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Post by bigbombr on Jun 3, 2018 6:00:07 GMT
I'm not saying fusion power is a foregone conclusion. I'm only saying that nothing short of fusion power can make you a multi planetary species. Why do you think so? Fusion is AFAIK too anemic (low thrust) to get into orbit, and it's certainly not the only high exhaust velocity drive. Neither is it the only viable energy source.
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Post by AtomHeartDragon on Jun 3, 2018 18:05:28 GMT
I'm not saying fusion power is a foregone conclusion. I'm only saying that nothing short of fusion power can make you a multi planetary species. NPP, pulsed NTRs, gas core NTRs. And then you have all various solar-* and beamed-* stuff.
Sure, fusion, especially proton-boron, especially if it could also be light, compact and have beefy TWR is kind of holy grail here, but I don't think it's absolutely necessary.
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Post by Kerr on Jun 3, 2018 18:22:57 GMT
I'm not saying fusion power is a foregone conclusion. I'm only saying that nothing short of fusion power can make you a multi planetary species. NPP, pulsed NTRs, gas core NTRs. And then you have all various solar-* stuff.
Sure, fusion, especially proton-boron, especially if it could also be light, compact and have beefy TWR is kind of holy grail here, but I don't think it's absolutely necessary.
Especially avoid pB11, it has little redeeming qualities, aneutronic fusion rockets aren't usually that worthwhile. Deuterium-deuterium would be the holy grail, and with autocatalytic detonations waves, you can also avoid those pesky neutrons. Laser propulsions seem rather promising, allowing for gas core - MPD performance without the technological investments. A lithium-solar sail would also work, doing a brachistochrone with them is totally plausible and still gives you better performance than using Hohmann transfers.
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Post by bigbombr on Jun 3, 2018 20:59:09 GMT
NPP, pulsed NTRs, gas core NTRs. And then you have all various solar-* stuff.
Sure, fusion, especially proton-boron, especially if it could also be light, compact and have beefy TWR is kind of holy grail here, but I don't think it's absolutely necessary.
Especially avoid pB11, it has little redeeming qualities, aneutronic fusion rockets aren't usually that worthwhile. Deuterium-deuterium would be the holy grail, and with autocatalytic detonations waves, you can also avoid those pesky neutrons. Laser propulsions seem rather promising, allowing for gas core - MPD performance without the technological investments. A lithium-solar sail would also work, doing a brachistochrone with them is totally plausible and still gives you better performance than using Hohmann transfers. What do you mean by "lithium-solar sail"?
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Post by Kerr on Jun 3, 2018 21:04:35 GMT
Especially avoid pB11, it has little redeeming qualities, aneutronic fusion rockets aren't usually that worthwhile. Deuterium-deuterium would be the holy grail, and with autocatalytic detonations waves, you can also avoid those pesky neutrons. Laser propulsions seem rather promising, allowing for gas core - MPD performance without the technological investments. A lithium-solar sail would also work, doing a brachistochrone with them is totally plausible and still gives you better performance than using Hohmann transfers. What do you mean by "lithium-solar sail"? Lithium can theoretically allow for an ultra-lightweight solar sail, but their mass alone they achieve 0.4m/s² at one AU. Add other components and you get average accelerations equal to that of some more sensible MPDs in CDE.
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Post by Hicks on Jul 3, 2018 17:39:23 GMT
That may work inside of earth's orbit, but every doubling of distance from the sun quarters the thrust output.
1AU: 40 cm/s 2AU: 10 cm/s 4AU: 2.5 cm/s (Jupiter ~5au) 8AU: 0.625 cm/s (Saturn ~9 au) 16AU: 0.15625 cm/s (Uranus ~19au)
And it just gets worse from there. I've been told that Magnetic plasma sails coupled to the solar wind that can porportunatly grow the farther you get from the sun can give near constant acceleration in the milliG, but those require at least a fission reactor to charge the plasma.
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