Question: what the fuck is Starship trying to accomplish over Falcon or Falcon Heavy? It seems like the design is a major regression in every imaginable way and its shimmering body screams another rushed, ugly EM pet project that's an expensive boondoggle like his ketamine fueled AutoCAD nightmare on wheels.
I think he has somehow managed to leave the CEO of SpaceX alone to do her thing - or likely she has managed him also as she seems incredibly competent.
Making space exploration 1000x cheaper basically. Not kidding, that’s roughly the goal I believe. That’s needed to make it possible to send enough stuff and people to Mars to make us a multi planetary species. It’s a completely crazy goal/idea, but that’s actually been the goal of SpaceX from the start. Getting Starship to work seems incredibly difficult and almost impossible, but so did landing a big booster rocket on a drone ship and today they do that so often it’s almost become boring.
LOX is liquid oxygen, which is not a fuel, but an oxidizer. Starship is fueled by liquid methane. Methane can not be made from just water, you need a source of carbon. On Mars for example methane could be produced from CO2 in the atmosphere and water from ice.
The only fuel you can make from water is hydrogen. The RS-25 engines used on the SLS core stage and the Space Shuttle used liquid hydrogen, as did the J-2 engines on the second and third stage of the Saturn V (but not the first stage, which used RP-1 (kerosene) burning F-1 engine)
Starship's Raptor engines use liquid methane however. There are a bunch of tradeoffs between the different fuels, but generally liquid hydrogen is more difficult and expensive to deal with. With low cost reusability being one of the primary objectives of Starship, liquid methane was chosen as the best option. The fact that it can also be manufactured on Mars was also considered, since CO2 is abundant in Martian atmosphere.