5 ms·

I believe it requires a refuel in orbit to get to the moon. So, two missions, but still super impressive.

simonh 6y ago
More than that actually, it takes I think 3 tankers to fully top up a Starship in orbit, and the Lunar model needs to go into an elliptical orbit towards the moon and have at least one more top up again before having enough fuel for the rest of the mission.
- throwaway316943 6y ago
  I thought the full refuel was only necessary for a Mars mission?
  - simonh 6y ago
    It’s interesting. Going to the moon, propulsive my landing, and propulsively taking off and returning to Earth takes more dV than just a boost to Mars. If you think about it boosting to Luna and Mars aren’t much different in dV, but then you have lunar landing and takeoff again to do. Even with a very thin atmosphere, you can still shed the vast majority of your interplanetary velocity with aero braking at Mars. As a result the Lunar variant actually needs a lot more fuel delivered to it than the Mars version. Even one full refuel in LEO isn’t enough, and it needs to boost part way to an intermediate elliptical orbit and get another top up.
beaner 6y ago
Genuine question, how will tankers get into space? If most of the ship's size is already dedicated to fuel that's burnt, that seems to leave little left for fuel payload. I also assume fuel payload would be much heavier than other types of payload, requiring more ship fuel to launch it, further taking up space. It seems like for every full refill you could provide in space it'd take an additional 3-4 ships just to get it up there?
- iso947 6y ago
  About that yes, but remember that a fully loaded starship in orbit can land on any solid surface in the solar system and return to earth (except for Venus) Starship’s usable volume is over 100 times that of an Apollo lunar lander.
  - dxdm 6y ago
    I don't get it, how does that answer the question about the economics of lifting fuel into orbit? Could you elaborate your point?
    - tjah1087 6y ago
      I think they are trying to imply that refueling a starship in orbit is worth it, whatever the cost - it gives a capability we didn't have before.
    - iso947 6y ago
      To land the volume of one starship on the moon takes 3 or 4 launches of a fully reusable craft - so just the fuel. To land that with Apollo would take 100 launches of a single use craft.
  - z3t4 6y ago
    You could also add 3-4 extra stages and put an even bigger tanker into space. But I guess there will be diminishing returns due to the crushing weight. It would probably be cheaper to make many smaller unmanned vessels and boost them via an electromagnetic rail, then assemble it in orbit.
    - samstave 6y ago
      Why not launch a bunch of larger payload tanker bays, empty, then link them together in orbit and then send Many smaller multiple regular trips to fill it up such that you have an orbital fueling station?
- paranoidrobot 6y ago

More than that actually, it takes I think 3 tankers to fully top up a Starship in orbit, and the Lunar model needs to go into an elliptical orbit towards the moon and have at least one more top up again before having enough fuel for the rest of the mission.

throwaway316943 6y ago
I thought the full refuel was only necessary for a Mars mission?
- simonh 6y ago
  It’s interesting. Going to the moon, propulsive my landing, and propulsively taking off and returning to Earth takes more dV than just a boost to Mars. If you think about it boosting to Luna and Mars aren’t much different in dV, but then you have lunar landing and takeoff again to do. Even with a very thin atmosphere, you can still shed the vast majority of your interplanetary velocity with aero braking at Mars. As a result the Lunar variant actually needs a lot more fuel delivered to it than the Mars version. Even one full refuel in LEO isn’t enough, and it needs to boost part way to an intermediate elliptical orbit and get another top up.

beaner 6y ago

Genuine question, how will tankers get into space? If most of the ship's size is already dedicated to fuel that's burnt, that seems to leave little left for fuel payload. I also assume fuel payload would be much heavier than other types of payload, requiring more ship fuel to launch it, further taking up space. It seems like for every full refill you could provide in space it'd take an additional 3-4 ships just to get it up there?

iso947 6y ago
About that yes, but remember that a fully loaded starship in orbit can land on any solid surface in the solar system and return to earth (except for Venus) Starship’s usable volume is over 100 times that of an Apollo lunar lander.
- dxdm 6y ago
  I don't get it, how does that answer the question about the economics of lifting fuel into orbit? Could you elaborate your point?
  - tjah1087 6y ago
    I think they are trying to imply that refueling a starship in orbit is worth it, whatever the cost - it gives a capability we didn't have before.
  - iso947 6y ago
    To land the volume of one starship on the moon takes 3 or 4 launches of a fully reusable craft - so just the fuel. To land that with Apollo would take 100 launches of a single use craft.
- z3t4 6y ago
  You could also add 3-4 extra stages and put an even bigger tanker into space. But I guess there will be diminishing returns due to the crushing weight. It would probably be cheaper to make many smaller unmanned vessels and boost them via an electromagnetic rail, then assemble it in orbit.
  - samstave 6y ago
    Why not launch a bunch of larger payload tanker bays, empty, then link them together in orbit and then send Many smaller multiple regular trips to fill it up such that you have an orbital fueling station?
paranoidrobot 6y ago