The (Not So) Simple Act of Building on Mars: The Engineering Challenges
“Mars is a hostile construction site for both human and robotic builders, and for the structures themselves.”
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Here are the five main engineering challenges of building on Mars.
1. Lower Gravity
Mars has a much lower gravity than Earth. Gravitational acceleration is about 3.7 meters per second squared, compared to 9.8 meters per second squared on Earth.
This means that structures on Mars need to be designed to withstand lower loads and forces than they would on Earth. This will involve structural designs that can provide stability and support in a lower-gravity environment.
2. Atmosphere Challenges
The Martian atmosphere is very thin, with a surface pressure only about 1% that of Earth's.
This low atmosphere pulls out all of the oxygen in a human’s blood, causing circulatory shutdown within a minute. So pressurized habitats are required to survive.
Inside of an airtight Martian structure, all of the oxygen and other gases keeping the humans alive are pushing up and outwards, just like a balloon being blown up. This makes the air pressure inside the structure 100 times higher than the air outside. A tear or leak causing decompression could lead to an explosion.
To be able to withstand the pressure differential between the inside and outside of the habitat, the Martian structures need to be super strong. This is why dome shapes are preferred, as space does not like right angles and corners (The Martian).
A super thin atmosphere also means that there is less protection against meteorites.
3. Weather and Temperature Design Features
Because of the harsh conditions and limited resources on the planet, settlements and structures need to be designed with systems in place to ensure that they can be maintained and repaired over the short and long term.
Dust Storms: The dust storms on Mars can last for weeks or months. These storms can cover solar panels with a layer of dust. As well as damage equipment, obscure visibility, and make it difficult to work and travel on the surface for both humans and robots – resulting in delayed construction projects.
Extreme Temperatures: Mars has extreme temperature variations, with surface temperatures at the equator ranging from +20°C (70°F) at noon, dropping to -73°C (-100°F) at night.
As a result, structures on Mars need to be well-insulated, able to maintain a stable interior temperature.
There are several materials that have high insulation values and could be used for building on Mars. Some of the most promising materials for insulation include:
Aerogel: Aerogel is an ultralightweight material that has very high insulation values. The liquid part of a gel has been replaced with a gas creating a network of tiny pores, which trap air and reduce heat transfer. Aerogel has been used for insulation on Earth, and could potentially be used on Mars as well.
Foam: Foam materials, such as polyurethane foam, have high insulation values and are commonly used for insulation on Earth. Foam materials are lightweight and easy to work with.
Wool: Wool has high insulation values and is a natural and renewable resource. Wool has the advantage of being a breathable material, which could be useful for regulating humidity and air quality in a Martian habitat. A habitat that is possibly used for raising Martian sheep or camels.
Mars also has Earthquakes.
4. Radiation Shields
Structures will need to be designed and built with integrated shields against harmful radiation.
Mars lacks the protective outer layer of a magnetic field, called the magnetosphere. Causing the red planet’s surface to be unprotected from solar radiation coming from the sun, and cosmic radiation which comes from other stars outside of the solar system. All of this radiation sterilizes the surface of Mars and is harmful to humans.
Settlements and habitats will need to be heavily shielded, or be built underground.
This will involve building with materials that have high radiation shielding capabilities, as well as incorporating other design features that can reduce exposure to radiation.
Some of the most promising materials for radiation shielding on Mars include:
Dirt: Covering habitats with Martian dirt will shield the structures from radiation, and is readily available to harvest.
Lead: Lead is a dense and heavy metal that is highly effective at absorbing and blocking radiation. It has a high atomic number, which means that it is able to absorb a high number of photons and other particles from radiation. Lead is commonly used for radiation shielding on Earth, and could potentially be used for building on Mars as well.
Polyethylene: Polyethylene is a lightweight plastic material that has high radiation shielding capabilities. Polyethylene has the advantage of being relatively lightweight and easy to work with.
Water: Water is a good absorber of radiation, and can provide effective shielding against many types of radiation. In a Martian habitat, water could be used as a radiation shield by surrounding the main living quarters (where astronauts spend the most amount of time) with a layer of water, or by incorporating water into the walls and other structural elements of the habitat.
The winning design of the NASA 3D-Printed Habitat Challenge, Marsha, used a water-filled skylight.
5. Power Sources: Feeding the Robots
All of the Martian construction machinery will need a power source for fuel, but solar energy is limited on Mars.
Mars is much further from the Sun than Earth. The average distance of Mars from the Sun is about 141 million miles (227 million kilometers), while the average distance of Earth from the Sun is about 93 million miles (149.6 million kilometers).
On average, Mars receives about 43% of the amount of sunlight that Earth does. Making the Sun appear about half as bright in the Martian sky as it does in the Earth's sky. This reduces the amount of energy that the solar panels are able to generate. And the extreme temperature changes also reduce the efficiency of the solar panels.
Solar panel technology on Mars needs to be much more efficient compared to the technology used on Earth in order to generate the same amount of energy.
And batteries are needed to store the energy generated by the solar panels. Which are heavy to transport.
There is also a limited lifespan: as the dust storms and temperatures reduces the lifespan of the solar panels and batteries. Requiring them to be replaced from Earth, making them less practical for long-term use on the planet.
Other renewable resources such as geothermal energy could potentially be harnessed to generate power on Mars.
Such as building near an active volcano.
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