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The trough is too long: http://dl.dropbox.com/u/576530/kickstarter/u_shape_full.png http://dl.dropbox.com/u/576530/kickstarter/u_shape_full.png See "Kickstarte

by helwr 15y ago

The trough is too long: http://dl.dropbox.com/u/576530/kickstarter/u_shape_full.png http://dl.dropbox.com/u/576530/kickstarter/u_shape_full.png See "Kickstarter: Shorter project durations lead to higher funding rates": http://news.ycombinator.com/item?id=2684511 http://news.ycombinator.com/item?id=2684511 They'd be better off investing in nuclear propulsion R&D on a 5-10 year scale (Project Rover, phase IV): http://en.wikipedia.org/wiki/Project_Rover http://en.wikipedia.org/wiki/Project_Rover

rbanffy 15y ago
If civilian nuclear power gets replaced by other forms of power generation, we'd have a surplus of rocket fuel. If present sentiment continues, investing in nuclear-thermal propulsion could result in something interesting. Maybe I should start lobbying against nuclear power ;-) However, before we start, we should have some clear, economically viable, destinations. An NTR is worthless for launching stuff to orbit and that is 99.999% of what current rockets do. Where it shines is in Earth-Moon ferries and in planetary exploration.
- juiceandjuice 15y ago
  I did a rough guesstimate, and in order to get a space ship the size of the Space Shuttle to Alpha Centauri in under 100 years and stop it, you need probably about 20x10^18 J of energy, assuming roughly 1% efficiency of mass to kinetic energy propulsion and with minimal effects due to relativity. I don't think this number is off by more than two orders of magnitude, but it's probably still much too conservative. That's a lot of energy, about 10 times more than all nuclear explosions ever. Close to half your mass would be fuel at 1% efficiency.
  - deleted 15y ago
    [deleted]
  - rbanffy 15y ago
    I assume NASA is saying they want a launch in less than 100 years, not getting there in 100 years. Getting there in less than a 100 years is woefully unrealistic. Anyway, we would gain so much just by having better propulsion capabilities, I am in, even if we don't launch an interstellar probe in 100 years. I'll be happy with a soccer-field-sized optical telescope in space.

by helwr 15y ago

rbanffy 15y ago

If civilian nuclear power gets replaced by other forms of power generation, we'd have a surplus of rocket fuel. If present sentiment continues, investing in nuclear-thermal propulsion could result in something interesting. Maybe I should start lobbying against nuclear power ;-) However, before we start, we should have some clear, economically viable, destinations. An NTR is worthless for launching stuff to orbit and that is 99.999% of what current rockets do. Where it shines is in Earth-Moon ferries and in planetary exploration.

juiceandjuice 15y ago
I did a rough guesstimate, and in order to get a space ship the size of the Space Shuttle to Alpha Centauri in under 100 years and stop it, you need probably about 20x10^18 J of energy, assuming roughly 1% efficiency of mass to kinetic energy propulsion and with minimal effects due to relativity. I don't think this number is off by more than two orders of magnitude, but it's probably still much too conservative. That's a lot of energy, about 10 times more than all nuclear explosions ever. Close to half your mass would be fuel at 1% efficiency.
- deleted 15y ago
  [deleted]
- rbanffy 15y ago
  I assume NASA is saying they want a launch in less than 100 years, not getting there in 100 years. Getting there in less than a 100 years is woefully unrealistic. Anyway, we would gain so much just by having better propulsion capabilities, I am in, even if we don't launch an interstellar probe in 100 years. I'll be happy with a soccer-field-sized optical telescope in space.