Originally Posted by jogdish
I wonder what compromise if any they will make to lunar star ship ?
Personally I just think spaceX will bid on anything and figure it out later if ever, I don't think the above is good news?
All of them required development of brand new human rated rocket and that's not cheap. SpaceX were already developing reusable ones anyway so are forking out most of the R&D costs anyway.
Starship is designed to stand the vacuum of space for a journey to Mars so thermal insulation and leak proffing. And land on Earth and Mars. You can't use aero braking on the moon, so very rough rule of thumb half you mass will need to be propellant for landing or take off. Working back if you take off with no cargo then 120t, so you need 120t propellant. So landing with 120t ship + 120 propellant + 100t cargo (worst case) means an all up weight of 680t which is about half it's max weight.
Moondust may be an issue ?
I found this comment too
There will be in orbit refuelling, but not explicitly defined by NASA. NASA wanted many details about prospective human landing systems but left how each HLS gets to Near Rectilinear Halo Orbit to the each provider.
Starships can put 100+t in low Earth orbit. The maximum payload drops rapidly for higher energy orbits because of the propellant that must be reserved for re-use. Getting the lunar Starship to NRHO requires refuelling in LEO for a "small" cargo and further refuelling in a highly elliptical orbit for the full 100+t. Getting a tanker Starship with a full cargo of propellant to meet another Starship in that elliptical orbit requires refuelling the tanker in LEO.
After the uncrewed test trip from NRHO to the Moon and back the lunar Starship will need refuelling for then next (crewed) mission. That will require sending a tanker Starship (or several) to NRHO (and back) and that tanker will need to be refuelled at LEO to get to NHRO. The payload for the second trip to the Moon also has to get to NRHO - by cargo Starship, which again requires more refuelling.
One of NASA's concerns with the SpaceX HLS was the large number of refuelling launches required for each trip to the Moon. The SpaceX bid overcame this because the vast majority of refuelling events take place in LEO so scheduling and extra refuel to cover a failure does not cause a huge delay or cost increase compared to any trip to NRHO.
One of the bits I liked was what happens if you are on the Moon and decide your ascent vehicle is busted. With a Starship you have a massively oversized cargo bay for extra food, a large LOX tank to breath and a methane+LOX to burn to stay warm and to provide water. The really scary thing about the Lunar Gateway is if you miss your launch window from the Moon you have to wait another 7 days for the gateway to get back to where you can meet it. Starship gives you three places to wait that out: the crew habitat and each of the two airlocks has independent life support.