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Neil deGrasse Tyson On How To Stop a Meteor Hitting the Earth
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.'"
I'm going to assume Astrophysicist Neil deGrasse Tyson is a much better source than you.
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.
If Slashdot were chemistry it would look like this:Cadaverine
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.
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.
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.
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.
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.
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.
"Stratigraphically the origin of agriculture and thermonuclear destruction will appear essentially simultaneous" -- Lee
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.
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.
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.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
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...
*Repent!Quit Your Job!Slack Off!The World Ends Tomorrow and You May Die!
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.
"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.
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.
When you are dancing with wolves, never limp
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.
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.
Amazing that they didn't think of that!!! You must be a genius...
Or... maybe they did consider that, then realised that many, many small asteroids are apparently heaps of weakly bound rubble, just as bad as a solid object when hitting the surface of earth, but impossible to attach a rocket to.
The "gravity tug" concept works the same regardless of the structural integrity of the asteroid, *that* is why this is the proposed mechanism, not because Tyson is stupid...
Bet you feel a lot less like a genius now, smarty-pants?
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.
I pity the cranially impoverished people who modded this up as "Insightful". Go back to high school, would you? The two forces you're referring to are exactly equal in size, as per Newton's third law. The probe gets positioned at a distance at which the thrust of the engine is equalized by the asteroid's gravity, and the probe consequently pulls the asteroid with identical force (modulo its sign) while keeping a stationary position above its surface.
What you get here is exactly what you'd get by putting the probe onto the asteroid and pushing it, but you're avoiding the potentially dangerous contact with the asteroid. Moreover, the probe is likely to be powered using solar arrays, and asteroids sort of tend to rotate, which would severely complicate your attempts at creating a sustained thrust, not to mention the fact that your thrust vector would also rotate. Separating the probe from the asteroid and acting gravitationally upon it gives you constant insolation of the panels and the ability to exert constant thrust in a single direction.
Ezekiel 23:20
But Tyson's pomposity sort of makes it hard for me to "like" him..
They're fine as long as they don't get uppity, eh?