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Neil deGrasse Tyson On How To Stop a Meteor Hitting the Earth

samzenpus posted about a year and a half ago | from the warm-up-bruce dept.

Space 520

An anonymous reader writes "Astrophysicist Neil deGrasse Tyson talks stopping extinction-level meteor hits: '...Here in America, we're really good at blowing stuff up and less good at knowing where the pieces land, you know...So, people who have studied the problem generally – and I'm in this camp – see a deflection scenario is more sound and more controllable. So if this is the asteroid and it's sort of headed toward us, one way is you send up a space ship and they'll both feel each other. And the space ship hovers. And they'll both feel each other's gravity. And they want to sort of drift toward one another. But you don't let that happen. You set off little retro rockets that prevent it. And the act of doing so slowly tugs the asteroid into a new orbit.'"

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Neil deGrasse Tyson (-1, Troll)

Vinegar Joe (998110) | about a year and a half ago | (#43061319)

The Dr Phil of astrophysics.

Re:Neil deGrasse Tyson (-1)

Anonymous Coward | about a year and a half ago | (#43061331)

I agree, he's great for explaining stupid shit to proles, but as far as a professional scientist goes he has very little credibility in my book.

Re:Neil deGrasse Tyson (5, Insightful)

paiute (550198) | about a year and a half ago | (#43061367)

I agree, he's great for explaining stupid shit to proles, but as far as a professional scientist goes he has very little credibility in my book.

Great. You'd be comfortable with this future:

Scientists: By the way, there is a huge hunk of rock that is going to hit the earth tomorrow and wipe us all out.
Public: Wait - what? Why didn't you warn us?
Scientists: We discussed it at length at our obscure meetings. Why should we have to take time out of our important work to explain complicated shit in your terms? Stupid proles.

Re:Neil deGrasse Tyson (4, Insightful)

GPierce (123599) | about a year and a half ago | (#43061647)

Actually according to Doug Adams definitive history:

On a planet called Golgafrincham there was an an nouncement that the planet would soon be destroyed in a great catastrophe They planned an evacuation using a group of arcs:.

The passengers of the “A” ark were to be all the brilliant leaders, scientists, great musicians, data analysts, engineers and architects. The passengers of the “B” ark were to be all the “middle men” , marketing executives, telephone sanitizers , sales assistants and telemarketers etc. The passengers of the “C” ark were to be the real workers, construction, manufacturing and other craftsman.

As I remember it, everyone fought for a place on the B Arc which blasted off into space programmed to land on the third planet of an obscure star at the edge of the galaxy. Shortly after its departure, they discovered it was all a mistake and the planet was not going to be destroyed.

Golgafrincham entered into a period of exceptional peace and prosperity.

The planet that was the destination of the B Arc had a different kind of history.

Re:Neil deGrasse Tyson (1)

jhoegl (638955) | about a year and a half ago | (#43061689)

Worst...


Writing...


Ever

Re:Neil deGrasse Tyson (1)

flex941 (521675) | about a year and a half ago | (#43061711)

Diffrent kind of future. US.

Re:Neil deGrasse Tyson (3, Informative)

Anonymous Coward | about a year and a half ago | (#43061777)

Actually, they died by a mysterious virus spread through their filthy phones unless I'm mistaken.

Re:Neil deGrasse Tyson (3, Informative)

Joce640k (829181) | about a year and a half ago | (#43061815)

Golgafrincham entered into a period of exceptional peace and prosperity.

Um, no. They all died from a virulent disease contracted from a dirty telephone.

Re:Neil deGrasse Tyson (4, Insightful)

hawguy (1600213) | about a year and a half ago | (#43061373)

I agree, he's great for explaining stupid shit to proles, but as far as a professional scientist goes he has very little credibility in my book.

It's scientists like him that are personable and able to "explain stupid shit to proles" that help keep people interested in science and help make sure the scientists in your "credibility book" get enough funding from the proles to do their work.

Re:Neil deGrasse Tyson (-1)

Anonymous Coward | about a year and a half ago | (#43061409)

y would u trust a black moran in sicence, the white made siecence, we know that shit

Re:Neil deGrasse Tyson (3, Insightful)

flyneye (84093) | about a year and a half ago | (#43061567)

Not Mike Tyson, it's Neil De Grasse Tyson, Miss Latella.

Re:Neil deGrasse Tyson (1)

avgjoe62 (558860) | about a year and a half ago | (#43061843)

Oh, I get it - whitey made science but can't spell worth a damn. Makes perfect sense.

Re:Neil deGrasse Tyson (0)

aurizon (122550) | about a year and a half ago | (#43061473)

The whole idea is conceptually idiotic. You spend a strong force of reaction mass ejection to maintain a weak force of gravity at a constant distance from the target mass producing a microscopic tug on the object. This guy must have received his degree in a box of crackerjack.
Place the reaction mass generator (be it ion jet, or rocket) directly on the mass and divert it. If this is done at a large distance, the force needed is quite small, and calculable.. Large explosions will also fragment the mass, if they are placed so explosive force is trapped and bursts the object from within. A mountain of gravel will fragment as it hits the atmosphere, but it is preferable to scatter it in advance so the impact is spread both in time and in space. A solid iron mass is the worst case for explosive disruption - needing many drilled holes and many explosives and it will resist fragmentation. It will also be most amenable to the reaction mass approach since it will provide a solid mounting surface and torque as well as thrust be be applied. If you emplace a one pound force thrust mechanism on a million ton mass, how much time is needed to move it one earth diameter.? One million tons = 2 billion pounds. Acceleration of .5 times 1.0 x -9.
s =5 a tt = 42 million feet = .5 x 1.0-9 x t x t
t x t = 42,000,000/.5 x 10--9 = 84,000,000 x 1.0 +9 = 84,000,000,000,000,000 ~300,000,000 seconds One year = ~32 million seconds, so you need 10 years of one pound and one year of 10 pounds thrust to move it one earth diameter. This is just rough math, so an error of 10 might be in there?

Re:Neil deGrasse Tyson (2)

Joce640k (829181) | about a year and a half ago | (#43061623)

Yep. Surely it's far better to fire a cable at it and give it a good pull at 100% engine thrust than wait for a microscopic amount of gravity to have an effect.

Use magnetism it's 10^34 times stronger (4, Interesting)

An dochasac (591582) | about a year and a half ago | (#43061715)

We don't have to follow the "fight fire with fire" methodology. If the weakest force in the universe is pulling an asteroid towards the earth, we needn't use the weakest force in the universe to steer it away. The electromagnetic force is 10^36 times more powerful. Superconducting magnets require only the energy to get them started and keep them cool. Most asteroids are more than one part in a undecillion feromagnetic. So make use of it. And if threat happens to be composed of a diamagnetic material (e.g. comet water), use that to repel it away. Using gravity is just daft unless you have no alternative.

Re:Neil deGrasse Tyson (5, Insightful)

eyenot (102141) | about a year and a half ago | (#43061479)

I usually welcome hearing Tyson's latest addition to lay science understanding.

I sort of like character-celebrity-scientists. Mister Wizard, Bill Nye, and local college instructor / news-show scientist "Chemical Kim" are just a few of the scientists I applaud for their work in bringing science to the masses as a fun and interesting subject.

I don't like the stand-in experts like Michiu Kaku or Tyson, who take a different tack of bringing science to just a large audience, not really packaged for the masses at all, often with their own opinions added, and typically very pompously presented.

Tyson manages to keep my respect by being relatively sane and mainstream, basing his conclusions and projections on "establishment" science.

I can't say the same for Kaku, who I haven't heard from in awhile because I purposefully stop visiting web sites and stop listening to radio shows that give him a podium (no, this is not a viable way to get me to stop visiting /.)

But Tyson also manages to capture my interest by doing the same thing Bill Nye does: making comments about human affairs and human nature. They both humanize science.

But Tyson's pomposity sort of makes it hard for me to "like" him. And I just read something about him recently, so now it's like a second serving of buttered scallops when I clearly had trouble finishing the first serving.

Re:Neil deGrasse Tyson (4, Funny)

flyneye (84093) | about a year and a half ago | (#43061553)

But, he just stomped on the idea for the Open Crowd Source Asteroids Initiative.
A giant bank of lasers spread over the Earth activated by an online MMG of people playing a "free" version of " Asteroids" fed by satellite for positioning and trajectory.
Some people just have no imagination...

Re:Neil deGrasse Tyson (5, Insightful)

PocketPick (798123) | about a year and a half ago | (#43061419)

Why do you say that? He's an established scientist and has a Bachelors in Physics and a Graduate/PH-D in Astrophysics. He's held positions at several universities and is the director of the Hayden Planetarium. Sure he goes on television more than your average physicist, but so did Carl Sagan. He's charismatic, and it works well for him. Nothing wrong with that.

Dr. Phil is a pool of waste that puts people on television and exposes their issues to millions of viewers, for the ratings and a fat pay check. He doesn't add anything to his profession, and his discussions on television don't enlighten anyone.

There's a huge difference.

Re:Neil deGrasse Tyson (-1)

Anonymous Coward | about a year and a half ago | (#43061761)

Really? They both work for the advertisers.

Dr. Phil (-1)

Sulphur (1548251) | about a year and a half ago | (#43061439)

The Neil deGrasse Tyson of Psychology.

Re:Neil deGrasse Tyson (0)

JustOK (667959) | about a year and a half ago | (#43061491)

he's gone downhill since he was the star on Doogie Howser.

Re:Neil deGrasse Tyson (has a degree) (0)

Anonymous Coward | about a year and a half ago | (#43061545)

That comment is so incredibly stupid that I wonder if it may have been typed by Dr Phil himself.

That feel... (1)

Anonymous Coward | about a year and a half ago | (#43061329)

that feel when you're feeling another's feel in space

Neil degrades Tyson on... (0)

Anonymous Coward | about a year and a half ago | (#43061337)

Reads more like an article on his talking about How other people talk about stopping one from hitting the earth.

Sorry, little retro rockets won't work for that (0)

flyingfsck (986395) | about a year and a half ago | (#43061339)

The blast from the little retro rockets hitting the much larger asteroid, will cancel the whole thing out - every action having an equal and opposite reaction and all that pesky old Newtonian conservation of momentum stuff...

Re:Sorry, little retro rockets won't work for that (5, Funny)

p0p0 (1841106) | about a year and a half ago | (#43061351)

I'm going to assume Astrophysicist Neil deGrasse Tyson is a much better source than you.

Re:Sorry, little retro rockets won't work for that (2, Interesting)

Anonymous Coward | about a year and a half ago | (#43061405)

I would normally agree but the whole thing sounds preposterous. The gravitational pull of a spaceship is negligible. If you're going to send a spaceship up there and let it "hover" why not just have it actually contact the meteor and use its thrusters to push it out of the way?

Re:Sorry, little retro rockets won't work for that (5, Informative)

Electricity Likes Me (1098643) | about a year and a half ago | (#43061449)

The asteroidmay not be solid rock. It could be a rubble-pile type, and there might not be anything solid-enough to apply force to in a consistent way. It might be two closely orbiting bodies of rock, in which case you can't push on one in any type of consistent direction.

The benefit of the gravity-tug approach is that if you have a body of some concentrated mass moving at you, then if you have a spaceship sit away from it and maintain a constant position relative to a point other then the asteroid, then you can act on it's entire mass consistently.

Find it early enough, and you can do this with high-efficiency ion thrusters, rather then needing inefficient chemical rockets.

Re: reactive force from retrorockets - you fire them off-angle to the asteroid so exhaust doesn't hit them. You can easily mount orthogonal engines which would carefully cancel the attraction of the asteroid without directing any exhaust at it.

Re:Sorry, little retro rockets won't work for that (0)

ls671 (1122017) | about a year and a half ago | (#43061571)

It might be two closely orbiting bodies of rock...

In that case, send the asteroid some closely orbiting space junk that is currently orbiting Earth. They should cancel each other and we get rid of the space junk, win-win.

Re:Sorry, little retro rockets won't work for that (0)

Anonymous Coward | about a year and a half ago | (#43061465)

Because meteors rotate?

Re:Sorry, little retro rockets won't work for that (5, Insightful)

zAPPzAPP (1207370) | about a year and a half ago | (#43061505)

Because we are currently unable to judge the stability of the object, or it's internal mass distribution just by looking at it from long range.
Pushing it at any point might just lead to breaking off a small piece, or the spaceship slowly sinking into and through it.
If we miss the mass center, the push will mostly be transformed into rotation.

All these problems are a non issue with gravitiational pull.

Re:Sorry, little retro rockets won't work for that (2, Insightful)

tgd (2822) | about a year and a half ago | (#43061597)

I would normally agree but the whole thing sounds preposterous. The gravitational pull of a spaceship is negligible. If you're going to send a spaceship up there and let it "hover" why not just have it actually contact the meteor and use its thrusters to push it out of the way?

The way the universe works doesn't really depend, in any way, upon you finding physics "acceptable".

And a great many people, who clearly are vastly more knowledgeable than you, have done the math and know what they're talking about

Re:Sorry, little retro rockets won't work for that (0)

Anonymous Coward | about a year and a half ago | (#43061679)

And a great many people, who clearly are vastly more knowledgeable than you, have done the math and know what they're talking about

Name six.

Re:Sorry, little retro rockets won't work for that (3, Funny)

JustOK (667959) | about a year and a half ago | (#43061725)

Don't know about six, but I can name 7 of 9.

Re:Sorry, little retro rockets won't work for that (2)

Anonymous Coward | about a year and a half ago | (#43061477)

Where's "-1, appeal to authority" when you need it? Either "flyingfsck (986395)" makes a good point or he doesn't. There's no point in even having a comments section if nobody's going to actually discuss the subject, and flyingfsck (986395) is certainly makigna better contribution to that than you are.

Re:Sorry, little retro rockets won't work for that (1)

Shavano (2541114) | about a year and a half ago | (#43061485)

I'm going to assume Astrophysicist Neil deGrasse Tyson is a much better source than you.

But the point is correct. The gravitational attraction of a spaceship to an asteroid is a weak force. It means you can only a apply a force equal to the weight of the ship on the asteroid. Also, the momentum of the propellant from the rocket pushes against the asteroid, countering the thrust of the rocket. (Unless you direct the rocket away from the asteroid, in which case the rocket escapes from the asteroid.) It's a bad idea.

Re:Sorry, little retro rockets won't work for that (2)

asylumx (881307) | about a year and a half ago | (#43061565)

So don't push against the asteroid. Spacecraft seem to be able to propel themselves in space just fine without something to push against. Aim the thrusters tangentially to the asteroid so the thrust force doesn't push against the asteroid.

Re:Sorry, little retro rockets won't work for that (4, Informative)

Vulch (221502) | about a year and a half ago | (#43061587)

the momentum of the propellant from the rocket pushes against the asteroid, countering the thrust of the rocket

Only if you let it. The Gravity Tractor idea usually uses two ion engines aimed so the exhaust goes either side of the body being towed. The tractor stays in place and there's no unwanted momentum transfer.

Re:Sorry, little retro rockets won't work for that (1)

sfm (195458) | about a year and a half ago | (#43061687)

Mod parent up !! This point is missed in most discussions on this topic

Re:Sorry, little retro rockets won't work for that (0, Flamebait)

tgd (2822) | about a year and a half ago | (#43061645)

I'm going to assume Astrophysicist Neil deGrasse Tyson is a much better source than you.

But the point is correct. The gravitational attraction of a spaceship to an asteroid is a weak force. It means you can only a apply a force equal to the weight of the ship on the asteroid. Also, the momentum of the propellant from the rocket pushes against the asteroid, countering the thrust of the rocket. (Unless you direct the rocket away from the asteroid, in which case the rocket escapes from the asteroid.) It's a bad idea.

Do they not teach basic science in the US anymore? The fact that it would work should be something can be easily proven by anyone who has taken highschool physics. You do realize that rockets don't take off because they're pushing against the ground, right? You just need to move the center of gravity the tiniest amount. When you're traveling a billion or two miles, and you're trying to miss something that is only 13,000km across, you don't need to put a lot of pressure on it, you just need to put a little pressure for a very long time.

Re:Sorry, little retro rockets won't work for that (1)

Shavano (2541114) | about a year and a half ago | (#43061735)

I'm going to assume Astrophysicist Neil deGrasse Tyson is a much better source than you.

But the point is correct. The gravitational attraction of a spaceship to an asteroid is a weak force. It means you can only a apply a force equal to the weight of the ship on the asteroid. Also, the momentum of the propellant from the rocket pushes against the asteroid, countering the thrust of the rocket. (Unless you direct the rocket away from the asteroid, in which case the rocket escapes from the asteroid.) It's a bad idea.

Do they not teach basic science in the US anymore? The fact that it would work should be something can be easily proven by anyone who has taken highschool physics. You do realize that rockets don't take off because they're pushing against the ground, right? You just need to move the center of gravity the tiniest amount. When you're traveling a billion or two miles, and you're trying to miss something that is only 13,000km across, you don't need to put a lot of pressure on it, you just need to put a little pressure for a very long time.

Do they not teach Newton's third law in your country, or has it been repealed for your convenience?

Re:Sorry, little retro rockets won't work for that (2)

goombah99 (560566) | about a year and a half ago | (#43061355)

The blast from the little retro rockets hitting the much larger asteroid, will cancel the whole thing out - every action having an equal and opposite reaction and all that pesky old Newtonian conservation of momentum stuff...

Just use a tractor beam instead.

Re:Sorry, little retro rockets won't work for that (0)

Anonymous Coward | about a year and a half ago | (#43061437)

The blast from the little retro rockets hitting the much larger asteroid, will cancel the whole thing out - every action having an equal and opposite reaction and all that pesky old Newtonian conservation of momentum stuff...

Just use a tractor beam instead.

Or use sharks ... with lasers ... it's the only way to be sure.

Use the EM drive (1)

goombah99 (560566) | about a year and a half ago | (#43061533)

the EM drive has no emissions:
http://en.wikipedia.org/wiki/EmDrive [wikipedia.org]

Re:Use the EM drive (1)

wonkey_monkey (2592601) | about a year and a half ago | (#43061601)

Pfft. Just pray.

Re:Sorry, little retro rockets won't work for that (4, Informative)

Athanasius (306480) | about a year and a half ago | (#43061369)

They don't need to be thrusting directly at the asteroid. Think 3 or more at angles, so they cancel each others' sideways thrust and the overall thrust misses the asteroid, whilst providing net 'away' thrust. Yes, this reduces efficiency.

Re:Sorry, little retro rockets won't work for that (1)

Shavano (2541114) | about a year and a half ago | (#43061511)

Putting an airbag on the front of the rocket and putting the nose of the rocket against the asteroid doesn't reduce efficiency. And you can put a nuclear powered ion drive on the thing and keep pushing for a long time.

Re:Sorry, little retro rockets won't work for that (1)

Anonymous Coward | about a year and a half ago | (#43061377)

Even if it wasn't the case, it seems to be it would be a hellva lot more efficient to use the rockets to just push the damn asteroid, rather than rely on gravity. A couple of tonnes of probe isn't going to exert much influence on a couple of hundred (thosand?) tonnes of space rock.

Re:Sorry, little retro rockets won't work for that (1)

ShanghaiBill (739463) | about a year and a half ago | (#43061459)

it would be a hellva lot more efficient to use the rockets to just push the damn asteroid, rather than rely on gravity.

Asteroids usually rotate. So the rocket (or more likely an ion thruster) would need to cycle on and off if it was on the surface of the asteroid. But it would still be far simpler and cheaper to just detonate a small fission bomb. Then instead of tons, it would just need to be a few dozen kg.

Re:Sorry, little retro rockets won't work for that (1)

cffrost (885375) | about a year and a half ago | (#43061641)

Asteroids usually rotate. So the rocket (or more likely an ion thruster) would need to cycle on and off if it was on the surface of the asteroid. But it would still be far simpler and cheaper to just detonate a small fission bomb. Then instead of tons, it would just need to be a few dozen kg.

To what effect? [nasa.gov]

Re:Sorry, little retro rockets won't work for that (1)

Entropius (188861) | about a year and a half ago | (#43061759)

This has always struck me as the most direct, reliable solution.

If you're going to use rockets with small thrust, you'd be better off just sticking two rockets on your probe, using one to push on the asteroid (with the exhaust gases or ions or whatever) and the other pointed in the other direction for station-keeping. Gravity is pretty damn weak.

Re:Sorry, little retro rockets won't work for that (5, Insightful)

hawguy (1600213) | about a year and a half ago | (#43061509)

Even if it wasn't the case, it seems to be it would be a hellva lot more efficient to use the rockets to just push the damn asteroid, rather than rely on gravity. A couple of tonnes of probe isn't going to exert much influence on a couple of hundred (thosand?) tonnes of space rock.

You don't need much deflection if you have enough time.

Re:Sorry, little retro rockets won't work for that (4, Informative)

bill_mcgonigle (4333) | about a year and a half ago | (#43061525)

No, because you use ion engines on the tug which are tremendously more efficient per launch weight than chemical thrusters.

This isn't a strategy for an "OMG - it's going to wipe us out next week!" asteroid - it's for ones where the orbit shows a near hit of Earth fairly far into the future. Small gravitational tugs over a long period of time are all that's required.

Now, ideally those asteroids can be brought into a useful orbit where they can be mined for more mass to deflect more and more asteroids. In the mid-term perhaps only the ion engines need to be sent up from Earth.

Tyson isn't inventing this - it's a well-accepted strategy in the community that he's trying to explain to a larger audience.

Re:Sorry, little retro rockets won't work for that (0)

Anonymous Coward | about a year and a half ago | (#43061891)

Perhaps. But you'll have to keep going back and forth - push away, decelerate and stop, return, push away again, etc. Wouldn't a series of chemical impulses like this move the mass more than gravity? Sure, you might have a pile of rubble instead, so you'd need a more complicated control system, but shit you already just flew an ion rocket next to an asteroid, I can't believe we can't take the next small step and design the appropriate control systems for sustained herding behavior.

Re:Sorry, little retro rockets won't work for that (0)

Anonymous Coward | about a year and a half ago | (#43061913)

BTW, I'm going to patent this, and hold the patent until the earth is in danger. Then I will sell if for a MILLION dollars! Hahahahaha!

Re:Sorry, little retro rockets won't work for that (1)

K. S. Kyosuke (729550) | about a year and a half ago | (#43061381)

The blast from the little retro rockets hitting the much larger asteroid

Have you notices how quickly gases expand in vacuum? There won't be any such thing as "hitting the much larger asteroid".

Re:Sorry, little retro rockets won't work for that (0)

Anonymous Coward | about a year and a half ago | (#43061517)

Have you notices how quickly gases expand in vacuum? There won't be any such thing as "hitting the much larger asteroid".

What range from the asteroid are you expecting this tiny little space probe to be at while its gravitational pull is deflecting the asteroid away from the Earth?

Re:Sorry, little retro rockets won't work for that (1)

hawguy (1600213) | about a year and a half ago | (#43061407)

The blast from the little retro rockets hitting the much larger asteroid, will cancel the whole thing out - every action having an equal and opposite reaction and all that pesky old Newtonian conservation of momentum stuff...

Just aim the rockets at an angle from the anchor ship so the mass from the retrorocket exhaust avoids the asteroid.

It's not clear how close the ship needs to be, if it's hundreds or thousands of miles from the asteroid, the gas plume from the rockets may have expanded to many times the diameter of the asteroid, so only a tiny fraction of the energy is transferred to the asteroid.

Re:Sorry, little retro rockets won't work for that (1)

Entropius (188861) | about a year and a half ago | (#43061769)

You can compute the force on the asteroid as a function of distance: if it's 1000km away from the asteroid, the acceleration of the asteroid is 7*10^-19 m/s^2 for a 10-ton spaceship. That r^2 in Newton's law of gravity is a bitch. If this is going to work at all you've got to get closer.

Re:Sorry, little retro rockets won't work for that (-1)

flightmaker (1844046) | about a year and a half ago | (#43061413)

Exactly what I was logging in to say. It just wouldn't work.

But, if you were to put your "little retro rockets" on BOTH SIDES of the space ship, you could blow on the asteroid with the rockets on one side to deflect it and keep the ship on station with the rockets on the other side. That might work.

Or, if you could use the other idea I've seen somewhere to hit it with a laser from a distance, and make the laser powerful enough, you might be able to knock chunks off it and get the same action and reaction to cause a deflection. If this could work the big advantage is you don't have to go chasing after the damn thing just shoot straight.

Re:Sorry, little retro rockets won't work for that (1)

angel'o'sphere (80593) | about a year and a half ago | (#43061417)

Why would the blast of the rockets hit the asteroid?

And if it would why would it cancel the movement of the satellite out? did you do the math? Do you even know how to do it?

Re:Sorry, little retro rockets won't work for that (0)

Anonymous Coward | about a year and a half ago | (#43061463)

Imagine a plane tied to a banner with a string. The plane turns on its propeller and somehow it can propel both itself and the banner. Now replace the plane with a spaceship, the turbines with little retro rockets, the banner with an asteroid, and the string with the force of gravity and you basically have the same setup. Momentum is conserved because the propellant is propelled in the opposite direction from the asteroid-spaceship system. If you don't aim the propellant at the asteroid then everything works out.

Re:Sorry, little retro rockets won't work for that (0)

Anonymous Coward | about a year and a half ago | (#43061829)

Anybody else who does not have a clue how rockets or impulse drive work? Is it "but once it is in vacuum, it will have nothing to push against any more" time again?

Fail (-1, Troll)

Dunbal (464142) | about a year and a half ago | (#43061343)

You can keep your fucking emo asteroids. Go feel somewhere else and cut your wrists for real while you're at it. Remember down the road not across the street.

Gravity is a poor tractor beam (0)

Anonymous Coward | about a year and a half ago | (#43061345)

The "pull" between a spaceship and an asteroid would be equal to the apparent weight of the spaceship on its surface, decreased by the square of the distance between the two objects. This would reduce the traction to a very limited amount.

You'd get better results with a cable from the ship attached to the surface, but the problem would be the rotation of both objects.

To do a decent job, the spaceship would need to collect a large quantity of mass before attempting to drag the asteroid.

Re:Gravity is a poor tractor beam (4, Informative)

hawguy (1600213) | about a year and a half ago | (#43061455)

The "pull" between a spaceship and an asteroid would be equal to the apparent weight of the spaceship on its surface, decreased by the square of the distance between the two objects. This would reduce the traction to a very limited amount.

You'd get better results with a cable from the ship attached to the surface, but the problem would be the rotation of both objects.

To do a decent job, the spaceship would need to collect a large quantity of mass before attempting to drag the asteroid.

I think the point is that you don't know how fragile the asteroid is (it could just be a big pile of rubble held together by its own gravity), so anything you do to it through physically touching it, like attaching a cable, landing on it, etc, may break it up into smaller pieces with the result that instead of one large asteroid, you now have a dozen or maybe hundreds of smaller asteroids that you have to deflect. And the set of smaller asteroids will have the same effect on earth as the one large asteroid.

Re:Gravity is a poor tractor beam (2, Informative)

egcagrac0 (1410377) | about a year and a half ago | (#43061691)

No, it won't. The surface/mass ratio will be different (smaller pieces can burn up more readily), and if they're spread out enough, instead of all that mass hitting at once, we just get a few nights of falling stars of little consequence.

We seem to survive the Leonids OK, and we've been surviving them for a long time.

Really Good (0)

Anonymous Coward | about a year and a half ago | (#43061349)

Speaking as an non American can I say that you are really REALLY good at blowing stuff up and shooting stuff too.

Re:Really Good (0)

Anonymous Coward | about a year and a half ago | (#43061427)

We're making up a list

Of those that won't be missed

And, if you get us pissed

We'll put you on the list!

The Reason (0)

DFurno2003 (739807) | about a year and a half ago | (#43061371)

We blow shit up so well is because we understand that accuracy by volume is the best way to hit your target. What makes this guy think anyone's going to meet up with an asteroid traveling at who knows what speed.

Re:The Reason (1)

Anonymous Coward | about a year and a half ago | (#43061493)

Because we've landed probes on asteroids, and we know their speed from trivial tracking.

Re:The Reason (1)

gatkinso (15975) | about a year and a half ago | (#43061599)

Trivial?

Newtons III? (0)

Anonymous Coward | about a year and a half ago | (#43061383)

Maybe I'm having a hard time understanding what he's talking about, but this sounds like a violation of Newtons III at a glance. Suppose you have an asteroid in space, and a rocket beside it. The asteroid attracts the rocket, and likewise the rocket the asteroid. For the rocket to "tug" the asteroid away, it will have to use some sort of propulsion, and all we really have are momentum-exchange drives - rockets, ion-thrusters, ect. To move, it must thrust with a larger force than the force of gravity, in exactly the opposite direction of the gravitiational force vector. The problem is, those particles used for thrusting the rocket, will impact the asteroid as well, assuming the asteroid is large enough to worry about moving. Even worse, some of them may even recoil! Wouldn't this absorbtion of momentum of the ions, gas, ect, undo the "tug" of the rocket in the first place?

Re:Newtons III? (1)

hawguy (1600213) | about a year and a half ago | (#43061483)

Maybe I'm having a hard time understanding what he's talking about, but this sounds like a violation of Newtons III at a glance. Suppose you have an asteroid in space, and a rocket beside it. The asteroid attracts the rocket, and likewise the rocket the asteroid. For the rocket to "tug" the asteroid away, it will have to use some sort of propulsion, and all we really have are momentum-exchange drives - rockets, ion-thrusters, ect. To move, it must thrust with a larger force than the force of gravity, in exactly the opposite direction of the gravitiational force vector. The problem is, those particles used for thrusting the rocket, will impact the asteroid as well, assuming the asteroid is large enough to worry about moving. Even worse, some of them may even recoil! Wouldn't this absorbtion of momentum of the ions, gas, ect, undo the "tug" of the rocket in the first place?

Don't aim your rockets at the asteroid, or stay far enough away that the gas plume from the rockets expands to a diameter much larger than the asteroid.

Re:Newtons III? (2)

Electricity Likes Me (1098643) | about a year and a half ago | (#43061501)

Imagine 3-orthogonally mounted rocket engines. The sum force of the asteroid has to ultimately be a vector combination of force in those 3 directions. You apply thrust off angle such that you counter the asteroid's attraction without thrusting at it.

Show it Putin's chest! (0)

Anonymous Coward | about a year and a half ago | (#43061387)

That's what stopped that meteor in Russia.

And this is new how? (0)

Anonymous Coward | about a year and a half ago | (#43061411)

Pretty sure this solution was given... decades ago.

Needs a 3D printer (0)

Anonymous Coward | about a year and a half ago | (#43061423)

Come on people, we need to mix up our delusions! It's more fun that way!

So how big a rock will it work on? (0)

Anonymous Coward | about a year and a half ago | (#43061435)

Or alternately, how big will the spaceship need to be? How quick would the space ship need to be for gravity to have any impact? Would it work on an asteroid couple of miles across, moving at say 25km a sec, which I am told is the average orbital speed?

More questions than answers I say.

Re:So how big a rock will it work on? (2)

Entropius (188861) | about a year and a half ago | (#43061721)

Well, we can work that out.

As was pointed out earlier, the spaceship needs to be far enough out that its exhaust gases (from the retrorockets used for station-keeping) don't mostly strike the asteroid and cancel the force of gravity. (Perhaps we can use multiple retrorockets at angles pointed away from each other to ensure all the gases miss the asteroid, but this is inefficient -- you can do the trig.) If the asteroid is 500m across, let's say that we'll need to be at least 500m away. But in computing the force we need to compute the distance to the center of mass of the asteroid, giving a total distance of 1km.

Let's say we have a 10-ton spacecraft (very expensive to launch) up there.

Then the acceleration on the asteroid is

(10^4 kg) 7 * 10^-11 / (1000)^2 m/s^2 = 7*10^-7 / 1*10^6 = about 7*10^-13 m/s^2.

A year is 3*10^7 sec, so after a year we'd have a delta-v of about twenty microns per second.

Google Calculator will do this for you too: google "gravitational constant * 10 tonnes / (1 km^2) * 1 year".

Need some advance planning (3, Insightful)

paiute (550198) | about a year and a half ago | (#43061445)

If you are going to use this method, then the more mass in your ship the better. Unfortunately, that means a more expensive launch. If you plan ahead, you figure out a way to accumulate debris and smaller rocks at some stable orbital point so when you need mass you can launch a light ship, go to the rockyard, and gather up more mass at reduced cost.

Re:Need some advance planning (1)

drinkypoo (153816) | about a year and a half ago | (#43061549)

The basic problem that I'm seeing is that if you're talking ELE it's a big rock, you're going to need a big mass to pull it off course. Coming to a position of relative rest quickly takes a lot of energy. The smaller the attractor ship, the earlier it has to get into position. But the larger the attractor ship, the more energy it will take to bring it to "rest". I'm still seeing impactors as the logical answer. You could collect rocks at stable points and then fire them at the mass.

If you could work out some sort of tethered swing-by, that would solve all of these problems. A sort of asteroid to asteroid bungee jump. It solves the "coming to rest" problem and you also don't need to carry fuel for parking. Whether we could build a strong enough tether is a valid point. I'd love to see the math on it, but I doubt I'd understand it anyway.

Re:Need some advance planning (1)

gatkinso (15975) | about a year and a half ago | (#43061631)

A tiny nudge early enough just might be enough.

Re:Need some advance planning (1)

Z00L00K (682162) | about a year and a half ago | (#43061551)

Another method is to place a very powerful laser in orbit around Earth or another suitable orbit and then fire at the asteroid. If the laser is powerful enough it will cause the asteroid to shed some material and through that slightly change the orbit. This will work fine given enough time and precise enough calculations.

The problem by having a spaceship approaching an asteroid is that it requires a lot of fuel to get there. In addition to that there's no easy way to beforehand get enough information about the composition of the asteroid either. Is it solid or is it just a pile of gravel that flies in a tight formation?

That plan cannot fail ! Really ? (0)

Anonymous Coward | about a year and a half ago | (#43061519)

Sure. Use rockets to get away from a close objet in vacum. Gravity is square root of distance and you use reaction engines is space. You see the pbm ? You push on the asteriod as much as you pull him. Too bad. bootstraping not a great concept in space me dynamics.

- Captain ! It works ! The aster moves towards us ! We saved mankind !
- Good. Now fire the rockets to bring him away.
- Captain when we fire the rockets it seems to push him away and send it back to earth
- Damn. You mean just like when we use rockets on earth to lift off ? That's a big surprise. Nobody ever though about that back there ? Are they really that stupid ? WTF saving them ? Lets leave them to their fate.
- Captain. What if we land on the other side and fire keep pushing from there ?
- Really ? Allo Houston ?

Great caution is Advised (1)

rcamans (252182) | about a year and a half ago | (#43061523)

If you change its orbit, the meteor may be set on a collision course in a later go-around. What you want to do is change its orbit so all future approaches are farther from impacting earth, not just this time. Another-words, pay attention to what you are doing. Do not just do something short term.

Put all of the "scientists" who appear on PBS . . (-1, Troll)

wrencherd (865833) | about a year and a half ago | (#43061541)

. (and anyone who works at a "museum for science/nature/mathematics") on a rocket and send them out to meet it.

Even if it doesn't work at least we will all at last know paradise, if only for a few brief moments.

That's no use against real asteroids (0)

tp1024 (2409684) | about a year and a half ago | (#43061583)

Using gravity to slowly nudge an asteroid from its trajectory is impractical and a foolish suggestion. Why?

All asteroids large enough to make this work are known and known not to collide with earth. All asteroids that are a threat to earth are small, unknown and liable to be discovered only a relatively short time - certainly not decades - before impacting earth. There is also good reason [wordpress.com] to expect those to be more common than the claim that they only hit earth "once a century". A typical dangerous asteroid to be discovered will measure between 15m and 100m. That's a simple matter of the chance to detect such asteroids being very small, while the numbers in which they occur are much larger than anything in the several 100m or km class.

We also happen to have just right stuff to do something about the typical asteroids - rockets capable to carry a few tons of stuff beyond earth orbit, anywhere within the solar system. Crash a compact impactor (lead, steel, depleted uranium ... whatever) into the asteroid at your typical speed of 10km/s or more (depending on the exact trajectory and propulsion used) and the kinetic energy released will be sufficient to break it up into small enough pieces. Each ton of material impacting at this speed has the energy of four Tallboy bombs. [wikipedia.org] Those had enough energy to make craters 24m deep and 30m wide on earth.

This works because the large energy is carried by a small mass with little momentum of itself, which means that the energy will be released in all directions, just like a conventional bomb would. Such a collision creates debris small enough to burn up harmlessly in the atmosphere (albeit in spectacular fashion).

Re:That's no use against real asteroids (0)

Anonymous Coward | about a year and a half ago | (#43061751)

Assuming we know for certain that an object is a meteoroid of dangerous size, could we know that soon enough to rendezvous with the object (fly out, catch up with, and apply force to)? It would take a fairly large craft to contain the necessary fuel and mass (for the gravity method). If it doesn't work then we have yet another meteoroid on the same path. Almost any scenario using nukes would be preferable because of the small craft and the amount of energy available.

Unknown unknowns (1)

sjbe (173966) | about a year and a half ago | (#43061811)

All asteroids large enough to make this work are known and known not to collide with earth.

All presently known asteroids large enough...

Fixed that for you. We find things in space all the time that we weren't aware of before. You are claiming we know of every body that could possibly threaten us when we cannot possibly be certain of that.

Re:Unknown unknowns (1)

tp1024 (2409684) | about a year and a half ago | (#43061867)

We know all km-sized asteroids including their trajectories for centuries - that's because they are few and stick out like a sore thumb in comparison with a 28m (equivalent) asteroid like 2012-DA14.

The danger are those asteroids we don't know about - and those are the small ones.

Why is "blow the thing up" a bad idea? (4, Interesting)

Entropius (188861) | about a year and a half ago | (#43061613)

"Knowing where the pieces land" seems like a red herring.

If we detect an asteroid a long way out on a collision course with Earth, then altering its velocity by just a bit will push it off of course and it'll miss us. If you set off an explosion near an asteroid, it will indeed likely fragment, but the only way we're still getting hit is if a large chunk somehow gets *no* delta-v from the explosion, and if that chunk is big enough to survive reentry.

OTOH, if we detect a big asteroid close to us, there may not be time for these things, and we need a large impulse quickly.

Either way, "nuke it" seems like the most sensible thing. Yes, this is a drastic thing, but if it's a true doomsday asteroid then it's called for.

Conversation of energy (2)

gatkinso (15975) | about a year and a half ago | (#43061621)

Wouldn't it just be better to smack into one side of the asteroid at full speed rather than use a bunch of energy to get to the asteroid, a bunch more to slow down and rendezvous, then use little puffs of energy to try and modify its orbit?

Seems to me that all that reaction mass would be much better served by hitting the rock traveling at 4X,000 MPH.

The spaceship doesn't have enough mass to attract (-1)

Anonymous Coward | about a year and a half ago | (#43061629)

This "physicist" fucker with the pretentious name is full of shit.

There is no way a spaceship we can actually launch is going to
be large enough to cause gravitational attraction sufficient to
effect the trajectory of an asteroid enough to matter.

The signal-to-noise ratio at Slashdot is approaching 100% uselessness.

Finally stopped tweeting crap. (0)

dadelbunts (1727498) | about a year and a half ago | (#43061673)

Im glad he stopped tweeting retarded shit that didnt even make sense in an attempt to look smart, and is doing actual science. Its hard to have respect for someone who claims a cars performance is based only on horsepower, cant understand why we use horsepower to measure engine output, yet uses AUs in his field of work every day, which are also relativistic non metric units of measurement.

What's with the knee-jerk anti-Americanism? (0)

brianerst (549609) | about a year and a half ago | (#43061705)

In the course of about seven paragraphs, he manages to take a shot at America twice (good at blowing things up and not dealing with the fallout, if American politicians find out about an extinction level asteroid hitting in 100 years time they'll just kick the can down the road).

I'm not saying that those two observations are false in more general terms, but what evidence does he have that we act that way when dealing with real civilization threats or difficult engineering challenges? He's talking about the one country that has actually landed people on the moon and brought them back - we may have (sadly in my view) changed priorities since then, but we've shown we can do it if we want/need to. And we've generally picked the right side on civilization threats (against fascism, totalitarianism, etc.) - not a perfect record, of course, but compared to the other great powers of the past few centuries, certainly on the better side of the curve (which of the following have we been significantly worse than in the past two hundred years - British Empire, Soviet Union, Germany, Imperial Japan, China?).

The more likely scenario is having to deal with 15 different but legitimate theories and methods to perform the deflection (the gravity solution he prefers, changing the albedo, giving it a nudge, etc.) and either some analysis paralysis based off that or panicked politicians picking the wrong one. Even we Ammurkins have seen enough killer asteroid movies to know something should be done. Heck, if SpaceX marketed it right, it could be a self-financing private venture posing as a movie...

Re:What's with the knee-jerk anti-Americanism? (0)

Anonymous Coward | about a year and a half ago | (#43061915)

Maybe someone ought to remind you that the moon landing was achieved on the shoulders of European scientists and engineers, and that before the post World War II exodus of scientists and engineers to America the US was, with a few exceptions that statistically fit a country of this size (after all, even a bigoted, backward country like Pakistan has Nobel laureate in physics) a scientific nonentity?

I don't see the problem (0)

lesincompetent (2836253) | about a year and a half ago | (#43061865)

Why can't we go the dinosaur way? What's wrong with that? When it's time it's time. It's extinction! Why bother extending our pathetic time slice on earth? I'd sort of feel good knowing that everyone is going to die the same day as me.
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