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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."
Then what does he propose that we nuke? Each other? The whales? Martians?
It's the only way to make sure.
To save you all the horror and pain of reading TFA (since TFS doesn't state), Schweickart is suggesting we either push or pull them away with unmanned spacecraft.
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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Please let one of the options be to send Ben Affleck into space. He has experience.
Find those advanced aliens that the other Apollo astronaut says are in our midst, and arrange for technology transfer briefings on asteroid redirection.
so, let me see if I got this right:
you would have a small triangular ship. Maybe two or three extras "just in case".
we could control it remotely. A rotational control and a forward thruster should suffice.
Then we could "fire" small nukes at the object. That would change their trajectory and break them into smaller pieces.
I think it sounds like a brilliant idea, but where would we be able to find someone who could operate such a machine?
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You can rain nukes on that asteroid till it glows, but that won't make much difference. Trick is, in the vacuum of space, nuclear explosion is weak. There is no air to create blast wave and thermal flash, so all you get is some hard radiation and hand-grenade level of blast from vaporized bomb casing. And that's it.
Project Orion would get around this problem by using thousands of little charges, detonated close to the reflector - and it would still take years to accelerate.
A volley of the kind of nuclear warheads we have now would not effectively change course of any asteroid big enough to be a threat.
And blasting it to pieces would make a little difference, only in distribution of the damage - we'd get stoned with a swarm of fragments instead of one big piece, yet the same mass and total energy.
The moon is not fully subjugated. I demand a second assault wave preceded by a massive nuclear bombardment.
Trying to use nukes to deflect the asteroid seems like the more difficult solution to me. The asteroid will be far away and moving fast. Earth is close and (relative to us) not moving at all!
Clearly the more practical way to avoid a collision is to use the nukes to deflect Earth out of the path of the asteroid.
paintball
Not really. Let's say that the most we can do with a nuke is slow the asteroid down by 1 f/sec. Doesn't sound like much, does it? but if you do it 30 days before impact, that shifts the asteroid back almost 491 miles. If you have six months, it's over 2000 miles. Considering that the Earth is a moving target, that might be enough to ensure a miss. You're not trying to blow up the asteroid, you're just trying to nudge it into a slightly different orbit that doesn't impact the Earth, and if you have time, it doesn't take very much.
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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.
"Live free or don't."
Oh man, oh man. I'm literally facepalming right now. Facepalming SO HARD.
Nuclear explosions follow the inverse square law. The further you are from the source, the less radiation is hitting you. Nuclear weapons on Earth derive most of their destructive power from the shockwave they create in our atmosphere. However, they are still incredibly powerful reactions, and if you're close to one in space, it will still fry you.
Project Orion would not 'take years to accelerate.' Unless you meant to add 'to a tenth the speed of light' at the end of that sentence. As it stands, Project Orion is the fastest, most practical spaceship would could design and build today. Chemical rockets don't even come close to what Project Orion is capable of.
And the Orion doesn't have a 'reflector', it has a pusher plate. It's a heavy metal plate, on the end of a gigantic shock absorber, coated in oil or similar [To reduce ablation.] that absorbs the energy from the nuclear explosion so that everyone on board the ship doesn't get splattered by the intense acceleration. The ship is ultimately pushed by a plasma wave created by the explosion.
An asteroid would be no different. Except that the surface might vaporize and act as additional reaction mass. The biggest problem I can envision with using a nuke to propel an asteroid is the difficulty you might have in predicting its new course.
You appear to misunderstand:
1. How much power is needed to apply an appropriate vector to the Significant (capital S is appropriate) mass.
2. The method used to propagate the blast energy into the asteroid.
The first item depends on the size of the asteroid, but the killers are usually pretty big, and need a big push. The amount of push depends on where in the orbit you find it, of course.
The second item is basically this: You can't rely on the atmosphere to transmit a 'shockwave' to the asteroid. In a vacuum, the actual shockwave is negligible once you get too far away (inverse square) and even up close, is only comprised of the limited mass of the bomb. Again, negligible effect. The actual propulsion comes from mass ejected by the asteroid itself. What would compel said mass to depart fast enough to create a thrust vector? Why, how about the sudden massive heating of one side? With a hydrogen bomb, you get the energy needed. For devices in the 15-20KT range, you're talking atomics, and the amount of usable energy that can be imparted is reduced significantly.
So the job of the bomb is not so much to "blow the asteroid off course", it is to convert the asteroid into a rock-rocket that fires molten asteroilava in one direction to create a vector for the larger mass in another.
Don't worry, your spelling is impeccable.
For a small object, yes.
For a object big enough to seriously worry about, no. Think of it this way. Take a rock the size of the one that killed the dinosaurs. It had roughly 300 million nuclear weapons worth of energy. Break it into a million equal size pieces, and there are a million rocks with 300 times the energy of a nuclear weapon, each of which would be more than large enough to punch through the atmosphere. The damage would be more focused on the surface of the Earth, and less would be "wasted" on deep layers of rock.
Small explosions are much more effective at destroying things than large explosions. That's why cluster bombs were invented.
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