CHOOSING THE SITE: RESOURCES, TERRAIN AND LOGISTICS
Our Mars City State Koemitan-Nahootsoii project assumes that by the time the cities are planted on Mars, exploration and limited settling of specific areas has been going on for decades and initial settlements extensively explored caves, lava tubes and other sheltering places with easy access to water. Also, we assume that the overall conditions of living, working, and prospecting on Mars will have been thoroughly worked out and that standard technological procedures are in place for building shelter, making fuel, generating electrical energy and producing water and oxygen. A small network of water prospecting sites and nuclear power sources is supposed to be scattered over the planet. Mars will already be permanently inhabited by people who consider the place their home; children will have been born and the roll of generations will have begun. Very high-resolution mapping of the entire planet is available; air transportation by vehicles with heavy-cargo ferrying capabilities is routine, complemented by suborbital vehicles.
Choosing an adequate site for a City State concerns mainly managing logistics. We chose a dual city design, with the two big centers of population and infrastructure separated by a very large distance, nearly half the planet´s circumference, so that every settlement or outpost does not lie at too great a distance from the Cities. The main driver for the City State location choice was the availability of water for consumption, rocket fuel manufacturing and energy production. We propose that water will be regularly obtained from buried ice deposits, mainly, but also permafrost and subterraneous aquifers . We considered several northern, low-latitude small craters for the approach known as paraterraforming . This approach is widely viewed as the best ethical and practical alternative to full terraforming, and consists in placing a limited (but possibly very large) amount of terrain under an artificial, transparent enclosing, where a breathable, N2+O2 atmosphere is kept, allowing open air activities. The height of the structure is ideally a few hundreds of meters and for the City State we propose a total covered area as large as 1,000 km2. This internal volume is large enough to possess limited weather and can easily accommodate millions of people, plus agricultural and leisure areas, administration, and some elements of the energy matrix. The solar power farms are an essential part of the energy infrastructure and are placed outside the paraterraforming enclosure.
FIGURE 1 – (top): site locations of Koemitan City, in Persbo crater at Cerberus Fossae, and Nahootsoii Town, in Guaymas crater at Chryse Planitia; (bottom): details of the Cerberus (left) and Chryse (right) locations: illustrative craters, in a range of sizes, are highlighted with diameters in kilometers and are deemed suitable for paraterraforming. Grid centers are given as latitude/longitude, approximately, in degrees – grid size is 2 degrees. Both craters have a “mud splash” aspect in their surroundings (best seen in figs. 2 and 3), evidence of subsurface ice melted violently during the formation impact.
The NASA Insight probe  identified in 2019 the Cerberus Fossae region at Elysium Planitia, at approximately 9oN latitude, as the epicenter of weak Martian quakes. This region also shows strong evidence of the action of water in the not too distant past, and very probably holds vast areas with large deposits of buried ice. Underground magmatic activity is hypothesized to have generated a system of aquifers, and therefore we propose this site for the main City – the one we named Koemitan City, from the Tupi language of South America. Craters with diameters in the 10-50 km range provide suitable environments for the paraterraforming proposal. Nahootsoii Town (the name stems from the Hopi language of North America), in its turn, was sited in our design to the southeast of the channel mouths of the Kasei Valles ancient drainage system, at approximately 25oN latitude, in Chryse Planitia. Both locations lie a few kilometers below planetary datum and offer increased protection from radiation due to a slightly denser atmosphere and, as we show below, they present a reasonable mineralogical diversity, translating to a varied resource availability, at least judged by the surface data . The specific chosen sites in the Elysium and Chryse regions are craters Persbo and Guaymas, respectively. In figure 1 we show the general locations of the two craters and their general topography. Figures 2 and 3 provide moe details on the topography of the two sites.
In figure 4 we show details of the general mineralogical mapping of the two locations: Koemitan City lies in the confluence of a variety of terrain: smooth plains of eolian deposits, crater plains made of lava (coated by loess), plus fissured lava plains and some orogen relics, with evidence of relief inversion, subsurface collapse, and ejecta. Nahootsoii Town is located besides lava plains and ancient volcanic shields, showing an abundance of fluvial and eolian deposits. Such terrain variety is interesting as different mineral and ore resources are likely to be available. In figure 5 we give some details on the results of the Insight probe detecting seismicity on the surface of Mars . Such seismicity is taken as circumstantial evidence of ongoing underground thermal activity, which are possibly linked to the existence of extensive aquifers – an extremely valuable resource [note: this remains highly speculative to date]. The siting of the double-city thus reflects flexibility, by having two great centers of population, and acknowledges logistics and sources of income. About the latter, Nahootsoii lies close to interesting and touristic landscape attractions such as Valles Marineris and Kasei Vallis: the great Tharsis volcanoes are approximately equidistant between the two cities.
Aerospace industry, which we consider a critical aspect of logistics and economics of the cities, requires a location close to the fuel producing industries and training centers, and not too far from the equator to gain delta-vee launch advantages from the planet’s rotation, with considerable fuel savings. Both City locations fulfill this need. The distance between the two sites is considerable: over 9,000 km, nearly half the planet´s circumference at the equator, but in or design each conglomerate is quite self-sufficient, and this distance is routinely overcome both by air transportation (slower but able to handle very heavy cargo) and suborbital flights (for light cargo and personnel transfer). A clear advantage of this wide separation is to minimize risks concerning regional hazards such as plagues and asteroid impacts. An array of much earlier, smaller settlements and outposts scattered over interesting terrain can be easily incorporated into this strategy.
Optimal general sites for the proposed design are craters with diameters in the range of tens of kilometers – the area within the crater is roofed over with plastic, metal and graphene-like structures to a height of a few hundred meters (ideally), taking advantage of the crater walls whenever convenient, and a breathable atmosphere is introduced, constituting the paraterraformed enclosure. A CO2+O2 atmosphere of 200-400 mb suffices for agricultural purposes and is maintained in separate enclosures; a higher pressure, 600-800 mb, N2+O2 atmosphere is kept inside the City proper. Living and working quarters are placed underground as much as possible, for increased protection against radiation and greater safety against sudden depressurization. Farming areas, parks and artificial ecosystems are found aboveground (details on next section) for practical and psychological reasons, offering open air for rest, recreation, and sporting practice.
An important aspect of the paraterraforming approach is that upwards of a certain enclosure size, even a large, sudden breach by a striking meteoroid will not deplete the inner atmosphere rapidly. Emergency shelters are strategically scattered above ground, so that people caught in open-air activities can speedily find shelter in the case of catastrophic breaches. The hardened sheltering of croplands for the event of breaches is not practical, and an advantage of the double-city design is that crop losses and soil bacteria death or degradation in the case of catastrophic depressurization and freezing can be compensated with help from the Sister City, by importing biomass and soil which are cultivated until full agricultural capabilities are restored. A rapid response robotic system is kept alert at all times and can easily handle small breaches of the enclosure: breaches in the scale of one meter are very quickly patched over with plastic plates and rapid-drying cement, a technique that essentially eliminates the danger from small impacts. Long term repair is subsequently carried out by isolating damaged sections, repairing, and reintegrating them to the main structure. Additionally, the City deploys a system of deep surveillance for space debris that is an integral part of Martian society and constitutes a service rendered off-world for revenue (more details on this system can be found in the section on economics). Present capabilities provide for the early warning against impacts from chunks down to a size of one meter or even less, and it is a very unlikely impactor that passes undetected through this system. As these capabilities are constantly improving and becoming more sensitive to ever smaller threats, fast-response teams are calibrated and the population duly warned and safeguarded, holding the promise of eliminating this danger altogether from Martian society.