Nukes Not the Best Way To Stop Asteroids, Says Apollo Astronaut 367
MajorTom writes "Right now, we are not tracking many of the asteroids that could destroy earth. But within the next decade, new telescopes will make that possible, and leave us with the tough decision of what to do about objects with an alarming chance of hitting our planet. Last year, NASA said that the best option is to nuke them. This week, Apollo astronaut Rusty Schweickart, explained that there are far better options, and he has started an organization to prove that they can work."
It depends on the timing... (Score:1, Interesting)
If we can detect it in time then a push from behind/side might have time to help enough. Seems to me a nuke would be more of a last minute Oh Crap choice.
Alternative sugestion (Score:5, Interesting)
Move it into orbit and mine it.
The interesting bit... (Score:5, Interesting)
He's saying pushing or pulling an asteroid is better than hitting it with a nuclear weapon, but the interesting thing is that he's claiming NASA issued its pro-nuclear statement last year in response to political pressure to put nuclear weapons in space.
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Re:It depends on the timing... (Score:5, Interesting)
Re:Alternative sugestion (Score:3, Interesting)
Assuming this is even possible what are the chances of the asteroid's orbit decaying and having it plummet to the earth anyway? How long would it stay in orbit before this occurred?
Going back to whether or not this is possible it seems like it would take monumental effort to make it happen with the possibility of little to no gain (aside from the obvious "we're not going to die from this particular asteroid"). Lets see, we would need to:
While your idea is an interesting one I'm going to go with the idea that at this point in time, with our current technology and knowledge, we're boned if anything larger than a kilometer in diameter is heading our way. Lets face it, while NASA has done a lot of great things their success rate hasn't exactly been spectacular. I'm not saying it is a completely impossible idea, just that it is highly improbable that we could successfully execute this plan.
Re:I always wondered (Score:3, Interesting)
AIUI, you have to have the blast very close to the surface, if not actually on it. The radiation from the blast will be enough to vaporize some small amount of the asteroid. That vapor will leave the asteroid very quickly in the direction the blast came from and the rest of it will move in the other direction, although very slowly. I agree that it's not going to be as effective as it would be in atmosphere, but there will be some acceleration from it, and as I pointed out in another post, it doesn't take very much if you can give it enough time to work.
Re:He's got a point - why nuke the asteroid? (Score:2, Interesting)
You don't get karma points for "funny" ratings, so some mods will give an exceptionally funny post an "insightful" rating instead. As Taco said, you have to be wise, not a wise-ass.
You don't get karma for "underrated" either, which is why that's not used instead.
Personally, I just rate the first 5 posts on idle as "overrated". It works out great. I get to ditch the mod points as fast as I can and statistically, I'm modding the posts correctly.
It's all about sum delta V (Score:3, Interesting)
Nukes are big lumps of dV, ion engines are small streams of dV. There's a range of options in between. Small, continuous thrust over time can equal large, impulse thrust over a few seconds.
It all depends on when you can identify and engage the celestial body under discussion. The less warning, the shorter the time you have to apply the necessary dV for the effect you want. The effect you want is a change in velocity vector, and how you need to change the moving body to go faster | slower | different direction depends entirely on the orbital mechanics of the individual event. Work the problem when you find out about it.
Re:It depends on the timing... (Score:5, Interesting)
Actually, I remember seeing some documentary on national Geographic (iirc), where they explored this exact topic.
The problems with nuking asteroids are (apparently) the inherent danger of radioactive fragments falling to earth and of course the fact that asteroids aren't actually solid --- they usually consist of a lot of small pieces of rock, hence making it hard to actually do anything to them with force. Of course, these weren't the only problems, but they're the ones I can remember. Might have been the same guy as the one from TFA pointing it out --- I'm not sure. Also, I'm a linguist, so my knowledge of astronomy and nukes is limited.
Re:Where to nuke? (Score:2, Interesting)
Re:The reason for nukes (Score:2, Interesting)
Re:The interesting bit... (Score:4, Interesting)
A strike on a country like Pakistan or India from space could probably be done with no retaliation at all, thier liquid fueled rockets just wouldn't be able to launch in time. And it would tip the scales massively against china, as it had a lot of land based missiles but only 1 nuclear submarine carrying only 12 single warhead missiles (as opposed to the US whch has 1152 warheads in it's submarines). So there are lots of reasons why the US would want nukes in space.
He's missing a word: *BIG* nukes in space (Score:1, Interesting)
The phrase "political pressure to put nuclear weapons in space" doesn't really reflect what they're trying to do. While there is some pressure for placing a military capability in orbit, most parties see such a move as too politically sensitive and destabilizing.
There is however a very powerful lobby that seeks government dollars for research, development and production of nuclear weapons, as their income almost ground to a halt in recent years. Deflecting asteroids now offers an excuse for getting those tax dollars flowing into their pockets again.
What's more, nuclear weapons capable of worrying an asteroid would have to be HUGE, which also means costly and hence very profitable. There is no precedent for making such enormous nuclear weapons, which means that umpteen billions will be (justifiably) requested for research in this area.
So, the pressure isn't really to put "weapons in space" as such, but to turn the paltry funding that nuclear weapons research currently gets into a torrent.
Re:The interesting bit... (Score:3, Interesting)
I think once you have over a certain amount it doesn't really matter how many more you add.
Tho to come back to your point, china has more than one nuclear missile submarine, but I don't think they leave port.
Re:TFS (Score:3, Interesting)
I think we've got the 'getting it up there' part figured out already...
Not if your payload includes a million ton pusher plate. The only way we could launch an orion would be to fly it as a pulse rocket directly from the ground. Which is how it was done in Footfall.
God was knockin and he wanted in bad...
Re:It depends on the timing... (Score:4, Interesting)
Even then, if you do the math on how much of the fragments will be radioactive (and how much) and how much of this will become embedded in bed rock (or deep in the oceans), I really doubt the radioactivity caused by the nuclear blast will have much effect. And depending on where the unfragmented asteroid hits, there's also a chance that the ejecta from that impact will include massive stores of radioative waste from the nuclear power industry.
Re:The interesting bit... (Score:3, Interesting)
There is the additional time of of a deorbit burn. the missile needs to lose its orbital velocity prior to starting its descent. The shuttle fires its retro rockets 1 hour before landing as a reference. A missle may do this faster with stronger and longer firing of retro rockets, but I think there is still ample warning, and I would think a faster deorbit would reduces accuracy.
Hit asteroid with "slap" very repeatedly. (Score:5, Interesting)
Weapons effects are extremely interesting and useful. The first effect to know about is that stuff survives amazingly close to a nuclear explosion. The second effect is that you can "tune" a fission bomb to direct its energy output largely in one direction. (Don't jump on me, this is in the open literature now.) Which gives a different method of dealing with asteroids; a series of powerful, but not shattering, plasma "slaps" to change its orbit.
Send a spacecraft armed with lots of quite small fission weapons that are set up to direct their weapons effects mostly in one direction and with a very basic, robust guidance system. Each one needs to get tossed out, line up with the asteroid, trigger, and "slap" it with high-speed plasma. Enough "slaps" change its orbital characteristics. You don't try to shatter it.
Each fission weapon looks like this: Wrap up a small (5 kt?) fission core with something like polyethylene or anything that absorbs prompt soft X-rays. Anything that has mass. The onboard computer works with guidance (my guess would be aims for a laser point on the asteroid, but who knows), the guidance just lines it up properly with the asteroid, and triggers the fission.
Position it so that when it goes off, the plasma of the polyethylene (and the former physics package, etc), moving around 2.5 million miles per hour, strikes the asteroid. You don't try to break the asteroid up -- far from it. You go for a series of "slaps" with very hot material. As the physics formula says, Mass times Velocity Squared -- and here you have all kinds of velocity.
As Lew Allen proved, with his famous tests with steel spheres just a few feet from ground-zero of a nuclear test survive just fine, and they are accelerated quite briskly. This was one basis of Project Orion later on.
It would be quite interesting to model this against some asteroid sizes and get an idea of what would be required to change the trajectory. We certainly have enough plutonium cores laying around.
Just an interesting thought.
Thanks,
Dave Small
unfortunately (Score:3, Interesting)
It was a nefarious excuse to put nuclear weapons in space.
Unfortunately, it looks like a hidden agenda is behind quite a bit of space policy.
Space solar power [nasa.gov] (now abandoned) was another attempt at getting weapons into space: collecting solar energy in space makes no economic sense, but it does make sense as an excuse to get a giant, city busting energy weapon into space.
Nuclear propulsion [space.com] is another such attempt: it makes no sense for solar system exploration, but it does make sense as an excuse to get atom bombs into space.