Living on Other Worlds

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Living on Other Worlds

Many things about Mars would remind a settler of Earth, but some things are quite different. Except for the lack of any vegetation, the sandy, rock-strewn landscape looks much like an earthly desert. Dust devils and blowing dust storms are often seen. A day on Mars is 24.6 hours, similar to Earth's day, so the circadian rhythm of a settler would not be upset. Mars's rotation axis is tilted at 25 degrees compared to Earth's 23.5 degrees, so Mars also has seasons. However, its year is nearly two Earth-years long because Mars is one and a half times farther from the Sun. Therefore, the seasons on Mars are much longer than Earth seasons. Martian gravity is only about four-tenths as great as gravity on Earth. A person weighing 60 kilograms (132 pounds) on Earth would weigh about 24 kilograms (53 pounds) on Mars.

The Moon, on the other hand, is extremely different from Earth. It rotates once on its axis in the same time it goes once around Earth. Consequently, the Moon's day is about twenty-seven and one-third days long—two weeks of sunshine followed by two weeks of darkness. Also, the same side of the Moon always faces Earth. To someone standing on the visible side of the Moon and looking up, Earth is always at the same spot in the sky. Although it has phases like the Moon does, it never sets. Gravity on the Moon is only one-sixth of Earth gravity. A person weighing 60 kilograms (132 pounds) on Earth would weigh about 10 kilograms (22 pounds) on the Moon.

In considering how people might live in a settlement on another world, one needs to examine both the necessities of life and the quality of life. The basic necessities are oxygen, water, food, and protection from radiation. Quality of life includes pleasant surroundings, having something worthwhile to do, good health, a general feeling of well-being.

The Basic Necessities

Oxygen is certainly the most important of human necessities. Humans can live for days without food or water but only minutes without oxygen. Earth is the only known place that has a breathable atmosphere. The Moon has no atmosphere, and the Martian atmosphere is 95 percent carbon dioxide at a pressure only one-hundredth that of Earth's atmosphere.

Airtight habitats are necessary. They come in various sizes, ranging from a large dome enclosing an entire settlement to a small space suit enclosing an individual. Inside the habitat, the temperature, pressure, and oxygen content would be controlled. Pressure must be sufficient that lungs operate efficiently and oxygen is absorbed into the bloodstream. On Earth, sea-level pressure is 14.7 pounds per square inch (psi), but people live comfortably in mountain towns where the pressure is less than 10 psi. Pressure in the habitats would probably be less than 10 psi. Lower pressure means less stress on the structure of the habitat and less leakage. Settlers would have to wear a space suit whenever they left the habitat on foot, but rover vehicles for exploration could be pressurized with a breathable atmosphere.

In the list of essentials, water is second only to oxygen. Water was recently detected in sheltered craters in the polar regions of the Moon where the Sun never shines. There is evidence in the images of Mars that water once flowed on the Red Planet. Although the surface of the planet is extremely dry, much of the water may still be frozen in the ground similar to the permafrost in Earth's arctic regions. Dormant volcanoes exist on Mars, and there are probably warm spots underground where liquid water may exist.

An initial supply of food would have to be brought from Earth. A lunar settlement could continue to be supplied from Earth; it is only a three-day trip from Earth to the Moon. A permanent settlement on Mars would construct greenhouses in which to grow its own food supply using the resources of the planet. Plants need carbon dioxide and Mars's atmosphere has plenty. As a by-product, plants produce oxygen.

Carbon dioxide and noxious gases would be cleansed from the habitat air. Fresh oxygen extracted from Martian minerals , water, and atmospheric carbon dioxide would be added to the habitat's air as needed. Lunar settlers could extract oxygen from the minerals ilmenite (FeTiO₃) and anorthite (CaAl₂ Si₂ O₈). Everything would be recycled—air and water, in particular. Solid waste would be recycled into fertilizer and other usable products.

Settlers would need protection against the high-energy particles in space, mostly protons and electrons from the Sun and cosmic rays from beyond the solar system. On Earth humans are protected from these hazardous particles by Earth's magnetic field, which deflects them away, and by the atmosphere, which absorbs them before they get to the ground. The Moon, without a magnetic field or atmosphere, affords no protection against them. Mars also has no current magnetic field. The thin atmosphere of Mars absorbs some of the particles, and a settlement's walls would reduce them to a tolerable level, no greater than living on a mountaintop on Earth. Occasionally solar flares on the Sun spew out very-high-speed particles in great number and intensity. For protection during such a storm, settlers would have underground "storm cellars," much as storm cellars are used for protection against tornadoes in the Great Plains of the United States.

From the above it is obvious that Mars is a more desirable place than the Moon to establish a new branch of human civilization.

A City in a Dome

The enclosure for the settlement would be an inflated sphere with the bottom half buried underground. A simple dome would be difficult to anchor down because the pressure of the air inside would tend to force the dome off its foundation. With a sphere, however, the downward air pressure and the weight of the dirt in the bottom half would hold the upper half in place. The dirt-filled lower half would contain tunnels for rapid transit and chambers for life-support equipment and storage.

To reduce the stress of being on an alien world, the homes should look like terrestrial homes, especially the interiors. Construction material from Earth would be at a premium, so buildings inside the spherical shell would be square. Using the same amount of material, a square building has more floor space than a rectangular building. The citizens of this strange new world would quickly learn to use indigenous materials. They would develop their own ideas of what a Martian home should look like and how to make it comfortable.

Obviously the city in the sphere would have a circular layout. The center of activity would be located in the center of the settlement with a circular street running around the perimeter and linear streets radiating outward from the center. With such a layout, everyone would have about the same distance to walk to reach the center.

Energy Sources

No oxygen-consuming or polluting fuels would be allowed; only electric energy would be used in the dome. Legs, bicycles, and electric carts would be the primary means of transportation.

Nuclear generators located outside the habitat some distance away would be a primary source of electric power. In addition, electricity could be generated by solar panels during the day when the Sun is shining. Sunlight, however, is only half as intense at Mars than at Earth because Mars is one and a half times farther from the Sun, so the solar panels would have to be twice as large to produce the same electricity. On the Moon, night is two weeks long during which time the Sun could not be a source of electric power.

Once the settlement is well established, indigenous fuels would be used. Methane could be manufactured from the carbon dioxide in the Martian atmosphere. Water can be electrolyzed into hydrogen and oxygen simply by running an electric current through it.

Communications within the settlement would be by cell phone and videophone. Mars and the Moon are both much smaller in diameter than Earth so the horizon is much nearer and line-of-sight television and cell phones would work only for much shorter distances. Low-frequency short-wave radio would work over longer distances on Mars because it has an ionosphere to reflect the radio waves beyond the horizon.

Communicating with Earth from Mars involves a time delay because of the distance the radio waves must travel. This means that a Martian settler talking to someone on Earth using a radiophone would have to wait for their response, ten minutes to half an hour, depending on how far apart Mars and Earth are in their orbits. The best way to communicate would be by e-mail.

The Workforce

From the above description of the settlement one can see the wide variety of jobs that must be done. The atmosphere control equipment, the water pumps and distribution system, the electrical generating and distributing system, the structure of the habitat, the vehicles, and the greenhouses, all require people who can do more than just repair the machinery. Members of the settlement would need to thoroughly understand how the entire system works so they could modify or redesign it to improve its operation. Besides keeping the habitat functioning, scientists and engineers would need to explore the planet to look for resources that can be mined, processed, and fabricated into useful products to build additional habitats for future immigrants.

In the beginning, with only a few settlers, there would be a labor shortage. A person who is expert in several trades and professions would be given the first chance to go. Construction engineers, mechanical engineers, agricultural engineers, and at least one medical doctor would likely be among the first settlers.

Eventually, the settlers would find products that can be manufactured on the Moon and Mars better and cheaper than on Earth, and they would have a surplus to sell to Earth in exchange for equipment that cannot easily be manufactured on other worlds. As the population grows, the settlement would become more self-sufficient, eventually establishing its own political system and declaring its independence from Earth.

see also Communities in Space (volume 4); Earth— Why Leave? (volume 4); Food Production (volume 4); Governance (volume 4); Habitats (volume 3); Human Missions to Mars (volume 3); Interplanetary Internet (volume 4); Land Grants (volume 4); Lunar Bases (volume 4); Lunar Outposts (volume 4); Mars (volume 2); Mars Bases (volume 4); Mars Missions (volume 4); Microgravity (volume 2); Moon (volume 2); Political Systems (volume 4); Property Rights (volume 4); Religion (volume 4); Settlements (volume 4); Social Ethics (volume 4).

Thomas Damon