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The actual problem is a power/fuel source to move mass-produced and well-understood things into space in the first place. What about this?: http://news.ycombin

The actual problem is a power/fuel source to move mass-produced and well-understood things into space in the first place. What about this?: http://news.ycombinator.com/item?id=429099 http://news.ycombinator.com/item?id=429099

gaius 18y ago
If such a hypothetical power source existed, we could literally replace the propulsion systems of nuclear submarines and have an instant space fleet... Complete with torpedoes ;-)
- gravitycop 18y ago
  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?
- gravitycop 18y ago
  If you are talking about single-stage-to-orbit (SSTO) submarines, I should tell you that the Sea Dragon is kind of like that. It is 75 feet in diameter, and produced in an ordinary maritime shipyard out of steel. This is larger in diameter than any submarine ever made. The Russian Typhoon submarine class is 75 feet wide, but it is not round (it is shorter high than it is wide; flat top). http://en.wikipedia.org/wiki/Typhoon_class_submarine http://en.wikipedia.org/wiki/Typhoon_class_submarine A major difference between the Sea Dragon and an SSTO submarine would be the fact that a Sea Dragon is a staged vehicle. Only part of it would make it to orbit. It does launch from the sea, by the way. It could potentially be scaled up to whatever your preferable size is. Is there a particular reason why you would want a big metal submarine in orbit?

gaius 18y ago

If such a hypothetical power source existed, we could literally replace the propulsion systems of nuclear submarines and have an instant space fleet... Complete with torpedoes ;-)

gravitycop 18y ago
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?
gravitycop 18y ago
If you are talking about single-stage-to-orbit (SSTO) submarines, I should tell you that the Sea Dragon is kind of like that. It is 75 feet in diameter, and produced in an ordinary maritime shipyard out of steel. This is larger in diameter than any submarine ever made. The Russian Typhoon submarine class is 75 feet wide, but it is not round (it is shorter high than it is wide; flat top). http://en.wikipedia.org/wiki/Typhoon_class_submarine http://en.wikipedia.org/wiki/Typhoon_class_submarine A major difference between the Sea Dragon and an SSTO submarine would be the fact that a Sea Dragon is a staged vehicle. Only part of it would make it to orbit. It does launch from the sea, by the way. It could potentially be scaled up to whatever your preferable size is. Is there a particular reason why you would want a big metal submarine in orbit?