Robert Zubrin published a detailed plan for generating rocket fuel on Mars several years ago. His book "The Case for Mars" is a good read.
Such a technology really is a game changer for the economics of the mission. And you can send your robotic fuel factory and make sure it's working before you commit to launching people.
I've actually got that book in my collection and you're right, it is a good read.
The idea of producing rocket fuel on Mars is not only a good one, but quite likely the only way such a mission would even be viable. The idea of hauling all that extra rocket fuel for the return trip to Mars and back simply doesn't work.
Such a technology really is a game changer for the economics of the mission. And you can send your robotic fuel factory and make sure it's working before you commit to launching people.