The first Mars pioneers will not build any shelters. They will bring habitats with them from earth. But, after the initial missions, permanent residents will need to make their own homes from the sand and rocks on Mars. After finding the needed key resources, the task of building and maintaining living areas will occupy a large portion of the Martian homesteaders time.

For some of the first missions, hybrid shelter systems might use some materials brought from earth in conjunction with Martian sand. One proposed shelter would be made from thick fabric materials that would be blown up like a balloon. Once fully inflated, they would be stiffened by some support structures and then covered with sand.

Since the average air temperature on Mars is a very cold -80 degrees F, any shelter built above ground would have to use heavily thermal insulation. The thin Martian atmosphere will also require the shelters to be air tight, so a near earth like environment could be maintained inside. Air locks would be needed to prevent the precious oxygen enriched breathable air from escaping into the Martian atmosphere as the Martian workers enter or leave the shelters.

Above Ground Shelters: The thin air of Mars will actually help to reduce the amount of insulation that would otherwise be needed if the air was thicker.

Although the air temperature is low, it is so thin that it will not conduct as much heat or cold as much thicker air would.

Conceptual drawing of Above Ground Habitat
(other paintings, like this one, may be
found on the web site of the
Mars Society

Above ground thermal insulation could, therefore, be made from multiple layers of plastic films with some low density foam insulation between.

For green house like shelters, multi-layer reflective type plastic films could be used. The films need to be designed so visible sunlight light would pass into the shelter but would block infrared heat light from escaping. This technique is often used in green houses on earth using panes of glass to trap the heat.

But, shelters that are built above ground using thin insulating walls, may not be the best solution for the permanent citizens of Mars. Because the atmosphere of Mars is so thin and since Mars has a very weak magnetic field, Mars may have much higher radiation levels from the sun and space than on earth. The thick atmosphere and strong magnetic field on earth naturally shields the humans from such harmful radiation. Long term exposure to such radiation on Mars may cause genetic damage in humans. One way to lower the radiation levels, is to place the living quarters for the Martian settlers below ground.

Below Ground Shelters:  Tunnel boring machines could be sent to Mars from earth. Once assembled, the machines could make miles of deep tunnels beneath the Martian surface. Living rooms, service shafts, air locks and trenches might all be made by robot machines. With a weak gravity, no Mars quakes and no liquid water seepage, Martian tunnels might be stable enough so little or no structural shoring would be needed. The drilling operation should leave the internal tunnel walls smooth, air tight but very cold. To make the tunnels suitable for humans, a lot of thermal insulation will be needed.

Spun glass (fiber glass) insulation might be made by sorting and melting a certain type of Martian sand.  A vapor barrier sheet would also need to be installed on the exposed inside of the insulated tunnel walls to prevent valuable water from working it way through the insulation and collecting on the cold tunnel walls.  Natural sunlight could be piped into the underground shelters using optical fibers. Water heated by the sun outside might be circulated around the inside of the tunnels to heat the air that is pumped into the tunnel.  The crushed rock and rubble that would be generated during the tunneling process would be pushed up to the surface and might be used for other shelter and building applications.  The rocks might also be studied to better understand the composition of the crust of Mars.   Smaller shelters above ground, might be made by digging holes into large boulders that lay on the surface. Such techniques might be ideal for emergency shelters.