Construction

Architecture

A dangerous environment

The natural environment of Mars is deadly for humans and more generally for all living terrestrial species. The atmospheric pressure is a quasi-vacuum, about 1% of the pressure at sea level on Earth. The temperature rarely exceeds 0 ° C in summer, its average is below -50 ° C, and it can approach -100 ° C in winter on the territory of Foundation. The thin atmosphere allows a level of irradiation from solar storms and cosmic rays of over 300 mSv / year in an unprotected environment, nearly ten times the usually prescribed maximum dosage for workers of the nuclear industry.


Architecture thus takes on a particularly critical dimension on Mars, because the buildings must ensure flawless protection of the people and of the ecosystems that they shelter. To this end, Martian architects commonly divide habitats into three spaces, each with its own constraints: the Exterior (deadly, where one only moves in spacesuits or in pressurized vehicles), Living Space (public, enclosed space, containing the ecosystem), and Chez-soi (private space). The atmospheric pressure of the habitats is generally fixed at 0.7 bar, of which 0.26 kPa is oxygen, the rest being made up of an approximately equal mixture of nitrogen and argon. These values ​​are historic and derive from a need to reduce the stresses on the structures, to reduce the work required to produce inert gases while guaranteeing perfect health and physical condition for the inhabitants. The buildings respect historic standards of protection against radiation, fixed during the construction of the first bases on Mars. They allow anyone who wishes to do so to spend their entire life in areas identified as guaranteeing a level of irradiation set at a maximum of <100 mSv accumulated over 5 rolling years, in line with the rules for the protection of nuclear personnel on Earth by the International Commission on Radiological Protection (ICRP). These standards are accompanied by meticulous medical monitoring. However, the strong feedback accumulated by several hundreds of thousands of cumulative lives in this environment has led to the confirmation of the weak effect of low radiation doses, as observed in the Ramsar region in Iran on populations very exposed to a level natural radioactivity (up to 260 mSv / year), almost comparable to that of Mars. In particular, with the exception of outside workers, citizens do not wear a dosimeter, and no one, apart from Terran tourists, loses any sleep over the time spent in open spaces without direct protection. People from the equatorial city of Surya, more accustomed to vast open spaces, are more relaxed in this regard than people from the northern city of Arcadia.

Protective architecture

The construction of buildings on Mars is, to a large extent, reversed with respect to Earth: the stresses on structures produced by internal pressure are much greater than those of gravity: the structures must be built to resist bursting rather than crushing.

In Foundation, the pressure structures mainly consist of flexible cylindrical envelopes, intended to ensure gas tightness and resist both hoop and longitudinal stresses. Stainless steel is usually preferred, although other assembly have also had some success. An intensive research effort has led to significant improvements in flexible glass, leading to a material with high transparency, high resistance and low intrinsic energy, the 300M “AresShield“. This allows for the creation of spaces that are as open and bright as possible, lighting up dwellings that might otherwise have been suffocating. This design using a continuous pressure envelope removes most of the forces from the foundations. These modules can be joined in many configurations to enlarge the space, usually at the cost of some radiation protection, as can be seen in the larger parks in Surya. The dimensions of these enclosures follow the historical evolution of the Foundation cities, towards more industrial capacity and comfort: the center of Arkadia is made up of Mk1 cylinders of 9 m in diameter, surrounded by Mk2 cylinders of 18 m in diameter. The most recent constructions of Surya reach 36 m to 40 meters in diameter, approaching the practical limits of such constructions. The orientation of the tubes is then a matter of choice, with clearly marked architectural differences between Arkadia, favoring vertical cylinders and Surya that favors horizontal ones.

Radiation protection is provided according to available materials and technologies, with the aim of keeping lines of sight as open as possible. It is usually made of regolith; sintered, compressed, bound with various cements. Walls and roofs are thick and heavy, adding their mass to the radiation protection. In short, light envelopes enclosing heavy buildings.

Public architecture

Foundation urban planners seek to create open spaces, while breaking the monotony that an entirely artificial environment might, in principle, create. They look for curves when possible by varying the internal environments, and architectural diversity is encouraged by multiple artistic competitions. Over half the average grade space is occupied by vegetation, walkways, squares and parks, maintained by neighborhood associations. Reminders, if such was necessary, of the love of Martians for gardening. The cities are spread over several levels: the most pleasant surface urban spaces bring together dwellings and shops in a vehicle free environment, while the underground spaces hold the grow rooms, light industries, technical and storage areas. This arrangement reduces spatial extension, and therefore promotes walking and health, while ensuring close proximity to open and pleasant spaces. They also make it possible to passively reduce the dose of radiation for much of the working day. Many underground spaces also serve as shelters in the event of an accident compromising the integrity of a pressurized surface enclosure. The regulations require that sealable underground areas must meet the basic needs of the population for a month. Sometimes in difficult but bearable living conditions, while the elements destroyed in the event of a major disaster can be rebuilt and relief organized by other districts or city states.

Interior architecture

The interior of the buildings are generally modular, so that the size of the apartments can be quickly adapted to the size of each home. The Martians' way of life is generally more communal than that of the Earthlings: it is not uncommon for sanitary facilities and kitchens to be shared between several homes, although this is more common in the older districts of Arkadia.

A typical Surya habitat cross section. The extremely heavy roof as well as the heaped up regolith on the right of the tubular structure provide radiation shielding.

Public space to the left has little radiation protection, private space is shielded, as well as all the bellow grade floors.

The first basement provides transportation space for autonomous vehicles.

The second and third basements holds grow rooms with artificial lighting and climate control, where much of the food for the city is grown.

The service areas at the base provide life support back-up systems, water treatment and storage.

Each cylindrical habitat is at least partially autonomous, but the entire system is linked to provide greater inertia to the ecosystem and life support.

The tent concept

The tent is a new concept on Mars, using domes and tension structures for the creation of arbitrarily large spaces. The design is based on a flexible membrane made from the new 300M flexible glass, held in a mesh of steel cables. These cables are fixed to foundations that are either driven deep into the Martian soil of ballasted to keep the tent in place. The theoretical maximum height of the tent is a few kilometers, the weight of the cables would then exactly compensate the internal atmospheric pressure, without requiring anchoring. In practice, the height of the tents is dimensioned by the cost of the cables and the pressure inside the tent. A first attempt using very low atmospheric pressure was built successfully for the Nicholson PSHP and may lead, eventually, to having plants growing directly on the planetary surface.

View towards Lake Nicholson

"Some microorganisms live under the ocean at a pressure 400 times greater than the one we live at on dry land. A whale hears our heart beating when we approach it underwater and a dragonfly flies at 100 km/h while spending only 2 Watts and can stand up to 30 Gs". I listen to the words of Mathilda Kampf with the delight of a child enjoying a fairy tale. Jumping up from her desk, Mathilda, a seventy-year-old curator and researcher in aquatic ecosystems, takes me through a series of corridors dotted with fragrant plants and punctuates our walk with an uninterrupted flow of anecdotes. I am swallowed by this gentle tornado and suddenly stop in front of a huge aquarium. On Earth I didn't really care for them, but here it's been 8 months since I've seen water in close proximity in such large quantities. It's a miracle. An aquarium without fish ,but still. Mathilda joins me in my enchantment and explains to me that the botanical gardens begin by questioning the visitor about this thing that is life. These seemingly empty aquariums, for example, contain the two things that gave birth to humanity: liquid water and phytoplankton, basis of the oxygen and carbon cycles. "Striking, isn’t it? " I recognize the acuteness of this question and let Mathilda continue on to a crescendo of wisdom that I am not soon to forget: "The concept of this dome goes further than that of a museum and it was not easy to work out, on a purely ethical level, as our initial wishes touched on the principle of ecopoiesis, that is to say, ultimately, succeed in reproducing an ecosystem in its entirety ”. Concentrating on the words of my new teacher, I enter a large wooded area. It smells so good! I am overwhelmed by nostalgia for Earth and it’s forests. But why? Aren’t they already here? Further on, there are clearings and small savannah that we cross through in glass corridor. My host pointing her finger upwards, showing me a light structure high above our heads. We are under a gigantic transparent tent, and the tube keeps us from the inadequate air pressure outside. Inadequate to us, but not to plants, and not for water. A vista onto an immense surface of water open up, the lower reservoir of the Nicholson pump-storage power station. I question Mathilda: "Why do you absolutely want to reproduce the entire Earth ecosystem? You know it's impossible, right? "

"Unfortunately, we felt that we had no choice", retorts Mathilda. Bending down to pick up a small insect on the ground, she puts it up high onto a branch and continues: "if only for the simple reason that Earth needs Mars, just like a computer needs backup. It may seem presumptuous to you, but think about what we can learn from such an approach as the Earth gradually loses its biomass diversity. Water and phytoplankton put man on Earth, man will have put water and phytoplankton on Mars. At best, it will stir up the pride of Earthlings and at worst, it will make a copy that may take several thousand years to make; but it is worth it. ” Mathilda finishes the visit with me, and leaves immediately with a young man in a white coat, popping out of nowhere to drag her away to a conference rooms. Stunned by information overload, I realize that it is on Mars that I am learning to really understand my own planet. (From Lucie's notebook).

Steel tubes were adopted by the team for construction when it was realized that using regolith mass or reinforced concrete did not add significant advantages. the quantity of reinforcing steel in a concrete tube vs the steel in a metal tube is essentially the same. The concrete joints will require sealant as well, that constitute a procurement challenge on Mars. The pressure vessel hull acts as a nearly perfect sealant, a lightweight structural element and a good backing to internal construction. The large volumes for the habitats were also a product of the realization that pressure vessel base cost is a factor of enclosed volume and not of tunnel diameter. A long narrow tunnel will have the same mass as a short tunnel with a much larger diameter, if the volume they contain are the same.