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298 points Teever | 1 comments | | HN request time: 0s | source
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habibur ◴[] No.45032963[source]
This won't enable perpetual space travel in case anyone thought so.

Rockets need to eject particles to generate force. And to eject 1 kg of fuel, its photo synthesis system has to lose 1 km of mass in one way or another.

The solution is to find a way to generate thrust without rocket fuel ejection.

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Buttons840 ◴[] No.45033094[source]
Can we "swim" through space? Collect particles from space, add energy, expell them backwards to generate a net thrust.
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aspbee555 ◴[] No.45033121[source]
no particles needed, we already have ion drive, just need electricity
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Taniwha ◴[] No.45033141[source]
Ions are atoms ..... tiny particles
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1. grues-dinner ◴[] No.45033491[source]
Quite big tiny particles in this application: Xenon is a fairly hefty atomic number of 54 - exactly double iron.

And you need quite a bit of it: even fairly small spacecraft like probes can have nearly a tonne of the stuff. Which, considering there's only 30-40ish tonnes extracted per year at a cost of about 1.5ish dollars per gram is quite a bit!