I’m a bit skeptical though. Forget the fact that the crew will still be carried by the Orion (equivalent to Apollo’s CM) and only the landing part is provided by Starship. Two small unmanned lunar landers already toppled on their sides because they couldn’t get a proper footing on the uneven and loose lunar regolith. The Apollo LM had a very low C.G. Starship on the other hand, is a full long rocket stage with enough thrust to dig a hole at the landing site. How confident are we of a proper vertical landing? A topple would be a death sentence for its crew.
Another big problem is their choice of propellant. Boil off is a well known issue with cryo propellants like LOX and liquid methane. So far, no rocket has used cryo propellants for any stage that doesn’t use it soon after filling. The longest wait after filling is done for stages that coast for a few hours. SpaceX plans to have a fuel depot in space that’s filled by multiple (12?) other starships. Even if we assume that SpaceX eventually gains the ability to rapidly reuse Starships, there is going to be practical limitations on how fast the orbital fuel depot can dock with refuellers. Considering that the refuellers themselves need part of the propellant to reach space, and that the fuel depot is going to have boil offs, how many actual flights and time will it take to refuel the depot to full? And remember that after all that, they need 2-3 days to reach the moon before executing the orbit insertion, deorbit and landing burns. Further, the lander will need to spend some time on moon (which depends on their mission and presence of a moon base). What about the boil off during all that time?
What about the engine relight? They were supposed to demonstrate engine relight during the last mission. But they abandoned it because the propellants were nearly fully consumed and they were tumbling out of control (which is weird because I couldn’t see anything like an RCS that could arrest the rotation). Let’s assume they would eventually demonstrate a raptor relight in space. That still doesn’t solve the full problem. Cryo engines need to be chilled and purged prior to any relights. For in-space relights, part of that is usually done on the ground. But that won’t help if you need to relight after several hours or even days. Where do you get the propellants for all that?
Agreed.
SpaceX is doing cool shit though.
I’m a bit skeptical though. Forget the fact that the crew will still be carried by the Orion (equivalent to Apollo’s CM) and only the landing part is provided by Starship. Two small unmanned lunar landers already toppled on their sides because they couldn’t get a proper footing on the uneven and loose lunar regolith. The Apollo LM had a very low C.G. Starship on the other hand, is a full long rocket stage with enough thrust to dig a hole at the landing site. How confident are we of a proper vertical landing? A topple would be a death sentence for its crew.
Another big problem is their choice of propellant. Boil off is a well known issue with cryo propellants like LOX and liquid methane. So far, no rocket has used cryo propellants for any stage that doesn’t use it soon after filling. The longest wait after filling is done for stages that coast for a few hours. SpaceX plans to have a fuel depot in space that’s filled by multiple (12?) other starships. Even if we assume that SpaceX eventually gains the ability to rapidly reuse Starships, there is going to be practical limitations on how fast the orbital fuel depot can dock with refuellers. Considering that the refuellers themselves need part of the propellant to reach space, and that the fuel depot is going to have boil offs, how many actual flights and time will it take to refuel the depot to full? And remember that after all that, they need 2-3 days to reach the moon before executing the orbit insertion, deorbit and landing burns. Further, the lander will need to spend some time on moon (which depends on their mission and presence of a moon base). What about the boil off during all that time?
What about the engine relight? They were supposed to demonstrate engine relight during the last mission. But they abandoned it because the propellants were nearly fully consumed and they were tumbling out of control (which is weird because I couldn’t see anything like an RCS that could arrest the rotation). Let’s assume they would eventually demonstrate a raptor relight in space. That still doesn’t solve the full problem. Cryo engines need to be chilled and purged prior to any relights. For in-space relights, part of that is usually done on the ground. But that won’t help if you need to relight after several hours or even days. Where do you get the propellants for all that?