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Nukes Not the Best Way To Stop Asteroids, Says Apollo Astronaut
Posted by
timothy
on Sun Jul 27, 2008 06:40 PM
from the thin-coating-of-flubber dept.
from the thin-coating-of-flubber dept.
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."
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Submission: Nukes Are Not the Best Way to Stop an Asteroid by Anonymous Coward
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Then What Do We Nuke? (Score:5, Funny)
Re:Then What Do We Nuke? (Score:5, Funny)
The darkness! I want to attack the darkness! ...
Fine, fine. . You cast nuclear fission at the darkness.
Parent
Re:Then What Do We Nuke? (Score:4, Funny)
The darkness! I want to attack the darkness!
So you DON'T believe in a thing called love?
I mean the music video has a space monster and everything!
Parent
He's got a point - why nuke the asteroid? (Score:5, Funny)
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.
Parent
Re:He's got a point - why nuke the asteroid? (Score:4, Insightful)
This got an insightful. I'm not sure to be proud of the mods for modding up a great bit of satire, or ashamed at how they did it.
Parent
Re:He's got a point - why nuke the asteroid? (Score:5, Insightful)
Parent
Re:Then What Do We Nuke? (Score:5, Funny)
Then what does he propose that we nuke? Each other? The whales? Martians?
Nuke the gay baby whales for Jesus.
Parent
Re:Then What Do We Nuke? (Score:5, Funny)
Parent
Nukes are the way to go (Score:4, Informative)
I saw a presentation by the group behind this report. Using a nuke to divert an asteroid is not a crazy idea. They basically explode the nuke and cause a debris cloud of dust and gravel from the surface of the asteroid that provides the thrust to divert it.
They did very detailed simulations and it is very doubtful that the asteroid would break up like in the sci-fi shows... The parts that see the explosion break up into itty-bitty pieces and flow around the asteroid like a liquid... the interior of the asteroid remains intact. This is true for many different models of asteroid composition.
Schweickart makes the over-the-top claim that the study report is trying to push some secret nukes in space agenda. This is pure conjecture on his part. If he would have put his giant astronaut ego aside and spoke to the people who did the report he would have found out that it was done by people who had a strong aversion to nukes, and that the panel had initially tried to leave out the nuclear option or marginalize it for political reasons. But they were persuaded by the strength of the science in the nuclear advocates' arguments.
I was convinced... and I am a Pugwasher pacifist... and the people I know on the committee who were persuaded are also of the same ilk. But when you look at the analysis, you see that nukes do work. And in terms of energy imparted to the asteroid compared to launch mass, nothing else comes remotely close to the efficiency of nukes (E=mc^2 and all that.)
Yeah nukes are awful things. But so are ICBMs... and ICBMs are the basis for most of the launch vehicles used for peaceful space exploration. Why not beat swords into plowshares and start developing some asteroid-stopping nukes?
Parent
Edgar Mitchell? (Score:4, Funny)
If Edgar Mitchell's involved, then we know for sure that nukes are the best option!
Nuke it from Earth. (Score:5, Funny)
It's the only way to make sure.
TFS (Score:5, Informative)
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.
Re:TFS (Score:4, Informative)
Parent
Re:TFS (Score:5, Informative)
I hope you realize that Pournelle and Niven didn't just make that up? Project Orion [wikipedia.org] was a very real attempt to develop nuclear pulse propulsion. It is still a viable option for space travel, as long we're not talking about a ground-launch using nuclear pulses. To get the sucker into orbit, we might have to resort to something a bit more mundane. Like a dozen SRBs or somesuch.
Parent
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
Parent
Re:TFS (Score:5, Insightful)
If you know how to do it, I think NASA would be extremely interested in your solution. 3000 metric tons to Low Earth Orbit (LEO) is a lot more than anyone has ever attempted before. The most powerful rocket in existence will be the Ares-V upon completion. It will be capable of lifting ~180 metric tons to LEO. Now scale that up by about 17x and we'll be good to launch an Orion.
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Re:TFS (Score:5, Insightful)
Really. I can't believe geeks would think that fabrication in space is impossible.
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Re:TFS (Score:4, Informative)
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Alternative sugestion (Score:5, Interesting)
Move it into orbit and mine it.
Re:Alternative sugestion (Score:5, Funny)
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Re:Alternative sugestion (Score:4, Funny)
In space, no one can tell that you're trapped in a glass box or walking against the wind.
-jcr
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Re:Alternative sugestion (Score:5, Funny)
Parent
That would take a lot of delta-V (Score:5, Informative)
Making it miss is a matter of nudging its orbit just enough that it doesn't intersect Earth any more. Capturing it requires slowing it down all the way to Earth-orbit speed. In space, just because something goes nearby doesn't mean it's easy to catch.
Parent
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.
---
Thousands are enslaved every day. http://www.riverofinnocents.com/ [riverofinnocents.com]
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.
Parent
Armageddon? (Score:5, Funny)
Please let one of the options be to send Ben Affleck into space. He has experience.
Re:Armageddon? (Score:5, Funny)
Parent
here's another approach (Score:5, Funny)
Find those advanced aliens that the other Apollo astronaut says are in our midst, and arrange for technology transfer briefings on asteroid redirection.
now this!? (Score:5, Funny)
Re:now this!? (Score:5, Funny)
Parent
Primary problem (Score:5, Funny)
The main problem with nukes is that criminals will be released from the Phantom Zone if a nuclear weapon goes off in space.
The reason for nukes (Score:5, Informative)
Nukes have been a popular options because:
1. We have them.
2. They have a high ISP (a measure of efficiency) when used as propulsion against a large object. Paradoxically, the ISP for Orion-style nuke propulsion increases with the size/mass of the object.
3. They're much more portable compared to most other types of methods.
Schweikart has identified the REALLY valuable truth, that we need to improve our detection method. We also need to develop deep space capability because the further out we can intercept them, the less energy is needed to perform the deflection. Lower energy can also mean less danger of fracturing the mass.
Re:The reason for nukes (Score:4, Informative)
Redirecting an asteroid on an Earth impacting trajectory was discussed in depth quite a few years ago in Scientific American magazine. There are a variety of ways to deal with such an asteroid, depending on size, composition, and how advanced the warning is.
There are two main responses: redirection and pulverization. If the asteroid is structurally week and small it can be pulverized so that the pieces will burn up on atmospheric entry. This has the advantage that it can be done with little advance warning. One novel proposal involved a 3 dimensional mesh built around tungsten nodes. It would be compact for launch yet still spread out and stay grouped together for a long distance strike.
Redirection is necessary for large or durable asteroids. Spin would make it difficult to have a vehicle in contact with it redirect it over time. Reliable redirection would require delivery of multiple kinetic payloads over time. Each payload strike would have the danger of fracturing the asteroid; widening the potential Earth-impact damage.
Focused, reflected, solar energy has been proposed to redirect ice based asteroids with much advanced warning. Even X-ray cannons have be proposed, along with other laser based solutions. A thermonuclear device ignited adjacent to an asteroid would vaporize a layer off its exposed surface, redirecting the asteroid. This would even be effective against iron-ore asteroids. There is also less likelihood of fracture than kinetic impact. Close asteroids can be acted upon multiple times for faster redirection.
A nuclear solution has the advantages of being effective at long range and at ranges to close for the other listed methods to be effective. It is less likely to cause fracturing and would work against any material composition.
Reliable long range detection would allow other methods to be effective, but thermonuclear warheads are a mature technology, would be effective at short range and we do not have to station them in space ahead of use.
Parent
Re:The reason for nukes (Score:5, Insightful)
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.
Parent
Why bother at all? (Score:5, Insightful)
The probability is vanishingly small we'll get crunchified and the likelihood of any bureaucratic solution even working is also damn low. So let's just accept that there's a nonzero probability that we'll all get wiped out. Worst case we all die someday anyway.
Nukes not best way to stop asteroids (Score:5, Funny)
Let's ask Atari (Score:5, Funny)
After all, they already had asteroid-blasting spaceships in the late 70's.
nukes only if not enough time for safe method (Score:4, Informative)
Wiki, Asteroid Deflection [wikipedia.org]
NYT Study suggests mirrors best [nytimes.com]
NASA has non-nuke plans [theregister.co.uk]
Using a 300Kg impactor [arstechnica.com]
Seems the consensus is that nukes would only be used if we discovered the asteroid too late for other methods to be effective.
1up (Score:5, Funny)
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?
Parent
Re:1up (Score:5, Funny)
You'd probably want to design the triangle to be able to move out of the way of the asteroid via some 'hyper space' mechanism as well, in case you were too close to thrust out of the way manually.
Parent
Re:I always wondered (Score:5, Insightful)
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.
Parent
Re:I always wondered (Score:5, Informative)
A nuclear warhead intended to deflect an asteroid could be designed to penetrate the asteroid prior to detonation. Blasting away debris from the surface of the asteroid would allow you to "push" it effictively.
And blasting it into little pieces would most certainly have an effect, since smaller pieces have more drag, they would be more likely to burn up harmlessly in the atmosphere (same total energy, much wider dispersion). Also none of the resulting pieces are likely to have exactly the same trajectory as the original asteroid. Depending on the angle of impact, they will be moving at a different speed or in a different direction than the original.
Parent
Re:I always wondered (Score:5, Insightful)
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.
Parent
Re:I always wondered (Score:5, Informative)
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.
Parent
Re:I always wondered (Score:4, Informative)
An Orion style propulsion system is capable of getting a craft from earth to Pluto and back inside a year. If we're talking about speeding up, slowing down and then repeating after turning around, we're only talking about a few months to accelerate 100+ tons of spacecraft to it's cruising speed. Now I'm sure the math is different when dealing with a planet-killer sized asteroid, but the normal orion system is not accelerating for years.
It bears mentioning that we don't need to stop or reverse a planet-killer sized mass, just push it off course for direct impact. Depending on how far out you're able to intercept it, you can get away with a very small push.
And there is something to be said for blowing one into small pieces. Even if it's hitting us with the same total energy, having it dissipate in the atmosphere as those small pieces vaporize seems preferable to having several hundred or thousand tons of mass vaporize seawater or throw up a nuclear winter style plume of dust on impact with the surface.
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Re:It depends on the timing... (Score:5, Interesting)
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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.
Parent
Re:It depends on the timing... (Score:5, Funny)
Don't worry, your spelling is impeccable.
Parent
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.
Parent
Re:Test Trial (Score:4, Funny)
Parent