Earth was the cradle of transhuman civilization, but Mars, with a population of 200 million, is now its heartland. When humanity began its spaceward diaspora, Luna was its first stop. Yet while Luna boasts a sizable population, Mars was the first world humans settled where they could thrive entirely on locally available resources.
During the first few decades, the early Martian settlers dwelt in tin can hab units, extracting methane from the local atmosphere for rocket fuel and water from the Martian permafrost, farming in inflatable greenhouses, and eventually manufacturing enough greenhouse gases to warm the planetary climate to the point where transhumans could walk the Martian surface unprotected, save for oxygen respirators.
The second phase of the great project of terraforming Mars—husbanding plant life and microbes engineered to rapidly replace atmospheric carbon dioxide with oxygen—was already underway at the time of the Fall. A belt of orbital mirrors helps to heat the planet by focusing the sun’s rays. The spread of plant life is a long-term project that will take several centuries to produce a fully breathable atmosphere, but the nigh-immortal transhumans of Mars are prepared to be patient. A new homeworld is worth the wait.
Research into new plants and microorganisms capable of releasing oxygen and nitrogen into the Martian atmosphere at an ever-accelerating pace is a major focus of economic activity.
In the meantime, the red planet is a place of startling contrasts, from the stark beauty of its mountain ranges and high desert, to the slowly-greening bottomlands of the equatorial Valles Marineris canyon system. In these bottomlands, oxygen levels are slowly rising, and liquid water can now be found in canals that had already been dry for millions of years when transhumanity’s ancestors came down from the trees.
Mars is a popular destination for travelers from around the system. Many Martians accrue wealth by operating lavish hotels, offering tours of historical sites, and leading wilderness expeditions to the rugged highlands and vast deserts of the untamed Martian frontier.
Mars now sports five vast, domed cities, mostly in the equatorial regions, along with numerous smaller settlements. Settlements are connected by surface roads, a network of near-sonic maglev trains, and air / spaceports from which suborbitals, airships, and near space rockets fly on regular schedules. Thanks to the abundance of methane fuel and the one-third Earth gravity, transhumans on Mars have finally got their flying cars as well, and all settlements have well-delineated rights of way for these vehicles.
Meanwhile, in the wild uplands, planetologists and terraforming engineers dwell in small villages, living the simple life in ruster morphs while seeing to the continued development of the Martian climate and atmosphere.
As a partially terraformed planet with vast tracts of unused land, Mars is one of the few places that can offer new sleeves to infomorph refugees. Martian brokerage houses do a brisk business in the purchase and resale of infomorph contract labor, with agreements (for some) leading to eventual sleeving. This has led to a sizable Martian underclass, however, organized as a growing resistance movement under the Barsoomian banner (though the hyperelite socialites disparagingly call them “rednecks”).