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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?
If Edgar Mitchell's involved, then we know for sure that nukes are the best option!
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.
First an Apollo Astronaut says that the government has covered up Alien contact, now this!?
The main problem with nukes is that criminals will be released from the Phantom Zone if a nuclear weapon goes off in space.
Write your own Choose Your Own Adventure. http://www.freegameengines.org/gamebook-engine/
Just turning the asteroid into pieces wont work, the pieces will still come in the same direction.
But the pieces will have more surface area and therefore will burn up in the atmosphere more efficiently.
But what about using nukes as some sort of "propulsion" system (as in the Project Orion), so they can change the direction of the asteroid? Wont be something for the last minute, but, could work?
That could work. Or we could change the direction of the Earth :P
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?
-- Sig under construction...
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.
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.
The simply answer is that the physics are already known, and it all depends on how far in the future the impact is before we detect it. Given a century just about anything would work. Given less than a year, almost nothing would.
Given a couple decades, yes, there are a number of non-nuclear options. A nice high impulse drive, perhaps a number of them, set into the surface of the asteroid. They thrust in the proper direction over a long period of time, and we end up being able to put the asteroid pretty much where ever we want it.
In a shorter time frame or larger asteroid, nukes might end up being the best choice. Of course, for best propulsion, like in the horrible movie, burying it might be the best option - that allows part of the mass of the asteroid to be used to propel the asteroid in the opposite direction. The ejecta, even though some is almost guaranteed to hit the earth, is okay because it'll overwhelmingly burn up in the atmosphere.
I don't read AC A human right
... asteroids vs duke nukem :D
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.
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 exactly what TFA is talking about, but I dislike how the very real threat of asteroids is trivialized in the public mind. Every time astronomers discover a remotely threatening asteroid, anything that hits 1 on Torino scale, journalists warn of a dangerous collision that could wipe out a continent, yadda yadda, while further observation of the asteroid over the next weeks shows that there's no chance of collision. So the public hears these stories about asteroids at least once a year and many thus think that it's a bogus threat because, oh, whenever journalists warn of a possible collision it turns out to be a non-threat, so it will never be a threat, right?
Makes me wish that journalists would just shut up about any objects lower than 3 on the Torino Scale.
If you identify objects on collision course in time, only a very minor adjustment in its trajectory will result in it missing by a very wide (and safe) margin.
"Waste not one watt!" - CZ
Well, duh! Nukes are second best, only to be used if Chuck Norris is unavailable.
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.
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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Didn't anyone ever watch Star Trek? This is such a simple problem. Just change the gravitational constant of the universe, thereby altering the mass of the object and making it easy to move. Oww! Where is that doctor?!
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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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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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."
An International Body - you mean like the U.N.? What do you think would happen if we put them in charge? They'd mail a letter to the asteroid explaining that they are very disappointed with its current trajectory, and in the end any direct action would be vetoed by China.
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.
Debian FTW
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 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.
Okay, I confess. We were trying to reduce the crapload of nuclear devices on this planet in a manner that seemed perfectly logical, with no casualties, only slightly technically flawed, but easier to explain. *You* just had to piss on this peacenik'x parade.
/me grumbles
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Wouldn't it make sense to try it as an experiment to gather hard data on how different types of asteroid react and as an excercise in examining the logistical problems and actual effect from a practical perspective?
It may make sense to have a gun, but if you don't know *which* gun to use...
My ism, it's full of beliefs.
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.
After all, they already had asteroid-blasting spaceships in the late 70's.
Don't worry, your spelling is impeccable.
Of course. I left the calculations for longer lead-times as an exercise for the reader. I figured that having shown how much of a change you could get in only six months was enough to demonstrate the principle.
Actually, now that I think about it, under some circumstances 2000 miles or so might well be ample. If the impact is expected along what might be called the Earth's trailing edge, or near one of the poles that would be enough to make it miss completely, without even skimming the atmosphere. Not all impacts are going to be dead center, you know.
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I guess the big question is, with all the weaponry we have lying around, why bet on one? I say machine gun nuke the thing to kind of coral it away from us. Send em up 2 or 3 at a time. One to divert the asteroid and the other two to slow/vaporize the mess the first one made. The wiki says we have somewhere around 10,000 in the US alone, so if an asteroid comes, lite it up!
But what if your nuke doesn't make it and destroys the only bridge out of town?
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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.
Even people that believe in pre-destiny look both ways before crossing the street.
I remember that show (not hard, as it's being rerun every two weeks or so), and one thing that they seemed to just skirt across was the alternative:
* Get hit by one huge asteroid that will get through the atmosphere with no problem
* Get bombarbed by thousands of much smaller pieces that will be heavily affected by the atmosphere and spread the now reduct impact over a much larger area
Hell, even if you just break it up into say 1,000 even sized pieces and don't manage a reduction in total mass, you could go from a civilization ruining even to something that is easier to recover from. If we did it to a ~5 km diameter asteroid heading for us, each impact meteor would be reduced from 83 km^3 to 83,000,000 m^3 or 500 m across.
But sure, if it's headed for some random country in Africa I suspect most politicians in the countries able to do something would just shrug their shoulders and prepare for after effects like ejecta and minor earthquakes.
We do not live in the 21st century. We live in the 20 second century.
You honestly believe that the flight time for an icbm allows the opportunity for the target to evacuate an area? fuel up lots of bombers? launch a counter strike?
With icbms there is no need for nukes in orbit to attack land targets. It is a totally pointless exercise *and* it leaves your nukes sitting around in orbit subject to damage from debris, jamming, capture, or attack from anti-sats or land based energy weapons.
Ridiculous.
I agree that in some cases 2000 miles would be ample, I certainly didn't mean to imply that every collision course was going to be a dead centre hit!
My point was that the distance required when such small deflections becomes a major hinderance to the mission. If we are planning to intercept an asteroid many months (years even) from impact we should be planning to do so well outside our solar system. This may mean we would need months or years for the intercepting weapon to reach the asteroid... not to mention the pre mission planning etc.
With all that (very vague argument) done, I would have speculated that the obvious "best" solution is to have a capability that can operate within a number of weeks of impact (or a few months). Not only does this allow response to late detections, but all asteroids travelling extremely quickly. Further more, there is less chance of some mishap occuring during the interception flight wich would also be much shorter. This would also make manner missions easier if humans are required for any part of the mission.
So I happily accept that a nuclear option may work, but if a shorter range and easier/faster to deploy option is available I would see it as preferrable.
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.
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.
We do not live in the 21st century. We live in the 20 second century.
We'd just need to put Jerry Bruckheimer on it. The asteroid will suck itself into oblivion.
Wiki, Asteroid Deflection
NYT Study suggests mirrors best
NASA has non-nuke plans
Using a 300Kg impactor
Seems the consensus is that nukes would only be used if we discovered the asteroid too late for other methods to be effective.
Anarchists never rule
> and in the end any direct action would be vetoed by China.
And likely Russia too. :-)
(Flying there later today... Russia, that is, not China or an asteroid, although I'm sure are those who would prefer I travel to the latter :-)
Ian Ameline
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
Why don't we just send up a bunch of Jehovah's Witnesses with pamphlets? I have seen even the biggest, strongest men hide behind the sofa when just one of them is at the door; it shouldn't take more than, say, ten to make an average sized asteroid go away.
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.
Yeah, blowing up (as opposed to imparting a net impulse) such a rubble-pile-type asteroid with a nuke would slightly disperse it temporarily, after which it would largely reassemble under its own gravity and continue on its old course (center of mass etc..), only now its radioactive as hell...
With a hard and rocky asteroid the nuke might fragment and disperse it effectively enough for the fallout to be worth it, but we better have some more tricks up our sleeve for the other types.
sudo ergo sum
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?
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