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Just recently nasa has announced the lunar starship as the winner of the Artemis lunar lander contract which i have to say I'm very excited about. In the latest render however, the nose cone of the starship has been modified such that instead of being capped, it has an exposed docking port, presumably for docking with the lunar Gateway. This makes sense for the most part, only that if this were a regular starship, this docking port would lead straight into the header tank. does this mean that the new lunar starship will forego the header tanks and just use RCS to ullage the tanks, or is there another more versatile method? I understand that it will be making use of many other landing motors seperate from the raptor engines, so could this mean they will have their own tank, possibly even pressure fed?

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This makes sense for the most part, only that if this were a regular starship, this docking port would lead straight into the header tank. does this mean that the new lunar starship will forego the header tanks and just use RCS to ullage the tanks, or is there another more versatile method? I understand that it will be making use of many other landing motors seperate from the raptor engines, so could this mean they will have their own tank, possibly even pressure fed?

As I understand things, the reason for the header tanks in Starship is to ensure reliable Raptor engine start whilst the ship is in the belly-flop. The headers have a feed pipe that leads to the side of the tanks (in vertical configuration! But it's the floor during belly flop), whereas for the main fuel tanks those pipes are on the floor of the tanks. During the belly flop fuel will probably settle onto the sides of the tank, I.E. away from the feed pipes to the engine, which risks the startup not working cleanly. So the headers exist to provide a reliable fuel source for the earth landing phase.

Everyday astronaut has a great article about Starship generally, which includes a section explaining this, from which I have sourced this image:

enter image description here

Lunar starship won't be returning to earth, so it won't need to perform the belly flop. I'm sure there will be a great many other engineering problems to solve, but as I understand things the specific problem that the headers are designed to fix won't be encountered by the HLS variant, so there's no need for them.

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