny course adjustment would be meaningful only over long distances. Which means that we have to hit the thing - in the right spot - while it is still insanely far from the Earth. The possibility of success for such a mission is quite small, considering the asteroid is going to be unevenly shaped, will be rotating, and hitting it in the right spot at just the right time.... yeah. It's composition will be uneven as well; an explosion on an iron surface will not have the same effect as an explosion on a granite surface.
It's not simply a matter of "let's make a rocket, load it up with a shit ton of explosives, and hit the damn thing!"
It's been a while since I took physics, and I don't know anything about astrophysics, so someone needs to check my math on this.
But.
Assume the keyhole width of roughly 400m and the asteroid velocity of roughly 31 km/s. At a distance of, let's say, the Moon, call it 400,000km for simplicity's sake, you have about 13,000 seconds (about three and a half hours) to move it.
To move it the full 400m (actually the most would be half that, but assume the full 400m) in that time would require shifting its velocity by about 0.03m/s. Note that's meters, not kilometers.
Now, and this is stretching my mechanics knowledge, I believe to move an object massing 2x10^10kg at 0.03m/s would take approximately 9,000,000 joules of energy.
Nine million joules probably sounds like a lot; for comparison's sake, one kilogram of TNT is equivalent to about 4,000,000 joules.
This isn't to say necessarily that you could shunt the asteroid with just a couple pounds of explosives, of course. But (again, if my calculations are correct) if you consider 400,000km to be "insanely far from the Earth", well... the sixties called. Just wanted to, you know, touch base.
Moon base.
We've put rockets way past the moon since then. :P
I think another important point that Ege is missing when discussing how hard it would be to hit these NEOs with any accuracy is that most of the objects that would be considered a significant threat are not coming in from vast distances in the space outside of our solar system. Apophis, for example, is in an orbit around the sun that is located entirely inside Mars' orbit and mostly inside Earth's. When we're able to accurately target landing zones on other planets, hitting a NEO is unlikely to be an impossible task.
Xaev on
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Right but worrying doesn't solve any problems. Do we have any feasible mechanisms for preventing a catastrophic event from occurring within a reasonable time span? I don't believe I saw any proposed in the thread but if there are some I apologize for overlooking them.
It's kind of like looking out for gamma ray burst. Fun and informative but ultimately worthless.
I think at least 4 have been proposed in the thread, and considering none are horibly complex, and most are limited mainly by inability to detect the things in time and lack of a sufficient method of getting them into orbit, I don't think those problems are all that insurmountable. We can already land shit on them and hit them with stuff*.
just where do you think those kind of things come from, if anything you argument implies that we should start spending money on developing that stuff too, to a greater degree. Of course that would also have all sort of useful technological breakthroughs too.
*"can" as in "we have already done it" I think NASA's stats are a whole lot better than those of the missile shield.
If asteroid impacts had a cyclical pattern of frequency, you would be right.
I see what you're doing. You claim impact frequency proves there's no issue, then when I claim that if we use frequency, it means we're due. Then you come back and acknowledge that we don't know the chances, as though you made some substantial point. Then you expect me to not notice that you acknowledged that we don't know, proving the value of investing in tech to better prepare.
I would say you're very dumb, but you probably plan these things way in advance. It's not dumb, it's sad.
We cannot use frequency to figure out when the next impact will occur. That is not how it works.
We can use frequency to figure out the likelihood that an impact will occur within the next X amount of time.
If event A occurs randomly, but on average once every 100 years, that means that at any given year, it has a 1/100 chance of occurring. In every 20 years it has a 20/100 chance of occurring.
Do you see how this works?
So what it proposed with this whole NEA funding thing is that we should spend X amount of money to figure out if, against all odds, there indeed is an asteroid large enough to pose a significant threat to us or to our children and grandchildren.
And I am saying that if you really want to figure out whether you should or not, you need to calculate the risk. Whether you are thinking in terms of against the odds or not, you cannot ignore the odds.
If asteroid impacts had a cyclical pattern of frequency, you would be right.
I see what you're doing. You claim impact frequency proves there's no issue, then when I claim that if we use frequency, it means we're due. Then you come back and acknowledge that we don't know the chances, as though you made some substantial point. Then you expect me to not notice that you acknowledged that we don't know, proving the value of investing in tech to better prepare.
I would say you're very dumb, but you probably plan these things way in advance. It's not dumb, it's sad.
We cannot use frequency to figure out when the next impact will occur. That is not how it works.
We can use frequency to figure out the likelihood that an impact will occur within the next X amount of time.
If event A occurs randomly, but on average once every 100 years, that means that at any given year, it has a 1/100 chance of occurring. In every 20 years it has a 20/100 chance of occurring.
Do you see how this works?
So what it proposed with this whole NEA funding thing is that we should spend X amount of money to figure out if, against all odds, there indeed is an asteroid large enough to pose a significant threat to us or to our children and grandchildren.
And I am saying that if you really want to figure out whether you should or not, you need to calculate the risk. Whether you are thinking in terms of against the odds or not, you cannot ignore the odds.
Ok, maybe you're just dumb.
We
A: Are going to get hit
B: Currently don't know which rocks will
Edit:
C: Have the means to stop ones we find, if we find them in time
ok the thing about blowing up/pushing gaint rocks is that theres no moral/ethical debate or major sacrifice there, its not abortion where its ""kill baby" or ruin life?"
its not global warming where its "no more dirty power supplies like coal, sorry developing world and current superpowers, your fucked, but... we could take the chance on WW3 decreased land mass and fucked up natural disasters if you like" its "take a chance at dying, or send a big fucking missile into space" people love explosions, they love space (especially when something cool happens there), they love fear (no matter how real, especially when theres a chance to spend lots of money on it) and, they love large objects hitting other large objects, oh, i almost forgot, they also tend to enjoy NOT DYING. big projects to save the world are generally popular, and it will have the definite potential for a movie deal. people like movies too.
and on top of that, its not easy to spin negatively, with the added advantage of being incredibly simple (as long as you stay general) theres something deep down in human nature that knows about hitting things with rocks, and theres something else that knows about NOT getting hit with rocks.
money isnt an issue, there are quite a few people with mindfuckingly large amounts of it who would really prefer not to die, and will do just about anything to avoid even a chance of it.
tannish2 on
i don't know who is reading this, but you're a terrible person who should be savagely beaten by a panda with a bag of kittens.
also, please excuse anything in the post that sounded stupid. it was. and thats how half lawyer half insurance agent chicken-bears conquered thailand, korea and, most of france in the late 1300s.
This is one of the things that will make or break us as a dominant species - can we avoid blowing ourselves up with the technology we manage to invent and instead use it to avoide getting blown up by a big rock, at least long enough to spread to a couple of other planets? The dinosaurs didn't do too well in that area, and they were around a lot longer than we've been. While extinction level impacts are rare, they ARE inevitable - all that stuff is flying around in a circle, crossing our planet's path over and over again. Depending on your math, you might find that we're already overdue for a pretty big one...
If asteroid impacts had a cyclical pattern of frequency, you would be right.
I see what you're doing. You claim impact frequency proves there's no issue, then when I claim that if we use frequency, it means we're due. Then you come back and acknowledge that we don't know the chances, as though you made some substantial point. Then you expect me to not notice that you acknowledged that we don't know, proving the value of investing in tech to better prepare.
I would say you're very dumb, but you probably plan these things way in advance. It's not dumb, it's sad.
We cannot use frequency to figure out when the next impact will occur. That is not how it works.
We can use frequency to figure out the likelihood that an impact will occur within the next X amount of time.
If event A occurs randomly, but on average once every 100 years, that means that at any given year, it has a 1/100 chance of occurring. In every 20 years it has a 20/100 chance of occurring.
Do you see how this works?
So what it proposed with this whole NEA funding thing is that we should spend X amount of money to figure out if, against all odds, there indeed is an asteroid large enough to pose a significant threat to us or to our children and grandchildren.
And I am saying that if you really want to figure out whether you should or not, you need to calculate the risk. Whether you are thinking in terms of against the odds or not, you cannot ignore the odds.
We don't know the odds. We would like to study asteroids to find out the odds.
You think you know the odds because you don't seem to understand how lack of knowledge of the past (remember that time in 1350 when a massive meteor missed the earth by the tiniest fraction? No? For all we know it happened) does not give you good data for a prediction of future events.
And risk management and evaluation is a lot more complicated than a*b.
We don't know the odds. We would like to study asteroids to find out the odds.
You think you know the odds because you don't seem to understand how lack of knowledge of the past (remember that time in 1350 when a massive meteor missed the earth by the tiniest fraction? No? For all we know it happened) does not give you good data for a prediction of future events.
And risk management and evaluation is a lot more complicated than a*b.
We know enough.
How many craters have left sizable craters? Not many.
Out of those, how many have caused global calamities? Very few.
Risk management is more complicated than a*b of course, but in the end it comes down to risk = (potential damage x likelihood). We already have a fairly accurate idea of the likelihood. And I showed in the first page that the average potential damage is not that high.
We don't know the odds. We would like to study asteroids to find out the odds.
You think you know the odds because you don't seem to understand how lack of knowledge of the past (remember that time in 1350 when a massive meteor missed the earth by the tiniest fraction? No? For all we know it happened) does not give you good data for a prediction of future events.
And risk management and evaluation is a lot more complicated than a*b.
We know enough.
How many craters have left sizable craters? Not many.
Out of those, how many have caused global calamities? Very few.
Risk management is more complicated than a*b of course, but in the end it comes down to risk = (potential damage x likelihood). We already have a fairly accurate idea of the likelihood. And I showed in the first page that the average potential damage is not that high.
Chances of ege grasping the fact that collisions of bodies in space are the norm, not a fluke: 0.7
The Earth will be hit. We need to know when, and how severe it will be, and what preparations we need to make (either building shelters or diverting it).
Chances of ege grasping the fact that collisions of bodies in space are the norm, not a fluke: 0.7
The Earth will be hit. We need to know when, and how severe it will be, and what preparations we need to make (either building shelters or diverting it).
Technically the Earth is hit all the time anyway, just by much smaller rocks.
The point is, you can't do risk management on fatal occurrences. OH&S principle - start by assuming what will happen if something goes wrong. If the outcome of an accident is death or incapacitating injury, then they will not let you implement that procedure until you have reduced the outcome of an accident well below those two eventualities.
The point is, you can't do risk management on fatal occurrences.
You can only not do risk management on fatal consequences if you assign fatal consequences the number infinity on the risk scale.
--
Okay, here is the question. Suppose we increase the funding for this NEO monitoring program, so that practically every NEO out there is monitored.
How soon can we detect NEOs that are on collision course with Earth? 10 years? 50 years? What is the time period here?
And what happens when we find out that there are no NEOs out there that are of no immediate concern to us? Do we cut the funding right back to its original level? After all, the program by then has served its purpose, which is to find out if we are in any immediate danger.
The point is, you can't do risk management on fatal occurrences.
You can only not do risk management on fatal consequences if you assign fatal consequences the number infinity on the risk scale.
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You can't do risk management in a situation where everyone dies or even a very large number of people die because the risk is essentially "you lose it all". That is the risk I am concerned with. 1000 years of civilization will mean jackshit if it's obliterated after that. That was the point of the OH&S example you omitted.
Although there have been a few false alarms, a number of asteroids are definitely known to be threats to the Earth. Asteroid (29075) 1950 DA was lost after its discovery in 1950 since not enough observations were made to allow plotting its orbit, and then rediscovered on December 31, 2000. The chance it will impact Earth on March 16, 2880 during its close approach has been estimated as 1 in 300. This chance of impact for such a large object is roughly 50% greater than that for all other such objects combined between now and 2880.[19] It has a diameter of about a kilometer.
We don't need to monitor NEOs, we need to find them and know what they're doing, then periodically update that information again. The estimate for a program to find 90% of NEOs out their is about $500 million USD over 20 years, so $20 million USD per year. Do you have a program with similarly well defined goals and implementation strategies which should compete for this type of funding?
And what happens when we find out that there are no NEOs out there that are of no immediate concern to us? Do we cut the funding right back to its original level? After all, the program by then has served its purpose, which is to find out if we are in any immediate danger.
Actually, any NEO monitoring program is great for hunting comets and other debris in the solar system which is of scientific interest since they find that much more often then actual near-earth objects. A program to comprehensively watch the night sky and catalog it would be incredibly useful for NASA and others.
The risk management is to ask how likely an impact is before a complete survey of the sky can be completed at least once and thus presumably detected with some lead time to impact. This can determine funding levels. Frankly, USD$20 million for a program with numerous scientific spin offs is a damn bargain.
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ThomamelasOnly one man can kill this many Russians. Bring his guitar to me! Registered Userregular
We don't know the odds. We would like to study asteroids to find out the odds.
You think you know the odds because you don't seem to understand how lack of knowledge of the past (remember that time in 1350 when a massive meteor missed the earth by the tiniest fraction? No? For all we know it happened) does not give you good data for a prediction of future events.
And risk management and evaluation is a lot more complicated than a*b.
We know enough.
How many craters have left sizable craters? Not many.
Out of those, how many have caused global calamities? Very few.
Risk management is more complicated than a*b of course, but in the end it comes down to risk = (potential damage x likelihood). We already have a fairly accurate idea of the likelihood. And I showed in the first page that the average potential damage is not that high.
120 impact craters are pretty clear to this day. One of which caused a mass extinction. Most of the rest would in the millions to billions of property damage.
I can't find figures on cost but the estimate cost of a mapping program ranges from USD$31 million - $USD 417 million for a 7 to 20 year program, so let's figure at the upper end USD$20 million per year.
Heh, I thought were talking billions of dollars. I'm with Shinto; trivial.
I can't find figures on cost but the estimate cost of a mapping program ranges from USD$31 million - $USD 417 million for a 7 to 20 year program, so let's figure at the upper end USD$20 million per year.
Heh, I thought were talking billions of dollars. I'm with Shinto; trivial.
Billions of dollars would be more of a big deal, but that's the thing - it costs such a pathetically small amount of money to run, and people do a lot of interesting science around it - better CCDs and techniques for spotting close by objects in space, that sort of thing, which has spin off applications all around. For example being able to see things in space and track them while they're close to you is decidedly important and handy for use on our space probes.
We don't know the odds. We would like to study asteroids to find out the odds.
You think you know the odds because you don't seem to understand how lack of knowledge of the past (remember that time in 1350 when a massive meteor missed the earth by the tiniest fraction? No? For all we know it happened) does not give you good data for a prediction of future events.
And risk management and evaluation is a lot more complicated than a*b.
We know enough.
How many craters have left sizable craters? Not many.
Out of those, how many have caused global calamities? Very few.
Risk management is more complicated than a*b of course, but in the end it comes down to risk = (potential damage x likelihood). We already have a fairly accurate idea of the likelihood. And I showed in the first page that the average potential damage is not that high.
120 impact craters are pretty clear to this day. One of which caused a mass extinction. Most of the rest would in the millions to billions of property damage.
If we assume it takes erosion and tectonic plate shifts 100 million years to erase a crater - make that 120 million to round the numbers - that means 1 impact crater every million years. The possibility per year of a meteor big enough to create a significant crater is 1 in one million. Per day, 1 in 365 million.
So tomorrow there is a 1 in 365 million chance that an NEO will hit the Earth and form a crater of considerable size.
But that's not it: the millions to billions of property damage would only be realized if the thing hit the Earth close to an urban center. Urban centers form 1.5% of the Earth's surface - round it up to 2% for smooth calculation - so the chance of an NEO hitting Earth at a spot where it would cause significant loss of life and property is 1 in 15 billion.
One. In. Fifteen. Billion.
Anyway based on what ELM explained I'm willing to concede that it may be a worthwhile investment, not for what the thing is actually intended for, but for the potential spin-offs and byproduct benefits.
We don't know the odds. We would like to study asteroids to find out the odds.
You think you know the odds because you don't seem to understand how lack of knowledge of the past (remember that time in 1350 when a massive meteor missed the earth by the tiniest fraction? No? For all we know it happened) does not give you good data for a prediction of future events.
And risk management and evaluation is a lot more complicated than a*b.
We know enough.
How many craters have left sizable craters? Not many.
Out of those, how many have caused global calamities? Very few.
Risk management is more complicated than a*b of course, but in the end it comes down to risk = (potential damage x likelihood). We already have a fairly accurate idea of the likelihood. And I showed in the first page that the average potential damage is not that high.
120 impact craters are pretty clear to this day. One of which caused a mass extinction. Most of the rest would in the millions to billions of property damage.
If we assume it takes erosion and tectonic plate shifts 100 million years to erase a crater - make that 120 million to round the numbers - that means 1 impact crater every million years. The possibility per year of a meteor big enough to create a significant crater is 1 in one million. Per day, 1 in 365 million.
So tomorrow there is a 1 in 365 million chance that an NEO will hit the Earth and form a crater of considerable size.
But that's not it: the millions to billions of property damage would only be realized if the thing hit the Earth close to an urban center. Urban centers form 1.5% of the Earth's surface - round it up to 2% for smooth calculation - so the chance of an NEO hitting Earth at a spot where it would cause significant loss of life and property is 1 in 15 billion.
One. In. Fifteen. Billion.
Anyway based on what ELM explained I'm willing to concede that it may be a worthwhile investment, not for what the thing is actually intended for, but for the potential spin-offs and byproduct benefits.
Hurr. You're assumptions are rooted in...what, exactly?
This handy website provides the current list of suspected Earth impacts, and lists 657 craters. An interesting read, what with the estimate 400-500km diameters on some of those impact sites.
Also found this graph, which while certainly only correlative, is interesting nonetheless:
So I think my basic point is, your attempts at saying this is a worthless endeavor fail on at least monetary grounds, but also on the grounds that you don't actually know a damn thing about what you're talking about, or, a damn thing about actually accurately determining the risk and cost/benefits of such a program as highlighted by the stunning ignorance of the idea of a cumulative impact chance in the quoted post above.
0: The likelihood of a collision is zero, or is so low as to be effectively zero. Also applies to small objects such as meteors and bodies that burn up in the atmosphere as well as infrequent meteorite falls that rarely cause damage.
Normal
(Green Zone)
1: A routine discovery in which a pass near the Earth is predicted that poses no unusual level of danger. Current calculations show the chance of collision is extremely unlikely with no cause for public attention or public concern. New telescopic observations very likely will lead to re-assignment to Level 0.
Meriting Attention by Astronomers
(Yellow Zone)
2: A discovery, which may become routine with expanded searches, of an object making a somewhat close but not highly unusual pass near the Earth. While meriting attention by astronomers, there is no cause for public attention or public concern as an actual collision is very unlikely. New telescopic observations very likely will lead to re-assignment to Level 0.
3: A close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of localized destruction. Most likely, new telescopic observations will lead to re-assignment to Level 0. Attention by public and by public officials is merited if the encounter is less than a decade away.
4: A close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of regional devastation. Most likely, new telescopic observations will lead to re-assignment to Level 0. Attention by public and by public officials is merited if the encounter is less than a decade away.
Threatening
(Orange Zone)
5: A close encounter posing a serious, but still uncertain threat of regional devastation. Critical attention by astronomers is needed to determine conclusively whether or not a collision will occur. If the encounter is less than a decade away, governmental contingency planning may be warranted.
6: A close encounter by a large object posing a serious but still uncertain threat of a global catastrophe. Critical attention by astronomers is needed to determine conclusively whether or not a collision will occur. If the encounter is less than three decades away, governmental contingency planning may be warranted.
7: A very close encounter by a large object, which if occurring this century, poses an unprecedented but still uncertain threat of a global catastrophe. For such a threat in this century, international contingency planning is warranted, especially to determine urgently and conclusively whether or not a collision will occur.
Certain Collisions
(Red Zone)
8: A collision is certain, capable of causing localized destruction for an impact over land or possibly a tsunami if close offshore. Such events occur on average between once per 50 years and once per several 1000 years.
9: A collision is certain, capable of causing unprecedented regional devastation for a land impact or the threat of a major tsunami for an ocean impact. Such events occur on average between once per 10,000 years and once per 100,000 years.
10: A collision is certain, capable of causing global climatic catastrophe that may threaten the future of civilization as we know it, whether impacting land or ocean. Such events occur on average once per 100,000 years, or less often.
Those last three values bear looking at. Specifically the timeframes.
Apophis reached 4 (current record), but was later downgraded to 0. The current impact probability that site gives is 2.2e-05 (about one in 45500)
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It depends on how it breaks up and how much spread there is. If I break it into two fragments that hug each other...that's bad. If I can get it to litterally gravel with a wide spread...then no. And while the effects you discribe are bad, they aren't world/civilization ending. It would be a climate change but not so radical that the system that is Earth won't compensate for them. It's the dust/heat effect of Krakatoa without the tidal waves.
We spend upwards of 400 billion tax dollars on education every year in this country.
What would it cost for an astronomy staff funded by the U.N. to chart the course of all the larger NEOs? two billion per year out of the world economy?
It would probably take less effort than one of the moon landings to get a missle up there with enough power to nudge the rock a bit. Especially considering it would be unmanned and there doesn't have to be a return trip.
Not a trivial task but well within current technology and the scale of project that have been pulled off multiple times in the past by the US.
Yes, but we'll get over it.
As for the actual odds of a major impact, does anyone have any links to actual studies about this? According to what I have been able to find, Tunguska-class events happen at a rate of about once every century. This event had an energy of about 10-20 megatons, so about a fifth of the largest H-bomb ever detonated. Somewhat smaller ones, but still capable of causing casualties in the hundreds of thousands if they hit a city occur at a rate of about 5 every century. Since 3/4 of the earth is water, we can expect at least one to hit land every century. If I remember correctly, about 1 % of the land-area of earth is considered urban, so... that would mean that there is a chance of 1 to 10000 every year that we will have a major meteorite-related catastrophy?!?
Hm, I don't know what to make of those odds... as a scientist, I'm all for more spending on things that expand our knowledge, but from a pure cost-benefit perspective? I have no idea how that risk corresponds to other things.
You don't shoot missles at an asteroid to blow it up. That's both stupid and for the larger ones not possible. You use the explosion to adjust its course by a couple tenths of a percent which is more than enough to turn a hit into a miss.
Yeah. Read this.
Hardly an "end of the world" scenario. Yes, it would still suck, but definitely not worth this "omg we can all die tomorrow!" scaremongering.
Simply put, risk is calculated by the formula: potential damage x likelihood
Potential damage is fairly high, but it is basically neutralized by the super-low likelihood.
And even then, when we calculate in detail the potential damage we have to take into account the fact that only 1/8th surface area of Earth is populated with humans. The rest consists of seas, mountains, and other impassible terrain. Furthermore, the majority of that 1/8th surface area is made of rural regions with low population density. Urban areas - places where the only considerable amount of damage to humans would occur - make only 1.5% of Earth's total surface.
Therefore potential damage ends up to be fairly small as well.
Considering this extremely low amount of risk, you gotta ask yourself if the cost would be worth mitigating the risk. And I'm saying "mitigating" because we can't completely eliminate it; even if we see the thing coming the best we can do is attempt to evacuate the area.
The tiny course adjustment would be meaningful only over long distances. Which means that we have to hit the thing - in the right spot - while it is still insanely far from the Earth. The possibility of success for such a mission is quite small, considering the asteroid is going to be unevenly shaped, will be rotating, and hitting it in the right spot at just the right time.... yeah. It's composition will be uneven as well; an explosion on an iron surface will not have the same effect as an explosion on a granite surface.
It's not simply a matter of "let's make a rocket, load it up with a shit ton of explosives, and hit the damn thing!"
You've already said in this thead that you don't know shit about astrophysics. Thanks for once again hammering that point home. A tiny course adjustment is all it takes. Do you have any idea how fast the Earth is moving and what a small target it is? Slowing down or speeding up an object (by knocking it off course by a couple tenths of a degree) enough so that it arrives seven minutes later / earlier than expected would result in a clean miss. Such a project would be nowhere near as complex as landing several humans on the moon and returning them, or the recent probe that intercepted a commet or even putting rovers on mars.
The only technological challenge here is building the detectors and improving the anyalysis of the data they provide. Even a kilometer sized iron asteroid could me nudged off course with present technology.
Where are you pulling this "low likelyhood" crap from? We don't know what the chances are because we don't know what's out there. That's the point.
By looking at the frequency of past impacts.
If I do that, we're way past due.
If asteroid impacts had a cyclical pattern of frequency, you would be right.
I see what you're doing. You claim impact frequency proves there's no issue, then when I claim that if we use frequency, it means we're due. Then you come back and acknowledge that we don't know the chances, as though you made some substantial point. Then you expect me to not notice that you acknowledged that we don't know, proving the value of investing in tech to better prepare.
I would say you're very dumb, but you probably plan these things way in advance. It's not dumb, it's sad.
It's been a while since I took physics, and I don't know anything about astrophysics, so someone needs to check my math on this.
But.
Assume the keyhole width of roughly 400m and the asteroid velocity of roughly 31 km/s. At a distance of, let's say, the Moon, call it 400,000km for simplicity's sake, you have about 13,000 seconds (about three and a half hours) to move it.
To move it the full 400m (actually the most would be half that, but assume the full 400m) in that time would require shifting its velocity by about 0.03m/s. Note that's meters, not kilometers.
Now, and this is stretching my mechanics knowledge, I believe to move an object massing 2x10^10kg at 0.03m/s would take approximately 9,000,000 joules of energy.
Nine million joules probably sounds like a lot; for comparison's sake, one kilogram of TNT is equivalent to about 4,000,000 joules.
This isn't to say necessarily that you could shunt the asteroid with just a couple pounds of explosives, of course. But (again, if my calculations are correct) if you consider 400,000km to be "insanely far from the Earth", well... the sixties called. Just wanted to, you know, touch base.
We've put rockets way past the moon since then. :P
The edge of the solar system.
Feel free to add me on whatever network, it's always more fun to play with people than alone
I think at least 4 have been proposed in the thread, and considering none are horibly complex, and most are limited mainly by inability to detect the things in time and lack of a sufficient method of getting them into orbit, I don't think those problems are all that insurmountable. We can already land shit on them and hit them with stuff*.
just where do you think those kind of things come from, if anything you argument implies that we should start spending money on developing that stuff too, to a greater degree. Of course that would also have all sort of useful technological breakthroughs too.
*"can" as in "we have already done it" I think NASA's stats are a whole lot better than those of the missile shield.
We cannot use frequency to figure out when the next impact will occur. That is not how it works.
We can use frequency to figure out the likelihood that an impact will occur within the next X amount of time.
If event A occurs randomly, but on average once every 100 years, that means that at any given year, it has a 1/100 chance of occurring. In every 20 years it has a 20/100 chance of occurring.
Do you see how this works?
So what it proposed with this whole NEA funding thing is that we should spend X amount of money to figure out if, against all odds, there indeed is an asteroid large enough to pose a significant threat to us or to our children and grandchildren.
And I am saying that if you really want to figure out whether you should or not, you need to calculate the risk. Whether you are thinking in terms of against the odds or not, you cannot ignore the odds.
Ok, maybe you're just dumb.
We
A: Are going to get hit
B: Currently don't know which rocks will
Edit:
C: Have the means to stop ones we find, if we find them in time
http://neo.jpl.nasa.gov/neo/report2007.html
Probably somewhere in there. I'm going to go read through the PDFs.
Edit: Looks like the page covers past and upcoming NEOs, and an analysis of each possible deflection technique.
its not global warming where its "no more dirty power supplies like coal, sorry developing world and current superpowers, your fucked, but... we could take the chance on WW3 decreased land mass and fucked up natural disasters if you like" its "take a chance at dying, or send a big fucking missile into space" people love explosions, they love space (especially when something cool happens there), they love fear (no matter how real, especially when theres a chance to spend lots of money on it) and, they love large objects hitting other large objects, oh, i almost forgot, they also tend to enjoy NOT DYING. big projects to save the world are generally popular, and it will have the definite potential for a movie deal. people like movies too.
and on top of that, its not easy to spin negatively, with the added advantage of being incredibly simple (as long as you stay general) theres something deep down in human nature that knows about hitting things with rocks, and theres something else that knows about NOT getting hit with rocks.
money isnt an issue, there are quite a few people with mindfuckingly large amounts of it who would really prefer not to die, and will do just about anything to avoid even a chance of it.
also, please excuse anything in the post that sounded stupid. it was. and thats how half lawyer half insurance agent chicken-bears conquered thailand, korea and, most of france in the late 1300s.
We don't know the odds. We would like to study asteroids to find out the odds.
You think you know the odds because you don't seem to understand how lack of knowledge of the past (remember that time in 1350 when a massive meteor missed the earth by the tiniest fraction? No? For all we know it happened) does not give you good data for a prediction of future events.
And risk management and evaluation is a lot more complicated than a*b.
Wikipedia is a predictably well informed resource.
We know enough.
How many craters have left sizable craters? Not many.
Out of those, how many have caused global calamities? Very few.
Risk management is more complicated than a*b of course, but in the end it comes down to risk = (potential damage x likelihood). We already have a fairly accurate idea of the likelihood. And I showed in the first page that the average potential damage is not that high.
The Earth will be hit. We need to know when, and how severe it will be, and what preparations we need to make (either building shelters or diverting it).
Technically the Earth is hit all the time anyway, just by much smaller rocks.
The point is, you can't do risk management on fatal occurrences. OH&S principle - start by assuming what will happen if something goes wrong. If the outcome of an accident is death or incapacitating injury, then they will not let you implement that procedure until you have reduced the outcome of an accident well below those two eventualities.
You can only not do risk management on fatal consequences if you assign fatal consequences the number infinity on the risk scale.
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Okay, here is the question. Suppose we increase the funding for this NEO monitoring program, so that practically every NEO out there is monitored.
How soon can we detect NEOs that are on collision course with Earth? 10 years? 50 years? What is the time period here?
And what happens when we find out that there are no NEOs out there that are of no immediate concern to us? Do we cut the funding right back to its original level? After all, the program by then has served its purpose, which is to find out if we are in any immediate danger.
We don't need to monitor NEOs, we need to find them and know what they're doing, then periodically update that information again. The estimate for a program to find 90% of NEOs out their is about $500 million USD over 20 years, so $20 million USD per year. Do you have a program with similarly well defined goals and implementation strategies which should compete for this type of funding?
Actually, any NEO monitoring program is great for hunting comets and other debris in the solar system which is of scientific interest since they find that much more often then actual near-earth objects. A program to comprehensively watch the night sky and catalog it would be incredibly useful for NASA and others.
The risk management is to ask how likely an impact is before a complete survey of the sky can be completed at least once and thus presumably detected with some lead time to impact. This can determine funding levels. Frankly, USD$20 million for a program with numerous scientific spin offs is a damn bargain.
120 impact craters are pretty clear to this day. One of which caused a mass extinction. Most of the rest would in the millions to billions of property damage.
Heh, I thought were talking billions of dollars. I'm with Shinto; trivial.
If we assume it takes erosion and tectonic plate shifts 100 million years to erase a crater - make that 120 million to round the numbers - that means 1 impact crater every million years. The possibility per year of a meteor big enough to create a significant crater is 1 in one million. Per day, 1 in 365 million.
So tomorrow there is a 1 in 365 million chance that an NEO will hit the Earth and form a crater of considerable size.
But that's not it: the millions to billions of property damage would only be realized if the thing hit the Earth close to an urban center. Urban centers form 1.5% of the Earth's surface - round it up to 2% for smooth calculation - so the chance of an NEO hitting Earth at a spot where it would cause significant loss of life and property is 1 in 15 billion.
One. In. Fifteen. Billion.
Anyway based on what ELM explained I'm willing to concede that it may be a worthwhile investment, not for what the thing is actually intended for, but for the potential spin-offs and byproduct benefits.
Hurr. You're assumptions are rooted in...what, exactly?
This handy website provides the current list of suspected Earth impacts, and lists 657 craters. An interesting read, what with the estimate 400-500km diameters on some of those impact sites.
Also found this graph, which while certainly only correlative, is interesting nonetheless:
So I think my basic point is, your attempts at saying this is a worthless endeavor fail on at least monetary grounds, but also on the grounds that you don't actually know a damn thing about what you're talking about, or, a damn thing about actually accurately determining the risk and cost/benefits of such a program as highlighted by the stunning ignorance of the idea of a cumulative impact chance in the quoted post above.
Those last three values bear looking at. Specifically the timeframes.
Apophis reached 4 (current record), but was later downgraded to 0. The current impact probability that site gives is 2.2e-05 (about one in 45500)