Calculating Size of Asteroid to Wipe Out Life on Earth

[Gale]

Just curious, you know the movie armageddon? well, i was thinking, how big would an asteroid really have to be in order to wipe out all the life on earth? and, what're the calculations you'd do to figure that out? Thanks...

~gale~

 

[SpaceTiger]

Just curious, you know the movie armageddon? well, i was thinking, how big would an asteroid really have to be in order to wipe out all the life on earth?

Really big. No asteroid has yet succeeded at that task and I suspect that there isn't one big enough to do the job. That would likely require something to happen to the sun (or for us to run into another planet). As for the size of asteroid required to kill all humans, I could give a very rough estimate of 3-5 km, but that's mostly a guess. The one that killed the dinosaurs is thought to be of order 10 km and I'm pretty sure that would kill us off.

and, what're the calculations you'd do to figure that out?

There's no simple calculation that will give you a definite answer, but perhaps the most important quantity is the total energy deposited:

$$E=\frac{1}{2}mv^2$$

where m and v are the mass and final velocity of the asteroid in question. This indicates that the asteroid's velocity is important, meaning we'd be worse off hitting one head on than taking it in the rear. A lot of other factors would have to be considered, however. For example:

- Where it hit. Ocean and land collisions would have a different effect, kicking up different kinds of materials into the atmosphere or inducing tsunamis.
- What it was made of. An asteroid that's more tightly bound would likely do more damage. Also, composition will determine whether it fragments in the atmosphere and what impact this will have.
- What its shape was. The reasons here are similar to the ones for composition.
- How fast it was rotating. This will change the character of the collision, as well as the amount of energy deposited.

 

[Pengwuino]

Arent there a LOT of asteroids out there that size or greater? You may be giving off the impression that asteroids of that size are very rare in the universe... unless I am mistaken

 

[SpaceTiger]

Arent there a LOT of asteroids out there that size or greater? You may be giving off the impression that asteroids of that size are very rare in the universe... unless I am mistaken

There are quite a few, yes. Why do you think I'm giving that impression?

 

[pervect]

Just curious, you know the movie armageddon? well, i was thinking, how big would an asteroid really have to be in order to wipe out all the life on earth? and, what're the calculations you'd do to figure that out? Thanks...

~gale~

You might be interested in the University of Arizona's "Impact Calculator" program on the WWw - it's at

http://www.lpl.arizona.edu/impacteffects/

A 25 km radius impactor won't "wipe out all life on earth", but it will (with the inputs I entered)

ignite all trees, grass, and most other flammable objects in the region from which the fireball is visible (about 2000 km according to the program).

Flatten all trees within 6000 km (the hemisphere of the impact), destroy all buildings within 3000km of the impact, shatter glass windows on the opposite side of the planet (12,000 km).

Put a LOT of dust and ejecta into the atmosphere (the climate effects are not modeled)

Impactors of this size arive avery few billion years on the average - the Earth has probably encountered one in its history.

 

[Chronos]

These days, most orbital bodies have found stable orbits. The risk is fairly small. Even Jupiter, the most likely candidate for a collision, rarely suffers them.

 

[Gale]

thanks pervect, that's a really neat little calculator. Thanks everyone for the replies, actually. Curious still, what sort of conidtions would be necessary to wipe out even bacteria? And, would an impact that size significantly effect the Earth in other ways too? like warp the orbit or spin? thanks again...


~Gale~

 

[Pengwuino]

There are quite a few, yes. Why do you think I'm giving that impression?

When you said "Really big.", to me it felt like you meant extraordinarily big because on a astronomical level... 5km wide doesn't seem like much at all.

 

[Pengwuino]

thanks pervect, that's a really neat little calculator. Thanks everyone for the replies, actually. Curious still, what sort of conidtions would be necessary to wipe out even bacteria? And, would an impact that size significantly effect the Earth in other ways too? like warp the orbit or spin? thanks again...

The atmosphere would be enormously affected. The spin might change... the orbit woudl change but not really sure by how much. Let's hope we never have to find out :D

 

[tony873004]

There are a few asteroids in the hundreds of kilometers range, (Ceres, Vesta, Pallas). None are in danger of hitting Earth in the forseeable future as their orbits are beyond the orbit of Mars.

To wipe out even bacteria, an impact would have to melt the Earth's crust, creating a magma ocean. But even if Ceres had enough energy to do that, and it struck, bacteria life could still survive in the following way: The collision would shoot rocks into solar orbits. Like the Martian meteor found in Antarctica, bacteria could survive for millions of years on these rocks. Many of these rocks would ultimately collide with the Earth again, delivering their bacteria back home.

Just my guesses.

 

[krab]

related thread

 

[stoned]

Massive asteroid passing relatively close to the Earth (not necessarily colliding with it) can cause huge cataclismic disturbance here on the earth.

 

[Billy T]

Massive asteroid passing relatively close to the Earth (not necessarily colliding with it) can cause huge cataclismic disturbance here on the earth.

true, but it had better be a lot bigger than the moon (not many of them) and come a lot closer (not very probable)

The number of stars that were larger (compared to sun) aged rapidly (compared to sun) died and now are gravitationally bound black holes is probably greater than all the stars that currently are emitting light! i.e. more than all the grains of sand on all the Earths beaches!

Iron meteors are probably produced during the irregular implosion of a supernova when the iron core can no longer make heat but the layers out side still can. That is the implosion is very asymeteric and pieces of the core escape. Probably there are big pieces somewhat separated also. If the first generation stars were roughly 100 solar masses (universe mush smaller and denser back then) it seem at least possible that some to 10 to 20 solar mass once iron chuncks could be separate, gravitationally-bound Black Hole pairs now. this also supports the idea that there may be a lot of them unseen, but existing. One of them could pass a million times the moon's distance from Earth and yet do us in, via producing an orbit more excentric which results in an new extreme ice age, etc.

 

[bettysfetish]

I'd like to digress a bit on this topic. You know it wouldn't be very difficult to launch small "Engins" that could meet up with an asteriod, of any size you wish, then grappel onto it and thru the magic of vector steering bring it into a stable orbit for mining. Some of those things must contain large amounts of various minerals. Now, about the doom and gloom aspect. I see no reason why we could not capture one of these things and hurl it at any military target on the planet; without even being on the side of Earth you want it to strike. One might simply choose an asteriod of the necessary size to produce the damage required over a given terrain. And afterwards, and here's the beautiful part, militarily I mean; there wouldn't be any nasty radiation to contend with. Just strike and move in after the dust clears. This would be a weapon that could be easily held ready for use with a minimum of cost, deployed on a moments notice. Why wait for nature when we can grab one of these babys and "play ball."
"NOTICE TO THE DEPARTMENT OF HOMELAND SECURITY"
"I have not now nor have I ever planned or assisted in the planning of any development or deployment of any kind of device that would be considered a risk to national security."
L8R

 

[russ_watters]

Unless there is an asteroid slowly overtaking us nearby, it would take an enormous amount of energy to steer one into orbit. Perhaps in 2029...

 

[bettysfetish]

Perhaps, but for the most part, and there are always exceptons, we are able to detect asteriods on a collision course with Earth sometimes years in advance. That considered, the nudge could be quite suttle, short term, and very effective. The size of the engines sent to retrieve the target would not need to exceed the current size of jet engines, and if a bigger nudge is necessary, or if time is of the essence, multiple engines could be deployed. I'm not really a nut case; I've been reading "The Medical Implications Of Nuclear War", published by "The Institute Of Medicine & The National Academy Of Sciences." It only made me wonder, "why we couldn't do just as much destruction without the radiation?" I mean if you have to bring some conflict to an abrupt halt, why contaminate everything in sight for decades? And like the development of the atomic and nuclear devices; "If you'r not first, you could be destroyed." As you know, we've already landed a camera on one asteriod, so actually doing it (grappling onto an asteriod i mean) would be easy. Steering it, with up to dozens of engines if you wish, provides no unworkable issues, - - - - I don't know, we'll see some day. If it can be done, and mankind thinks of it, it will be done. I just hope it's my country does it first. And 2029 isn't that far away that planning couldn't proceed, even at some investigative level. I'm 50. One should not consider this out of reach.
Just me I guess. Hope I've at least provided an interesting topic.
L8R

 

[Billy T]

Perhaps, but for the most part, and there are always exceptons, we are able to detect asteriods on a collision course with Earth sometimes years in advance. That considered, the nudge could be quite suttle, short term, and very effective. The size of the engines sent to retrieve the target would not need to exceed the current size of jet engines, and if a bigger nudge is necessary, or if time is of the essence, multiple engines could be deployed. I'm not really a nut case; I've been reading "The Medical Implications Of Nuclear War", published by "The Institute Of Medicine & The National Academy Of Sciences." It only made me wonder, "why we couldn't do just as much destruction without the radiation?" I mean if you have to bring some conflict to an abrupt halt, why contaminate everything in sight for decades? And like the development of the atomic and nuclear devices; "If you'r not first, you could be destroyed." As you know, we've already landed a camera on one asteriod, so actually doing it (grappling onto an asteriod i mean) would be easy. Steering it, with up to dozens of engines if you wish, provides no unworkable issues, - - - - I don't know, we'll see some day. If it can be done, and mankind thinks of it, it will be done. I just hope it's my country does it first. And 2029 isn't that far away that planning couldn't proceed, even at some investigative level. I'm 50. One should not consider this out of reach.
Just me I guess. Hope I've at least provided an interesting topic.
L8R

I don't want to lend any support to your idea because either it requires:

(1) Enormous expenditure of energy (and money and luck to find the asteroid) or
(2) Very long range planning (small expenditure of energy, many years in advance of use)

COMMENTS:
(1) is obviously not going to happen and
(2) not a good idea. For example, if it had been placed into effect in 1940 to wipe out Japan, where would your game boy come from?
More seriously:
I want to note also that Asian nations are now working on the seventh generation of flat screen displays and the US still can not make in commercial yield quantities the first.

A few quotes form Physics Today page 30 March 2005 issue:

(1) "From 1994 to 1998 the number of Chinese, South Korean and Taiwnese students who chose to pursue Ph.Ds in their own countries nearly doubled... and those coming from there to US dropped 19%..." (If more recent data were available, it would be much worse. - The US "terror fear" immigration policy has made the net influx near zero, if not negative. I know of some good Asian professors who have "gone home.")

(2) "The ratio of college undergraduates degrees in natural sciences is 5.7 per 100 students in the US ... "Taiwan and South Korea each award about 11 per 100." For several other countries listed the ratio ranges between 8 to 13.

(3) Between 1988 to 2001, East Asian papers in science and engineering have increased by 492% while US production has actually decreased slightly!

(4) From 1980 to 2001 the US share of worldwide high-tech exports fell from 31% to 18% and China and South Korea's share climbed from 7 to 25%

Many other sad facts also reported there. More also at www.DarkVisitor.com

In short, in about one generation US will have lost scientific leadership to Asia. It has already lost technological leadership. No US based firm can even beginning to think of making a humanoid looking robot walk while playing a bugle as was recently demonstrated in Asia. In one generation your choice of jobs will be limited to those that can not be exported, like cutting someone's hair or serving fast food. You may not know it but there is a good chance your recent X-ray was interpreted by an India doctor during the night while you slept and his report was back in your US doctor's office the next AM. Indians not only speak English, are smart, well educated, work for less, etc. but they also work while you sleep. Part of the software I am now using was produced there. US is "going down the tubes" and does not realize it.

Fortunately there is no need to worry about US using your idea - It will soon lack the capacity. US can not even afford to save Hubble telescope!

 

[bettysfetish]

O. K. - - - Let us start with this; "What might the average speed of an asteriod be??"
You should be able to do some calculations from there, you think?
L8R.

 

[Billy T]

O. K. - - - Let us start with this; "What might the average speed of an asteriod be??"
You should be able to do some calculations from there, you think?
L8R.

I assume you are interested in the speed it has as it crosses Earth's orbit, but there is no simple answer, especially if you really interested in the speed it would impact Earth if it were to do so. (Same asteroid hitting on the "trailing side" of Earth produces less damage than by hitting on the leading side. (leading and trailing defined by Earth's motion about the sun.)

If the asteroid were Earth crossing and in a slightly elliptical orbit, it would have approximately the same speed as Earth about the sun. Thus there would be an enormous difference between a "leading hit" and a "trailing one" but in both cases, the fall in the Earth's gravity field would add kinetic energy. We can be 100% sure there are currently no large asteroids like this, one could scatter off Mars etc and come into being.

If the asteroid were in a very elliptical orbit, then as it crosses Earth's orbit it would have much higher velocity. - It needs the extra energy to climb back up the sun's gravitational well when going back to its apogee point.

hope that helps.

 

[bettysfetish]

Well, - - - There are certainly more variables to be considered than I could possibly keep straight, but let's start at, what seems to "me" at least, with the most basic piece of information. I know it's all relative, but "is there" an average volocity range we could assign to asteriods; I mean, is there a highest and lowest miles/kilometers per hour we could expect asteriods, in general, and relative to Earth of course, to be moving through space ??
Being in a N.E. orbit is not relavent as we could reach out far in advance with the proper data. Wouldn't a leading "or" trailing impact still create tremendous damage?? I'm not sure the asteriods original trajectory will be a concern anyway other than to plot a point in space to grab it; and when and where we grab it may depend on where and when you want it to land somewhere. Now back to the point for this post; How much thrust will it require to stop (relitively, of course) an asteriod of predetermined mass traveling at X volocity, and how many engines of what capacity would be required? This requires formulas that I am not schooled on.
As with any other developmental program in it's infancy, "cost" is not the primary consideration at this time. The question is, "Can we stop an asteriod?"; "Is it within our means?"
I comprehind completely your last two paragraphs.
Thanks, we'll see if mankind can muster the horsepower to stop one of these puppys.
L8R.

 

[Kura_kai]

Ok using that fancy dandy calculator someone used way back when but i figured it out.
Projectile Diameter: 8046700000.00 m = 26393176000.00 ft = 4997000.70 miles
Projectile Density: 9000000 kg/m3
Impact Velocity: 5000.00 km/s = 3105.00 miles/s (Your chosen velocity is higher than the maximum for an object orbiting the sun)
Impact Angle: 45 degrees
Target Density: 2750 kg/m3

And it comes up with
The Earth is completely disrupted by the impact and its debris forms a new asteroid belt orbiting the sun between Venus and Mars.
Also i doubt this type of of asteroid will never come

 

[bettysfetish]

Well, - - - that was certainly insightful, but perhaps we could start with an object slightly less than "Four million nine hundred ninty seven thousand miles in diameter"?? Did I read that right ?? My god, that's the size of a planetary orbit; albait a small one. I think one about five miles in dia would do just fine. Could we start there? What might the speed of that asteriod be? I really hadn't invisioned pulverizing the entire planet. That would suck. In the interim, I will try to search out how fast an asteriod can travel.
L8R

 

[bettysfetish]

:zzz: O.K., it's 1:30 in the morning; everybody wake up.
To start, "Our" volocity ranges between 24.1 and 31.1km/s. An asteriods volocity can vary greatly, as I expected. That in turn leads one to think there should be many within an acceptable range. There are 30 in excess of 200km in dia., all the 100km plus asteriods we know about. There seem to be apx 1,000,000 of the 1km to 10km range; and here we approach a workable range. Well, - - 10km may be pushing the envelope a bit. Here too we begin to have a difficult time locating these. A 1km collision occures apx every 1,000,000 years and look at the potential damage there. Now, apx how much might a 1km dia asteriod made primarily of iron or nickle weigh?? If said asteriod is moving at say 5km/s, how much reverse thrust would be required to stop it (relativly of course)? If this is within our capabilitys then any other manuver would only require less energy. With the necessary time available, redirecting it should be relativly simple thru established Newtonian theorys.
Can we re-affirm the question at hand? Could we stop or intentionally redirect an asteriod? I hate to sound "Quantum" but I haven't seen anything yet that says "it cannot be done". If not; if it's absolutly impossible, let's hear it. Show us no one on this planet could, as a group or singlehandidly, devise a workable plan.
If anything here doesn't make sense, I'm just very tired and losing focus.Hope to hear from one of you soon. And to: Kura kai, think smaller for me. It seems you know how to do some calculations or formulations. What could we do with something say 1 or two km in dia.??
L8R

 

[rayjohn01]

To Betty irrispective of your fettish --- are you worried -- would like to cling to life ?
Well you are more likely to be hit by some alchoholic driver than an asteroid -- remember that even with impacts every several million years or so Life has survived -- Not anyone in particular mind but just life in general or perhaps just the planet
Most of our planets (i.e the sols ) have either zero or very simple life -- but it is the
simple life if any which survives . WE are very lucky to have any life at all -- basically it's only quarks which survive , nucleii , atoms molecules and such are dispensible
or may disappear down black holes . Now if you were a quark then maybe you could experience such a journey but since you wish to cling to some Human existence then it follows what follows . Human life is clearly very special amidst millions of other species here we are the only ones to be able to communicate by the written word
and by an extended and complex voice structure which can be recorded by Us .
WE have lived for some 4-7 million years only out of 4 billion of the Sol and much less of the Universe --- there is absolutely no guarantee that we will survive for long along with any other form of complex life . If we avoid one moveable asteroid it is a given that another will destroy most of life as we know -- so what -- this is the way of the Universe to recreate new life and which benefits from the past as well .
Who knows maybe a couple of your atoms will survive and become part of the next generation -- just like the molecules which make you -- did you know that your molecules are millions and maybe billion yrs old -- born in some superNova --- They created you ---- wow --- what will you create ??
Ray.

 

[bettysfetish]

RayJohn01, Hi. Theres no fetish, it's just the name of a band I played bass in till the drugs tore up a couple of the band menbers and ruined everything - - - oh well. Cling to life - - - hummm, - - I guess most of us do. Me ? I've done all the damage to my body that it can possibly take. If there's anything after, I'm ready now; but that's just me. All things must pass. That alcoholic driver "used to be me." And yes life "has"survived such impacts before; and that is essientially one of my points. You don't want to obliterate the entire planet do you? The next several sentences really don't address my questions although the conversation has been pleasent. I'm clearly aware of the history of the particles that comprise "Me". And on that specific point I'd like to add that my constituant particulate matter (and yours) at or below the atomic level was created in generation 3 stars, and possibly G2 stars. ( not including such things as electrons and such; they were produced "in the beginning" ) The carbon and silicone was not produced in 1st generation furnaces.
Anyhow, perhaps you could address the original cunundrum. I'd really rather not type it all again. If it's not too much trouble mabey you could go over a couple of my posts again. You know we've already landed a camera on a traversing asteriod just 1 or 2 years ago. If we can do that then why couldn't we reach one of these asteriods with an engine? "OR" multiple engines?? And herin lies one question; "How much reverse thrust would be required to stop a rock, primarily of iron or nickle, of X mass, moving at X volocity in one year?" . That is, of course, considering using a rock of less than 5km in dia.; like I said, we don't want to destroy the whole neighborhood.
L8R

 

[rayjohn01]

Well Bettys Fetish (I was not being too serious ) -- someone told me the best way to handle an asteroid was to change it's direction at it's slowest speed , Earth crossing orbits are probably elliptical , and the typical speed of an asteroid is 17 Km/sec (circular ) . Your 2.5 Km radius chunk at 4 gms/cc would weigh about 2.6 .10^14 kgms . Let's assume that at periheion that it's radial speed is zero and it's tangential speed is quite small ( hence elliptical ) the job is to accelerate it to 17 km/sec so that it goes circular.
Now we can equate the required energy m.v^2/2 to a nuclear mass m1 being totally
converted to energy e = m1 . c^2
This comes to about 433 metric tons of perfect nuclear fuel.
Offhand I do not know about typical nuclear efficiencies you can probably search that somewhere , I think I have seen 17 % mentioned .
Any way it's a lot of material if I have my numbers anywhere near right it's
equivalent to 10 million Megatons of TNT actual yield.
It cannot be too far out an estimate of asteroid impacts of 15km size run to 100 million Megatons .
The basic idea here is to put it back into a safe orbit and match it's speed to other asteroids so is does not knock some other object in a serious way --
I am sure you could use a lot less energy just to avoid a collision.

Ray .

 

[bettysfetish]

Well, good to hear from someone addressing my questions. Grabbing an asteriod at it's slowest speed makes sense and would be the most logical with time permitting. I see you put some thought into this, thanks. So, we have a rock about 2 miles in dia moving at about 13 or 14 miles a second, right? And it weighs "what"? What does 2.6 x 10^14 kgms convert to, in apx pounds?? As you can see I don't understand a lot about equations, formulas and calculations. Sorry. As I've read on, I do understand periheion, radial speed, tangential speed and acceleration ( "or" changing the speed or direction of a mass ). I would like to lead on from here by asking; at the givin volocity and mass, away from a strong gravitational field ( in space ), how much reverse thrust would stop it, relative to us, of course ). With, say, 100,000 lb/thrust working against what ever the 2.6 x 10^14kgms weighs in pounds, could we stop it within say 100 hours, 200 hours; would it take a month; a year?? What do you think? At this point I'm really not concerned with the obvious roadblocks in front of me. Just trying to get a ballpark number on what it might take to "capture" an asteriod, and it only seems logical that the first step, beyond finding it ,of course, is how to stop it (relatively). The steps you mention may be quite helpful for bringing small asteriods into a geologically stationary orbit for storeage. I'm sure their "shelf life" is very long indeed. This would not be radiologically any danger would it?? It's seems you've implyed a nuclear capability; did I misinterpet that?? Perhaps you were only making measures of destructivness? It would seem the level of destruction required would determin what size asteriod you took out of storage. My town would require no more than something the size of a beachball. After the sizes I'm interested in certainly don't need to be big enough to kill dinosaurs, so capturing things in this range would be relitively easy, I think As you closed, you made one very excellent point; safety first I always say; yes - - - being able to put them into a safe orbit is a plausable idea. But to classify them as dangerious enough to necessitate moving them to safe orbits also implys that they are unusually large enough to cause great damage and that in itself implys great mass. The excessive mass is the problem everyone has pointed out to me. They don't realize that I'm only looking for "baby asteriods". I don't think I would require anything bigger than a tank (military). As you can see, my train of thought here is a tactical one. Why nuke some region and tick off the neighboors with radiation. This provides a much "healthier" option as a deterent. Hope you'll do a few more equations along these established guidlines for me.
L8R

 

[rayjohn01]

Bettysfetish , I see you are trying snare one of these little beasts , well in some circumstances the relative speed could easilly approach 50 km/sec , sort of 25 for the Earth and 25 for the asteroid -- so let's consider your 'Tank' sherman M4
mass 30,000 Kgms or 66,000 pounds . Travelling at that speed so the energy is
( all units for now are meters kilograms seconds - it makes the calcs simple )
m. v^2 /2 = 30 . 10^3 . 50^2 . 10^6 / 2 or -- 3.75 .10^13 Joules
Now work or energy is force x distance or E = F.d but also F = m.a or force = mass x accelleration .
Here we have a choice (lot of force for small time or vice versa ) . If you decide to decellerate the mass in a constant manner from v to 0 we can use the average speed v/2 and say a = v/2/t --- combining these things we have
distance d let's say 10 kilometers then from F = E /d we have

F = 3.75 . !0^13 / 10^4 = or 3.75 . 10 ^ 9 Newtons (force ) or about 800 million pounds force. The time taken is the average speed and distance . So if d= v(ave) . t
then t = d/v = 10000 / 25,000 -- secs or 0.4 secs .
So I guess you would like to take it slower and use a little less force -- you can choose your distance and work out the force and time -- the equations are good .
The conversion from Newtons (force) to pounds (force ) is 1 N = 0.22 pounds .
Personally I always use the MKS system having done so for the last 45 yrs -- I can no longer think in pounds and odd ball things like poundals .
But you must realize that force and weight are not the same thing weight only applies here in Earth's gravity . A Newton is about 1/10 of a kilogram of Earth weight , and a kilogram is a very hearty slab of beef .
PS. I was not suggesting Nuking it but using nuclear fuel to decellerate or accellerate the mass . ( but nuclear ways are the only ones capable of delivering that amount of energy ) . The trouble is the speed even a gram could detroy a spacecraft at 50 km/sec . example (MKS units )
1 gram at 50 km/sec ----- E = m.v^2/2 = 10^-3 . 50^2 . 10^6 / 2
= 1.25 million joules
I am going to assume that this little object comes to rest in about 1 foot
i.e. 30 cms or 0.3 meters
from E = F x d or F = 1.25 . !0^6 / 0.3 or ~ 4 . 10 ^6 Newtons
e.g. about 1 million pounds . So you can see that although the object mass is important it is the speed due to v^2 that can really hurt .

Yours Ray .

 

[DaveC426913]

I'd like to digress a bit on this topic. You know it wouldn't be very difficult to launch small "Engins" that could meet up with an asteriod, of any size you wish, then grappel onto it and thru the magic of vector steering bring it into a stable orbit for mining. Some of those things must contain large amounts of various minerals. Now, about the doom and gloom aspect. I see no reason why we could not capture one of these things and hurl it at any military target on the planet; without even being on the side of Earth you want it to strike. One might simply choose an asteriod of the necessary size to produce the damage required over a given terrain. And afterwards, and here's the beautiful part, militarily I mean; there wouldn't be any nasty radiation to contend with. Just strike and move in after the dust clears. This would be a weapon that could be easily held ready for use with a minimum of cost, deployed on a moments notice. Why wait for nature when we can grab one of these babys and "play ball."
L8R

"easily held ready for use with a minimum of cost, deployed on a moments notice".

These statements are as far from reality as it is possible to get. Of all methods for attack, asteroid bombardment meets these goals the poorest.



- Build and launch a spaceship (or many) into deep space just for a single "bomb". $$$
- Wait many, many months or years, as the asteoid is slowly moved.
- Calculate the trajectory with exquisite accuracy so you don't miss and hit friendlies.
- Your enemies will see your attack coming for *months*. They can just move.
- You can't abort the attack.
- It is open to being usurped by the enemy, and may rain on your own head - or on the heads of random civvies.
- It accomplishes no goal of war - it leaves nothing but destruction. We frown on this at the best of times.

 

[Billy T]

"easily held ready for use with a minimum of cost, deployed on a moments notice".
These statements are as far from reality as it is possible to get. Of all methods for attack, asteroid bombardment meets these goals the poorest.
- Build and launch a spaceship (or many) into deep space just for a single "bomb". $$$
- Wait many, many months or years, as the asteoid is slowly moved.
- Calculate the trajectory with exquisite accuracy so you don't miss and hit friendlies.
- Your enemies will see your attack coming for *months*. They can just move.
- You can't abort the attack.
- It is open to being usurped by the enemy, and may rain on your own head - or on the heads of random civvies.
- It accomplishes no goal of war - it leaves nothing but destruction. We frown on this at the best of times.

Nice summary. I pointed out to BF in early post that if we had done this in 1940, Japan would not now be supplying the walkmans etc. - the fact that the project time scale is longer than our enemy is our enemy.

There is the very remote possibility that might be worth a few minutes of thought - if two asteroids, one being iron nickle, could be induced to scatter off each other (no contact) perhaps the iron nickel one could then be scattered again into a orbit that slowly over takes Earth, (only with help of Earth's gravity to not hit too hard in some dessert). A source of iron/nickle, but even with fantastic luck in the initial orbits and technology of 100 years into the future, I bet the the cost of project is more that the global economy's GNP for several years.

 

[bettysfetish]

Oh well, I guess your right; it was a whimsical thought at best I suppose. You guys have pointed out a couple things that may be prohibitive, although I dispute a couple of points as well, but a chain is only as strong as it's weakest link, and this idea, obviously has a couple very weak links. Thanks for your input. Thats what I came to you for. Hey - - - - Mabey a good movie; that's the ticket.
Thanks again.
L8R