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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 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?
"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.
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?
Actually maybe a little farther to ensure you don't hit the asteroid with any of the propellant.
In a vacuum, the gas from the propellant won't dissipate quite as much...
An additional force to think about - if you're using gas propellant, or perhaps an electrostatically accelerated ion engine, you're going to build up quite a charge throwing those ions around, aren't you? You'd have to consider that in your calcs. Might change the shape of the attraction curve between the two bodies.
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