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What's the whole thing about drilling a hole and dropping a nuke to split the asteroid up? I mean, I liked the Aerosmith song from that movie (Armageddon) but d

What's the whole thing about drilling a hole and dropping a nuke to split the asteroid up? I mean, I liked the Aerosmith song from that movie (Armageddon) but doesn't that actually seem like a sensible idea for a bigger rock? Looks like some experts agree w me: http://www.space.com/21333-asteroid-nuke-spacecraft-mission.html http://www.space.com/21333-asteroid-nuke-spacecraft-mission....

yongjik 11y ago
Mankind never had to drill a hole in zero gravity, so I don't think we have such a tool in the first place. Besides, even if we had something like that, I imagine they would be rather heavy. Hauling it all the way to the asteroid will take a lot of fuel and money.
- mithras 11y ago
  Could a very strong laser potentially work for this?
- hguant 11y ago
  I would imagine a simple drill bit would do the trick - that action isn't dependent on gravity, and in an enclosed area (the bore) the simple action of the screw should do it. The real trick would be making sure the ejecta doesn't hang around. For small particulates you could use a static field, but larger masses would be harder.
  - yongjik 11y ago
    But how are you going to press against the ground without gravity? If you don't press firmly, the drill bit will just scratch the surface instead of boring in. You don't have gravity, and you can't use suction cups (no air!), and I'm skeptical if you can grab on something and hold on to that. (It will require a lot of robotic engineering, and what if the surface is filled with loose gravel?) Maybe you could fire a rocket in the opposite direction the whole time, but that increases fuel requirement even further.
    - gizmo686 11y ago
      Any landing on a such a low gravity object object would require some form of anchoring, which you can use to to get the drill started. The Philae lander (was designed to) use its impact velocity to drive ice screws into the surface, before fireing a harpoon. Presumably such a harpoon could give sufficient leverage to get run a drill. Of course, if you followed the landing, you know that things didn't quiet go as planned, and Philae bounced a few times (and almost escaped the gravity), so this is definitely a difficult problem, but I suspect that once you have a lander that can anchor itself enought to not bounce, you could probably anchor yourself enough to drill.
    - hguant 11y ago
      I was thinking abut this, and it seems to me that the Third Law problem only exists when you're starting the drilling (pressing down) and removing the drill (pulling up). During the actual drilling procedure, there should be a force from the action of the drill bit digging into the rock, and from the stuff being bored away from the drill. Shouldn't there be an equilibrium point where the pressure you're exerting on the drill (pushing you up) matches the force of the drill pulling you down? I feel [1] that higher torque speeds would impact this. [1] "I feel," "It seems," etc. - I don't have the maths or the physics to back this up beyond intuition and a hasty free body diagram sketch, which admittedly seems to work well-ish for most problems in classical mechanical physics.
      - jschwartzi 11y ago
        Basically, if there's nothing stopping you from spinning then the drill will spin you but with the bit stationary. The fixture holding the drill needs to be secured somehow so that the motor in the drill spins the bit against the surface. On Earth, this is commonly achieved using your feet and friction.
        JoeAltmaier 11y ago
        Exactly. There are so many problems with drilling/mining asteroids, its going to be one of the most enormous challenges ever undertaken.
  - bryondowd 11y ago
    You need leverage to drill. You have to push down a bit on whatever you are drilling into, which will push you away from it. So, until you drill in enough to get leverage on the target, you've got to either counteract this force, or keep extending your drill arm as you drift away.
gilgoomesh 11y ago
If you can deflect with a simple impact, it's always going to be the most reliable. If you look at the numerous things that went wrong with the Philae lander... https://en.wikipedia.org/wiki/Philae_%28spacecraft%29 https://en.wikipedia.org/wiki/Philae_%28spacecraft%29 you wouldn't want any of that to happen on a life-or-death mission. Also... a landing either requires enormous amounts of fuel or between months and years of manoeuvring time.
vortico 11y ago
It works for small <10m astroids, but for anything bigger than that, its own gravity will pull the segments back together after the explosion since they do not reach escape velocity, and nothing will have changed due to conservation of momentum. A better method is to detonate an astroid up to 100m away so it heats up the surface. The heat will blow off small particles at more than escape velocity, so by conservation of momentum the astroid will be pushed in the opposite direction.
- Sodel 11y ago
  Hey, that's a really cool idea! Using an asteroid as its own propellant.
  - zkhalique 11y ago
    Yeah! Has anyone actually investigated this or written about it??
    - throwaway5752 11y ago
      https://en.wikipedia.org/wiki/Asteroid_impact_avoidance#History_of_government_mandates https://en.wikipedia.org/wiki/Asteroid_impact_avoidance#Hist... - Project Icarus is almost 50 years old. There was a paper about laser ablation 2 years ago. Lot of literature on many different collision avoidance strategies.
    - vortico 11y ago
      There was a talk this year at LLNL showcasing a few methods, each with high resolution mesh-based simulations. Hopefully that's enough information so you can find the slides online.
- siberianbear 11y ago
  Can you explain why the nuke option wouldn't work? It seems to me that most of Earth's protection against asteroids is them burning up in the Earth's atmosphere. Let's assume that you did blow up an asteroid, and the constituent parts loosely reassembled. Wouldn't they they break apart again as soon as they started to experience the turbulent effects of the Earth's atmosphere? And once they did, the surface area to mass ratio of the asteroid matter would be an order of magnitude or higher, pretty much guaranteeing all of the mini-asteroid parts would burn up. No doubt I'm wrong. I'm a programmer, not a physicist or an astronomer. So I'm seeking to get 'educated' more than I am to argue with you.
jakeogh 11y ago
DOE NNSA SSGF 2015: NNSA Activities in Planetary Defense: https://www.youtube.com/watch?v=AeBxuwXC6GA https://www.youtube.com/watch?v=AeBxuwXC6GA There is another very similar video, maybe of the same slides with a inset of the speaker, but I can't find it atm.
simonh 11y ago
There are some situations in which this might work, but many other where it wouldn't. The asteroid would have to be small enough that the bomb could fragment it sufficiently, we'd also have to be able to hit it early enough and fragment it enough that most of the fragments would miss the earth. If the asteroid was above the fragmentation capability of the warhead, or if it was detected late enough that the fragments would mostly still hit the earth then it wouldn't help. Bear in mind that if most of the fragments still hit earth, the net energy delivery would still be about the same. This could actually be worse for the planet as a whole than a single hit. Finally, whether such a bomb could be effective would also depend on the structure of the asteroid or comet. This is due to the bugsplat effect, army slang for the fact that when a bomb hits a building or vehicle, the energy seems to be expended very asymmetrically. If you crush a bug with your boot, one part of the exoskeleton will weaken before the others and the insides get sprayed out in that direction. Similarly, if a bomb hits a vehicle often the majority of the explosive effect tends to get directed primarily in one direction. There are cases of people close to one side of a vehicle surviving unharmed, while people much further away in other directions get incinerated or hit by fragments. Similarly if the internal structure of the asteroid is asymmetrical, you could end up with material on one side of the asteroid (perhaps made up of already loose boulder material and dust) being thoroughly fragmented while larger more dense parts of it on the other surviving. Instead of many similarly sized fragments, you might well end up with a large percentage of the object remaining intact and all you did was scrub off looser material.

yongjik 11y ago

Mankind never had to drill a hole in zero gravity, so I don't think we have such a tool in the first place. Besides, even if we had something like that, I imagine they would be rather heavy. Hauling it all the way to the asteroid will take a lot of fuel and money.

mithras 11y ago
Could a very strong laser potentially work for this?
hguant 11y ago
I would imagine a simple drill bit would do the trick - that action isn't dependent on gravity, and in an enclosed area (the bore) the simple action of the screw should do it. The real trick would be making sure the ejecta doesn't hang around. For small particulates you could use a static field, but larger masses would be harder.
- yongjik 11y ago
  But how are you going to press against the ground without gravity? If you don't press firmly, the drill bit will just scratch the surface instead of boring in. You don't have gravity, and you can't use suction cups (no air!), and I'm skeptical if you can grab on something and hold on to that. (It will require a lot of robotic engineering, and what if the surface is filled with loose gravel?) Maybe you could fire a rocket in the opposite direction the whole time, but that increases fuel requirement even further.
  - gizmo686 11y ago
    Any landing on a such a low gravity object object would require some form of anchoring, which you can use to to get the drill started. The Philae lander (was designed to) use its impact velocity to drive ice screws into the surface, before fireing a harpoon. Presumably such a harpoon could give sufficient leverage to get run a drill. Of course, if you followed the landing, you know that things didn't quiet go as planned, and Philae bounced a few times (and almost escaped the gravity), so this is definitely a difficult problem, but I suspect that once you have a lander that can anchor itself enought to not bounce, you could probably anchor yourself enough to drill.
  - hguant 11y ago
    I was thinking abut this, and it seems to me that the Third Law problem only exists when you're starting the drilling (pressing down) and removing the drill (pulling up). During the actual drilling procedure, there should be a force from the action of the drill bit digging into the rock, and from the stuff being bored away from the drill. Shouldn't there be an equilibrium point where the pressure you're exerting on the drill (pushing you up) matches the force of the drill pulling you down? I feel [1] that higher torque speeds would impact this. [1] "I feel," "It seems," etc. - I don't have the maths or the physics to back this up beyond intuition and a hasty free body diagram sketch, which admittedly seems to work well-ish for most problems in classical mechanical physics.
    - jschwartzi 11y ago
      Basically, if there's nothing stopping you from spinning then the drill will spin you but with the bit stationary. The fixture holding the drill needs to be secured somehow so that the motor in the drill spins the bit against the surface. On Earth, this is commonly achieved using your feet and friction.
      - JoeAltmaier 11y ago
        Exactly. There are so many problems with drilling/mining asteroids, its going to be one of the most enormous challenges ever undertaken.
- bryondowd 11y ago
  You need leverage to drill. You have to push down a bit on whatever you are drilling into, which will push you away from it. So, until you drill in enough to get leverage on the target, you've got to either counteract this force, or keep extending your drill arm as you drift away.

gilgoomesh 11y ago

If you can deflect with a simple impact, it's always going to be the most reliable. If you look at the numerous things that went wrong with the Philae lander... https://en.wikipedia.org/wiki/Philae_%28spacecraft%29 https://en.wikipedia.org/wiki/Philae_%28spacecraft%29 you wouldn't want any of that to happen on a life-or-death mission. Also... a landing either requires enormous amounts of fuel or between months and years of manoeuvring time.

vortico 11y ago

It works for small <10m astroids, but for anything bigger than that, its own gravity will pull the segments back together after the explosion since they do not reach escape velocity, and nothing will have changed due to conservation of momentum. A better method is to detonate an astroid up to 100m away so it heats up the surface. The heat will blow off small particles at more than escape velocity, so by conservation of momentum the astroid will be pushed in the opposite direction.

Sodel 11y ago
Hey, that's a really cool idea! Using an asteroid as its own propellant.
- zkhalique 11y ago
  Yeah! Has anyone actually investigated this or written about it??
  - throwaway5752 11y ago
    https://en.wikipedia.org/wiki/Asteroid_impact_avoidance#History_of_government_mandates https://en.wikipedia.org/wiki/Asteroid_impact_avoidance#Hist... - Project Icarus is almost 50 years old. There was a paper about laser ablation 2 years ago. Lot of literature on many different collision avoidance strategies.
  - vortico 11y ago
    There was a talk this year at LLNL showcasing a few methods, each with high resolution mesh-based simulations. Hopefully that's enough information so you can find the slides online.
siberianbear 11y ago
Can you explain why the nuke option wouldn't work? It seems to me that most of Earth's protection against asteroids is them burning up in the Earth's atmosphere. Let's assume that you did blow up an asteroid, and the constituent parts loosely reassembled. Wouldn't they they break apart again as soon as they started to experience the turbulent effects of the Earth's atmosphere? And once they did, the surface area to mass ratio of the asteroid matter would be an order of magnitude or higher, pretty much guaranteeing all of the mini-asteroid parts would burn up. No doubt I'm wrong. I'm a programmer, not a physicist or an astronomer. So I'm seeking to get 'educated' more than I am to argue with you.

jakeogh 11y ago

DOE NNSA SSGF 2015: NNSA Activities in Planetary Defense: https://www.youtube.com/watch?v=AeBxuwXC6GA https://www.youtube.com/watch?v=AeBxuwXC6GA There is another very similar video, maybe of the same slides with a inset of the speaker, but I can't find it atm.

simonh 11y ago

There are some situations in which this might work, but many other where it wouldn't. The asteroid would have to be small enough that the bomb could fragment it sufficiently, we'd also have to be able to hit it early enough and fragment it enough that most of the fragments would miss the earth. If the asteroid was above the fragmentation capability of the warhead, or if it was detected late enough that the fragments would mostly still hit the earth then it wouldn't help. Bear in mind that if most of the fragments still hit earth, the net energy delivery would still be about the same. This could actually be worse for the planet as a whole than a single hit. Finally, whether such a bomb could be effective would also depend on the structure of the asteroid or comet. This is due to the bugsplat effect, army slang for the fact that when a bomb hits a building or vehicle, the energy seems to be expended very asymmetrically. If you crush a bug with your boot, one part of the exoskeleton will weaken before the others and the insides get sprayed out in that direction. Similarly, if a bomb hits a vehicle often the majority of the explosive effect tends to get directed primarily in one direction. There are cases of people close to one side of a vehicle surviving unharmed, while people much further away in other directions get incinerated or hit by fragments. Similarly if the internal structure of the asteroid is asymmetrical, you could end up with material on one side of the asteroid (perhaps made up of already loose boulder material and dust) being thoroughly fragmented while larger more dense parts of it on the other surviving. Instead of many similarly sized fragments, you might well end up with a large percentage of the object remaining intact and all you did was scrub off looser material.