One concept for a Mars settlement supported by Starship vehicles. (credit: SpaceX) Why a business case for Mars settlement is not required

Some people have claimed that a “business case” for profitable interplanetary trade with a Mars settlement, or at least the identification a saleable product for trade, is required before such a settlement can be established or supported by business or government. But there is no reasonable prospect for trade in any significant mass of physical material from a Mars settlement back to Earth in the near future due to the high transport costs. In his recent article in the National Review, “Elon Musk’s Plan to Settle Mars,” Robert Zubrin makes exactly the same point: a business case based on physical trade is not necessary and makes little sense. Later trade and commerce via non-physical goods such as software is probable once a settlement is fully operational. More significant and interesting economic situations will occur on Mars. For a Mars settlement, motivation and economics are interwoven. A good model for the expenditures needed to found colonies is the Greek and Phoenician expansion all across the Mediterranean and Black Sea areas in the period early in Greek history (before about 600 BC), leading to the founding of one of the greatest trading cities in history, Carthage. The cities who founded each colony did not expect immediate profit, but wanted good places for an expanding population and knew that, once the new cities were established, trade would also become established. Most of the cost was probably in building more ships. When European colonies were first established in the New World by Spain and Portugal, the emphasis was initially on a search for treasure, not production of products. English and Dutch colonies later led the way to commerce across the Atlantic, with tobacco, sugar, and cotton suddenly becoming a major part of world trade. A look at some of the steps required to create a Mars settlement will help us understand at least a little about Mars settlement economics. For a Mars settlement, motivation and economics are interwoven. It is possible for at least a partial business case to be made for the transport of settlers and the materials they will need to initiate some phase of Mars settlement. This includes the current effort to create a large number of reliable, low cost, and reusable super-heavy boosters and spacecraft, able to take payloads of 100 tons or more of cargo and passengers to Mars and land them at the right location. Part of this development and construction cost will be defrayed by commercial and government uses of the same vehicles, such as placing very heavy payloads in LEO and taking equipment and passengers to and around the Moon. Mars is the only planetary body in our solar system beyond Earth that has substantial but moderate gravity, a lot of volatiles, and no massive, crushing atmosphere or extreme temperatures, so it is the logical location for a surface settlement “in space.” People can work, operate equipment, and build structures on and under the surface of Mars, and protect themselves from the moderate galactic cosmic radiation (GCR) flux. An existing Mars settlement would also make continuing government and possible private efforts to explore Mars geology and climate history vastly easier, so the government should support settlement efforts if it can. This will require spending a significant amount of money, both on the transport system and the establishment of an initial settlement, before any “regular” settlers arrive, but due to the innovation, efficiency, and flexibility of private enterprise, the cost will be vastly less than any government effort. This early work will likely be done by SpaceX employees, some of whom may want to stay on Mars after their work is done. Elon Musk, SpaceX, and many of his very hard-working employees are clearly and strongly motivated by the desire to create a Mars settlement relatively soon. They see the multiple risks to humanity and the biosphere of existing on only one planet. The employees would probably get a free ride to Mars, as they would need to set up an initial development base from scratch. The money to support the SpaceX Mars settlement effort will probably come from other SpaceX business ventures, including launches for profit and its burgeoning swarm of communications satellites in low Earth orbit. Therefore, there is no business case needed to establish an initial development base and settlement as long as the financial support continues to exist from companies owned by Musk and his supporters. Most of the work on designing and building the transport system will happen right on Earth, at SpaceX sites like Hawthorne and San Pedro, California, Boca Chica and McGregor, Texas, and Cape Canaveral in Florida. Such a system could be tested as early as 2022 with cargo-only flights. Elon Musk has said that trips to Mars for crew and passengers would be at higher speed than current NASA missions, cutting months off the travel time and reducing exposure to space radiation. This means encountering Mars at a higher velocity, but either aero-capture into orbit or direct entry from an interplanetary trajectory would use the atmosphere to get rid of most of the excess interplanetary velocity, as it would be comparable to entry into Earth’s atmosphere on return from Mars. Cargo flights would probably use a standard minimum energy transfer orbit so that more cargo could be carried. In most cases, thanks to the Mars atmosphere, both passenger and cargo vehicles would not need to use rocket power to slow down more than about one kilometer per second before landing. Going into orbit first would generally mean a more accurate landing, but radio beacons at the landing site, a Martian version of GPS, and active trajectory management for each vehicle landing will increasingly improve accuracy. Assuming development of the Starship and Super Heavy proceed approximately on schedule, the first payloads to Mars in support of future settlements will probably be launched by SpaceX before any new NASA mission to Mars after the 2020 rover. The next probable NASA Mars missions after that could be a sample return mission launch in 2026, along with possibly an orbital radar mission dedicated to more precisely locating ice deposits. Some at NASA have accepted the priority of ice deposits as crucial to a human landing since 2015. If Musk launches payloads to Mars before that orbital mission reaches Mars orbit and has not had a chance to accurately map the locations, depth, and composition of the ice deposits, he might put his payloads down in a location without any ice deposit, which would waste the mission since he will need ice for his vehicles to take off again. Currently most of the near-surface ice seems to be north of latitude 32 degrees north, with less information about ice in the southern hemisphere. The closer to the equator a landing site is, the more sunlight and warmth there is. A NASA-sponsored group called the Mars Human Landing Site Study, an outgrowth of a 2015 conference on landing sites, has held Internet meetings every few months ever since and NASA now clearly recognizes the importance of proving that a landing site does have ice deposits. Assuming development of the Starship and Super Heavy proceed approximately on schedule, the first payloads to Mars in support of future settlements will probably be launched by SpaceX before any new NASA mission to Mars after the 2020 rover. Assuming that a good development base site with proven ice can be located before Musk launches the first Starship payloads to Mars, or at least before they attempt to land, between two and up to several Starships would land in 2022 or 2024, probably carrying a combined minimum of 200 tons or more of supplies and equipment. If SpaceX doesn’t have the time to develop much in the way of Mars-specific hardware, more generalized cargo like food, excavators, and other basic equipment would be sent that would be used by the first crew to arrive by 2024 or 2026, probably with about 25 people. If SpaceX can build Starships at the high rate Musk suggests, the second expedition (with the first crew), could have a dozen or more vehicles arriving at the base site, with more than 1,000 tons of equipment and supplies. The crew members would initially live in the voluminous habitation space inside the towering Starships, which would have to land some distance from each other to prevent damage from flying gravel. To create the development base, some think that the crew would continue to live in the Starship quarters until a tunneling system was operational. Alternatively, above ground habitats might be used for a while, but this would also expose the crew to unnecessary GCR flux. A quicker alternative to get the first crew protected from the GCR hazard would be simply burying a small number of hard-shell habitat modules in trenches, dug by the same kind of excavator that would later excavate Mars ice. Since the GCR flux is not lethal, but would significantly degrade overall health and raise cancer risk with time, this alternative makes the most sense. At some point, we will find out if this is part of the plan. Five or six such modules, connected together and with at least two airlock modules, would be able to hold the whole crew, who would get a negligible radiation dose while below ground. Crew members would take turns working above ground with crops and construction work outside on the Mars surface, versus working below ground in the habitats, to reduce individual exposure to GCR radiation. With the surface construction crews spending at least 50% to 70% of its time below ground, and habitat maintenance crews most of the time, the average GCR exposure should be reduced from the surface average of 0.72 millisieverts (mSv) per day down to about 0.25 mSv per day or about 0.01 mSv per hour. This early exposure rate would add up to about 88 mSv per Earth year. This compares to the 100 mSv limit for one year to radiation workers in the US. Construction crew members working on the surface could wear a “water jacket” around their torso to further reduce their dose, especially when sitting and operating heavy machinery, which could have shielding over the worker’s seat. As the operation shifts more into tunnel construction, fewer workers would be required on the surface, but some would still be needed to build, maintain, and operate the ice mines, energy plants and the propellant production plants, as well as other significant base infrastructure. Surface shift times and doses would get smaller and smaller. The near-surface Mars regolith layer (looser soil and rock) seems to be quite deep above solid bedrock, which may itself be partly shattered kilometers deep by ancient asteroid impacts. Minerals dissolved in ancient moving ground water may have partly cemented the regolith together in many areas before the water all froze. More recent areas with lava flows may have more intact basalt bedrock, but this reduces the chance of finding an ice deposit nearby. (However, you would not want to build a settlement too close to an ice deposit to prevent structural damage if the ice should melt.) The tunneling system must thus be able to deal with both loose rock and sediment and solid rock, as well as creating tunnel spaces that can be made airtight with a liner. A reasonable plan would be for a main tunnel with side tunnels first dug off from it at 90 degrees and later connected together, with excavation of the main tunnel continuing to enable the creation of more side tunnels. All excavation would be done at normal Mars air pressure (a physiological vacuum), so below-ground airlocks would be needed for access to the working tunnel-boring machines from the pressurized habitat areas. Several different sizes of machines could create vehicular tunnels, pedestrian tunnels, and multi-story habitat tunnels. The settlers will all need relevant skills and they will all have important jobs of some kind. Vertical shafts above the tunnels being dug would be needed at intervals to remove the ground-up tunneling debris. The side tunnels could then be lined and pressurized with airlocks connecting to the surface. If desired, the tunneling level can be fairly shallow or deep or multi-level. Living and working areas—some multi-story depending on the tunnel diameter—would then be built into the tunnels. Old debris-removal shafts can later be converted into surface access points with spiral stairwells, which could also lead to surface “Mars cupolas”. These would have thick roof shielding with overhangs over the windows, allowing people to observe surface activity without going outside or getting a radiation dose. In a similar manner, some buildings, even multi-story ones, but with heavily shielded roofs and windows well overhung with shielding layers, can be built above ground with direct connections to the tunnel system. This would somewhat reduce the total amount of excavation needed, and the ground-up excavated material can be used for shielding. Once the pressurized zone with completed habitat areas reaches a certain size, with multiple life support equipment and backup supplies and fundamental services such as energy and food production, settlers could start arriving. The “regular” settlers, who will pay several hundred thousand dollars to use the Mars transport system, will probably be expected to do their share of work on expanding and maintaining the settlement in addition to their own work specialty. Part of the motivation of a Mars settler is the excitement of being part of a growing community, where the physical community is growing and expanding, and where the settlers would be participating in that physical growth. (In large areas of the US and Europe, there is a strong anti-growth attitude among part of the population and most levels of government, which may feel stifling to those who want larger families, and enjoy building and being creative.) This will become the new settlement frontier, and many people still have the frontier spirit in their blood. The settlers will all need relevant skills and they will all have important jobs of some kind. If settlers who pay for transport to Mars volunteer to work above ground or on the expansion of the settlement, they would almost certainly get a large transport or rental discount for every day they spend above ground or when working in more risky environments. There also may be settlers who have lots of money and do not want to participate with work on the settlement expansion, so they might pay a higher transport rate. They might also have to pay a rental rate for their accommodation in the below-ground settlement. Other settlers would either be working on maintaining the settlement or doing kinds of jobs much like those on Earth. Settlement expansion work would be paid for by the company or local government that is expanding the settlement, while maintenance would be paid for by the settlers in some form such as a service fee or tax. The settlements would allow continued support of both science and mineral exploration, with some of it still being funded by NASA and some by the Mars communities. The area and volume of the settlement would grow steadily, initially mostly underground. Based on potential use of very efficient aerogel insulation in pressurized structures, parts of the plant growth areas might be able to be above ground. This decision depends on multiple factors which are still being analyzed, as aerogel insulation technology is still improving. A major cost for building subsurface growing areas is the tunneling, while a major cost for the surface farming is the construction of large, insulated, pressurized structures. The food growing area per person needed is much larger than most people realize, with a significant number of workers required to maintain the plants, harvest the crops, and later manage animals. Aboveground shift time would have to be limited because of the GCR flux. Subsurface growth chambers have one advantage in that, for short crops, several levels of growth surface can be accessible in each growth chamber, each with its own lighting. If the large aboveground structures prove feasible and cost-effective, they may evolve into large but limited areas of what is called “paraterraforming,” the holding of breathable air pressure against the surface with artificial structures instead of gravity. Having settlements built in the ground under such structures would also create a very large safety factor against accidental decompression of part of a settlement, but they would not protect against the cosmic radiation. That is why the settlements must be mostly underground for now. This description of settlement construction gives some idea of how many different jobs and skills will be required, even with significant parts of certain processes highly automated. A lot of fabrication may be done by additive manufacturing, and crop care will also be more automated. However, all machinery needs repair and maintenance by people who know how to do it. Much of our technology is already part of the “black box” repair category, which takes a specially trained technician to fix. Ask yourself when was the last time you were able to repair a household appliance like a washer or dryer yourself. As groups of regular settlers begin arriving every 26 months, the number of job categories would quickly multiply. At the same time, the number of skills each person would need to have to have would decrease. It is obvious that even if an economic system is devised in advance to cover payment for the use of skilled time, it would probably evolve gradually under social and political pressure. Differences in skill levels and the value placed on each skill, such as medicine, would result in different pay rates. Some services might be part of a package deal for settlers, while others might be part of a more normal monetary exchange system. It is possible that the settlers would use “Mars Dollars” instead of whatever currency they used on Earth. At some point, the original early SpaceX crew members would either switch to being paid by other member of the community or its local government, or developers linked to SpaceX or other companies would hire them to create development bases and then settlements at new locations. Some of them might pay to return to Earth. The settlements would allow continued support of both science and mineral exploration, with some of it still being funded by NASA and some by the Mars communities. One of the highest priorities would be to develop a more automated system for getting drill cores of polar and glacial ice so that the geological record of Mars stored in the layers of ice over both poles and in other areas can be preserved before the Mars settlers start terraforming the planet and start all the polar ice melting. Drilling for ice cores would be dangerous and difficult while wearing spacesuits, so the equipment must be designed to protect the workers from damage to their suits. A dedicated science base might be established at each pole to support the drilling operations. It is obvious that trade between Mars settlements will be far more important than any off-planet trade, unless that trade is in software or information such as entertainment or data processing. This shifts the whole “business case” argument ahead in time to when the settlements already exist. At some point, Mars settlements would grow to a size where Earth governments might be interested in exercising governance over them. They would probably have been governed up to some point by rules initially put in place by SpaceX, with the approval of the settlers. Other settlements could have been started by other countries, and some settlements would probably be multinational. Since there would be trade between settlements, such as one at an iron ore mining site, currency values would need to be defined. If Mars, with its lack of plate tectonics, proves (as we currently assume) to have more limited resources of concentrated minerals than the Earth, this could create conflicts between the settlements. If some settlements were initially built in low-lying areas, the start of terraforming operations would eventually begin to slowly flood these areas. This could be another source of conflict unless parts of the low-lying settlements were designed from the start to be able to be moved uphill at some point. All of these changes and interactions will have economic consequences. It is obvious that trade between Mars settlements will be far more important than any off-planet trade, unless that trade is in software or information such as entertainment or data processing. This shifts the whole “business case” argument ahead in time to when the settlements already exist. Economics is not simple, but it is now clear that the way will soon be open to Mars settlement—even for economists. 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