/sci/ - Science & Math

>>10546824
Oops, should have just said bipropellants.
>>10546826
And only for upper stages which aren't going to be operating for long stretches of time. The LH2 has to either be re-chilled, spent entirely, or wasted in offgassing if it stays out there for long, and as the other Anon is pointing out the exposure to LH2 will permanently reduce the working strength and flexibility of many of the components that work with it to the point that those components will be useless for rocketry a second time even if they are retrieved. Building a heavy lift vehicle which uses an LH2 first stage is like trying to run an 18 wheeler with a formula 1 racecar engine and once you turn the engine off the whole block is permafucked and can never be used again.