3 ms·

That’d be inconceivably far in the future. It’d need to be more economical to transport goods through space…

abecedarius 5y ago
Two-way cargo transport through vacuum has zero net energy cost, just like a counterweighted elevator on Earth, only more so -- no vacuum here. With reasonable intelligence and infrastructure we should approach that limit. Design sketch from 1978, with numbers: https://frc.ri.cmu.edu/~hpm/project.archive/1976.skyhook/papers/free.txt https://frc.ri.cmu.edu/~hpm/project.archive/1976.skyhook/pap...
- goodoldneon 5y ago
  There isn’t energy cost between bodies, but there are huge energy costs getting into orbit, leaving orbit, and getting into the destination body’s orbit
  - abecedarius 5y ago
    Factories, refineries, and raw materials don't need to be on planets. There are disadvantages to siting on planets besides the added transport costs. > getting into the destination body's orbit I said round-trip energy costs. The delta-v for arriving cargo to enter orbit equals the delta-v for departing cargo. Over a full cycle of sending equal payloads both ways, the net change of energy and momentum is zero. I linked to an analysis of one way to harness this. When the skyhook in the linked example boosts a payload from Venus-Earth Hohmann to Earth-Mars Hohmann, the skyhook's orbit gets perturbed; but it gets the opposite perturbation on the boost on the opposite traffic. (This is not the only non-rocket approach to free-space transport with potentially low marginal cost.)
    - politician 5y ago
      Heavy industry in space is a ludicrous idea for the next few centuries. We will need to significantly rework industrial processes to avoid the heat buildup currently offset by the planet. No one will be operating a foundry in space anytime soon. Niche applications like low-temperature ZBLAN manufacturing might make more sense.
      - abecedarius 5y ago
        I disagree about centuries because the rate of progress so far belonged to a regime of launch costs of thousands of dollars per kg or worse. (Though "centuries" is at least more realistic than "inconceivably far". People were conceiving it in the 1970s and earlier.)
        politician 5y ago
        Maybe we'll use mass drivers to cool platforms in a couple hundred years. Maybe we'll reuse the slugs to excavate other bodies.

Two-way cargo transport through vacuum has zero net energy cost, just like a counterweighted elevator on Earth, only more so -- no vacuum here. With reasonable intelligence and infrastructure we should approach that limit. Design sketch from 1978, with numbers: https://frc.ri.cmu.edu/~hpm/project.archive/1976.skyhook/papers/free.txt https://frc.ri.cmu.edu/~hpm/project.archive/1976.skyhook/pap...

goodoldneon 5y ago
There isn’t energy cost between bodies, but there are huge energy costs getting into orbit, leaving orbit, and getting into the destination body’s orbit
- abecedarius 5y ago
  Factories, refineries, and raw materials don't need to be on planets. There are disadvantages to siting on planets besides the added transport costs. > getting into the destination body's orbit I said round-trip energy costs. The delta-v for arriving cargo to enter orbit equals the delta-v for departing cargo. Over a full cycle of sending equal payloads both ways, the net change of energy and momentum is zero. I linked to an analysis of one way to harness this. When the skyhook in the linked example boosts a payload from Venus-Earth Hohmann to Earth-Mars Hohmann, the skyhook's orbit gets perturbed; but it gets the opposite perturbation on the boost on the opposite traffic. (This is not the only non-rocket approach to free-space transport with potentially low marginal cost.)
  - politician 5y ago
    Heavy industry in space is a ludicrous idea for the next few centuries. We will need to significantly rework industrial processes to avoid the heat buildup currently offset by the planet. No one will be operating a foundry in space anytime soon. Niche applications like low-temperature ZBLAN manufacturing might make more sense.
    - abecedarius 5y ago
      I disagree about centuries because the rate of progress so far belonged to a regime of launch costs of thousands of dollars per kg or worse. (Though "centuries" is at least more realistic than "inconceivably far". People were conceiving it in the 1970s and earlier.)
      - politician 5y ago
        Maybe we'll use mass drivers to cool platforms in a couple hundred years. Maybe we'll reuse the slugs to excavate other bodies.