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Why do you think they would need to do those launches in quick succession? If the lunar lander starship is parked in orbit without a crew it can be refuelled ov
by pharke 5y ago
Why do you think they would need to do those launches in quick succession? If the lunar lander starship is parked in orbit without a crew it can be refuelled over any convenient period of time. Once it's fuelled just send up the crew in a dragon capsule and off you go. The dragon would probably make a good lifeboat if you brought it along for the ride somehow.
- NortySpock 5y agoThey may have solved the LOX boiloff problem, but perhaps not.
- cookingrobot 5y agoEven if they need to refuel quickly, why not launch 6 starships for that mission? They’re planning to build lots of them aren’t they?
- jsmcgd 5y agoAs long as the crewed starship is fuelled in orbit not too long after the last tanker ship launched, then the amount of boiloff will be negligible. I suspect Spacex will develop cooling systems to re-liquefy any gaseous propellants as this will be more of a concern for the ~6 month mission to Mars.
- pharke 5y agoWikipedia[1] cites a 2010 study that gives a boiloff rate of 0.1% per day for hydrolox. Not sure if it would be less for pure LOX. Methane would remain stable so I wonder if there's a way you could balance the fuel load so that you can deliver only methane on some of the trips and then all the LOX in one trip to avoid having it hang around in orbit. [1] https://en.wikipedia.org/wiki/Propellant_depot#Feasibility_of_propellant_depots https://en.wikipedia.org/wiki/Propellant_depot#Feasibility_o...
- laverya 5y agoOxygen is the vast majority of the propellant mass, I'm afraid. Methalox is CH4+2O2->CO2+2H2O, so you need 4 Oxygen atoms for every Carbon atom (with Hydrogen being a rounding error).
- xixixao 5y agoDragon is 4.4 meters (14.4 feet) tall and 3.66 meters (12 feet) in diameter. Starship fairing payload envelope is 22m tall and 8m in diameter. More than 3 dragons would comfortably fit inside.
- jessriedel 5y agoI think the idea is that the fueled-up Starship in LEO would have already have most the payload inside since it launched. The only thing it would be lacking is the astronauts, so they can come in a much smaller vehicle. That said, this contract has astronauts boarding Starship in lunar orbit, not Earth orbit.
- jessriedel 5y agoThis contract is to take astronauts from lunar orbit to the lunar surface. They get from Earth to lunar orbit with SLS/Orion.
- jsmcgd 5y agoAlso it does not need to be the same tanker to do the resupply. The plan is to make 2 starships per week. There should be plenty available to continue refuelling missions if one is not available.