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A comment on Experts Urge U.S. To Continue Support for Nuclear Fusion Research. Parent comment

Re:Experts Urge U.S. To Continue Support for Nuclear Fusion ... by philwelch on Monday December 17, 2018 @12:02AM (#18696993)
That's a little reassuring in the sense that 100,000 Isp is, by at least an entire order of magnitude, too good to be true.

But, who knows? Energy is such a limiting factor that maybe you could, with enough energy, make a gigantic space-ark in space and fill it with hydrogen and have a massive fusion-powered rocket with 100,000 Isp. Maybe that's how we reach Alpha Centauri.

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Re:Experts Urge U.S. To Continue Support for Nuclear Fusion ... by pfdietz on Monday December 17, 2018 @12:12AM (#18697017)
Beamed energy propulsion makes a lot more sense.

One huge problem with any extremely high Isp rocket is heat dissipation. Any heat hitting the vehicle has to be radiated (there is insufficient reaction mass flow for that to cool the engines, as it does in chemical rockets). So it pays to keep the powerplant separate and beam low entropy energy at the vehicle.

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Re:Experts Urge U.S. To Continue Support for Nuclear Fusion ... by philwelch on Monday December 17, 2018 @12:48AM (#18697127)
> One huge problem with any extremely high Isp rocket is heat dissipation.

Oh, yeah, shit. I keep forgetting that's the defining difference between science fiction and reality when it comes to space travel.

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