How To Deflect an Asteroid With Today's Technology 264
Matt_dk writes "Apollo 9 astronaut Rusty Schweickart is among an international group of people championing the need for the human race to prepare for what will certainly happen one day: an asteroid threat to Earth. Schweickart said the technology is available today to send a mission to an asteroid in an attempt to move it, or change its orbit so that an asteroid that threatens to hit Earth will pass by harmlessly. But what would such a mission entail?"
Let's get this over with. (Score:5, Funny)
Bruce Willis.
Spoiler alert (Score:5, Funny)
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I, for one, would like to throw my support towards any effort that results in Ben Affleck being shot at an asteroid.
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You liked Titanic and you know it.
If you miss being non-monogamous so much, you should've stayed that way... I don't think it's far-fetched to expect the Slashdot crowd to grok alternative lifestyle choices.
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If you miss being non-monogamous so much, you should've stayed that way...
I miss the young more than the non-monogamous, and I didn't get a choice on that.
It's true that I do miss parts of being single at times or are nostalgic for its bright spots, but it's also true that I do overall prefer the life I've chosen to replace it with. My wife is amazing. Family life with anyone else I'd met or dated never seemed like a good idea, but this is right for me.
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Re:Let's get this over with. (Score:5, Funny)
Why not use Prism's Armageddon (Score:2)
It all depends on detection... (Score:5, Insightful)
Re:It all depends on detection... (Score:5, Interesting)
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Re:It all depends on detection... (Score:4, Interesting)
- Dan.
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a small impact could still devastate a city, and we could actually deflect it.
... to a neighbouring city, preferably one with a hated sports franchise.
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A big asteroid impact would also likely be out of our hands in terms of prevention
Depends on the value of "big". The biggest asteroids in the system have been mapped, and aren't threats. There's an upper limit on the size of any celestial body that might wander into us, baring something extrasolar. AFAIK, there is nothing that could impact us, could be detected, but couldn't be moved.
The key is time, as was rightly noted further up the thread. If the would-be impactor is still a year away, and we've got or can get the equipment needed to divert it ready to go in a hurry, we're fine.
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Then again, when we're talking at the "survival of the human race" level, city busting asteroids aren't really that big of a concern. Most likely, it would hit an ocean, or some piece of rural land with limited population. Even if it hit a city, humanity would go on. Of course it would be preferable to deflect it, but I think efforts should be directed at detecting and diverting extinction scale asteroids.
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It needs to be off-planet to see better.
Place it on the moon, in one of the 2 LaGrange points, in orbit, or where ever it makes $en$e.
Because right now we have next to nothing and this currently popular "manage by crisis" management style will do nothing to help.
Re:It all depends on detection... (Score:5, Interesting)
A vehicle placed at Venus's orbit, though, would be able to see those potentially dangerous asteroids quite well.
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The TWO Lagrange points? There are five last I checked.
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Do we have evidence that small asteroids can be detected this way? Does a small asteroid's albedo ever get high enough to be picked up by a small telescope?
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Depends on what you call small.
There's a mailing list, Minor Planet Mailing List [yahoo.com], where amateur and professional asteroid hunters congregate and their equipment covers the gamut from 8" up meters wide scopes.
Regardless of scope size, they are all limited by the fact that it's hard to look towards the sun to spot asteroids whose orbits are primarily sunward of us. A well shaded scope parked at a Lagrange point could go a long ways towards addressing that threat.
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Keep in mind that c-type asteroids have an average albedo of 0.03. Basically, pretty damn dark. But there will be points on these that are not. They will be seen as flashes of lights, which are normally ignored. However, if you have a dozen scopes looking in the same area of sky and are very remote from
Re:It all depends on detection... (Score:5, Interesting)
We don't only find the monster ones.
We commonly track asteroids under 500 feet wide [msn.com]; much smaller than a planet-killer.
It will be comparatively easy to detect a planet-killer sized asteroid and determine its trajectory in plenty of time to launch a deterrent mission.
A surprise impact by anything with major destructive capability is vanishingly unlikely at this point. Improvements in detection shouldn't be prioritized, but should be allowed to continue at a normal pace.
Deciding how to minimize the destruction should be the focus, and we don't really know how to do it with a high degree of confidence, yet. So deflection technology should be prioritized.
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I don't know why the solution is always to blow it up or crash something into it. We have a wonderful history of knowledge about how objects have avoided hitting the earth. A few giant planets in orbit farther from our sun than we are, and a moon. You don't crash things into the moving object. You let the moving object crash into your defenses.
For example, if someone is shooting at you, do you shoot at their bullet? No, you hide behind cover, or carry it with you.
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What now? You think that its easier to *MOVE THE MOON* or *LAUNCH A NEW MOON* rather than use a kinetic impacter or slow-push gravity tractor on an asteroid.
Anyway when you don't have a solid fixed reference (like the ground), the difference between trying to hit something or putting something in the way is really nonexistent. Just consider a kinetic impactor putting something in the way of the asteroid and you'll be happy.
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Well, we've only had a 50% success rate hitting Mars, so ya, I think a shield in closer proximity to earth would be a lot more manageable.
But, if you read the article, it's actually clear.
Where is the private sector here? (Score:2, Troll)
The Tennessee Fire Brigade has shown the right way. A subscription based detection system. Only the Asteroids that are going to hit the subscriber's home will be detected. If you don't pay the
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Cost of preventing impact >>> (cost of impact * probabilitiy of impact)
About once a century we get an impact that's equivalent to a few megatons, and there's a 75% chance of it hitting an ocean and about a 99% chance of not hitting a heavily populated area. Sucks if your farm happens to be ground zero, but there's no sane reason to spend billions of dollars a year trying to prevent it.
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Cost of insurance >>> (cost of all you own * risk of total burn-down)
Still sucks to be the one whose house is on fire. Expect, in this case, "one" is really "six billion" and "house" is "planet".
But other than that, yeah, you're right.
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I don't know why people keep saying this. LLNL were tasked with determining whether or not a big close asteroid could be diverted using nuclear weapons - that is, find out what the last resort is..
http://www.youtube.com/watch?v=1eOJ9doYtN0 [youtube.com]
They found that indeed, the use of nuclear weapons could deflect or even destroy an incoming asteroid. Yes, long term deflection using less extreme methods are much more preferable, but should it be necessary to take out an asteroid that is detected so late that it is al
Re:It all depends on detection... (Score:4, Interesting)
So please, stop doomsaying, the experts say they are ready to nuke the sucker if that's what needs to be done.
MIT were saying that back in the 60s, so it's not really news.
But there's the slight problem of being able to _get_ a nuke to the asteroid in the first place; the MIT study used an Apollo CSM on top of a Saturn V with a 100MT nuke on board, and there's not much hope of being able to fix up one of the remaining Saturn Vs to fly at short notice and nuke an incoming asteroid today (they also planned to launch 5-6 of them to allow for failures and near misses).
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oh come on. We know the nukes are already in orbit. Just ask Sean Connery or the guys from Def-con 4.
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Obviously it depends on detection time. If we detect the asteroid years ahead of time, then even tiny changes in course will save us from impact.
If you detect it years ahead of time, can you actually measure the orbit accurately enough to prove that it's going to hit, when a small error in orbital measurements could make the difference between impact and missing?
If you had a tiny error in the orbital measurement which just happened to match the tiny course change you applied a few years before impact, then you could take an asteroid which wasn't going to hit the Earth and _cause_ an impact.
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This could be done by simply crashing a small probe into it.
Not necessarily. With very dense asteroids (mostly iron) it would work, the impact should nudge it into a less dangerous path. However, if the asteroid isn't dense (think pumice stone) then the impact will either be totally absorbed and nothing will happen, or the asteroid will be shattered into multiple large fragments which will cause multiple smaller craters on the Earth's surface instead of one large one.
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You couldn't do it by station-keeping next to the asteroid. You'd have to maintain thrust directed at the asteroid. First, the thrust couldn't last very long, and second, it would just push the asteroid back away from the ship. You could fire it in a conical pattern, but then you decrease the effective thrust you get from your fuel.
All you really do by putting a lightweight object near an asteroid is create a heavier asteroid. If you have enough reaction mass to manage the sort of station-keeping you im
put it in a wormhole and have it jump over earth! (Score:2)
put it in a wormhole and have it jump over earth!
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tough choice (Score:3, Interesting)
What if we only have the ability to divert it a little bit, if and when that comes? Then we only control WHERE it hits, not WHETHER it hits. So how do we choose, I wonder?
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What if we only have the ability to divert it a little bit, if and when that comes? Then we only control WHERE it hits, not WHETHER it hits. So how do we choose, I wonder?
If the asteroid is big enough, it won't really matter where it hits. Anywhere on the planet will be a global disaster.
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Though most should be small enough that it will make a difference. Oh well, I'm sure what's good for space-faring countries will have to be good for humanity (of course it will get really funny if 2+ of them disagree)
And this mess is pretty much inevitable - in the initial stages of deflection, a risk for some places will rise while it gets smaller for some other (luckily: the uncertainties involved should be big enough so that it won't be clear which are which)
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Re:tough choice (Score:4, Interesting)
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Not to mention how much of the central parts of North America, Europe, Africa and Asia are mostly farmland, Grains and Veggies are amongst the most important to our diet, and we don't even have enough food to feed the world as it is.
So even if the dust was somehow not an issue, the kind of devestation that would happen on land is far worse than anything on the coasts. Having a few dozen cities evacuated and rebuilt is far preferable to mass starvation.
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Early Detection (Score:2, Interesting)
The most beneficial thing we could do is build a system to detect such asteroids as early as possible. Once located, it's easy to deflect an asteroid that's far away. A small nudge or impact from a probe or the like would push it out of an intercept course while it's still far away. The closer it gets, the more force is required to push it off at an angle that will keep it out of our way. It may take a few newtons of force to deflect an astroid coming in from as far away as saturn, but much more to defl
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It would be more fun to just blow it up.
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Think of deflection as playing interplanetary billiards (deflect one asteroid by just a little bit and have it strike another one such that both get out of our way, or deflect it so that instead of hitting Earth it hits Mars or Venus.) Actually, what would be really
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Yes.
So put the solar sail based power station up there, and start collecting the free solar energy. Then when we detect a threatening asteroid, we turn the beam on it. The material burning off of one small spot will be like a jet to coral the roid into the orbit more to our liking. We can continue to use the beam for as long as necessary.
The cost... (Score:4, Insightful)
Re:The cost... (Score:4, Funny)
None of them want to pay taxes again. Ever.
I don't think a spaceshipload of teabaggers is going to be the right choice skillset-wise for effectively deflecting an asteroid. Can't we just put them on the B-Ark and fly them into the Sun?
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Not that it's quite that dichotomy, but those "teabaggers" you ridicule aren't as stupid as you think that their politics are.
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Talking about the apocalypse... (Score:4, Informative)
This of course means that when the world does end it isn't our fault- it's the fault of the people from the future failing to post-predict the apocalypse and make a time machine to stop it.
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Speaking of the apocalypse:
Of course doomsday predictions are always for a future date. It would be much more interesting if someone figured out a doomsday prediction for a date 3 years past. That would mean someone has to make a time machine to go back and warn them that the world is about to end. Knowing the world didn't end we could be certain that we will succeed in the time-travel mission.
This of course means that when the world does end it isn't our fault- it's the fault of the people from the future failing to post-predict the apocalypse and make a time machine to stop it.
The interesting thing about this is that there are theoretically an infinite number of "people from the future," and an infinite amount of time for them to develop time travel and a method for averting an apocalypse.
So, if a world-ending apocalypse does happen, we'll at least know that time travel really is impossible.
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ok, here's one (Score:2)
Just point the LHC at it and poof, asteroid immediately gone when it entered the event horizon of a miniature black hole that was created.
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Nah. It would just continue on its route barely affected and now in black hole form. The positive is that it might pass through the earth with neither affected to much.
The best defense (Score:2)
NO! (Score:2)
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can someone make a slight "miscalculation" with the nukes and get rid of the Gary, Indiana problem, please?
solutions from the article (Score:4, Interesting)
The "impact" method stands the chance of splitting the asteroid into man little pieces, and since that process of splitting absorbs energy less of it is available to deflect the body from its current course. To have enough mass going at a high enough velocity to contain enough energy to nudge it into a different trajectory you need heavy lift rockets with very fast final stage projectiles. The more velocity the more energy, but the more of that energy that will create debris that potentially causes even more problems. The best solution would be a very heavy object moving slowly, but the would be impossible to lift and deploy. Using nukes would allow a smaller projectile, but would very likely cause radioactive debris to renter earth's atmosphere. Not good. Its better to land on it and push it into the sun's gravity well.
The 'Gravity tractor' method requires just as much energy as pushing the asteroid, but you need LOTS of mass to make it work. Again you need heavy lift equipment to make this work, and I seriously doubt you can lift enough mass into space, and move it to where it needs to be, in time to effect the trajectory by much. You are still better off using that same fuel to get there quickly and push it lightly for a while into a new trajectory.
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Using nukes would allow a smaller projectile, but would very likely cause radioactive debris to renter earth's atmosphere. Not good. Its better to land on it and push it into the sun's gravity well.
I thought the idea for nukes was to set the off well away from the surface so that one side of the asteroid ablates off producing a net thrust. This is preferred because it doesn't waste energy breaking a large rock into smaller pieces, doesn't create debris, and can also be effective on 'rubble pile' type asteroids.
And of course, the biggest advantage for a nuke is that it's the densest form of energy storage that we have, you can send a nuclear warhead up for way less delta-V than an equivalent amount of
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Or solar sail. Or utilize Yarkovsky effect by spraying the object with paint and/or shading it & illuminating different parts of it (again, basically a sail). With so many possibilities, we should be fine - assuming early enough detection.
Re:solutions from the article (Score:5, Interesting)
The ablation thing is inefficient. Use a nuclear reactor on the asteroid surface to melt itself down, melting a portion of the asteroid and directing it through the melt hole into space. You can send up a big reactor, use the asteroid itself as reaction mass, and get much more efficiency than a blast and an ablation.
As for "rubble pile" asteroids, those would tend to break up and explode in the atmosphere. The more you can disperse them before they hit the atmosphere, the better. So embed a nuclear bomb and explode it when it's a few days out, so it doesn't have time to reform.
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ESA has one nice analysis here [esa.int]
No, if early enough it doesn't require a very big mass at all, or some particularly asteroid-shattering impact (one other interesting, even if probably not particularly useful, method in the link above: centrifugal fragmentation; considering many asteroids seem to be barely held together rubble piles...)
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PS. Also, I'm curious, what exactly do you mean by "push it into the sun's gravity well"? It's constantly in it... virtually all the objects in our system are.
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Lassie: *BARK*
Lassie: *BARK*
Lassie, you're an evil little bitch.
Lassie: *BARK* *wags tail*
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Correct in the physical sense obviously, but somewhere along the line I...accreted an usage where "getting out of some gravity well" is a valid description; when it no longer keeps the body captive (doesn't the name itself, "well", suggest such usage)
And yeah, delta-v for plunging something into the Sun is typically higher than one required to reach some other stars. All the more reason to ask what it meant.
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He probably intended to say solar orbit as that ~30km/sec delta-v to actually "drop" an object into the Sun is a hinderance.
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I suppose one should calculate of what materials the Asteroid is made, and determine the least material necessary to make a combustion from those materials. If, for example, the Asteroid is ice; one could land, then use sunlight to convert water into hydrogen and oxygen, then fire off jets at optimal moments in the rotation. This isn't very complicated, and we've already intercepted an asteroid.
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If it is made of ice, use a microwave laser in orbit. Then you don't have to try to navigate a complicate piece of machinery all that way, while loosing weeks to travel time. If it is made of something else, use a carbon laser.
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Generally yes; but being there allows for combustion - one might have to bring part of a combustible mix. Are ice asteroids a threat - given the tendency to burn up in atmosphere?
With lasers, we can only hope to throw off some mass with the energy of sublimation; this I fear may be minimal.
If we are facing a death star, we should employ the best means at our disposal (include lasers), but intercept and combust should be considered - including nuclear' this BS about ew, it will enter our atmos is tripe - we'
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One concern I have with the gravity tractor idea is that it involves putting a huge mass into almost exactly the same orbit as the satellite to start.
Unless this is done VERY carefully, if there is a failure early in the process you end up with yet another big heavy thing that will hit the Earth.
It might be possible to plan the maneuvers such that at no point does the interceptor have a trajectory that will impact Earth. Essentially you'd have to aim "to the side" of the target, not so much literally as fr
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NASA worked out a 20ton gravity tractor a while ago that would do the job given a decade. The nudge and the tractor don't have to be excessive.
Other options include painting the object to change it's albedo (reflectivity), docking ion or nuclear engines to it, using magnetic accelerators and (long term) using the entire rock up for industrial use before it impacts.
So much depends on time-to-impact.
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The 'Gravity tractor' method requires just as much energy as pushing the asteroid, but you need LOTS of mass to make it work.
If you detect it early enough, then you really don't. A ton or two would be more than sufficient, and is easily liftable. I prefer this method if at all possible because it avoids all the problems of impactors, which also include having to make sure you hit it dead-on in the direction you want with no tangential deflection and at the center of mass.
The actual missions to deflect ast
Armchair astronomy (Score:2)
The article suggests two approaches:
...a kinetic impact would roughly “push” the asteroid into a different orbit, and a gravity tractor would “tug slowly”...by using nothing more than the gravitational attraction between the two bodies.
I didn't think we could produce enough kinetic energy to affect anything large enough to be a threat. Similarly, I would be surprised if we could get any significant mass into space to attract it via gravity. Am I totally off-base here? It seems to me that we would need to rely on either 1) nuclear power or 2) external power (solar?) to have any significant impact. For example: attach a solar sail to the asteroid to slow it down or change the direction. Or a solar-s
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Just because your target mass is large, doesn't mean you need a lot of mass to change its course. If you have a spaceship "heavy enough" to move a 1-ton rock, then it's also "heavy enough" to move a 100-ton rock because an object's deflection in a gravitational field is independent of that object's own mass.
This is an extension of an experiment you've probably seen in high school physics. Drop a tennis ball and a bowling ball, and they move just the same under gravity's influence.
But that's not to say tha
The Earth would be fine (Score:2, Insightful)
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Not so much "pedantic" as "meaningless". There is no measure by which to assess the wellbeing of the Earth; only its suitability to a purpose. The phrase "threat to the Earth", when used by a human, means "theat to the Earth's suitablity as our home".
Nukes (Score:2)
People hate to admit it, but this really is a mission that is best done with nuclear explosives.
Not to "blow it up," no-- but to produce an impulse to nudge it onto a slightly altered course, a surface nuclear blast is about the best technique you can think of. Nukes have extremely high energy to mass ratio. And, despite what Hollywood would have you think, you don't need to have Bruce Willis dig a hole in the asteroid to plant it.
Some analysis is needed to make sure that you nudge the asteroid, not fragm
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Nukes provide just a very short impulse; transferring it to the whole rubble pile might turn out to be problematic.
Gravity tractors (and few other methods) can work months, years; and force from them works uniformly (or in the case of some other methods - very gently)
Gorath - 1962 (Score:3, Informative)
You don't move the asteroid... you move the Earth! With lots of giant hydrogen powered rocket tubes at the South Pole!
http://www.youtube.com/watch?v=mf2lvRStVdg [youtube.com]
How to move asteroids. (Score:3, Insightful)
You find out its orbital and mechanical properties as early as possible.
Then you send a gravity tug to change the orbit.
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For the big asteroids, a single bullet would split the asteroid in half. Another two carefully aimed bullets would split the first halves in half again. A final set of four bullets would vaporise the asteroid fragments, as shown below.
O
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A
ETA: 2 days (Score:4, Informative)
Early detection must be improved... that some of the asteroids that we know could take 15 years to get here and so give us enough time to prepare don't mean that some unknown or even known ones (if you want, because somehow changed its orbit) could be in its way here and detected when is already too late.
wouldnt it be easier to... (Score:3, Funny)
I think we are looking at this the wrong way. We should instead be trying to turn the moon into our own deathstar. That way we can change its orbital position to deflect or intercept the asteroid. That way we get multiple uses out of it and can also rule the solar system once our deathstar becomes fully operational. How hard would it be to put enough rockets on the moon to be able to drive it around... Seriously NASA WTF are you guys doing trying to land a little rocket on a asteroid when you could be asking for funding to drive the Moon.
His plan won't work (Score:3, Funny)
On the other hand, if one of the scientists said that there was a possibility that the asteroid had a diamond core, a private sector solution would no doubt be undertaken by DeBeers.
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I see where you're going: Load up Rush Limbaugh in to Glen Beck's huge mouth. The pressure from all the hot air being unable to escape will build up. Very quickly that hot air will blast Rush Limbaugh in to space to impact the asteroid. This collision will be enough to deflect the asteroid back out towards space.
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Those don't actually solve the problem. As usual.
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