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Paintball Pellets As a Tool To Deflect Asteroids

Soulskill posted about a year and a half ago | from the get-'em-good dept.

Space 153

SternisheFan sends this quote from an article at MIT's Technology Review: "In the event that a giant asteroid is headed toward Earth, you’d better hope that it’s blindingly white. A pale asteroid would reflect sunlight — and over time, this bouncing of photons off its surface could create enough of a force to push the asteroid off its course. How might one encourage such a deflection? The answer, according to an MIT graduate student: with a volley or two of space-launched paintballs. Sung Wook Paek, a graduate student in MIT’s Department of Aeronautics and Astronautics, says if timed just right, pellets full of paint powder, launched in two rounds from a spacecraft at relatively close distance, would cover the front and back of an asteroid, more than doubling its reflectivity, or albedo. The initial force from the pellets would bump an asteroid off course; over time, the sun’s photons would deflect the asteroid even more."

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153 comments

Too tenuous (4, Funny)

hessian (467078) | about a year and a half ago | (#41792081)

That's a long shot plan right there.

I think sending Bruce Willis with a thermonuclear device and a boatload of family drama might work even better.

Re:Too tenuous (1)

ThunderBird89 (1293256) | about a year and a half ago | (#41792111)

It certainly would, for turning the equivalent of an FMJ round into a shotgun shell. My vote is for a big-ass chemical thruster, those still have the greatest specific impulse we can muster on short notice.

Re:Too tenuous (3, Informative)

Dr_Barnowl (709838) | about a year and a half ago | (#41792287)

Rockets have *terrible* specific impulse, around 450s for a complex bi-propellant liquid rocket, and 250s for the stable, reliable solid rockets.

Ion engines have specific impulse up in the thousands to tens of thousands of seconds.

Rockets have a lot more thrust per unit of engine mass, but getting enough propellent up there to give an asteroid sufficient delta-V would be all but impossible - for every big-ass rocket, you'd need a 10x bigger assed rocket to get it there in the first place.

Re:Too tenuous (4, Interesting)

Dekker3D (989692) | about a year and a half ago | (#41792455)

You could avoid half the delta-V by not slowing down-... just have the rocket speed up to max speed and slam into the asteroid. Calculate the engine size and fuel amount to be okay for the range you need it at, then make a few rockets to stand ready for various ranges. Crumple zones would let all the impact go into pushing, rather than shattering the thing. Even use some kind of internal room full of tiny airbags if you must. One-way valves (with a tiny air-hole for letting them deflate on impact and not burst prematurely) on all of them, inflate them the usual way or use a small amount of rocket exhaust that you cool down somehow. Simple, really.

Re:Too tenuous (2)

ShanghaiBill (739463) | about a year and a half ago | (#41792787)

just have the rocket speed up to max speed and slam into the asteroid.

But that "max speed" would not be very high. Rockets only make sense if you need a LOT of thrust in a very short period of time (say, to get off a planet's surface). But if we are going to deflect an asteroid we will need to do it when it is still months or years away from hitting the Earth. Which means you will have months or years (rather than minutes) to get up to speed. So an ion engine would make more sense. They provide little thrust, but they can keep it up for a very long time. For a given amount of fuel, they provide much more total delta-v.

Re:Too tenuous (0)

Dekker3D (989692) | about a year and a half ago | (#41792845)

That means I had the wrong timescales in mind. But yeah-... calculate projectile size, -type- and fuel amount for the range you need. It was implied, because at those ranges ion engines are more effective.

Re:Too tenuous (1)

toastar (573882) | about a year and a half ago | (#41792317)

Chemical Thrusters don't have high specific impulses, They have high thrust. If you want a specific impulse engine you'd use an ion thruster or a even a nerva.
The issue with any type of engine is first you have to arrest the asteroid's spin.

Re:Too tenuous (1)

TFAFalcon (1839122) | about a year and a half ago | (#41792925)

You could also some sort of a mass driver, only firing it when it's pointing in an appropriate direction.

Re:Too tenuous (5, Funny)

Anonymous Coward | about a year and a half ago | (#41792261)

Spaceballs ?

Re:Too tenuous (2)

Lt.Hawkins (17467) | about a year and a half ago | (#41793579)

Oh shit. There goes the planet... (surprisingly less off topic than one would suspect!)

Re:Too tenuous (1)

PolygamousRanchKid (1290638) | about a year and a half ago | (#41792349)

It would be better to give this to the Mythbusters crew. They seem to be particularly adept at blowing things up. The myth would be, "Humanity can be saved from an impending asteroid collision". It would suck if it gets busted.

Or now that we can make Higgs' Bosons in CERN, can't we shoot Higgs' Bosons at the asteroid, or something? Or if we untangle Superstring Theory, can't we just shove the asteroid into another unseen dimension?

Please be creative with your answers, Hollywood is monitoring this thread . . .

Re:Too tenuous (5, Insightful)

paiute (550198) | about a year and a half ago | (#41792461)

That's a long shot plan right there.

I think sending Bruce Willis with a thermonuclear device and a boatload of family drama might work even better.

Modded funny but is actually insightful. What would happen is that the chance of the giant asteroid actually hitting the earth will start out less than certain, so the large expense of sending a mission to deflect it far from earth using a gentle push would result in debate and delay. Then the odds of impact will increase, but the expense of the mission will still be high. We will piss and moan, and a loud minority of self-anointed space experts who begin to say that the rock is actually going to miss, that it is all a liberal/conservative/alien conspiracy, that there is really no asteroid, etc. will get a lot of press. Finally the thing will be visible from earth and the shit will hit the fan but by then it will be too late to use mild persuasion, and we will have to send up whoever passes for Bruce Willis with a crapload of nukes. We will blow it into chunks, maybe even into gravel whose kinetic energy strips away the atmosphere.

science. (0)

Anonymous Coward | about a year and a half ago | (#41792085)

Not as uncool as you thought!

How accurate is his simulation? (0)

Anonymous Coward | about a year and a half ago | (#41792093)

first or second order accurate.
Either way I don't feel safe!

Re:How accurate is his simulation? (1)

jamesh (87723) | about a year and a half ago | (#41792583)

first or second order accurate.
Either way I don't feel safe!

If they declare that an asteroid is "headed towards earth" without taking into account the effect of photons in the first place, i'd have to wonder a little. What if they decide that an asteroid is not headed towards earth, but it happens to be "blindingly white" and the photons change its course so it is headed towards earth.

Why worry (0)

slashping (2674483) | about a year and a half ago | (#41792097)

The chance of getting killed by a car when crossing the road is orders of magnitude larger than the chance of getting killed by an asteroid.

Re:Why worry (3, Insightful)

MightyYar (622222) | about a year and a half ago | (#41792137)

That's true, but there's something more unnerving about losing the entire human race.

Re:Why worry (3, Interesting)

slashping (2674483) | about a year and a half ago | (#41792195)

It would take a huge asteroid to wipe out the entire human race. We're talking once every 100 million years, or so. Before we spend any resources on detecting and deflecting asteroids, let's wait another 1000 years. On the scale of large asteroid impacts, a 1000 year delay is insignificant, but on the scale of human civilization, 1000 years is huge. If our civilization is much more advanced in 1000 years, we don't need our dated asteroid impact plans. If civilization crashes, our plans will be useless anyway.

Re:Why worry (4, Insightful)

tnk1 (899206) | about a year and a half ago | (#41792321)

Your point is valid, except that the problem with estimates like that is while they are useful for estimating the risk, they don't say much about whether an asteroid of the required size is actually on its way. In other words, we don't get a do-over if the rock shows up earlier than we thought it would. Not to mention that rocks of the necessary size could be generated by the effects of a collision with another body which then suddenly expels a rock on a collision course with Earth. In that situation, we may well not see it coming until just before the window in which we need to take action to deflect it.

Existential threats like asteroid impacts are situations that you start planning to deal with as soon as you have the knowledge to do so. There is really no reason not to, since given the extreme consequences, it doesn't seem particularly absurd to maintain those plans in a constant state of revision. We know that an asteroid of sufficient size is going to hit again. It's only a matter of time. Maybe that time is a million years from now, maybe it's a week from now. I grant that we shouldn't be building an expensive specialized asteroid defense grid or mineshaft shelter/habitats right now, but an actual plan that could be feasible in the event that we end up with an unforeseen visitor is the right thing to do. In this case, scientists realize that it is very easy to miss Earth if you poke at the asteroid just a little bit when it is far enough out. It's a reasonable plan that really should not require that much expenditure to make happen, if required.

Re:Why worry (1)

slashping (2674483) | about a year and a half ago | (#41792347)

I agree it won't hurt for people to spend some time brainstorming about this in their spare time. But before we actually set up a budget to look into this on a more structured scale, it would probably be better to use the same budget to improve road safety, for example, or encourage people to stop smoking.

Re:Why worry (1)

davester666 (731373) | about a year and a half ago | (#41792467)

We've got more than enough already. It's ok for the herd to be thinned a bit through stupidity and/or poor choices so we can spend a bit more on reducing the chances that everybody is lost.

Re:Why worry (4, Insightful)

Opportunist (166417) | about a year and a half ago | (#41792563)

Problem is, the herd thinning would not be done by brains power but by purchasing power. Now imagine an Earth where only managers and bankers will survive. The living will envy the dead.

Re:Why worry (1)

symbolset (646467) | about a year and a half ago | (#41793861)

Our ability to gauge these isn't perfect, but Extinction asteroids do come about every 100 million years, and the next one is either due now or late. The distribution isn't random. It's cyclic.

Re:Why worry (0)

Anonymous Coward | about a year and a half ago | (#41792289)

That's true, but there's something more unnerving about losing the entire human race.

I knew it wouldn't take long for someone to bring up "race" into the discussion.

Re:Why worry (1)

Opportunist (166417) | about a year and a half ago | (#41792545)

Why? You say that as if it's something bad?

Probability and magnitude are both relevant (5, Insightful)

perpenso (1613749) | about a year and a half ago | (#41792139)

The chance of getting killed by a car when crossing the road is orders of magnitude larger than the chance of getting killed by an asteroid.

True. However one asteroid can kill all of us, unlike one car.

The probability of an event must be combined with the magnitude of an event when assessing the risk.

Re:Probability and magnitude are both relevant (1)

slashping (2674483) | about a year and a half ago | (#41792161)

But there's not just one car, there are about a billion cars, so even if you multiply the probability by the magnitude, the asteroid is still insignificant.

Re:Probability and magnitude are both relevant (1)

Anonymous Coward | about a year and a half ago | (#41792279)

I'm not sure you've thought this through. The likelihood of the Earth being hit by an impactor that's large enough to wipe out humanity is 1 in 1. It's going to happen. The likelihood of humanity being wiped out by all the cars on the planet is somewhat less than that.

Re:Probability and magnitude are both relevant (0)

slashping (2674483) | about a year and a half ago | (#41792323)

The likelihood of the Earth being hit by an impactor that's large enough to wipe out humanity is 1 in 1

No, because there's a good chance humanity will be gone before that big impactor hits the earth.

Re:Probability and magnitude are both relevant (0)

Anonymous Coward | about a year and a half ago | (#41792373)

While you are at it, can you tell me the winning lottery numbers?

Re:Probability and magnitude are both relevant (0)

Anonymous Coward | about a year and a half ago | (#41792657)

While you are at it, can you tell me the winning lottery numbers?

39, 69, 3, 34, 84, 25

For some lottery, eventually, probably before the extinction level asteroid strike though.

Re:Probability and magnitude are both relevant (1)

Roachie (2180772) | about a year and a half ago | (#41793529)

ya know its really too bad you posted as AC, I would have bumped this one up.

Re:Probability and magnitude are both relevant (0)

guises (2423402) | about a year and a half ago | (#41792355)

Things that happen after I die aren't important. I don't know why people keep railing on about this "environment" nonsense either, somebody wasted my time with his "endangered species" prattle just this morning - I could eat nothing but Ethiopian wolf every day for the rest of my life. That's not a shortage.

- Rush

Re:Probability and magnitude are both relevant (1)

jamesh (87723) | about a year and a half ago | (#41792651)

Things that happen after I die aren't important. I don't know why people keep railing on about this "environment" nonsense either, somebody wasted my time with his "endangered species" prattle just this morning - I could eat nothing but Ethiopian wolf every day for the rest of my life. That's not a shortage.

Millions of years have ensured that the surviving genes are the ones that do things to ensure the survival of their offspring.

You, sir, are an evolutionary dead end, so I guess the problem takes care of itself.

Re:Probability and magnitude are both relevant (1)

ThatsMyNick (2004126) | about a year and a half ago | (#41793829)

Is you last name Limbaugh, by any chance?

Re:Probability and magnitude are both relevant (1)

Rhywden (1940872) | about a year and a half ago | (#41792351)

Ah, I see now. That's why some people are so dead-set against self-driving cars!

Re:Probability and magnitude are both relevant (0)

Anonymous Coward | about a year and a half ago | (#41792533)

Ah, I see now. That's why some people are so dead-set against self-driving cars!

Perhaps we should require that all self-driving cars must carry a passenger. The survival of humanity is at stake after all.

Re:Probability and magnitude are both relevant (1)

Hentes (2461350) | about a year and a half ago | (#41792941)

Assuming that you care about the survival of the human race. For people who don't, fear of asteroids is irrational.

Re:Why worry (0)

Anonymous Coward | about a year and a half ago | (#41792145)

As soon as an asteroid wipes out the human population, those odds are gonna shift a bit.

Re:Why worry (1)

fuzzyfuzzyfungus (1223518) | about a year and a half ago | (#41792187)

As soon as an asteroid wipes out the human population, those odds are gonna shift a bit.

True, the odds of anybody getting killed in a car accident will be substantially lower than they are now after an apocalyptic asteroid strike...

Re:Why worry (1)

tnk1 (899206) | about a year and a half ago | (#41792329)

We could all end up in a future like The Road Warrior. Looked to me like everybody in that post-apocalyptic situation died in some sort of car-related accident.

Re:Why worry (1)

fox171171 (1425329) | about a year and a half ago | (#41792205)

The chance of getting killed by a car when crossing the road is orders of magnitude larger than the chance of getting killed by an asteroid.

The odds of winning big in the lottery aren't very high either, but guess what? It happens to someone on a fairly regular basis.

As for an asteroid striking the Earth... maybe not likely in the short term (where it is almost infinitely unlikely), but in the long term the likelihood becomes very high (long enough term and it becomes infinitely probable).

And maybe, just maybe, you'll win the lottery and be struck by a car while the driver is looking up at an incoming asteroid.

Re:Why worry (1)

slashping (2674483) | about a year and a half ago | (#41792251)

In the long term, we're all dead anyway. And I don't play in the lottery either. It's just as silly as worrying about asteroids hitting me.

Re:Why worry (1)

MisterSquid (231834) | about a year and a half ago | (#41792947)

In the long term, we're all dead anyway.

Rationalizing action or inaction with the fact that everyone and everything will one day be dead always fails to convince. The fact of our mortality and the eventual end of everything we know is obvious to anyone who is alive to contemplate reality.

The more interesting course of behavior is to strive even in the face of such facts, precisely as so many of us do.

Re:Why worry (1)

GrumpySteen (1250194) | about a year and a half ago | (#41792209)

On noes! Someone is doing something that I don't think is worthwhile! Make them stop!

Re:Why worry (1)

slashping (2674483) | about a year and a half ago | (#41792245)

Hey, they can fantasize all they want, but I get to vote whether I want to have my tax money diverted to crazy projects.

Re:Why worry (1)

Opportunist (166417) | about a year and a half ago | (#41792601)

Not really, you only get to decide which crazy project your tax money will be wasted on.

Re:Why worry (1)

Alwin Henseler (640539) | about a year and a half ago | (#41792215)

Depends on where you're walking; if you walk right in front of an asteroid, your chances of getting killed by it go up quickly.

Re:Why worry (0)

Anonymous Coward | about a year and a half ago | (#41793053)

Five-hundred meteorites hit Earth each year. Megaton-sized Tunguska-style meteor airbursts happen every 300 years, but kiloton versions (i.e. as powerful as the nuke dropped on Hiroshima) happen about every year (usually over the ocean). One km meteorites hit every half-million years, ten kilometer meteorites hit every ten million years, and every 27 million years there's a mass extinction.

Thus, it wouldn't be surprising if thousands or millions of people were killed by an impact event during our lifetime. That's dwarfed by the number of vehicle fatalities, but it's still high enough to make it an important concern.

Of course, if it doesn't work (0)

Anonymous Coward | about a year and a half ago | (#41792127)

We can all die a colorful death

Re:Of course, if it doesn't work (0)

Anonymous Coward | about a year and a half ago | (#41792155)

We can all die a colorful death

Not really. Its just white paint, seems kind of boring.

Re:Of course, if it doesn't work (2, Funny)

Anonymous Coward | about a year and a half ago | (#41792167)

Not really. Its just white paint, seems kind of boring.

Steve Jobs just turned twice in his grave.

Re:Of course, if it doesn't work (0)

Anonymous Coward | about a year and a half ago | (#41792335)

It'll be white on one side, dark-coloured on the other, and it'll have rounded corners. Steve Jobs just started wanking again.

Re:Of course, if it doesn't work (1)

Opportunist (166417) | about a year and a half ago | (#41792621)

...and sued the organization staging the project into oblivion, resulting in no money being left to save the human race. But you have to understand, he had to do it to protect the shareholder value.

why not a simple rocket (1)

cats-paw (34890) | about a year and a half ago | (#41792149)

with enough advance warning would simply landing a rocket on the asteroid and having it provide a constant thrust be enough to have the asteroid miss ?

at a great distance it would take very little course adjustment which could be provided by a very low thrust.

the obvious complication being if it's tumbling. even then it seems that such a scheme would still work as the rocket could align itself under guidance or using the stars and provide force at the proper time.

not sure why this is never mentioned as an option.

Re:why not a simple rocket (0)

Anonymous Coward | about a year and a half ago | (#41792211)

If you have enough time, and enough resources, there are lots of options. The more advanced version of this is steering the asteroid into orbit, then mining it.

Re:why not a simple rocket (1)

slashping (2674483) | about a year and a half ago | (#41792223)

How much thrust would you be able to generate for long periods of time, and where does the energy come from ? Huge solar panels ?

Re:why not a simple rocket (0)

Anonymous Coward | about a year and a half ago | (#41792239)

That's the issue. On the other hand, dropping paint on the asteroid provides thrust as if powered by a solar panel the size of the painted area, so paintballs > simple rocket.

Re:why not a simple rocket (1)

Anonymous Coward | about a year and a half ago | (#41792285)

Not really. Photons carry a lot of energy, but hardly any momentum. It is much more efficient to use the energy collected from a solar array to power a thruster of some sort (which ejects reaction mass, i.e. propellant) to generate the momentum change, rather than relying on the miniscule momentum imparted upon the array directly.

Re:why not a simple rocket (1)

Opportunist (166417) | about a year and a half ago | (#41792735)

Would be cool if that propellant could somehow be mined out of the asteroid itself. Kinda like pressing pellets of the asteroid soil and hurling it into space.

Hey, how's that more crazy than shooting at it with paintball guns?

Re:why not a simple rocket (1)

Roachie (2180772) | about a year and a half ago | (#41793591)

Because with paintball pellets we will have to put some goggles or a mask on the asteroid.

Re:why not a simple rocket (0)

Anonymous Coward | about a year and a half ago | (#41793211)

To be more quantitative, when you throw something at non-relativistic speed v, the momentum-to-energy ratio is 2/v, so you want to eject reaction mass as slowly as possible -- ideally just barely above escape velocity. Photons have a momentum-to-energy ratio of 1/c -- the smallest possible.

Re:why not a simple rocket (1)

SJHillman (1966756) | about a year and a half ago | (#41792225)

It's been mentioned quite often... probably why it's no longer considered news

Re:why not a simple rocket (1)

tnk1 (899206) | about a year and a half ago | (#41792405)

Painting the asteroid, assuming there was a good way of doing it, is probably more reasonable than building an engine to do it. The rocket engine would be more complicated and need to be lifted off Earth and make it to the asteroid in operable condition, whereas all you need to do with the paint is disperse enough of it to thinly cover the asteroid.

There is also the possibility that if you believed that the underlying material of the asteroid was lighter or would outgas, you could set off explosions to disrupt the top layer of material on the object and expose the lighter colored material to the sun which would then start causing release of those materials in gaseous form. That would probably work best with a comet, since they are probably chock full of volatiles. The only issue is that if you did rely on outgassing from the comet, you'd have to make sure the new route was predictably away from Earth. Of course, given how hard it is to hit Earth in outer space, as long as you didn't win the lottery, almost any change in its velocity or bearing would make it miss.

Re:why not a simple rocket (0)

Anonymous Coward | about a year and a half ago | (#41792407)

extinction level asteroids are very large. Good fun to calculate the burns required to accomplish this, assuming it's detected 3 years out, and making decent estimates about the art of the possible for asteroid thrusters.

Re:why not a simple rocket (3, Insightful)

Arker (91948) | about a year and a half ago | (#41792419)

Actually 'landing' on it would be a huge problem. An asteroid is not typically one large smooth rock, after all. And it will definitely be 'tumbling' in relation to you as well. So it would be a very difficult docking maneuver on an uncertain surface. And remember these things arent large enough to generate enough gravity to notice either. So it's basically all in zero-g.

Spraying a load of paint at it would be orders of magnitutude easier, and still wouldnt exactly be easy.

Re:why not a simple rocket (2)

gman003 (1693318) | about a year and a half ago | (#41792425)

The problem is fuel. We don't have rockets that can fire for months. We have rockets that can fire for minutes. They provide a huge amount of thrust during that time, but you would need far, far more thrust than any existing rocket can provide to move an asteroid off-course.

A vague possibility is an ion engine of some sort. These have much lower thrust, but can run much longer off the fuel they carry. The technology still isn't very proven, though - and trying to land an engine, intact, on an asteroid, it a tough proposition.

The paint idea sounds more feasible. It's basically making it into a cheap, inefficient solar sail. It doesn't require tricky landings, it doesn't require a lot of fuel, you just aim some "paintballs" on a ballistic intercept path. The only downside is that, being inefficient, you have to catch it early. But if you've got a decade's warning or so, you should be good.

Re:why not a simple rocket (2)

Opportunist (166417) | about a year and a half ago | (#41792723)

Not as easy as it is on the drawing board. First, that rocket would have to be aligned EXACTLY with the center of gravity or all you accomplish is giving it a nice spin. Now, we don't even know for sure just what the asteroid is made of, let alone know the exact point of its COG. Many asteroids are anything but spherical, making the matter even worse. Considering how there is very little gravity acting on it, is it solid in the first place? Or composed of many smaller rocks held together by their gravity?

But let's even assume that you manage to find out the COG. Now you have to not only land a rocket fairly softly on the rock, you also have to be able to provide thrust on the OTHER end, because you want to push TOWARDS the rock after landing on it. Now, rocket engines are not really lightweight, and putting a few pounds into space is already a feat and a half, and we're not even close to talking about having enough fuel left to push that rock. There is a reason that Saturn V was an effin' HUGE rocket that put a relatively tiny payload onto the moon. And that all only worked because the moon gravity is a tiny fraction of Earth's gravity (which is, btw, one of the big problems of a manned Mars mission, but I digress). And you now don't just want to put that payload, i.e. a few rocket engines and a fair lot of fuel, up the gravity well towards the Moon but most likely beyond that, because if the asteroid is already THAT close, I guess the amount of fuel necessary to even push it from hitting New York to hitting Los Angeles would be unfeasible. At the very least I'd estimate you have to intercept that rock halfway between Earth and Mars. But people with more background in gravity astronomy might provide more insight here.

TL;DR version: We know too little about asteroids to push at the right spot, and putting an engine with fuel on an asteroid costs a damn lot of fuel.

Re:why not a simple rocket (1)

Nyeerrmm (940927) | about a year and a half ago | (#41793181)

Landing on a tumbling small body is not something you 'simply' do. Doing it to apply significant thrust is even harder due to center-of-gravity issues.

A better way to have the same effect is to use a gravity tractor approach. By hovering away from the asteroid, you can use the gravitational attraction of the spacecraft on the asteroid in the same way. Since you'd need to use low thrust engines to get a significant amount of force over a reasonable time frame, the fact that the gravity tractor limits the amount of force you can apply is not too much of a constraint.

However, the advantage of this painting method (we studied something similar in graduate school, the sticking point is how to get it to adhere to the surface) is that it requires the spacecraft to perform a one-time operation, but the effect is permanent, and over 50 or 100 years it could push an earth-crossing asteroid onto an orbit that was perfectly safe. If you could send one mission out to take care of a few of the more risky ones you could do it fairly inexpensively, assuming you figure out the material issues.

Too hard, just move the earth (0)

Anonymous Coward | about a year and a half ago | (#41792175)

Have everybody sun-facing to hold up a mirror or something....

Why would increasing the albedo... (1)

taylormc (926607) | about a year and a half ago | (#41792243)

...change the number of photons impinging on the asteroid, or increase their effect?

Re:Why would increasing the albedo... (3, Informative)

slashping (2674483) | about a year and a half ago | (#41792365)

Increasing the albedo makes the photons bounce back, which requires a bigger change in momentum than just stopping them.

Better off using marbles (1)

Gothmolly (148874) | about a year and a half ago | (#41792263)

For the same weight, you'll transfer a lot more KE to the asteroid with a marble.

Re:Better off using marbles (1)

jklovanc (1603149) | about a year and a half ago | (#41792381)

The KE is only a small part. The paint will increase the albedo of the asteroid therefore the thrust from the sun.

Re:Better off using marbles (1)

jo_ham (604554) | about a year and a half ago | (#41792415)

Is that weight under Earth gravity, weight during acceleration to the asteroid, weight during cruise, or weight while it's being fired at the surface?

Re:Better off using marbles (1)

oodaloop (1229816) | about a year and a half ago | (#41792691)

Yes.

Re:Better off using marbles (1)

Nyeerrmm (940927) | about a year and a half ago | (#41793135)

The immediate transfer of kinetic energy is a small effect. The larger effect is a change in the albedo, particularly on a rotating asteroid, because that allows you to affect how the Yarkovsky effect is applied.

When you change the Yarkovsky effect, it changes a force that is applied along the velocity direction, causing it to speed up or slow down: this is the most effective way to change the orbit in a way to avoid an impact. Because the force is applied for a very long period of time, it can avoid both the immediate impact risk and cause the object to move to an orbit that is permanently safe -- however, thats a 50 or 100 year effect.

Of course this all applies to small asteroids. For a large one you're still left with with gravity tractors/explosives/etc.

And a near miss? (1)

edibobb (113989) | about a year and a half ago | (#41792297)

So I'd better hope the one that's headed for a near miss is black, so it doesn't curve and land on my house. It is senseless to worry about something with such infinitesimal odds, though. We should worry about the baggage retrieval system at Heathrow instead.

We need better tracking first (3, Informative)

runeghost (2509522) | about a year and a half ago | (#41792313)

We've known that incoming (and outgoing - the Yarkovsky effect) radiation can alter an asteroid's trajectory for ages. But such a solution needs to be implemented far in advance of any pending impact. At present, we don't know the trajectory of potential impactors, like 9942 Apophis, to sufficient precision to make a deflection strategy like this useful. While it's true the odds are exceedingly small, accidentally putting an asteroid into a dangerous orbit would be disastrous. Apollo astronaut Rusty Schweickart proposed putting a tracking beacon on Apophis in order to further refine its orbit, which would allow us to use such gentle deflection strategies as the one outlined in the article. NASA turned him down. Fortunately, the Russians are currently planning a mission to Apophis; so maybe it will end up getting deflected via a generous application of paint.

Long shot entrepreneurialism (1)

macraig (621737) | about a year and a half ago | (#41792341)

I'm getting into the paintball manufacturing business on Monday. Look for my Kickstarter project, peoples.

albedo sounds like libido!? (0)

Anonymous Coward | about a year and a half ago | (#41792353)

pellets full of paint powder, launched in two rounds from a spacecraft at relatively close distance, would cover the front and back of an asteroid, more than doubling its reflectivity, or "libido"

lasers! (0)

Anonymous Coward | about a year and a half ago | (#41792369)

the right answer is always lasers!

Re:lasers! (0)

Anonymous Coward | about a year and a half ago | (#41793443)

the right answer is always lasers!

Nope, blasters.

Re:lasers! (1)

Roachie (2180772) | about a year and a half ago | (#41793625)

The problem with lasers is that you always seem to have to divert power from your shields and warp drive.

Momentum transfer (1)

GrahamCox (741991) | about a year and a half ago | (#41792383)

I'm not sure if I'm right, but my first thought was "surely the colour doesn't matter, since the momentum of the photons are transferred whether they are absorbed or reflected?". Perhaps someone with more knowledge of the relevant physics can answer.

In any case, it seems like a very impractical proposal. Shouldn't students be given more useful topics to make studies of?

Re:Momentum transfer (1)

jamesh (87723) | about a year and a half ago | (#41792727)

I'm not sure if I'm right, but my first thought was "surely the colour doesn't matter, since the momentum of the photons are transferred whether they are absorbed or reflected?". Perhaps someone with more knowledge of the relevant physics can answer.

In any case, it seems like a very impractical proposal. Shouldn't students be given more useful topics to make studies of?

I'm not a physicist, but if the overall momentum of the system is constant, and we consider the original state of the system where a photon is headed towards the asteroid, then the alternate resulting states of the system are:

1. photon is absorbed by the asteroid.

2. photon is reflected by the asteroid and is now moving in the opposite direction

and state 2 must have the asteroid moving slower relative to the direction it was hit by the photon to conserve the total momentum of the system.

Of course photons travelling at the speed of light may not strictly obey newtonian physics, so I may be way off...

Re:Momentum transfer (0)

Anonymous Coward | about a year and a half ago | (#41793251)

I think the heating/radiating effect is what we're actually after here. Lets keep our eye on the ball, people.

Asteroid deflectors will get FREE advertising! (3, Funny)

crovira (10242) | about a year and a half ago | (#41792431)

Imagine your company logo emblazoned across the surface of an asteroid.

Not only will your company have done something great for all mankind, but mankind will be reminded of it in perpetuity.

First we paint the whole thing white and then get computer controlled pain ball guns to splatter, like an inkjet printer, your company's logo all over the asteroid.

Think of watching a Papa John's ad every time you look up in the sky and having to say a little prayer that you can actually enjoy a large nutritious Papa John's pizza instead of having been reduced to a smokin' crater . :-)

Re:Asteroid deflectors will get FREE advertising! (1)

zammer990 (2225956) | about a year and a half ago | (#41793121)

The inevitable problem is betting shops would offer really good odds on an asteroid not hitting the earth, and then have a big black square painted onto the asteroid

Issues. (2)

jklovanc (1603149) | about a year and a half ago | (#41792517)

Timing;
According to the article the paint would have to be applied 20 years before the asteroid approach. Add to that the time to get the craft to space, load up with paint and get out to the asteroid. That may take another 20 years. That may mean a 40 year lead time at launch to be remotely viable.
Control
Paint is not a guidance system. Sure it may be able to move the rock around but it will just be in an indefinite direction. It is just as possible to move the rock closer to earth as away. Sure it moves the rock away from earth but into a trajectory that interacts with a planet that pulls the rock back toward earth.
Other celestial bodies.
As other asteroids impact or come close to the "rock on question" they will alter the path. As the rock enters the Sol system planets will exert gravitational pull on the rock. The part or all 20 years of movement may be wiped out by interaction with another object.

To me the only viable option would be to land thrusters on the rock. Use them to stop the rotation (if any), re-position to one side of the rock and apply constant thrust to alter the course. The thrusters would have to be ion based (low fuel, long duration) and probably powered by solar satellites. A solar sail could be added for additional thrust once the rotation has stopped. The issue with icy asteroids can be dealt with by limiting the thrust of the engines so as not to break the asteroid.

If the rotation was not stopped it would require many more thrusters as they could only fire part of the time.

This "proposal" sounds like "paint and pray".

Society Of Protection of Asteroids (2)

jamesh (87723) | about a year and a half ago | (#41792679)

The Society Of Protection of Asteroids (SOPA) will not stand for this. Anything that stands in the way of an asteroids natural path is against nature and against God.

We're going to have to move the Earth out of the way instead... how much paint is that going to take?

Ok in theory but there are better methods (0)

Anonymous Coward | about a year and a half ago | (#41792783)

This would really only work for asteroids far out enough that a nuke detonated right next to them would move them enough. Also to launch a paint ball big enough to cover an asteroid that needs to be diverted would be half the size of the asteroid itself and any asteroids smaller than say a 3 story house would be burned up in our atmosphere and dont pose threat to require something like this to begin with so what they are talking about is a pair of paint ball big as the hubble and launching them at the front and back of a rock the size of a oil tanker or bigger... Oh and the launch mechanism would be the size of the iss and would have to be within spitting distance of the asteroid to begin with...

Yeah i have seen anime with better ideas than this one (stratos 4)

I think as far as a sustained method for redirecting a massive asteroid like this would be a pulsed ion drive so when ever the asteroid turned or rotated to a certain direction the pulse would go off and push the asteroid out of the path it was on or a pair of them one to get it spinning on an axis then another to push it after it is stabilized.

energy content (1)

Iamthecheese (1264298) | about a year and a half ago | (#41792791)

I can't believe this would perform better pound for pound than high explosives

I donno (0)

Anonymous Coward | about a year and a half ago | (#41792851)

If an asteroid is coming our direction with the goal of a deep impact, I am not sure increasing its libido is a good idea

Ice doesn't splatter (0)

Anonymous Coward | about a year and a half ago | (#41793343)

How can this get past so many people. In order for paint to splatter and cover some thing it must be kept liquid which in space its ABSOLUTE ZERO. The paintballs will hit like rocks and bounce off.

Re:Ice doesn't splatter (2)

guttentag (313541) | about a year and a half ago | (#41793763)

In order for paint to splatter and cover some thing it must be kept liquid which in space its ABSOLUTE ZERO. The paintballs will hit like rocks and bounce off.

It doesn't matter, because the amount of CO2 necessary to launch that many paintballs that distance would contribute so much to global warming we'd be better off taking our chances with the asteroid.

What we really need is a giant tinfoil hat to enhance the asteroid's reflectivity and a North Korean missile guidance system to ensure it can't hit anything.

movie trailer (0)

Anonymous Coward | about a year and a half ago | (#41793389)

One destiny. One planet.
In the biggest collaboration of human-kind in history.
A team of brave scientists set out to device
the biggest paint ball shooting spacecraft in history.

Now read that with the movie trailer guy voice

Remember (1)

rossdee (243626) | about a year and a half ago | (#41793453)

When playing Paintball in space, you will be pushed backwards by the recoil too

Frozen Paintballs (2)

TheSwift (2714953) | about a year and a half ago | (#41793607)

Among the many other problems already listed is whether or not paintballs will pop at 2.7 degrees kelvin.

Deflect what? (1)

user-hostile (1177051) | about a year and a half ago | (#41793731)

Did anyone else read that as "Paintball Pellets As a Tool To Deflect Assholes?"
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