3 ms·

"Might as well plan a controlled re-entry of the rock to the surface. Drop it into the desert somewhere, then go mine it on the surface." Any commercially-viab

"Might as well plan a controlled re-entry of the rock to the surface. Drop it into the desert somewhere, then go mine it on the surface." Any commercially-viable amount of rock dropped from orbit into the desert would probably hit with enough force to cause a second K-Pg extinction event. Even if it hit the middle of the Pacific Ocean, we'd be horribly screwed. The amount/cost of fuel needed to control the descent of any commercially-viable quantity of rock would probably outpace the mineral value itself.

kolinko 7y ago
I might be wrong, but asteroids hitting earth are a problem more because of the speed than their mass? (E=m*v^2) Asteroids usually hit earth with speeds from 16 to 32 km/sec, but if we brought it to earth it would be closer to 0.5km/sec
- lightedman 7y ago
  Any commercially-viable asteroid would need to be at least a mile in some dimension or another to have enough minable material. Let's assume 3200 Phaethon was our target - three mile wide asteroid, mass of 140 x 10^12 Kg. I'll let you do the math, but just the 10^12 kg along should tell you that the idea is quite infeasible before you ever get to doing the actual calculation. BTW it's easier to just do (KE) = 1/2mv^2 as your calculating formula.
  - zamfi 7y ago
    > I'll let you do the math, but just the 10^12 kg along should tell you that the idea is quite infeasible before you ever get to doing the actual calculation. Did you try the math? 10^12 J (i.e., 10^12 kg moving slowly) is a lot, but it’s not an extinction-level event. 4 x 10^12 J is 1 kiloton of TNT equivalent. A big boom, but if well placed...
    - lightedman 7y ago
      How much energy are you going to expend to ensure that hundred-trillion+ kilogram rock can fall at the rate desired by the prior positor? Half a kilometer a second is supersonic speed. We get 1.3E+19 J now as the energy level we need to fight against. That's higher than a 100 megaton nuke by two orders of magnitude. Now fight against that every second! Don't forget to calculate the pull of gravity as well! There's still more numbers to pop into the equation! We don't have the energy capacity to begin with. The rock would smash into us, and we'd die.
      - zamfi 7y ago
        Nice goalposting there. My issue was only with your implication that the mass alone was enough. Obviously impact speed matters too, that was the point. I assume your 500m/s comes from the assumed algebra in my post, but the real issue is the gravitational potential energy as you allude to. To get that rock from 2000km up (low earth orbit) to the surface means somehow dissipating 10^21 J -- two orders of magnitude higher still than your claim. I like that other poster's idea of a "giant parachute". I hope it's made of 4000% heat shields. Maybe we can cover it with wind turbines and power the entire US for a year. [0] [0] https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)#1018_to_1023_J https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)#1...
        lightedman 7y ago
        "I assume your 500m/s comes from the assumed algebra in my post" I assume you didn't even READ my post, as the very first sentence is "How much energy are you going to expend to ensure that hundred-trillion+ kilogram rock can fall at the rate desired by the prior positor?" Key words - AT THE RATE DESIRED BY THE PRIOR POSITOR - as in the person who I was originally responding to in this thread, and not you. Since you did not read my post and obviously didn't read theirs, I'm not entertaining yours. You lack the required information to make a useful contribution to this thread.
        zamfi 7y ago
BurningFrog 7y ago
You should be able to make some kind of primitive parachute. Not that makes a soft landing, but where it only crashes with moderate speed. You do touch on a very important issue: Anyone who can move an asteroid to Earth can also extinguish at least a city at will. I foresee this business being very heavily regulated by the big military powers.

kolinko 7y ago

I might be wrong, but asteroids hitting earth are a problem more because of the speed than their mass? (E=m*v^2) Asteroids usually hit earth with speeds from 16 to 32 km/sec, but if we brought it to earth it would be closer to 0.5km/sec

lightedman 7y ago
Any commercially-viable asteroid would need to be at least a mile in some dimension or another to have enough minable material. Let's assume 3200 Phaethon was our target - three mile wide asteroid, mass of 140 x 10^12 Kg. I'll let you do the math, but just the 10^12 kg along should tell you that the idea is quite infeasible before you ever get to doing the actual calculation. BTW it's easier to just do (KE) = 1/2mv^2 as your calculating formula.
- zamfi 7y ago
  > I'll let you do the math, but just the 10^12 kg along should tell you that the idea is quite infeasible before you ever get to doing the actual calculation. Did you try the math? 10^12 J (i.e., 10^12 kg moving slowly) is a lot, but it’s not an extinction-level event. 4 x 10^12 J is 1 kiloton of TNT equivalent. A big boom, but if well placed...
  - lightedman 7y ago
    How much energy are you going to expend to ensure that hundred-trillion+ kilogram rock can fall at the rate desired by the prior positor? Half a kilometer a second is supersonic speed. We get 1.3E+19 J now as the energy level we need to fight against. That's higher than a 100 megaton nuke by two orders of magnitude. Now fight against that every second! Don't forget to calculate the pull of gravity as well! There's still more numbers to pop into the equation! We don't have the energy capacity to begin with. The rock would smash into us, and we'd die.
    - zamfi 7y ago
      Nice goalposting there. My issue was only with your implication that the mass alone was enough. Obviously impact speed matters too, that was the point. I assume your 500m/s comes from the assumed algebra in my post, but the real issue is the gravitational potential energy as you allude to. To get that rock from 2000km up (low earth orbit) to the surface means somehow dissipating 10^21 J -- two orders of magnitude higher still than your claim. I like that other poster's idea of a "giant parachute". I hope it's made of 4000% heat shields. Maybe we can cover it with wind turbines and power the entire US for a year. [0] [0] https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)#1018_to_1023_J https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)#1...
      - lightedman 7y ago
        "I assume your 500m/s comes from the assumed algebra in my post" I assume you didn't even READ my post, as the very first sentence is "How much energy are you going to expend to ensure that hundred-trillion+ kilogram rock can fall at the rate desired by the prior positor?" Key words - AT THE RATE DESIRED BY THE PRIOR POSITOR - as in the person who I was originally responding to in this thread, and not you. Since you did not read my post and obviously didn't read theirs, I'm not entertaining yours. You lack the required information to make a useful contribution to this thread.
        zamfi 7y ago

BurningFrog 7y ago

You should be able to make some kind of primitive parachute. Not that makes a soft landing, but where it only crashes with moderate speed. You do touch on a very important issue: Anyone who can move an asteroid to Earth can also extinguish at least a city at will. I foresee this business being very heavily regulated by the big military powers.