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from the fully-armed-and-operation-battle-station dept.
NASA's Brian Muirhead has speculated about the best way to construct a "Death Star" or other weaponized space station:
The best way to build a Death Star is to construct one out of an already-existing asteroid, says Brian Muirhead, chief engineer at NASA's Jet Propulsion Laboratory. "It could provide the metals," he says. "You have organic compounds, you have water—all the building blocks you would need to build your family Death Star."
And Muirhead knows a thing or two about asteroids. He's actually working on NASA's Asteroid Redirect Mission, which will land on an asteroid, collect a piece, and then place it in orbit around the moon. A crewed mission will then go collect samples from that chunk while it's in orbit. (OK, so it's not quite building a Death Star, but it's still pretty cool.)
The Wired article includes a video.
(Score: 3, Interesting) by Covalent on Monday December 14 2015, @06:42PM
You don't even have to impact...just pass by close enough to perturb the orbit of the planet, thus ejecting it from its solar system or throwing it toward its star. And now your "death star" is reusable, too. Doesn't have the shock and awe value of an impact, but it's just as deadly. You can even use the mass of the asteroid as reaction mass...AND you can have it impact the planet, too...
Geez, now that I think of it, there are SO many way to kill everyone on a planet. hehehe
You can't rationally argue somebody out of a position they didn't rationally get into.
(Score: 2) by Runaway1956 on Monday December 14 2015, @06:57PM
Can't fault your thinking, because that story has been written several times already. But, most authors envision a dark star, or at least a giant planet, to have enough gravity to pull a planet out of orbit, and send that planet out of the solar system. Cixin Liu put a new twist to the story here: http://www.amazon.com/Wandering-Earth-Short-Stories-Cixin-ebook/dp/B007JL6IYU/ref=pd_sim_351_3?ie=UTF8&dpID=51a%2BTuKt9AL&dpSrc=sims&preST=_UX300_PJku-sticker-v3%2CTopRight%2C0%2C-44_AC_UL160_SR113%2C160_&refRID=1E5KFH0FPMDBXMCW52VY [amazon.com]
(Score: 2) by Covalent on Monday December 14 2015, @07:34PM
Fascinating. I suppose an asteroid wouldn't have the mass to significantly perturb a large planet (for smallish values of "asteroid"). I guess the name Death STAR is somewhat more appropriate than I had previously considered.
So here's the follow-up question: Is it possible to PROPEL a "star" or supermassive planet like this? I mean, they're mostly gas...so how do you push them around?
And if we can't perturb a planet to its demise, then perhaps we must impact. Or, at least, perhaps we break off chunks of our "death asteroid" and bombard with those. A 1,000 mile wide asteroid could slough off a 10-mile-wide chunk that would pretty effectively decimate the life on a planet, and this could be repeated 100 times.
You can't rationally argue somebody out of a position they didn't rationally get into.
(Score: 2) by Runaway1956 on Monday December 14 2015, @07:44PM
Well, I'll mention Cixin Liu again - he's propelling the earth with thousands of fusion engines, anchored to the living rock of the earth's crust. I suppose it is within the realms of the scientifically possible, without considering what is economically possible, or politically possible.
I suspect that anti-gravity might provide an engine sufficient to propel planets and planetoids. Anti-matter engines might be more feasible. Fusion engines are probably the most viable option today.
"Give me a lever long enough, and I'll move the world" - or words to that effect. Mankind has not yet learned how to wield that lever, so I certainly can't answer the question. Given sufficient fuel resources, we have the engines available today to move some pretty massive bodies. Of course, our inefficient little rocket and/or ion engines aren't going to move them very fast!
Science is going to have to find answers, or we're going to be traveling quite slowly when we leave this planet!
(Score: 3, Funny) by DECbot on Monday December 14 2015, @07:01PM
As one evil mastermind to another, I really appreciate the elegance of your doomsday device. It is really quite simple once you solve the energy requirements of changing the orbit of an asteroid of sufficient mass to cause an earth shattering kaboom. If I wasn't so vested in my greenhouse gas doomsday strategy, I would assist with yours as its simplicity and effective impact is most apparent. Yet it is not to be as I'm quite engaged maintaining the world's dependence on carbon emitting energy. You see, as a fringe benefit of destroying the earth with green house gases, I become filthy rich investing in oil and natural gas!
If you could please excuse me, these climate denial blogs don't write themselves...
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(Score: 2) by Foobar Bazbot on Monday December 14 2015, @07:45PM
You don't even have to impact...just pass by close enough to perturb the orbit of the planet, thus ejecting it from its solar system or throwing it toward its star.
Yes, kiloyears later, after hundreds of perturbations with your asteroid, you will have the last laugh as the planet goes flying off into deep space!
I'm not sure you realize how tiny the mass of even a big asteroid like Ceres is, compared to a planet like Earth -- the ratio is over 6000:1!
But let's run some numbers -- you talked of ejecting planets, let's start with Earth. We need to accelerate Earth from its orbital velocity of 30km/s, to solar escape velocity of 42 km/s; so we need a delta-v of 12km/s.
Let's say you drop a rock with negligible velocity from deep space, so its velocity as it passes through Earth's vicinity is about 42km/s. Moreover, we'll contemplate a super-efficient slingshot treating Earth as a point mass, whereas the need to avoid a collision makes real-world slingshots worse.
The rock comes in at 42km/s, leaves at (42km/s + 2 * 30km/s) = 102 km/s, so the rock's delta-v is 144km/s.
Momentum is then 144km/s*mrock, and the same momentum is stolen from the planet; this gives a delta-v for the planet of 144 km/s * (mrock / mplanet).
For a Ceres-mass rock, where mrock / mplanet < 1/6000, this is about 24 m/s. At this rate, you'll need over 500 passes -- and after each one, your rock is headed into deep space at 60km/s, so you have to dump that delta-v and come back in. (Practically, you're better off letting that rock go, and finding 500 different rocks in the Oort cloud to drop.) Venus or Mars would be a little easier -- the orbital/escape velocities all remain proportional, mass ratio is all that changes, so it's still hundreds of closest-possible slingshot passes.
Assuming your goal is to depopulate the planet, and not some specific reason to move planets around a solar system, you're really much better off just hitting them with asteroids.
(Score: 2) by HiThere on Monday December 14 2015, @08:10PM
If the goal is to depopulate the planet, then you it would suffice to put the asteroid into a parabolic, or even hyperbolic, orbit with the closest approach well within the atmosphere. This should create a sonic boom loud enough to destory everything living on the planet. It MIGHT result in the asteroid being captured as a moon, but that's unlikely. If so, there would be repeated close encounters until the orbit either decayed or stabilized.
I don't, however, think that a close pass would suffice. (Someone else suggested that 6,000 close passes might suffice, but I have my doubts unless each one was precisely figured to change the orbit in the exact same direction.)
OTOH, a deep ocean strike by a much smaller asteroid would probably also suffice to destroy the ecosystem. The one the article in Analog figured was a five mile cube of nickle-iron. Larger than most astroids, but not larger than all of them. I think that the scenario figured that this would first raise the temperature by about 50 degrees Fahrenheit, and then make it drop by a more than equal amount as vaproized steam formed into inpenetrable clouds. Something much smaller at the edge of the ocean sufficed to kill off the dinosaurs.
P.S.: The article was called "Giant Meteor Impact" by J.E. Enever. It was the cover story for the issue (March 1966). I no longer have access to that issue, so I may well have gotten some of his estimates wrong.
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(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @06:09AM
Why go to all that trouble so that you can "reuse" the asteroid (guess how much energy you need to adjust the trajectory for a new target). Not like there aren't other asteroids to use for other targets. You probably use less energy for nonreusable extinction event asteroids than for a reusable strike.
(Score: 2) by Covalent on Tuesday December 15 2015, @01:53PM
I'm impressed with your math and I think in spirit you're correct: in a 1-planet system, it takes too much energy to remove said planet from the system. But few systems appear to be the 'only children' variety.
The dynamics will be far more complex in a multi-planet system. Even small perturbations can cause major disruptions within a system, including (but not limited to) ejection of planets from the system. You don't have to provide all of the energy to kick Earth out of the solar system with just your asteroid...you just have to nudge it a little closer to the sun or Venus or Jupiter and the chaos of orbits will take it from there. I am certain that if you could move Ceres (and that's a huge if) into a near miss with Earth, you would devastate the planet with enormous tides in the short term and massively perturb its orbit in the long term. It might take years, but eventually Earth would be in a less-than-habitable orbit, if it's in the system at all.
But you bring up another good point: The amount of energy needed to move something the size of Ceres is so massive, you might as well not bother with the asteroid and, instead, direct those energies right at the planet. I don't even know how you would go about moving something the size of Ceres in a reasonable amount of time, but if you could do that, bottle up your energy source and throw it at the planet in bomb form. So the original Death Star idea might be right after all.
You can't rationally argue somebody out of a position they didn't rationally get into.