# Nuking Asteroids **URL:** \ **Category:** Factual Questions\ **Created:** [September 4, 2003, 5:37pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561 "2003-09-04T17:37:28Z")\ **Posts on this page:** 16\ **Page:** 2
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [September 5, 2003, 12:43am UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/21 "2003-09-05T00:43:51Z")
Note that it appears that comets and such generally already have a good size spin to them. Attaching something like a rocket or nukes intended to fire in one direction is beyond our tech for the foreseeable future. OTOH, this spin is good if you intend to break it up. The slightly different velocities will cause it to spread out a bit, given enough time between blast and, umm, the next blast. The truth is, we are still talking about something like 2+ years crash program. No shuttles, no ICBMs, nothing launched from shuttles, will do it. The Russians have the best heavy lifters right now. I can see the talk: “So, we’re going to ship some really big nukes to Russia. Put 'em on a rocket. Let it rip. And this is better than getting hit by a snowball because …?” ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [September 5, 2003, 1:09am UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/22 "2003-09-05T01:09:09Z")
Of course, if you did deploy a spaceship with nuclear missiles, you run the risk of simply fragmenting the asteroid into two smaller but still dangerous chunks, each of which can be split into still smaller but dangerous chunks. You can always hit the Hyperspace button if you get in trouble, but there are risks. Plus those damn alien spaceships keep showing up. ---
**Author:** ![Tranquilis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tranquilis/32/3639_2.png) [@Tranquilis](https://boards.straightdope.com/u/Tranquilis)\ **Post date:** [September 5, 2003, 2:08am UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/23 "2003-09-05T02:08:31Z")
> [@](#): > > \*Originally posted by Squink \* > \*\*Not so. Asteroids are ALREADY DEAD ! \*\* _snerk_ ---
**Author:** ![alterego](https://avatars.discourse-cdn.com/v4/letter/a/6bbea6/32.png) [@alterego](https://boards.straightdope.com/u/alterego)\ **Post date:** [September 5, 2003, 5:39am UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/24 "2003-09-05T05:39:36Z")
> [@](#): > > \*Originally posted by Grey \* > \*\*Never forget, given enough time small forces can move large masses. It depends on when and for how long you do it. > > Let us take this hunk of rock moving at 31000 m/s and massing at 2.6x10^12 kg. Let us make it move in a straight line (x) for simplicity’s sake and have it 1 AU away from the Earth. > > Subject it instantly to 10^6 N of force in the (y) direction. You would have moved the asteroid by ~4500 km in the (y) direction by the time the thing reached Earth. Given the Earth is ~12600 km across that’s pretty impressive work and likely the difference between an unpleasant geology lesson or paying the mortgage. \*\* The original quote was by me, and I never said I doubted the ability of a small force to move a large mass. I simply doubted the ability of a space shuttles engines to move an asteroid. That brings in a few more variables. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [September 5, 2003, 1:18pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/25 "2003-09-05T13:18:37Z")
A string of smaller nukes, detonated 40% of the asteroid’s radius above the surface will cause a series of smaller nudges, and hopefully not break the loosely packed type up too much; I suggest we start experimenting rather than leave it to chance. It would take several months to get a series of devices into a rendezvous with an asteroid that would allow such accuracy, of course. You can’t just meet them head on at 40km-s. * * * SF worldbuilding at [http://www.orionsarm.com/main.html](http://www.orionsarm.com/main.html) ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [September 5, 2003, 1:43pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/26 "2003-09-05T13:43:24Z")
> [@](#): > > \*Originally posted by ftg \* > \*\*The truth is, we are still talking about something like 2+ years crash program. No shuttles, no ICBMs, nothing launched from shuttles, will do it. The Russians have the best heavy lifters right now. I can see the talk: “So, we’re going to ship some really big nukes to Russia. Put 'em on a rocket. Let it rip. And this is better than getting hit by a snowball because …?” \*\* Huh? The shuttle would have no problem whatsoever getting nukes into orbit. Nukes aren’t all that big…certainly no sweat for the space shuttle to lift. I would also think the shuttle could carry rocket motors into orbit that would be sufficient to take a nuke to the asteroid. The rocket motors can be _much_ smaller than what is used from the surface of the earth considering they are already in space. They can also be small since the payload isn’t all that much (the warhead mostly). I don’t know that we have such rockets invented (rockets to take items from earth orbit off into space along with guidance and so on) but I see no reason the Space Shuttle couldn’t get the stuff up to earth orbit (possibly requiring a little assembly once up there but that should be doable too if it is nothing more than bolting warheads to their motors). ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [September 5, 2003, 1:51pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/27 "2003-09-05T13:51:42Z")
> [@](#): > > \*Originally posted by eburacum45 \* > **It would take several months to get a series of devices into a rendezvous with an asteroid that would allow such accuracy, of course. You can’t just meet them head on at 40km-s.** Is this such a bad idea? Hitting it head on at 40km-s (or faster)? Seems to me you can forego the nuke altogether and let kinetic energy do the work for you. Maybe setup a railgun in orbit and shoot at the asteroid like a machine gun over the course of months to refine your accuracy and get a few hits (I know that railguns don’t shoot like machine guns but my point is you cna take many, many shots over the course of days or weeks). Anyone care to do the math on the energy released when a 5 kg projectile moving at 40km-s hits something? ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [September 5, 2003, 2:07pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/28 "2003-09-05T14:07:13Z")
With no explosive, you can use a simple collision calculation. Momentum is conserved in elastic collisions: m[sub]1[/sub]v[sub]1[/sub] + m[sub]2[/sub]v[sub]2[/sub] = m’[sub]1[/sub]v’[sub]1[/sub] + m’[sub]2[/sub]v’[sub]2[/sub] ---
**Author:** ![paulberserker](https://avatars.discourse-cdn.com/v4/letter/p/c4cdca/32.png) [@paulberserker](https://boards.straightdope.com/u/paulberserker)\ **Post date:** [September 5, 2003, 2:14pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/29 "2003-09-05T14:14:26Z")
there was a program on channel 4 a couple of weeks ago on how to deal with this, but it wasnt the 2014 asteroid, it was one that was expected to possibly strike in about 800 years. they did ballistic tests on parts of different asteroids found across the globe from previous strikes, to test out the theory of rather than blowing it into a million huge chunks that obliterate life on earth instead of it being one great big chunk, detonating nukes or equivalent futuristic weapons by its side to change the trajectory, so it misses Earth at safe distance. first test: solid rock/metal asteroid fragment - ballistic test showed it would react to a nearby detonation and get knocked off course second test: asteroid fragment they found in alaska, with air pockets (i know theres no air inspace, but if you imagine it to be like an asteroid sponge) - ballistic testing had no effect. it simply absorbed the effects of the detonation. I think they ended up concluding that technology would be in place in the future to get round this problem if its like the second asteriod, were all good if its a solid mass. plus they have to get to it far enough out so its mass/gravity passing by the earth doesnt have an adverse effect. this is all my recollection by the way from 2 or 3 weeks ago, i apologize if its a bit vague, but im sure somebody more qualified than my bad self will be along to explain it better and give cites soon. ill try a bit of googling to see whats up. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [September 5, 2003, 2:37pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/30 "2003-09-05T14:37:52Z")
> [@](#): > > \*Originally posted by Squink \* > \*\*With no explosive, you can use a simple collision calculation. > Momentum is conserved in elastic collisions: m[sub]1[/sub]v[sub]1[/sub] + m[sub]2[/sub]v[sub]2[/sub] = m’[sub]1[/sub]v’[sub]1[/sub] + m’[sub]2[/sub]v’[sub]2[/sub] \*\* It’s not the actual math I fall apart on…it’s making sense of the results. It’s been so long since I dealt with such problems (high school) that I have utterly forgotten what units to use (although I assume kilograms and kilometers or meters). What’s more I don’t know how the combined units once calculated relate to another unit (i.e. is the answer in Newtons, Amps, Watts, etc. [I know some of that is silly…just illustrating my point). Finally, I don’t know how to relate the answer to something meaningful to me. Is 1,000 newtons equivalent to a firecracker, stick of dynamite or a nuke? I have no clue. That said here are the numbers for this problem I have come up with based on a 2.6 million ton rock moving at 75,000 mph and an 11 pound projectile moving at 8,948 mph. If someone else could make sense of the resulting collision that’s be great. Here are the numbers I figure need to be used: Asteroid: 2,358,694,000 kilograms 33.528 kilometers/second (or 33,528 meters/second) Projectile from Railgun: 5 kilograms 4 kilometers/second (or 4,000 meters/second) ---
**Author:** ![paulberserker](https://avatars.discourse-cdn.com/v4/letter/p/c4cdca/32.png) [@paulberserker](https://boards.straightdope.com/u/paulberserker)\ **Post date:** [September 5, 2003, 3:05pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/31 "2003-09-05T15:05:40Z")
try these: [http://www.swri.edu/3pubs/ar2001/engng.htm](http://www.swri.edu/3pubs/ar2001/engng.htm) [this link](http://www.abc.net.au/catalyst/stories/s924535.htm) is to the program i was talking about. it was horizon on BBC2 rather than channel 4, but there you go. [transcript of said show](http://www.bbc.co.uk/science/horizon/2003/armageddontrans.shtml) try googling ‘averting asteroid threats to earth’ ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [September 5, 2003, 3:12pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/32 "2003-09-05T15:12:57Z")
> [@](#): > > \*Originally posted by alterego \* > \*\*The original quote was by me, and I never said I doubted the ability of a small force to move a large mass. I simply doubted the ability of a space shuttles engines to move an asteroid. That brings in a few more variables. \*\* Ah, you’re right. The coding threw me off. Apologies to **justthefacts**. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [September 5, 2003, 5:46pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/33 "2003-09-05T17:46:23Z")
> [@](#): > > \*Originally posted by alterego \* > \*\*The original quote was by me, and I never said I doubted the ability of a small force to move a large mass. I simply doubted the ability of a space shuttles engines to move an asteroid. That brings in a few more variables. \*\* Yeah, but the _original_ original statement was by _me_ and I said “spaceship”, not “space shuttle”. The original original _original_ statement, of course, was by the OP. As an incidental totally unrelated note, I’m watching _Master of Disguise_ for the first time, and if an asteroid was to wipe out Dana Carvey and his body of work, I’d say bring it on. ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [September 5, 2003, 6:15pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/34 "2003-09-05T18:15:24Z")
> [@](#): > > \*Originally posted by Whack-a-Mole \* > \*\*Asteroid: > 2,358,694,000 kilograms > 33.528 kilometers/second (or 33,528 meters/second) > > Projectile from Railgun: > 5 kilograms > 4 kilometers/second (or 4,000 meters/second) \*\* M1 = 5 kg V1 = 4000 m/s M2 = 2.358694e9 kg V2 = 33528 m/s V2final = 29000 m/s (roughly Earth’s orbital speed) n = ??? Number of projectiles we need to fire off Turns out V2final = (M2V2-nM1V1)/(M2+nM1) so we need to fire off 64 million projectiles. At 1 projectile a minute we would need ~120 years to slow it down. Now say we make a 1 ton slug and fire it every half hour…~300 thousand for about 18 years. I assumed that the projectile’s mass get completely incorporated in the asteroid, which makes it progressively _more massive and so harder to stop_. It would be better to land the rail gun on the damn thing and uses pieces of the asteroid as projectiles. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [September 5, 2003, 6:27pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/35 "2003-09-05T18:27:20Z")
> [@](#): > > \*Originally posted by Grey \* > **Turns out V2final = (M2V2-nM1V1)/(M2+nM1) so we need to fire off 64 million projectiles. At 1 projectile a minute we would need ~120 years to slow it down.** I wasn’t talking about slowing the asteroid down but rather blasting it into pieces. The impact of the railgun slug would be significant. I was curious how significant it would be. People talk about tossing nukes at the thing and I was wondering if a railgun could achieve the same effect with several shots. ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [September 5, 2003, 6:42pm UTC](https://boards.straightdope.com/t/nuking-asteroids/199561/36 "2003-09-05T18:42:46Z")
Well, your projectile would have 40 MJ of energy when it hits. A 1 MT nuclear weapon releases 4.6 PJ. Say only 10% of that energy is actually intercepted by the asteroid’s surface so you now only need to reach 4.6e14 J. You would need 10 million slugs in your rail gun to get an equivalent energy release. Your approach has the advantage that we could “chip way” at the thing and avoid the nasty surprises of released gases, fragments crashing down on our head etc. [Previous page](https://boards.straightdope.com/t/nuking-asteroids/199561.md?page=1)