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Nukes Not the Best Way To Stop Asteroids, Says Apollo Astronaut
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."
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.
Move it into orbit and mine it.
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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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.
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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.
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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.
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The residual radiation from a nuclear blast is pretty much zero after a week. Ask any physicist who has visited Hiroshima or Nagasaki (i.e. me ;o) ). The idea that debris from a nuclear explosion is permanently radioactive (and maybe glows green!) comes from fiction.
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Actually wouldn't it be easier to just not build the better telescopes. That way things don't change. Outta sight, outta mind!
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.
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.
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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
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 (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 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.