3 ms·

> but with two to five times the efficiency I suspect from the number that they're talking purely about Isp. Once one performs a whole system analysis, it's mu

• robonerd 4y ago
  I agree. Furthermore, besides the mention of Mars they're also talking about cislunar space in that same paragraph, but chemical propulsion seems sufficient in cislunar space. It's only takes a days to return from the moon with chemical propulsion, which proved sufficient in the past.
  • jhgb 4y ago
    LANTR would improve performance of lunar landers/cislunar shuttles, especially for variable specific impulse which is what LANTR could plausibly do without much trouble -- start with high oxygen flow for high thrust and high propellant mixture density, decrease oxygen flow later in flight for higher terminal Isp. This brings you the performance of a multi-stage vehicle without staging, and LANTR can even with high oxygen flow deliver Isp significantly higher than what hydrolox has, with propellant density several times higher than what pure-hydrogen NTR gives you. I've thought about trying to optimize the performance of such a variable Isp vehicle, but it requires calculus of variations skills that I'm lacking at the moment. I guess I need to take a look at that. But there's a decent chance that with a such a vehicle, you could move from the "we need to mine ice on the Moon" to the "we just need to extract oxygen from lunar soil; we can bring hydrogen from LEO" territory, which would be a win for lunar flights (for example you wouldn't be limited to polar region bases where you'd need to mine water to get back home).
  • deleted 4y ago
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