The only explicitly mentioned mission to Mars was the Red Hope craft, which almost certainly failed; its success would have required a sustained support effort from the Swarm, and that didn't seem likely.
Over five thousand years, however, it seems unlikely that nobody would try again. They clearly had access to deeper parts of the solar system, capturing comets to re-hydrate Earth. The book, however, focuses on describing the societies on and around Earth in that time period. Describing the process of colonizing Mars and the cultural collisions between Martians and Terrans(?) would pretty much be an entire other book, so I'm fine with Stephenson eliding the topic altogether.
If I am permitted headcanon, I would guess that the Red faction would have sent out Mars colonists some time before the events of Part Three, but terraforming Mars was a longer and harder process than terraforming Earth, so the exciting bits would happen chronologically after Part Three.
I agree with this thread wholeheartedly! I would have loved to have heard of the ending of the Mars mission, even if it was a footnote. Did they land on the red planet, die en route? Feasibly (well... STRETCHING feasibility...) they could even have survived a generation or two. CERTAINLY there was no chance of them surviving the milenia between parts two and three... but having them leave and that be it was rough on my brain! lol
Also I totally agree with James that a sequel or at least another footnote/world-building comment could have been about Terraforming Mars. Certainly it would be a greater challenge than even disaster-ridden Earth, but it seems like it would be completely doable with the lessons learned on Earth. And, genetically altered though they are, I'd like to think the human drive for "next" wouldn't have faded even 5K years later...
As I understand it, the biggest remaining challenge to long-term occupation of Mars (since our Seven Eves have masted the concept of rebuilding an atmosphere using customized microorganisms to create gasses and condensates en mass, dropping oceans onto a planet using comet debris, and so on!) is the lack of a strong magnetic field to shield from radiation. Would have loved to have seen what Neal Stephenson and our future generations did with this challenge!
Kim Stanley Robinson's Mars trilogy definitely helps satisfy this yen... but still, I would have loved another author's take...
AMAZING book, incredible concepts... I love when my biggest complaints all revolve around "I wanted MORE!"
Like other commenters, I agree that Aïda was clear about the fate the Mars mission, but this question makes for a fascinating topic...
I think that over the course of the next several thousand years, there surely would be new attempts to colonize Mars. In fact, just as they're trying to "TerReForm" Earth in the book, it's easy to imagine that a "terrAform" of Mars was underway, too. You could also surmise that humans would try to colonize more asteroids (in the book they had, after all, already succeeded in colonizing at least one – Cleft).
After The Agent, Hard Rain, etc., it's not hard to imagine that humankind would be attempting to "hedge its bets" on survival by trying to create planetary habitats in as many locations throughout the solar system as possible. Smarter people than me have given this topic a lot of consideration: Wikipedia article on colonizing the solar system
The original Red Rover mission failed. Of the 800 odd arkies who broke away from Izzy to follow the Julian faction, eleven survived. Everyone else died because of solar mass ejections or starvation when agriculture tanked.
Since Kath Two doesn't mention any later effort to colonize Mars, I don't see any reason for the survivors to have gone there. They did colonize / mine other lunar fragments and built the Ring Habitat. Otherwise, effort went into bringing the Hard Rain to an end and re-seeding Earth with a viable atmosphere, oceans and an ecosystem. That would have been much harder on Mars, which is smaller, colder, and very far away.
I could see Mars being a future target of Red colonization, maybe... but Aïdan aims seem to be more pragmatic and political than idealist or imaginitive. The Mars mission was never necessary nor feasible. Unlike the Ymir mission, which was necessary to secure enough water for Izzy and the Cloud Ark, the Mars jaunt was a romantic daydream - the kind of thinking that Aïda was opposed to.
I agree that the supposition that the mars gambit failed is reasonable, but I still hope this subject remains a tickle in the back of Mr. Stephenson's mind and that perhaps it will develop into a sequel at some point.