Asteroid defense office

[Workable Goblin]

5 hours ago, WedgeAntilles said:

My exact words were "Nigeria has pretty much nothing in the way of a space program". Your description counts as "pretty much nothing".

There's a reason I used those boldface words. Rule of Debate #47-A: always use weasel words so nobody can pin you down.  (Rule of Debate #47-B is the cautionary clause to 47-A, and states that any time you don't use weasel words, somebody WILL call you on it)

So let's get right down to it: does Nigeria have anything that could spot an incoming space rock? Yes or no? Actually, that's academic. Fact is, most nations of the Earth have no way to verify the truth when someone tells them "hey, there's a giant rock headed for Earth, we need you to spend money to help us stop it".

Most nations actually do, if you get down and look at it. Basic observational capabilities are cheap. Really cheap. Which is why amateurs--you know, people who have very little in the way of resources--can make useful research contributions (particularly in the case of, what do you know, asteroid observations).

It's all a red herring anyways. It doesn't really matter if every nation can independently verify whether there's a killer asteroid coming or not, what matters is whether important nations--that is, wealthy nations, which do have their own developed astronomical and space programs--can do so. If the United States, European Union, Russia, and China all say that there's a killer rock coming, there's not going to be many people disagreeing, whether or not they can verify it themselves.

And, incidentally, operating satellites and working on building your own satellites is a long, long ways from "pretty much nothing" by global standards. Most countries don't even have that.

[Kerbart]

On 11 January 2016 at 3:55 PM, Kaos said:

I you have an illness and there is only one medicine that might help you, but the probability of helping is low. Would you take it anyway?

The fun part about analogies is that you can twist them to your advantage.

You don't have an illness, but there's this brilliant medicine on the market that will lower your risk of developing dementia (pick any bad disease of choice) later in life. Problem is, you will have to take a dose now and it's so expensive that, in order to do so, you will have to sell your house and live on the street.

Would you do that? Or risk illness later and keep paying the mortgage and food bills?

The problem is more complex than "would you pay to save humanity from extinction." The chances are very small and it means not spending money on other things that offer a much bigger payoff when measured in saving lives per dollar spent.

 

 

[WinkAllKerb'']

we must be rdy to act just in case. better sooner than later. simple.  and explain to people it's done worldwild ... that's some serious stuff, everyone has to know, everyone has to contribute to the effort with it's brain and whatever the dayregular work that contribute to it, new idea from educated people can the save the world , uneducated people will end like dinosaur ...  next thread

Edited January 13, 2016 by WinkAllKerb''

[Red Fang]

I'd like to see international effort to test some nuclear golf concepts on asteroids. It may prove to be a viable option, for some, or most intercepts. Depending on number of shots, development prices may skyrocket like a Sprinting Gazelle, especially if it turns out development of new warheads is needed. 

Nuking an asteroid to give it several cm/s or m/s to change its orbit enough to miss Earth would answer several questions. 
- Is it feasible at to use nukes to disturb asteroid orbits?
- How do different asteroids react to different nukes? (solid iron, solid rock, rubble piles, comets... vs. regular/neutron/shaped charges)
- What are optimal parameters (ie, standoff distance, yield, warhead type) for redirecting different asteroids?
- What are ultimate limitations of nuke-the-asteroid method in regards of object size, composition, mass, orbit, warning time etc...
 

And an additional, programmatic questions:
 - How to integrate warhead, kill vehicle and launch vehicle in a way that is low-cost, storable long term, and quick to launch (hours/days).
- How many different rocket types would you need to have on-hand?  (Would a heavy ICBM derived vehicle do for most cases?  ...like Dnepr-1. Would you need capability to quickly integrate, fuel and launch a pulse unit on a heavy/medium launcher such as DeltaIV heavy, Proton, Ariane 5 / Soyuz, Falcon 9 ?)
- How would you store pulse units to make them safe from theft and unauthorized access?

 Now that I have listed all those things, I think this would not be cheap.  Lets say 5-10 test-shots, with several test-launches... developing 1-3 standard delivery vehicles in different weight classes. Potential development of new warheads. In the end, buying a stand-by force of some 20 ( ? ) launchers and delivery vehicles, new storage facilities, refurbishing some dozen ICBM silos, paying for storing those things for decades... Yeah, this goes well into tens of $ billions easily. At best, I can imagine someone, somewhere having a paper project on how to crash-launch a nuke to intercept an asteroid...

[GeneralVeers]

 

8 hours ago, Workable Goblin said:

Most nations actually do, if you get down and look at it. Basic observational capabilities are cheap. Really cheap.

"Basic" doesn't cut the mustard for searching out incoming asteroids. You need high resolution, which is expensive and which also unavoidably means a smaller viewing area, which in turn means more telescopes......which are, as I said, expensive.

 

8 hours ago, Workable Goblin said:

It's all a red herring anyways. It doesn't really matter if every nation can independently verify whether there's a killer asteroid coming or not, what matters is whether important nations--that is, wealthy nations, which do have their own developed astronomical and space programs--can do so.

Which is exactly the point I already covered, under the label "E.L.E. poker". A few people at the table have the power to prevent everybody from losing the game. Everybody at the table knows this. Therefore each individual player's best move is to do nothing and wait for one of "the few" to cave in and pony up for everybody else. In a world where there are already plenty of examples of people screwing each other over to get ahead, frequently with global implications, this shouldn't be such a stretch. When you consider the fact that the above is how many nations already have reacted to various disaster scenarios, it's no stretch at all.

 

8 hours ago, Workable Goblin said:

And, incidentally, operating satellites and working on building your own satellites is a long, long ways from "pretty much nothing" by global standards. Most countries don't even have that.

My previous post already made clear that I disagree. No other notes needed there.

Mostly-unrelated side note: the number one reason a nation needs to launch its satellites on its own rockets? Because when you send your satellite to some other nation to launch (Russia says hi), there's nothing stopping that other nation from monkeying with your satellite, and, ohhh, I dunno, installing spyware on it? Just a thought.......

 

2 hours ago, Red Fang said:

Nuking an asteroid to give it several cm/s or m/s to change its orbit enough to miss Earth would answer several questions. 
- Is it feasible at to use nukes to disturb asteroid orbits?
- How do different asteroids react to different nukes? (solid iron, solid rock, rubble piles, comets... vs. regular/neutron/shaped charges)
- What are optimal parameters (ie, standoff distance, yield, warhead type) for redirecting different asteroids?
- What are ultimate limitations of nuke-the-asteroid method in regards of object size, composition, mass, orbit, warning time etc...

Something you'll want to add to this list: the option to shatter the target. This is something sci-fi always gets wrong--seen it in movies, TV, even computer games. The eggheads in the story say that shattering the asteroid merely creates many smaller impacts which do just as much (or more!) damage, which is bogus. Mass for mass, smaller chunks burn up faster on their way through the Earth's atmosphere, meaning that when the chunks are smaller a lower percentage of the incoming mass hits the ground. Below a certain size, the mass doesn't hit the ground at all. If the 65-million-years-ago asteroid had been a barrage of basketball-size rocks instead of one six-mile chunk, the dinosaurs would be fine (oh, and it would be dinosaurs playing Kerbal Space Program today! "Dinosaurs! ON A SPACESHIP!!" lol)

[fredinno]

35 minutes ago, WedgeAntilles said:

My previous post already made clear that I disagree. No other notes needed there.

Mostly-unrelated side note: the number one reason a nation needs to launch its satellites on its own rockets? Because when you send your satellite to some other nation to launch (Russia says hi), there's nothing stopping that other nation from monkeying with your satellite, and, ohhh, I dunno, installing spyware on it? Just a thought.......

 

Something you'll want to add to this list: the option to shatter the target. This is something sci-fi always gets wrong--seen it in movies, TV, even computer games. The eggheads in the story say that shattering the asteroid merely creates many smaller impacts which do just as much (or more!) damage, which is bogus. Mass for mass, smaller chunks burn up faster on their way through the Earth's atmosphere, meaning that when the chunks are smaller a lower percentage of the incoming mass hits the ground. Below a certain size, the mass doesn't hit the ground at all. If the 65-million-years-ago asteroid had been a barrage of basketball-size rocks instead of one six-mile chunk, the dinosaurs would be fine (oh, and it would be dinosaurs playing Kerbal Space Program today! "Dinosaurs! ON A SPACESHIP!!" lol)

Which is why countries carefully choose their launch provider to come from a nation that they are allies to.

And the shattered chunks idea might work in a rubble pile, but a more solid rock might just break into a few larger fragments, which then hit Earth. Those fragments have a unknown trajectory, and you'd have to pulverize those chunks too before they hit Earth. Fun!

[GeneralVeers]

When the incoming rock is six miles across and pretty much guaranteed to destroy everything, "a few fragments" is still a big improvement. Remember, "half the size" means "much less than half the impact energy", down to a particular size (depending on composition) where the rock doesn't even reach the ground.

 

3 hours ago, fredinno said:

Which is why countries carefully choose their launch provider to come from a nation that they are allies to.

In theory. In reality, it's common knowledge that national governments do "stupid" all the time.

Edited January 14, 2016 by WedgeAntilles

[Bill Phil]

We just got to put enoug energy into it to move it. 

But the problem isn't the deflection, it's the detection.

[fredinno]

3 hours ago, WedgeAntilles said:

When the incoming rock is six miles across and pretty much guaranteed to destroy everything, "a few fragments" is still a big improvement. Remember, "half the size" means "much less than half the impact energy", down to a particular size (depending on composition) where the rock doesn't even reach the ground.

 

In theory. In reality, it's common knowledge that national governments do "stupid" all the time.

On the other hand though, more flight failures mean less commercial flights and money for launch providers...

2 hours ago, Bill Phil said:

We just got to put enoug energy into it to move it. 

But the problem isn't the deflection, it's the detection.

We're working on the detection, and we should get to 90 % of destructive NEOs found in a decade, at the most. I'm more worried about comets, which are much more powerful, and may not be found until it is too late due to their long orbits.

[Nikolai]

17 hours ago, WedgeAntilles said:

Something you'll want to add to this list: the option to shatter the target. This is something sci-fi always gets wrong--seen it in movies, TV, even computer games. The eggheads in the story say that shattering the asteroid merely creates many smaller impacts which do just as much (or more!) damage, which is bogus. Mass for mass, smaller chunks burn up faster on their way through the Earth's atmosphere, meaning that when the chunks are smaller a lower percentage of the incoming mass hits the ground. Below a certain size, the mass doesn't hit the ground at all. If the 65-million-years-ago asteroid had been a barrage of basketball-size rocks instead of one six-mile chunk, the dinosaurs would be fine (oh, and it would be dinosaurs playing Kerbal Space Program today! "Dinosaurs! ON A SPACESHIP!!" lol)

That's not quite true.  You might end up with less surface deformation, but if all your chunks intercept the Earth's atmosphere, then all the energy is still delivered to Earth -- even if it just gets dumped in the atmosphere.  So if your problem is (say) a dinosaur-killer that could release enough heat on impact to really screw with the climate for years and cause mass extinctions, you haven't made the problem go away by shattering the target.  And if enough dust remains in the atmosphere from all the little pieces, you have "nuclear winter".

All that assumes, of course, that all of your chunks are small enough to burn up in the atmosphere and not, say, detonate when hitting the denser layers and cause damage that way.  Keep in mind that the Chelyabinsk meteor is thought to have been only 15 meters across or so.  For those that do get low enough, the damage radius is proportional to the cube root of the impact energy, and now you have a lot more radii scattered about.  (Less of the energy is spent carving out depth in one crater in one spot, and more of it is spent obliterating the surface all over.)  There's a reason MIRVs and cluster bombs are fearsome weapons.

You could do this well if you had some control over the size of the resultant pieces when you shatter the big one, but the reality is that you don't, and you don't want to experiment under these circumstances.  The eggheads are right.

[Nikolai]

To illustrate what I mean: If the damage radius is proportional to the impact energy, and the damage area is proportional to the square of the damage radius, then the damage area is proportional to the impact energy to the two-thirds power.

The impact energy of any asteroid is 0.5*m*v², where m is the mass of the asteroid and v is its impact velocity.  Let's say you take an asteroid with mass m and split it up into ten equal pieces (each piece has a mass of 0.1*m), each of which are inbound.  Then you have two scenarios:

Case I: Asteroid remains intact: damage area is proportional to (0.5*m*v²)^(2/3), or proportional to 0.5^(2/3)(m*v²)^(2/3).

Case II: Asteroid is shattered: damage area is in ten areas, each with damage proportional to (0.5*0.1*m*v²)^(2/3), or (0.05)^(2/3)*(m*v²)^(2/3).  The total damage is thus 10*(0.05)^(2/3)*(m*v²)^(2/3).

Since the expression (m*v²)^(2/3) appears in both Case I and Case II, we can divide it out as a proportional constant.  Thus, in Case I, damage area is proportional to 0.5^(2/3), and in Case II, damage area is proportional to 10*(0.05)^(2/3).

When you turn the crank, you get that Case I has a damage area proportional to 0.63, whereas Case II has a damage area proportional to 1.36.  In other words, your option to shatter has more than doubled the amount of area damaged.  Don't dismiss the eggheads.

Edited January 14, 2016 by Nikolai
Grammar

[WinkAllKerb'']

On 13/1/2016 at 7:38 PM, Red Fang said:

 golf concepts

as this turn to political kind of stuff, my answer is simple: kill/jail/isolate completly not partially single , for "against earthbeingty" take heritage ship in the process and reinvest, replace by another single.

(notice that i m not speaking of humanity but earthbeingty this is slighty different, why most dinosaur and reptile disapeared, hungerness and greedness simple)

Edited January 14, 2016 by WinkAllKerb''

[GeneralVeers]

4 hours ago, Nikolai said:

That's not quite true.  You might end up with less surface deformation, but if all your chunks intercept the Earth's atmosphere, then all the energy is still delivered to Earth -- even if it just gets dumped in the atmosphere.

Exactly. Atmosphere. The reason the Six Mile Rock triggered an E.L.E. 65 million years ago is because it hit the ground. It wasn't the explosion energy per se that caused a mass extinction. It was the fact that the impact blasted a huge amount of dirt and pulverized rock into the atmosphere. An asteroid that burns up--or detonates!--high up in the atmosphere isn't going to do that.

The reason MIRV nuclear weapons are so nasty has nothing to do with this. A single large nuclear bomb is a waste of energy (and uranium) because the detonation energy at ground zero is a few billion times more than is needed to flatten buildings and kill people. With lots of smaller bombs, each individual ground zero is only a thousand times more than needed to flatten buildings and kill people, covering a larger surface area with a lower amount of energy--less deadly, but still deadly.

As you said: with lots of fragments instead of one big rock, less energy is spent carving out depth in one spot. But carving out depth is exactly what has to happen in order to produce this type of extinction event. You have to punt X tons of pulverized mass into the air, or else no E.L.E. And to do that you need a single, intact asteroid that's big enough to reach the ground and deliver sufficient energy into the ground once it hits. Otherwise there will be localized damage but no global extinction event.

 

[fredinno]

10 hours ago, WedgeAntilles said:

Exactly. Atmosphere. The reason the Six Mile Rock triggered an E.L.E. 65 million years ago is because it hit the ground. It wasn't the explosion energy per se that caused a mass extinction. It was the fact that the impact blasted a huge amount of dirt and pulverized rock into the atmosphere. An asteroid that burns up--or detonates!--high up in the atmosphere isn't going to do that.

The reason MIRV nuclear weapons are so nasty has nothing to do with this. A single large nuclear bomb is a waste of energy (and uranium) because the detonation energy at ground zero is a few billion times more than is needed to flatten buildings and kill people. With lots of smaller bombs, each individual ground zero is only a thousand times more than needed to flatten buildings and kill people, covering a larger surface area with a lower amount of energy--less deadly, but still deadly.

As you said: with lots of fragments instead of one big rock, less energy is spent carving out depth in one spot. But carving out depth is exactly what has to happen in order to produce this type of extinction event. You have to punt X tons of pulverized mass into the air, or else no E.L.E. And to do that you need a single, intact asteroid that's big enough to reach the ground and deliver sufficient energy into the ground once it hits. Otherwise there will be localized damage but no global extinction event.

 

Still, dust particles can block out the Sun. Also, shock waves are still devastating to humans, especially when over a larger area (thus more of a chance to hit a city).

[Nikolai]

18 hours ago, WedgeAntilles said:

Exactly. Atmosphere. The reason the Six Mile Rock triggered an E.L.E. 65 million years ago is because it hit the ground. It wasn't the explosion energy per se that caused a mass extinction. It was the fact that the impact blasted a huge amount of dirt and pulverized rock into the atmosphere. An asteroid that burns up--or detonates!--high up in the atmosphere isn't going to do that.

The reason MIRV nuclear weapons are so nasty has nothing to do with this. A single large nuclear bomb is a waste of energy (and uranium) because the detonation energy at ground zero is a few billion times more than is needed to flatten buildings and kill people. With lots of smaller bombs, each individual ground zero is only a thousand times more than needed to flatten buildings and kill people, covering a larger surface area with a lower amount of energy--less deadly, but still deadly.

As you said: with lots of fragments instead of one big rock, less energy is spent carving out depth in one spot. But carving out depth is exactly what has to happen in order to produce this type of extinction event. You have to punt X tons of pulverized mass into the air, or else no E.L.E. And to do that you need a single, intact asteroid that's big enough to reach the ground and deliver sufficient energy into the ground once it hits. Otherwise there will be localized damage but no global extinction event.

An asteroid that burns up or detonates high up in the atmosphere isn't going to blast ground rock into the atmosphere, but it will still leave plenty of dust.  Rocks that burn up in the atmosphere aren't reduced to atoms; they turn into dust.  A sufficiently large asteroid could still present "nuclear winter"-style problems if it's pulverized in the atmosphere instead of colliding with the ground.  And you still have the problem of all of the energy being dumped into the atmosphere if everything manages to burn up there, which simply moves your problem -- it doesn't eliminate it.  If the dino-killer had dumped all of its energy into the atmosphere, it would still have created a chaotic climate for years.  Your contention that "carving out depth is exactly what has to happen in order to produce this type of extinction event" is misleading.  The "block out the Sun with ground-carved material" kind of extinction is only possible with a ground impact, yes.  But an asteroid as large as the dino-killer was would still have caused mass extinctions if all of its energy had been dumped into the atmosphere.

You don't have to take my word for it.  Here's an astrophysicist: http://www.badastronomy.com/bad/movies/di2.html  Note, especially: "Some people actually think it might be better to simply let a big one hit rather than blow it up, because the Earth itself can absorb the energy of impact better than the atmosphere can."  (You're taking all the energy that would have deformed solid Earth and using it to change the atmospheric conditions.)  He also opines that blowing up the comet in Deep Impact as a damage-mitigation strategy is the worst science in that movie.

The idea that a MIRV covers "a larger surface area with a lower amount of energy" was precisely my point.  Unless you can somehow be absolutely assured that your pieces will be small enough, you're setting yourself up for the very real possibility of more destruction with the "shatter it!" strategy.  That guarantee would be terribly difficult to make.  Moreover, it's pretty hard to split it all into tiny little chunks, because volume grows quickly.  (Let's say an asteroid of a particular composition with a particular entry angle can make it to the ground if it's 15 meters across -- which is pretty typical for a stony asteroid at a high impact angle.  If you want ten pieces with that volume that can make it to the ground, your original body has to be only 32.3 meters across.)

Consider that the impact energy of the dino-killer is estimated to be around 240 million megatons.  (http://sp.lyellcollection.org/content/140/1/155.short)  If you manage to shatter that asteroid into 240 million pieces -- nearly a quarter of a billion! -- you've just peppered Earth with 240 million one-megaton weapons.  (I should note that Little Boy, the bomb that flattened Hiroshima, had an explosive yield of about 14 kilotons -- a little over one percent of the yield of each dino-killer fragment here.)  Even if you managed to get all of that energy dumped into the atmosphere somehow, you're still talking about mass extinction -- probably even worse than if you had just let it hit the ground.

Edited January 15, 2016 by Nikolai
Added Little Boy stats for reference

[GeneralVeers]

6 hours ago, Nikolai said:

An asteroid that burns up or detonates high up in the atmosphere isn't going to blast ground rock into the atmosphere, but it will still leave plenty of dust.  Rocks that burn up in the atmosphere aren't reduced to atoms; they turn into dust.

All of which is travelling at the same velocity the parent rock was. So, what happens to the dust.....? The Earth gets hit by dust every day--meteors the size of specks of dust. They vaporize instantly. They never hit the ground.

 

6 hours ago, Nikolai said:

And you still have the problem of all of the energy being dumped into the atmosphere if everything manages to burn up there, which simply moves your problem -- it doesn't eliminate it.

Precisely. The problem--in this case a massive amount of heat--gets moved into the upper atmosphere. Where it radiates back into space.

Whatever problems would be caused by massive heating of the atmosphere on one side of the planet are entirely theoretical. Fact is, you're guessing.

 

6 hours ago, Nikolai said:

The idea that a MIRV covers "a larger surface area with a lower amount of energy" was precisely my point.

No, it was mine, and you can't have it.

MIRV technology makes nuclear weapons more deadly, because nuclear weapons don't do damage by hitting the ground. They do damage by irradiating the surface with energy.

MIRV makes asteroids less deadly, because asteroids only do significant damage when they hit the ground. You can't simply convert the kinetic energy of the asteroid into raw numbers of joules. An asteroid impact will kick up far more debris than an airburst nuclear bomb or earthquake of the same energy. X joules of energy does not produce Y amount of damage. It depends where the energy ends up going (for anything that burns up in the atmosphere, most of that energy goes UP). An extinction event of the type that happened 65 million years ago requires the rock to hit the ground and blast a large amount of rock and dirt into the air. For that to happen, a certain amount of asteroid mass must hit the ground. Split the one asteroid into lots of chunks, each chunk burns up faster and less total mass reaches the ground. And each smaller, more localized impact most likely won't kick dust and debris high enough to envelop the whole planet. Problems? Maybe (see above--you're guessing). Extinction event? No.

If we do nothing and simply let the six-mile asteroid hit, we're all dead. Or we blast the rock into chunks, at which point we have no idea what would happen. Yes, the unknown is scary. In this case, the unknown is better.

 

[Nikolai]

On 1/15/2016 at 4:44 PM, WedgeAntilles said:

All of which is travelling at the same velocity the parent rock was. So, what happens to the dust.....? The Earth gets hit by dust every day--meteors the size of specks of dust. They vaporize instantly. They never hit the ground.

 

Precisely. The problem--in this case a massive amount of heat--gets moved into the upper atmosphere. Where it radiates back into space.

Whatever problems would be caused by massive heating of the atmosphere on one side of the planet are entirely theoretical. Fact is, you're guessing.

 

No, it was mine, and you can't have it.

MIRV technology makes nuclear weapons more deadly, because nuclear weapons don't do damage by hitting the ground. They do damage by irradiating the surface with energy.

MIRV makes asteroids less deadly, because asteroids only do significant damage when they hit the ground. You can't simply convert the kinetic energy of the asteroid into raw numbers of joules. An asteroid impact will kick up far more debris than an airburst nuclear bomb or earthquake of the same energy. X joules of energy does not produce Y amount of damage. It depends where the energy ends up going (for anything that burns up in the atmosphere, most of that energy goes UP). An extinction event of the type that happened 65 million years ago requires the rock to hit the ground and blast a large amount of rock and dirt into the air. For that to happen, a certain amount of asteroid mass must hit the ground. Split the one asteroid into lots of chunks, each chunk burns up faster and less total mass reaches the ground. And each smaller, more localized impact most likely won't kick dust and debris high enough to envelop the whole planet. Problems? Maybe (see above--you're guessing). Extinction event? No.

If we do nothing and simply let the six-mile asteroid hit, we're all dead. Or we blast the rock into chunks, at which point we have no idea what would happen. Yes, the unknown is scary. In this case, the unknown is better.

 

No, Wedge, they don't vaporize when they become dust.  I don't know why you insist on making stuff up.  Meteor dust can remain in the upper atmosphere for months, where large amounts can affect climate in deleterious ways by blocking light and heat from the Sun and by catalyzing chemical reactions in the atmosphere.  http://www.nature.com/nature/journal/v443/n7108/full/443141a.html

Heat also does not magically get radiated back into space and ignore the rest of the atmosphere and the ground.  Heat is also eventually radiated into space from a ground collision, but that's not the point.

And I'm not guessing.  Energy is energy.  You're right that a certain amount of energy doesn't necessarily equate to a certain amount of damage, but it all becomes heat eventually; the heat being dumped into the atmosphere quickly and directly can be more damaging than energy poured into the deformation of the ground.  I've provided a direct citation from an astrophysicist writing about precisely this problem for a lay audience.  So far, you've given me nothing but your personal say-so.

Asteroids do not only do massive damage when they hit the ground.  The Tunguska impactor (15 megatons releasing at about 8 km up) and the Chelyabinsk impactor (half a megaton releasing at around 30 km up) never hit the ground.  Hitting the lower layers of the atmosphere with sufficient energy is all that is necessary.

This is not guesswork.  I've provided citations and analysis, and you're projecting some kind of magic asteroids that know to radiate most of their heat energy "up" under special circumstances, and magic dust that vaporizes instead of remaining in the upper atmosphere the way that measurements indicate.  I invite you to provide citations or more in-depth analyses than the hand waving involved in "They would vaporize" or "The heat would go 'up'".

Edited January 17, 2016 by Nikolai
Clarifying why quick heating of the atmosphere can actually be worse

[Nikolai]

I also invite you to examine these papers, which do a much more thorough examination of the damage created by an asteroid that has fragmented (and how asteroids fragment) than I:

Hills J.G. and Goda M.P., "The Fragmentation of Small Asteroids in the Atmosphere," The Astronomical Journal, Vol. 105, No. 3, 1993, pp. 1114-1144.

Chapman C.R. and Morrison D., "Impacts on the Earth by asteroids and comets: assessing the hazard," Nature, Vol. 367, 1994, pp. 33-40.

I feel to some extent that we've been talking past one another, and that hasn't been helped by my lack of pointing out where I'm doing BOTE calculations, where I'm trying to be more careful, and where I'm going substantially off-script to point out the magnitude of the problem.

Edited January 17, 2016 by Nikolai

[GeneralVeers]

33 minutes ago, Nikolai said:

No, Wedge, they don't vaporize when they become dust.

They have to. I don't care how many "citations" you provide, anybody who tries to argue against basic physics is not worth listening to. Dust travelling twenty kilometers per second experiences extreme friction in the atmosphere. It melts, boils, and vaporizes. The only way a significant amount of atmospheric schmutz can get into the air is from a ground strike (which propels the debris UP).

 

Quote

Heat also does not magically get radiated back into space

Of course heat doesn't get magically radiated back into space. Heat gets thermodynamically radiated back into space.

 

Quote

And I'm not guessing.  Energy is energy.  You're right that a certain amount of energy doesn't necessarily equate to a certain amount of damage, but it all becomes heat eventually; the heat being dumped into the atmosphere quickly and directly can be more damaging than energy poured into the deformation of the ground.

Those two words in there that I boldfaced? Those prove that you are, in fact, guessing.

 

Quote

The Tunguska impactor

......is theoretical. Science isn't sure that explosion was actually caused by a meteor. In any case, the explosion was localized, and as we know from the laws of physics (and experience) twice the megatonnage doesn't produce twice the destruction distance. To double the radius of destruction you need EIGHT TIMES the megatonnage. We've seen that in nuclear bomb tests. (side note: nuclear winter is only possible with ground bursts) When anything besides a nuke explodes high up in the atmosphere, all the effects are localized and temporary, all the heat dumped into the atmosphere quickly goes away, the quantity of dust is not worth sneezing at (get it? dust? sneeze? lol) and an E.L.E. is impossible.

 

Quote

 I've provided a direct citation from an astrophysicist writing about precisely this problem for a lay audience.

Well, now you've got a better direct citation. From me. My experience at observing other scientists on the job is this: they're frequently wrong, and predictions of disaster almost always turn out to be milder than expected. The guy predicting "ho hum" (in this case, me) is more likely to be right.

[fredinno]

42 minutes ago, WedgeAntilles said:

Well, now you've got a better direct citation. From me. My experience at observing other scientists on the job is this: they're frequently wrong, and predictions of disaster almost always turn out to be milder than expected. The guy predicting "ho hum" (in this case, me) is more likely to be right.

Yes, because a random person on the net is more accurate than someone who studies that stuff for a living....

[GeneralVeers]

In other words, some other random person on the net, who I'm willing to guess you've never met, or even seen.......

(the fallacy you just slipped on, by the way, is called "ad hominem"--you don't have to have a PhD in mathematics to say 2+2=4 and be right)

Something I forgot to mention, Nikolai: the real place you're slipping up lies in the fact that the Rock That Killed Off The Dinosaurs was an extinction event. A few times you've said stuff along the lines of "shattering an asteroid could be worse". In the case of a six-mile global killer: no. You can't get "more extinct". If the incoming projectile is big enough that it's basically guaranteed to Death Punch the entire human race, and the ablation laser has failed, and the solar sail has failed, and the gravitic collimated field displacement projector (pat. pend.) has failed, there's no reason not to smack the thing with a large nuke.

[Nikolai]

15 hours ago, WedgeAntilles said:

Dust travelling twenty kilometers per second experiences extreme friction in the atmosphere.

This is yet another reason I know why you don't know what you're talking about.  The heating does not (largely) come from friction in the atmosphere, but from compression as the object moves rapidly through the atmosphere.

Again, please read the paper I cited.  The amount of dust left in the atmosphere by disintegrating meteors is not theoretical -- it's been measured, it's capable of altering the climate in bad ways for months, and the amount of dust left by a completely pulverized dino-killer is prodigious indeed.

13 hours ago, WedgeAntilles said:

In other words, some other random person on the net, who I'm willing to guess you've never met, or even seen.......

(the fallacy you just slipped on, by the way, is called "ad hominem"--you don't have to have a PhD in mathematics to say 2+2=4 and be right)

Actually, the fallacy you think you're catching is the "argument from authority" fallacy.  ("Ad hominem" is the fallacy that attacking a person's character amounts to attacking their argument.)

But in this case, it's meant to point out that I'm not making stuff up, and moreover that I have no reason to believe that you know what you're talking about.  Without analysis deeper than the handwaving you've made thus far, there's no reason that I have to take your word for things over this astrophysicist.  It's an attempt to step up the game, in other words, since my own citations don't seem to be demonstrating to you that you have a deeper burden of proof than just your assertions.

15 hours ago, WedgeAntilles said:

Of course heat doesn't get magically radiated back into space. Heat gets thermodynamically radiated back into space.

Yes.  I meant to point out that it isn't magically all directed "up".  Before it all eventually ends up being radiated back into space, it can and will do bad things if it first heats up the atmosphere significantly.

15 hours ago, WedgeAntilles said:

To double the radius of destruction you need EIGHT TIMES the megatonnage.

If it's all going to be released in one place, yes.  I think we've successfully shown that spreading the megatonnage out can create much more surface damage.

15 hours ago, WedgeAntilles said:

When anything besides a nuke explodes high up in the atmosphere, all the effects are localized and temporary, all the heat dumped into the atmosphere quickly goes away, the quantity of dust is not worth sneezing at (get it? dust? sneeze? lol) and an E.L.E. is impossible.

That's true when that thing is relatively small.  When that thing is dumping the equivalent of 240 million megatons' worth of energy into the atmosphere all at once, and spreading the concomitant amount of dust into the high atmosphere from an asteroid large enough to do that as well, no.

[Nikolai]

15 hours ago, WedgeAntilles said:

My experience at observing other scientists on the job is this: they're frequently wrong, and predictions of disaster almost always turn out to be milder than expected. The guy predicting "ho hum" (in this case, me) is more likely to be right.

I have to ask, though: What specific predictions of disaster have you seen from scientists?  Why do you think those situations map well to this?  How do you know these experiences form a typical situation so that you can accurately assess this likelihood?

[Nikolai]

To go back to my "talking past each other" thing, I think there's a sense in which I've been barking up the wrong tree.  You're right in that when we're fairly certain that we're expecting an ELE, we don't have anything to lose by pitching a last-ditch something at it.  But I think you're a bit confused about the mechanics of what happens after that last-ditch something.  There are scenarios where we're every bit as dead, even if it all burns up in little pieces in the upper atmosphere.  (And the "greater surface damage" thing is beside the point, as you point out, when we're going from fairly-certain-ELE to lots-of-surface-damage.  It's worth pointing out, though, that if it's not a fairly-certain-ELE, breaking it up is likely to worsen the problem.)

[GeneralVeers]

On 1/17/2016 at 11:09 AM, Nikolai said:

Actually, the fallacy you think you're catching is the "argument from authority" fallacy.  ("Ad hominem" is the fallacy that attacking a person's character amounts to attacking their argument.)

Ummm.....no. It was an ad hominem that fredinno committed when he referred to me as "some random guy on the Internet instead of somebody who studies this stuff for a living". Which is kind of ironic because he has no idea who I am, and no idea what I actually do for a living.....

 

On 1/17/2016 at 11:09 AM, Nikolai said:

This is yet another reason I know why you don't know what you're talking about.  The heating does not (largely) come from friction in the atmosphere

Then, the heat shielding on a space shuttle is for what, precisely.....? There, that takes care of that.

 

On 1/17/2016 at 11:09 AM, Nikolai said:

Again, please read the paper I cited.  The amount of dust left in the atmosphere by disintegrating meteors is not theoretical -- it's been measured, it's capable of altering the climate in bad ways for months, and the amount of dust left by a completely pulverized dino-killer is prodigious indeed.

And none of this happened with the recent Russian impact.

 

On 1/17/2016 at 11:09 AM, Nikolai said:

Yes.  I meant to point out that it isn't magically all directed "up".  Before it all eventually ends up being radiated back into space, it can and will do bad things if it first heats up the atmosphere significantly.

Which we have not seen with any of the many nuclear bomb tests (or the two real nuclear strikes) humans have done. Just for a kick I looked up the Tsar Bomba in a few places, and didn't find any mention of significant effects from atmospheric heating. Heat that reached the ground? Yes. Everything within around thirty miles of ground zero was incinerated. Shock wave created by sudden heating of air? Yes. It was measurable for three full trips around the Earth. Actual side effects of atmospheric heat? None mentioned. Temporary and local effects. No E.L.E.

Side note: pretty much everything you're citing is theoretical. I'm using, as evidence, things that actually happened.

 

On 1/17/2016 at 11:09 AM, Nikolai said:

If it's all going to be released in one place, yes.  I think we've successfully shown that spreading the megatonnage out can create much more surface damage.

It actually doesn't. A 50 megaton monster dropped on a city will vaporize everything within several miles of ground zero. People? Might as well have been disintegrated. Buildings? Postage stamps. Twenty or thirty 50-kiloton devices, on the other hand, will vaporize very little. They will merely kill people instead of cremating them (except very close to ground zero), and knock buildings over instead of completely wiping them off the map. But the city that got hit won't really care, because there's no such thing as "more dead". Lower amount of destruction, over a wider area, but still enough to make things dead and render the city irrelevant to the war effort. In order to kill a person, you don't need to hit him with a 200-pound anvil; a 22 caliber bullet to the face will do it.

Spreading out the megatonnage "will definitely" (note that I said "will definitely" instead of "can") render an E.L.E. impossible. Because all the hits from a shattered rock will be on one side of the planet and each will be too small to have any global effects (as all human nuclear detonations, the Russian meteorite, and other incidents have demonstrated). A large number of small localized hits produce small, localized effects instead of an E.L.E.

 

On 1/17/2016 at 11:20 AM, Nikolai said:

I have to ask, though: What specific predictions of disaster have you seen from scientists?  Why do you think those situations map well to this?  How do you know these experiences form a typical situation so that you can accurately assess this likelihood?

Well, letsee......first thing that comes to mind: scientists predicted disaster due to global warming. Then global cooling. Then global warming. Then global cooling. Then global warming. No joke here, that's what actually happened over the course of the last century or two. Every time the temperature trend changed its mind and headed in the other direction, Science changed its Doomsday prediction accordingly.

Then there's the actual effects of chemical warfare, aerial bombing (when the concept of massed groups of bombers was invented somewhere between WWI and WW2, "modern" science predicted it would single-handedly win wars and render entire nations lifeless--which of course didn't happen), predictions about the Large Hadron Collider accidentally destroying the Earth (yes, some of the people making those ridiculous predictions were scientists!) and of course a personal favorite of mine, the Y2K bug. Also, when I said "scientists are frequently wrong" I wasn't only talking about Doomsday predictions. They've been wrong about Fermat's Last Theorem at least six times, for example. Aaaaand here's my very favorite: when I was a kid reading up on Albert Einstein, I came across his use of a "cosmological constant" in his equations to make the universe static instead of expanding, and right away I realized he'd committed a science foul. Gives me a warm fuzzy feeling inside when I catch a mistake in Albert Einstein's work.

Bottom line: scientists are people. They make mistakes.

What does that have to do with this thread? Simple: it forms a trend.

 

On 1/17/2016 at 0:26 PM, Nikolai said:

To go back to my "talking past each other" thing, I think there's a sense in which I've been barking up the wrong tree.  You're right in that when we're fairly certain that we're expecting an ELE, we don't have anything to lose by pitching a last-ditch something at it.  But I think you're a bit confused about the mechanics of what happens after that last-ditch something.  There are scenarios where we're every bit as dead, even if it all burns up in little pieces in the upper atmosphere.

And as I already explained: that's irrelevant. There's no such thing as "more extinct".

Random side note: shattering an asteroid in space will produce an expanding debris cloud. Meaning some of the fragments (actually most of them) will, instead of hitting Earth straight-on, hit the atmosphere at an angle. Some of the fragments will therefore skip off the atmosphere and back into space. If the asteroid isn't going to hit Earth dead-center (and a dead-center hit is very unlikely), the shattering projectile should be fired from the "more center" direction to knock the asteroid more off center. Moral of the story? Hit the asteroid with the shattering weapon when it's as far away as possible, to disperse the debris cloud as widely as possible--or maybe even cause the whole thing to bounce off the upper atmosphere and back into space without hitting Earth at all!