3 ms·
> you have to throw away 88.9% of the water that you mine on site Nobody cares about that. People care only about the end results, not about the efficiency (or
by credit_guy 4y ago
> you have to throw away 88.9% of the water that you mine on site
Nobody cares about that. People care only about the end results, not about the efficiency (or inefficiency) of the intermediate steps. As long as you can travel to Mars and back in half the time it takes with a chemical rocket, exactly zero people will shed tears for all the oxygen wasted after splitting water on Mars.
Besides that, chances are you will be able to find uses for the oxygen you produce. I don't need to remind you that people breathe oxygen, astronauts included.
- wumpus 4y ago> People care only about the end results, not about the efficiency (or inefficiency) of the intermediate steps. Look up for the guy claiming hydrogen is best and most efficient, even though performance per dollar is poor.
- zardo 4y agoSpeaking of performance per dollar, what does the nuclear fuel for an NTR cost?
- credit_guy 4y agoThe NERVA engine [1], [2] used 60kg of 92.5% enriched Uranium. The online nuclear fuel cost calculator [3] shows that at current Uranium market prices, the cost for 1kg of such highly enriched Uraniums is about $50k, so the whole engine core would come at about $3 MM. This engine had a weight of about 2.5 metric tons, a thrust of 75 kN and a specific impulse of 860s. For comparison, the weight of a SpaceX Raptor engine is about 1.5 tons, it has a thrust of 1.8 MN (24 times higher than Nerva) and a specific impulse of 360 s (2.4 times lower than Nerva's). [1] https://en.wikipedia.org/wiki/NERVA https://en.wikipedia.org/wiki/NERVA [2] http://www.astronautix.com/n/nervaalphaengine.html http://www.astronautix.com/n/nervaalphaengine.html [3] https://www.uxc.com/p/tools/FuelCalculator.aspx https://www.uxc.com/p/tools/FuelCalculator.aspx