Asteroid warfare! Really???

Read this, please, and tell me if this is actually feasible…

It seems to me, with my somewhat lacking knowledge of physics, that a large number of variables would interfere with your targeting… asteroid composition (would affect how the blast would shape the orbit), surface irregularities (ditto), the blast perfection/shape/etc. (ditto ditto).

If it IS feasible, how likely is it that any government in the world (other than the US, England, France, China, and a few others) could/would actually DO it?

Anyone out there have a few extra nuclear warheads and some time? We could take out something on the moon for practice… then, when we have worked out the bugs, we can work on terrestrial targets! :wink:

Enquiring minds want to know…

Hmm… I wonder if it can be done with things other than asteroids… old Russian space stations perhaps…

-takes out his calculator-

It seems clear to me, based on my knowledge of physics (which actually is my field), that this could be done and would work. More to the point, would it be a good choice given all the alternative methods one nation could choose from if they want to whack another.
The biggest negative is that it’d be quite alot of work. This isn’t something Iran and Iraq are going to do to one another. Rogue states may be able to put a rocket into space, but we’re talking making every one of five or ten or fifteen space missions successful, or else having a sufficiently diverse approach to the problem that losing a mission or two doesn’t spoil the whole show. One example of a prerequisite for this kind of work that a rogue state would be hard pressed to deliver: a network of large radio dishes scattered over many time zones and weather regions, so Mission Control could talk to their probe when they needed to.
Besides, it wouldn’t be that easy to hide what was being done. If Syria entered the field of space exploration, and had nine missions that the rest of the world saw running off to “asteroid rich” regions (such as they are), and they published no scientific results, and then Israel got cratered, somebody from the SDMB would start spreading ideas…

I read the article. Sounds to me like a bunch of astronomers with WAY too much time on their hands…

Sounds to me like these astronomers have read a number of the same science fiction books I have.

This has been used in numerous books, so it’s not all that new an idea, so I’m guessing someone reading about it was having a bull session with his astronomer buddies and said “Could we do that with today’s technology?”

Look Ma, all the power of a nuclear explosion without the radiation! <sigh>

Most recent book I can think of that use this would be Ian Douglas’s book Luna Marine, second book inThe Heritage Trilogy, printed June 1999.


IANA physicist, but I am someone who lives in 21st century America. Here’s your biggest problem, right here.

I’m, like, huh? With all those eyes watching, NASA’s just going to say, “Oops” and shrug? Or Syria. Or Iraq, or India, or China, or whoever. People might buy it the first time, sure, but if it keeps happening? Don’t think so.

I think it makes more sense to send a team of oil rig workers, captained by Bruce Willis, to play bumper cars with the asteroids and just push them into the proper trajectories. Kind of a long-term assignment, see? You go up, you shove all those big rocks into different orbits, and 30 years later, the air raid sirens go off in downtown Baghdad.

“Next, the warheads would be stacked up in orbit around an asteroid about 200 metres wide. Each weapon would be landed on the asteroid and detonated over the course of 18 months”

I’m thinking those warheads would have to carry a lot of booster fuel to orbit a small asteroid for up to 18 months.

The concept is obviously feasible; it was demonstrated through computer simulation, and it’s not like astronomers don’t know the variables involved in moving things around in orbits. :wink:

The more difficult part to swallow is the assertion that no one would have any warning. We actually have a number of programs in place that aren’t classified that involved watching the skies for near miss asteroids. It would be difficult for me to accept the idea that an asteroid would change orbit significantly without someone noticing. I’m also guessing that the US government, at least, has at least one classified program watching for something similar.

Further, it’s not like nuclear weapons are just free and easy to find, install in a form usable in space and launch. Also, we track all SORTS of junk in space; rarely are things like probes lost unless they get lost WAY out away from the earth. By that time, we’d know that the ‘probe’ wasn’t headed to its stated destination. Other reasons it would be hard to do clandestinely come to mind.

I happen to be an astronomer with too much time on my hands, and my opinion is that you shouldn’t lay awake nights worrying about it, at least for a few decades. I can think of numerous problems, in addition to the practical political problems in getting a nuke into outer space (which is a major violation of the Outer Space Treaty, by the way.)

You can find a lot of information if you check out the work of astronomers trying to work out a way to deflect an asteroid on a collision course with Earth.

  • You have to know how the asteroid will respond to the nuke, and there are a million things that will affect that: its chemical composition, its porosity, whether there are large voids on the interior, etc. Let me emphasise: This stuff is not well-known for any asteroid, even Eros. If you want to target this thing as a weapon, you need even more information. It’s (relatively) easy to hit the Earth. It’s very, very hard to hit a specific point on Earth. You’d better send lots of massive instruments along with your warheads. (That glug-glug-glug sound is your propellant tank getting bigger.)

  • You’d have to plan it years in advance, and start making orbit corrections a decade before you wanted the impact. If you decide after you begin modifying the asteroid’s orbit that you no longer want to paste your enemy, you’ve got a problem. Maybe you can arrange an near miss, this time around, but what about the next time its orbit brings it around to Earth, and the time after that, and the time after that?

Other practical problems I can imagine:

  • If you want to disguise your asteroid-deflector as a civilian mission, you’d convince the international community that the spacecraft is going where you say it’s going. A spacecraft taking warheads to a near-earth asteroid is going to have totally differnet propellant requirments than a spacecraft delivering a scientific payload to Mars, or to Earth orbit. I don’t think you’re going to be able to fool anyone that way. You’ve got to do it secretly, and various agencies are going to be tracking your efforts to figure out what you’re up to. That’s not to say that you couldn’t do it, just that it’s not as easy to do it above-board as they imply.

  • I wonder how easily detectable a nuclear explosion in the inner solar system would be. We watch for these things on the Earth’s surface using satellites, and those gamma-ray detectors are, in general, omnidirectional. (That’s how gamma-ray bursters were discovered.) It depends on the yield of the warhead, and the sensitivity of the detectors (and the DoD doesn’t exactly put that up on their website.)

I find it strange that they talk about landing the nukes on the asteroid. First, that’s devilishly difficult: NEAR had a hard time doing it. Crash the nuke, and it’s not going to detonate. Second, a nuke is much more effective at deflecting the asteroid if its stand-off distance is approximately one asteroid radius.

Remember, this is “Dr Holloway, a former military scientist at the Atomic Weapons Establishment at Aldermaston.” There are a lotta cold warriors looking for something to do with their skills. Not a lot of money in nuking Commies these days, so it’s only natural that they’re trying to find something else to nuke.

Some astronomers (notably J. Melosh at Arizona) argue that we should not develop nuclear weapons for asteroid deflection for two reasons. First, the danger of a nuclear accident might outweigh the danger posed by asteroid impacts. Second, we’d have exactly this problem: we’d deploy a technology that’s just as effective at diverting asteroids toward the Earth as away.

IANA scientist, but wouldn’t these nukes need something to push with? Some form of reaction mass to push the asteroid? Simply exploding wouldn’t push the asteroids, unless surface sublimation yields some propulsive force.

IIRC, the reason nukes are so destructive is that the energy liberated by the fission/fusion process pushes superheated air to expand outward from the core-source violently. The energy impacts upon structures, setting them on fire, but this is largely a secondary effect as the superheated and supercompressed air comes along a few seconds later and smashes the largely smoldering yet-to-combust-structures flat.

In the vacuum of space, what is there to push with?

Thanks Podkayne!

And ExTank, I believe the idea is to vaporize a portion of the surface, and derive a “delta V” (as they say) from the sudden and violent burst of gas escaping from the asteroid… there might possible also be enough radiation pressure to affect the orbit as well (remember, even a photon has momentum).

Most of the energy delivered by the nuke to the asteroid is in the form of high-energy neutrons (and a smaller fraction in the form of gamma rays), which heat up and vaporize the surface of the asteroid. The gas flies off into space, momentum is conserved, and the asteroid goes in the other direction. Just like a rocket, except that the gas flies off rather inefficiently in all directions instead of being directed by a nozzle. Remember, the amount of delta vee produced is going to be very small–this is why you have to do it years ahead of time. A small change in the asteroid’s orbit at the right time makes the difference between a collision with the Earth and a near miss (or vice versa.)

ExTankis right that superheated air does much of the damage in terrestrial detonation, but the air gets superheated by neutrons. If the air wasn’t in the way, the neutrons would be heating up something else. In the case of the asteroid, much of the energy will be wasted to space. That’s why the best standoff distance is 1 asteroid radius–that maximizes the volume of asteroid mass that will be vaporized for a given nuke.

The photon pressure is negligible.

Carl Sagan discussed this topic a lot in his book Pale Blue Dot. As others have already mentioned, this is certainly feasible with modern technology. However, as Podkayne said, humans still have no experience with altering the orbits of asteroids, so it would not be easy. It may just be easier to send the nuke to the other country than to try to send the nuke into space to bring down an asteroid onto a well-aimed spot on Earth. But, to answer one of your questions, yes, I think there are people in power who are crazy enough to actually do such a thing if they could.

Another problem C.S. mentioned was accidental impacts. Someday, it may become economically beneficial to move asteroids around and mine them for valuable ores. All we need is for Asteroid Valdez to run aground. :eek:

I don’t think alerting the public of a possible danger is a waste of time.