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I guess I'm not following you. What problem is this hypothetical power source attempting to solve? Before, it sounded like you were talking about a need to laun

I guess I'm not following you. What problem is this hypothetical power source attempting to solve? Before, it sounded like you were talking about a need to launch cargo into orbit. Why are you using the term power source? By the way, high-thrust, and high Isp (rocket fuel efficiency = propellant speed), goals generally conflict with each other. To launch from Earth requires high thrust. To travel through space requires high Isp.

gaius 18y ago
Because to do anything useful in space we've got to get stuff there, i.e. heavy industrial machinery for mining, and people to operate it, and a way to sustain them, and a way to get what they produce back to Earth. Getting in an out of a gravity well has to be routine. It's only expensive and difficult now because we don't have anything with enough energy density to do it. If you can make a powered re-entry you don't even need to bother with the Shuttle's elaborate heat shielding, you just take your time, match orbit with the Earth and come "straight down" in an hour or two. Power source, energy source, fuel, these terms are interchangeable.
- gravitycop 18y ago
  to do anything useful in space we've got to get stuff there, i.e. heavy industrial machinery for mining That is what the Sea Dragon is for. The payload capacity is 1.2 million pounds, and can be expanded with minor modifications. - It's only expensive and difficult now because we don't have anything with enough energy density to do it. We have kerosene and liquid oxygen. Chilled propane works, too. Are you thinking that these fuels and oxidizers are somehow not adequate? If so, in what way? - If you can make a powered re-entry you don't even need to bother with the Shuttle's elaborate heat shielding The Shuttle requires elaborate heat shielding for reasons that have nothing to do with the fact that it does not make powered re-entries. The Russian Soyuz capsule re-enters with a basic heatshield and lands on the Kazakh steppes. It's cheap. It's reliable. Powered re-entries to Earth are not feasible and not desirable. They would be outrageously expensive and probably unreliable (read: dangerous).
  - gaius 18y ago
    Powered re-entries to Earth are not feasible and not desirable If you've just mined a million tons of iron from an asteroid, I think you would want to bring it back in a controlled fashion!
    - gravitycop 18y ago
      Do you consider the Apollo or Soyuz re-entries to be too uncontrolled?

gaius 18y ago

Because to do anything useful in space we've got to get stuff there, i.e. heavy industrial machinery for mining, and people to operate it, and a way to sustain them, and a way to get what they produce back to Earth. Getting in an out of a gravity well has to be routine. It's only expensive and difficult now because we don't have anything with enough energy density to do it. If you can make a powered re-entry you don't even need to bother with the Shuttle's elaborate heat shielding, you just take your time, match orbit with the Earth and come "straight down" in an hour or two. Power source, energy source, fuel, these terms are interchangeable.

gravitycop 18y ago
to do anything useful in space we've got to get stuff there, i.e. heavy industrial machinery for mining That is what the Sea Dragon is for. The payload capacity is 1.2 million pounds, and can be expanded with minor modifications. - It's only expensive and difficult now because we don't have anything with enough energy density to do it. We have kerosene and liquid oxygen. Chilled propane works, too. Are you thinking that these fuels and oxidizers are somehow not adequate? If so, in what way? - If you can make a powered re-entry you don't even need to bother with the Shuttle's elaborate heat shielding The Shuttle requires elaborate heat shielding for reasons that have nothing to do with the fact that it does not make powered re-entries. The Russian Soyuz capsule re-enters with a basic heatshield and lands on the Kazakh steppes. It's cheap. It's reliable. Powered re-entries to Earth are not feasible and not desirable. They would be outrageously expensive and probably unreliable (read: dangerous).
- gaius 18y ago
  Powered re-entries to Earth are not feasible and not desirable If you've just mined a million tons of iron from an asteroid, I think you would want to bring it back in a controlled fashion!
  - gravitycop 18y ago
    Do you consider the Apollo or Soyuz re-entries to be too uncontrolled?