Asteroid 2011 AG5 Will Definitely Miss Earth

[McMullen]

If an asteroid was likely to hit the earth why can't it be nuked?
I know it sounds weird but is that really impossible?

Because the debris would be worse.
In the grand scheme of thing we'd be better off with one cataclysmic world ending asteroid than a million smaller but equally cataclysmic asteroids.

But wouldn't it be possible to nuke it to pieces that will just burn up in the atmosphere?, Or hell why only use 1 nuke you could send enough nukes to turn it into a rock the size of your fist.

It's fairly common for people to overestimate the power and utility of nuclear weapons. They're not nearly as effective as movies make them out to be.

For one thing, getting any artificial object to intercept an asteroid or comet is still a tall order, even though we've actually done it once that I know of.

Second, most of the energy from a warhead would go into space, not into the rock.

Third, without an atmosphere to heat up, there's no shockwave, and so very little mechanical energy is imparted to the rock. Keep in mind that surface detonations on earth do not produce deep craters, even with the added oomph from the superheated atmosphere. In order to actually break the rock you have to drill down and plant the bomb at least several tens of meters below the surface.

This means that additional nukes would have little or no effect on any fragments that you would get, supposing you could even fracture the rock in the first place.

 

[Killclaw Kilrathi]

For the record, a 460 foot (140m) asteroid like 2011 AG5 is not going to cause an extinction level event. It would do lots of damage on a local scale and leave a sizable crater, but it's not going to have a global impact. Anything under 40m will burn up in the atmosphere, and anything under 1km will only do local damage, above that you're looking at some environmental impact. The asteroid that did in the dinosaurs is estimated to have been about 15km. The one in this article is a pebble by comparison, and now we know it's not even going to hit us anyway.

 

[Killclaw Kilrathi]

If an asteroid was likely to hit the earth why can't it be nuked?
I know it sounds weird but is that really impossible?

Because the debris would be worse.
In the grand scheme of thing we'd be better off with one cataclysmic world ending asteroid than a million smaller but equally cataclysmic asteroids.

But wouldn't it be possible to nuke it to pieces that will just burn up in the atmosphere?, Or hell why only use 1 nuke you could send enough nukes to turn it into a rock the size of your fist.

It's fairly common for people to overestimate the power and utility of nuclear weapons. They're not nearly as effective as movies make them out to be.

For one thing, getting any artificial object to intercept an asteroid or comet is still a tall order, even though we've actually done it once that I know of.

Second, most of the energy from a warhead would go into space, not into the rock.

Third, without an atmosphere to heat up, there's no shockwave, and so very little mechanical energy is imparted to the rock. Keep in mind that surface detonations on earth do not produce deep craters, even with the added oomph from the superheated atmosphere. In order to actually break the rock you have to drill down and plant the bomb at least several tens of meters below the surface.

This means that additional nukes would have little or no effect on any fragments that you would get, supposing you could even fracture the rock in the first place.

Would exploding the nuke in front of it be enough to alter it's course?

For a 140m long asteroid? Maybe, but keep in mind that nukes behave differently in space and they really aren't designed for this sort of thing. You also have to keep in mind that these objects aren't just floating along, they're being pulled by gravity. It might be better for us to invent a new type of weapon designed specifically for deflecting near earth objects, I believe there's currently a lot of research going on about that.

 

[Therumancer]

So first the Mayans get the date wrong then it turns out the big space rock will miss? This is not a good start to 2013. Oh well life goes on.

Oh don't worry, some "good" can still come from this. Still some time for the police to find a cult of voluntarily castrated cultists dead in some compound, with letters explaining that they offed themselves so they could spiritually join the aliens living on that asteroid which is just passing by to pick them up.... You know, positive, upbeat things like that. Have faith, I'm sure 2013 will have lots of ummm... "highlights" even if it this chance is entirely missed.

That said, I'm not sure if this asteroid was actually big enough to present that much of a problem. It's not so much what the asteroid would do if it hit earth, but whether or not it's something we could divert. This one is apparently under 500' in size if I read it correctly, and while big, I'd imagine we could find a way to give that one a nudge if
we really had to scramble to do it. I've seen some stuff over the years about the plans supposedly in place for exactly that kind of thing, I think they even did one TV show comparing the reality of emergency plans to movies like "Armageddon", the simple truth being that if we ever did find an asteroid heading towards earth all "doomsday predictions" by "experts" aside, the international space programs could probably handle it, and it wouldn't even
involve Bruce Willis on a suicide mission. It could be wrong (or just hype intended to allay fears) but I doubt it, since some of the plans seemed fairly plausible if you had the USA and what's left of Russia's space program working together (never mind anyone else getting involved) given some of the plans. Anything short of a rock the size of a continent (thousands of miles accross) is liable to not be an issue, and honestly anything that big is likely to give lots of warning as upposed to being something that's relatively hard to track, and like most things, the earlier the warning, the more of a chance to divert it.

 

[McMullen]

If an asteroid was likely to hit the earth why can't it be nuked?
I know it sounds weird but is that really impossible?

Because the debris would be worse.
In the grand scheme of thing we'd be better off with one cataclysmic world ending asteroid than a million smaller but equally cataclysmic asteroids.

But wouldn't it be possible to nuke it to pieces that will just burn up in the atmosphere?, Or hell why only use 1 nuke you could send enough nukes to turn it into a rock the size of your fist.

It's fairly common for people to overestimate the power and utility of nuclear weapons. They're not nearly as effective as movies make them out to be.

For one thing, getting any artificial object to intercept an asteroid or comet is still a tall order, even though we've actually done it once that I know of.

Second, most of the energy from a warhead would go into space, not into the rock.

Third, without an atmosphere to heat up, there's no shockwave, and so very little mechanical energy is imparted to the rock. Keep in mind that surface detonations on earth do not produce deep craters, even with the added oomph from the superheated atmosphere. In order to actually break the rock you have to drill down and plant the bomb at least several tens of meters below the surface.

This means that additional nukes would have little or no effect on any fragments that you would get, supposing you could even fracture the rock in the first place.

Would exploding the nuke in front of it be enough to alter it's course?

If not buried in the asteroid, it probably wouldn't make any measurable difference. The concussive force of a nuclear weapon is due to a rapidly expanding, because superheated, atmosphere. In space, there is no atmosphere, and so there is no concussive force, and all you get is a really bright light. This does actually generate force on the rock, both through a phenomenon called radiation pressure (I'm not sure how it works, you'll need to ask a physicist or look it up), and also by vaporizing the upper millimeter or so of the asteroid's surface and causing it to expand. Still, this force is absurdly small compared to the kinetic energy of the asteroid.

You might actually alter the trajectory of the rock with a strategically placed subsurface detonation or maybe even a surface detonation, which would vaporize a bigger portion of the surface near ground zero, and the expanding vapor would act like a short-lived rocket engine. However, if it's already on its final approach towards Earth, the rock may not be deflected enough. An attempt at deflection would have to be made early, and where it might end up later on would be uncertain. Suppose for example the asteroid is expected to splash down in the Pacific. Would it be better to let it hit the ocean, or try a deflection attempt and risk diverting it not to space, but to a densely populated continent? Who makes that decision, and who answers for the billions of lives lost if a mistake is made?

 

[lechat]

don't forget the large numbers when dealing with celestial bodies
an asteroid travels roughly 20-30 km/sec. we are talking about 28 years worth of warning about its approach. provided we save at least a few years of that after calculating trajectories and building a big ass bomb we would prolly only need to alter its speed by a 1 m/sec for it to miss earth by a huge margin (i'm sure an astro physicist could do the maths for me)

fact is if you got to the asteroid early enough you could fart in it's general direction and alter it's course enough for it to miss earth

 

[Vegosiux]

For a 140m long asteroid? Maybe, but keep in mind that nukes behave differently in space and they really aren't designed for this sort of thing. You also have to keep in mind that these objects aren't just floating along, they're being pulled by gravity. It might be better for us to invent a new type of weapon designed specifically for deflecting near earth objects, I believe there's currently a lot of research going on about that.

I suggest battleplates [http://www.schlockmercenary.com/2002-12-29]. That's what they will have been made a few centuries from now.

But uh yeah, another rock will veer by and miss us. Well, even our solar system is mostrly empty. It's a lot easier to not hit something on your way through here.

 

[Dascylus]

I'm just waiting for Apophis to turn up.

In fact the whole Apophis thing is a far more interesting story.
I can put on my tinfoil hat and play paranoid theorist all day with that one.

Oh and if that baby hits you can forget your nukes... Krakatoa Baby.

It's ok though, they have the "Don Quixote" mission planned to "study the effects of impacts on asteroid trajectory"...

Make of that what you will.

 

[Dascylus]

damnit!
that damn asteroid ows me money!
now i will never see my bling bling again...

It's ok though, they have the "Don Quixote" mission planned to "study the effects of impacts on asteroid trajectory"...

dude, its good that they even try to map those asteroids, even when it is a hopeless and neverending endeavour wwith shitty payment.

I'd rather send a bunch of deep sea oil drillers.

 

[DaxStrife]

Pardon me, but:
"Asteroid 2011 AG5 Will Definitely Miss Earth"
...then just below that:
"[sic] ...has a lower chance of hitting earth."

You do know those are two separate things right? "No chance" isn't the same as "lower chance."

 

[Olas]

If an asteroid was likely to hit the earth why can't it be nuked?
I know it sounds weird but is that really impossible?

Without an actual atmosphere nukes become expensive cherrybombs. Both the extreme heat and shockwave require air, and while radioactive fallout is a deadly for humans it obviously matters not to a big rock.

 

[Callex]

So instead of nuclear force, why not just kinetic? Launch a massive object into space and use big giant rockets to rapidly propel the object at the meteorite?

Pretty much this. For an asteroid to impact the Earth it needs to pass through a narrow keyhole region. Ramming a satellite into it (as has been done before) early on would be enough to nudge it onto a safer trajectory. No need for explosives.

 

[McMullen]

If an asteroid was likely to hit the earth why can't it be nuked?
I know it sounds weird but is that really impossible?

Because the debris would be worse.
In the grand scheme of thing we'd be better off with one cataclysmic world ending asteroid than a million smaller but equally cataclysmic asteroids.

But wouldn't it be possible to nuke it to pieces that will just burn up in the atmosphere?, Or hell why only use 1 nuke you could send enough nukes to turn it into a rock the size of your fist.

It's fairly common for people to overestimate the power and utility of nuclear weapons. They're not nearly as effective as movies make them out to be.

For one thing, getting any artificial object to intercept an asteroid or comet is still a tall order, even though we've actually done it once that I know of.

Second, most of the energy from a warhead would go into space, not into the rock.

Third, without an atmosphere to heat up, there's no shockwave, and so very little mechanical energy is imparted to the rock. Keep in mind that surface detonations on earth do not produce deep craters, even with the added oomph from the superheated atmosphere. In order to actually break the rock you have to drill down and plant the bomb at least several tens of meters below the surface.

This means that additional nukes would have little or no effect on any fragments that you would get, supposing you could even fracture the rock in the first place.

Would exploding the nuke in front of it be enough to alter it's course?

If not buried in the asteroid, it probably wouldn't make any measurable difference. The concussive force of a nuclear weapon is due to a rapidly expanding, because superheated, atmosphere. In space, there is no atmosphere, and so there is no concussive force, and all you get is a really bright light. This does actually generate force on the atmosphere, both through a phenomenon called radiation pressure (I'm not sure how it works, you'll need to ask a physicist or look it up), and also by vaporizing the upper millimeter or so of the asteroid's surface and causing it to expand. Still, this force is absurdly small compared to the kinetic energy of the asteroid.

You might actually alter the trajectory of the rock with a strategically placed subsurface detonation or maybe even a surface detonation, which would vaporize a bigger portion of the surface near ground zero, and the expanding vapor would act like a short-lived rocket engine. However, if it's already on its final approach towards Earth, the rock may not be deflected enough. An attempt at deflection would have to be made early, and where it might end up later on would be uncertain. Suppose for example the asteroid is expected to splash down in the Pacific. Would it be better to let it hit the ocean, or try a deflection attempt and risk diverting it not to space, but to a densely populated continent? Who makes that decision, and who answers for the billions of lives lost if a mistake is made?

If an asteroid was likely to hit the earth why can't it be nuked?
I know it sounds weird but is that really impossible?

Because the debris would be worse.
In the grand scheme of thing we'd be better off with one cataclysmic world ending asteroid than a million smaller but equally cataclysmic asteroids.

But wouldn't it be possible to nuke it to pieces that will just burn up in the atmosphere?, Or hell why only use 1 nuke you could send enough nukes to turn it into a rock the size of your fist.

It's fairly common for people to overestimate the power and utility of nuclear weapons. They're not nearly as effective as movies make them out to be.

For one thing, getting any artificial object to intercept an asteroid or comet is still a tall order, even though we've actually done it once that I know of.

Second, most of the energy from a warhead would go into space, not into the rock.

Third, without an atmosphere to heat up, there's no shockwave, and so very little mechanical energy is imparted to the rock. Keep in mind that surface detonations on earth do not produce deep craters, even with the added oomph from the superheated atmosphere. In order to actually break the rock you have to drill down and plant the bomb at least several tens of meters below the surface.

This means that additional nukes would have little or no effect on any fragments that you would get, supposing you could even fracture the rock in the first place.

Would exploding the nuke in front of it be enough to alter it's course?

For a 140m long asteroid? Maybe, but keep in mind that nukes behave differently in space and they really aren't designed for this sort of thing. You also have to keep in mind that these objects aren't just floating along, they're being pulled by gravity. It might be better for us to invent a new type of weapon designed specifically for deflecting near earth objects, I believe there's currently a lot of research going on about that.

So instead of nuclear force, why not just kinetic? Launch a massive object into space and use big giant rockets to rapidly propel the object at the meteorite?

You should submit this line of questions to What If at xkcd. I'd like to see a quantitative treatment of it.

The best current plan I've heard of does involve a kinetic impactor, perhaps in combination with a precisely timed nuclear detonation. The problem is that asteroids are dangerous because they already carry kinetic energy in amounts that can exceed the combined yield of the world's nuclear stockpiles. The energy of the deflecting impactor would have to be enormous in order to significantly alter the rock's course, and it would have to come from fuel, or the gravity of other planets. The rocket would have to be huge, since the more fuel you take, the more you have to burn to lift it.

It's possible, if you do it early enough, but pulling it off would be very difficult.

 

[iblis666]

at 450 feet its not even worth worrying about, with our luck it will probably just explode in the atmosphere giving some near by town a pebble shower

 

[kortin]

Well the Mayan calendar was all about the end of the world ...I mean it was all over the news how could you miss it?

People interpreted it as the end of the world. That does not mean it was about the end of the world.

 

[LordLundar]

So instead of nuclear force, why not just kinetic? Launch a massive object into space and use big giant rockets to rapidly propel the object at the meteorite?

You're on the right track, but depending on the size of the object and the speed, it would have considerable kinetic energy in of itself. For a safe deviation given a reasonable intercept point (remember, that we can locate an object FAR sooner than we can reach it) would either require a very large object (which is difficult o get out of the atmosphere) and or traveling at a relatively high rate of speed.

You do have the right idea, it's just the capability to do it accurately and with a large enough margin isn't terribly practical given current tech.