5 ms·

Not to mention asteroids made of iron would be much harder to knock boulders off of.

chongli 3y ago
Yeah if there's some solid iron asteroid out there heading right for us we're totally screwed. That's like a core of a planetessimal! Very dense stuff! It could also be some lighter rock (a matrix) with iron clasts, created from a collision between a huge, light asteroid and smaller iron planetessimal fragments. Then if our planetary defense system breaks off a bunch of boulders, some could contain the heavy iron fragments and some might not, so different things would happen on reentry for each boulder.
- JumpCrisscross 3y ago
  > if there's some solid iron asteroid out there heading right for us we're totally screwed Isn’t this among the easier to deflect? You literally smash other asteroids into it without much fear of it breaking up.
  - chongli 3y ago
    No. That’s going to be extremely difficult to deflect due to the momentum. You’d have to catch it much earlier. As for smashing “other asteroids” into it, that’s likely not feasible due to the vast distances between asteroids and the masses involved.
    - JumpCrisscross 3y ago
      > going to be extremely difficult to deflect due to the momentum Momentum is a function of mass and velocity. The momentum of two similarly-massive asteroids, one rock the other metal, is the same. Given existing technologies, deflecting a solid-ish body is easier than a loose pile of gravel.
      - chongli 3y ago
        The average distance between asteroids (and their nearest neighbours) in the asteroid belt is about 8 times the earth-moon distance. Most of these asteroids have roughly the same orbit, so they have almost no relative velocity. So to achieve a collision we have to dramatically change the velocity of one of them in order to hit the other in a reasonable time frame. But this doesn’t take into account the masses. Asteroids vary in size from about 1 metre across to the dwarf planet Ceres, at 1000 km across. A giant asteroid is unlikely to have other giant asteroids nearby. If one giant asteroid is on a collision course with earth, what is the likelihood we’ll find a similar-enough sized one within a reasonable enough distance to be able to make them collide? Extremely remote.
        JumpCrisscross 3y ago
        The point is composition has no influence on momentum. Nobody doubts causing two bullets, already mid-flight, to collide by shooting other bullets at them is nontrivial. To the degree I have seen it discussed, it’s in using a dense asteroid to gravitationally perturb a loose one. Precisely because dense, metallic asteroids’ orbits are easier for us to manipulate than rubble piles’.
- deleted 3y ago
  [deleted]

Yeah if there's some solid iron asteroid out there heading right for us we're totally screwed. That's like a core of a planetessimal! Very dense stuff! It could also be some lighter rock (a matrix) with iron clasts, created from a collision between a huge, light asteroid and smaller iron planetessimal fragments. Then if our planetary defense system breaks off a bunch of boulders, some could contain the heavy iron fragments and some might not, so different things would happen on reentry for each boulder.

JumpCrisscross 3y ago
> if there's some solid iron asteroid out there heading right for us we're totally screwed Isn’t this among the easier to deflect? You literally smash other asteroids into it without much fear of it breaking up.
- chongli 3y ago
  No. That’s going to be extremely difficult to deflect due to the momentum. You’d have to catch it much earlier. As for smashing “other asteroids” into it, that’s likely not feasible due to the vast distances between asteroids and the masses involved.
  - JumpCrisscross 3y ago
    > going to be extremely difficult to deflect due to the momentum Momentum is a function of mass and velocity. The momentum of two similarly-massive asteroids, one rock the other metal, is the same. Given existing technologies, deflecting a solid-ish body is easier than a loose pile of gravel.
    - chongli 3y ago
      The average distance between asteroids (and their nearest neighbours) in the asteroid belt is about 8 times the earth-moon distance. Most of these asteroids have roughly the same orbit, so they have almost no relative velocity. So to achieve a collision we have to dramatically change the velocity of one of them in order to hit the other in a reasonable time frame. But this doesn’t take into account the masses. Asteroids vary in size from about 1 metre across to the dwarf planet Ceres, at 1000 km across. A giant asteroid is unlikely to have other giant asteroids nearby. If one giant asteroid is on a collision course with earth, what is the likelihood we’ll find a similar-enough sized one within a reasonable enough distance to be able to make them collide? Extremely remote.
      - JumpCrisscross 3y ago
        The point is composition has no influence on momentum. Nobody doubts causing two bullets, already mid-flight, to collide by shooting other bullets at them is nontrivial. To the degree I have seen it discussed, it’s in using a dense asteroid to gravitationally perturb a loose one. Precisely because dense, metallic asteroids’ orbits are easier for us to manipulate than rubble piles’.
deleted 3y ago
[deleted]