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> I've always liked the idea of bringing the asteroid to park into an orbit around earth to make it easier/cheaper for multiple deliveries I think you're drama

> I've always liked the idea of bringing the asteroid to park into an orbit around earth to make it easier/cheaper for multiple deliveries I think you're dramatically underestimating the difficulty of doing this. If you look at rockets, they're 90-95% propellant. Even relatively svelt upper stages like Centaur III (the upper stage from Atlas v) are more than 50% propellant. And that's for just taking payloads to LEO - for higher energy missions, the usable payload gets smaller, which means the percent of the upper stage that's propellant increases. How difficult would it be to get an amount of propellant, say, 5 times the mass of the asteroid to the asteroid? You'd also have to get the engines and other structures to let you use the propellant in a productive way. It's way easier to extract valuable parts from an astroid and move a lot less mass there and back.

api 2y ago
Moving mass back with a free return trajectory is much easier than getting stuff out of Earths gravity well and up there. Escape velocity from an asteroid is low and if you yeet it with enough precision you can send it on a trajectory that will land it on Earth. As for moving the asteroid you could use extremely high specific impulse ion thrusters, in situ propellant from the asteroid itself, or a solar sail. But you are right that simply firing the valuable stuff back to Earth is probably easier.
lolinder 2y ago
Not to mention the governance and liability implications of the plan. If a company mining something on Earth screws up really badly, they can ruin the environment for a hundred miles around. If a company mining an asteroid in LEO screws up really badly, the literal blast radius would wipe out a significant percentage of life on earth.
- dylan604 2y ago
  Why does it need to be parked in LEO? It could be kept in an orbit at the same distance as the Moon and it would still be relatively close compared to where it is now
  - lolinder 2y ago
    Fair. I don't think we'd want that either, though, for the same reason. The moon is too close for comfort for smaller objects that we've proven we can move.
Teever 2y ago
What about using the asteroid itself as fuel? Even if the asteroid is devoid of hydrocarbons that could be turned into fuel for conventional engines iron make a suitable (albeit inefficient) fuel for ion thrusters powered by solar panels. Mass drivers and linear rails are also viable ways of bringing raw material into Earth's orbit from asteroids of a certain size.
- IgorPartola 2y ago
  This was my thought as well. Also for what it’s worth iron oxidation is slow but very exothermic. So what you’d want is a LEO starting point/station. You launch a barge from there to snag an asteroid. You could use a mass driver using solar or nuclear and mass from a previously spent asteroid to get to the asteroid belt, then snag an asteroid and use its mass to get back. You strip the important parts of it, construct a capsule for what you mined, and nudge it so it falls someplace in say a shallow part of the ocean. Then recover from there. Or hell why mine it up there? Simply nudge an asteroid on a collision course towards Earth to make sure it falls someplace “safe”. Sure most of it will burn up but not all. It’s free material after all.
  - dylan604 2y ago
    Didn't the asteroid that destroyed the dinosaurs hit the ocean?
    - IgorPartola 2y ago
      Sure. So size matters. If you drop a rock in the ocean it doesn’t darken the skies, does it? Meteors fall onto Earth all the time. It is a matter of composition, trajectory, and mass, no?
      - dylan604 2y ago
        > It is a matter of composition, trajectory, and mass, no? We're talking very specifically about an asteroid made up of iron. Logic would follow that it would be on the more massive end of the scale. No? That's like the worst possible composition and the very type that worries the doomsday types.
BobaFloutist 2y ago
Ok, just park an ion drive on the asteroid and your descendant's descendants' descendants' get to mine it from LEO?

api 2y ago

Moving mass back with a free return trajectory is much easier than getting stuff out of Earths gravity well and up there. Escape velocity from an asteroid is low and if you yeet it with enough precision you can send it on a trajectory that will land it on Earth. As for moving the asteroid you could use extremely high specific impulse ion thrusters, in situ propellant from the asteroid itself, or a solar sail. But you are right that simply firing the valuable stuff back to Earth is probably easier.

lolinder 2y ago

Not to mention the governance and liability implications of the plan. If a company mining something on Earth screws up really badly, they can ruin the environment for a hundred miles around. If a company mining an asteroid in LEO screws up really badly, the literal blast radius would wipe out a significant percentage of life on earth.

dylan604 2y ago
Why does it need to be parked in LEO? It could be kept in an orbit at the same distance as the Moon and it would still be relatively close compared to where it is now
- lolinder 2y ago
  Fair. I don't think we'd want that either, though, for the same reason. The moon is too close for comfort for smaller objects that we've proven we can move.

Teever 2y ago

What about using the asteroid itself as fuel? Even if the asteroid is devoid of hydrocarbons that could be turned into fuel for conventional engines iron make a suitable (albeit inefficient) fuel for ion thrusters powered by solar panels. Mass drivers and linear rails are also viable ways of bringing raw material into Earth's orbit from asteroids of a certain size.

IgorPartola 2y ago
This was my thought as well. Also for what it’s worth iron oxidation is slow but very exothermic. So what you’d want is a LEO starting point/station. You launch a barge from there to snag an asteroid. You could use a mass driver using solar or nuclear and mass from a previously spent asteroid to get to the asteroid belt, then snag an asteroid and use its mass to get back. You strip the important parts of it, construct a capsule for what you mined, and nudge it so it falls someplace in say a shallow part of the ocean. Then recover from there. Or hell why mine it up there? Simply nudge an asteroid on a collision course towards Earth to make sure it falls someplace “safe”. Sure most of it will burn up but not all. It’s free material after all.
- dylan604 2y ago
  Didn't the asteroid that destroyed the dinosaurs hit the ocean?
  - IgorPartola 2y ago
    Sure. So size matters. If you drop a rock in the ocean it doesn’t darken the skies, does it? Meteors fall onto Earth all the time. It is a matter of composition, trajectory, and mass, no?
    - dylan604 2y ago
      > It is a matter of composition, trajectory, and mass, no? We're talking very specifically about an asteroid made up of iron. Logic would follow that it would be on the more massive end of the scale. No? That's like the worst possible composition and the very type that worries the doomsday types.

BobaFloutist 2y ago

Ok, just park an ion drive on the asteroid and your descendant's descendants' descendants' get to mine it from LEO?