SpaceX talks about Mars Plans

Space dot com has a write up about it. Plus this: Pockets of frozen carbon dioxide in lunar cold traps

Comment:

Musk is already going to the moon. Would a more robust transportation system be a good enough reason to go to Mars via the moon? What would such a system require? Why would the current system be less robust?

Taking the second question first, the current system requires a very long trip. It needs to be very robust to accomodate so many people for so long. An eight month journey is a very long time in a weightless environment. Not to mention the radiation. The system Musk envisions would not be good enough for the trip. There needs to be an artificial gravity system and more protection from radiation would be desirable as well.

Launching from the moon can give some advantages that aren't available on Earth. For one thing, the transportation system can be built there if you can get enough material there to do the job. But a lot of material already exists there. His stainless steel rockets could be manufactured with iron obtained from the moon itself. The moon has no atmosphere, and there wouldn't be the requirement to make it aerodynamic. It can take on an odd shape and still "fly". For example, the lunar module used during the Apollo mission had a skin as thin as aluminum foil, but it went hypersonic speeds. Regulatory approval shouldn't be an issue as nobody lives there.

He can let his creative juices flow in that environment. It may add a bit more time to the timeline, but if you are going to do a thing, then do it right. A direct flight to Mars for a small crew may make some sense, but a million people? He needs something even more extraodinary than his Starships. Yes, even more extraordinary than a bigger gargantuan version of Starship called version two. He could build that sort of thing on the moon, and it could fly there as soon as he can get it constructed.

It is the "constructed" part that may be the most time-consuming. He will need a lunar version of the starbase. It could be the collecting point for a lot of people, and it could be the debarkation point for the long journey to Mars. Instead of a direct mission from Earth, just have the thing take off from the moon. It will use less fuel to get the delta v needed, and the ship can be as big as you wish it to be. It could be heavier so as to allow for more shielding against radiation. A bigger ship could be spun up at fewer rpm in order to get the artificial gravity needed to help with the weightlessness.

Instead of a tall ship, a short donut shape could be considered. A torus could be spin up for artificial gravity. A 200 meter in diameter torus could be spun up to 2 rpm in order to approximate Mars gravity.

If it is too big to land on Mars, you could build a welcoming station in Mars orbit. Just launch it from the moon. Or use the ship itself to hold people while they are shuttled down to the surface.

Musk is already going to the moon. A lunar base is not that big of a stretch, and it would be a good training and proving ground for his starships no matter what he does with his plans. While there, why not try something really bold? If these aren't the best approaches perhaps another approach in materials or methods could be better. It may need to be because what he has now entails more risks. There is less risk in making something more robust which would launched from the moon towards Mars.