Mars habitat

A Mars habitat is a hypothetical place where humans could live on Mars. Mars habitats would have to contend with surface conditions that include almost no oxygen in the air, extreme cold, low pressure, and high radiation. Such a habitat might be placed underground, which would help to solve some problems but create new difficulties. One challenge is the extreme cost of transporting building materials to the Martian surface, which by the 2010s was estimated to be about US$2 million per brick. While the gravity on Mars is lower than that on Earth, there are stronger solar radiation and temperature cycles, and high internal forces needed for pressurized habitats to contain air. To contend with these constraints, architects have worked to understand the right balance between in-situ materials and construction, and ex-situ to Mars. For example, one idea is to use the locally available regolith to shield against radiation exposure, and another idea is to use transparent ice to allow non-harmful light to enter the habitat. Mars habitat design can also involve the study of local conditions, including pressures, temperatures, and local materials, especially water.

Overview

Significant challenges for Mars habitats are maintaining an artificial environment and shielding from intense solar radiation. Humans require a pressurized environment at all times and protection from the toxic Martian atmosphere. Connecting habitats is useful, as moving between separate structures requires a pressure suit or perhaps a Mars rover. One of the largest issues lies in simply getting to Mars, which means escaping Earth's atmosphere, sustaining the journey to Mars, and finally landing on the surface of Mars. One helpful aspect is the Mars atmosphere, which allows for aerobraking, meaning less need for using propellant to slow a craft for safe landing. However, the amount of energy required to transfer material to the surface of Mars is an additional task beyond simply getting into orbit. During the late 1960s, the United States produced the Saturn V rocket, which was capable of launching enough mass into orbit required for a single-launch trip holding a crew of three to the surface of the Moon and back again. This feat required a number of specially designed pieces of hardware and the development of a technique known as the Lunar Orbit Rendezvous. The Lunar Orbit Rendezvous was a plan to coordinate the descent and ascent vehicles for a rendezvous in Lunar orbit. Referring to Mars, a similar technique would require a Mars Excursion Module, which combines a crewed descent-ascent vehicle and short stay surface habitat. Later plans have separated the descent-ascent vehicle and surface habitat, which further developed into separate descent, surface stay, and ascent vehicles using a new design architecture. In 2010 the Space Launch System, or growth variants therefore, is envisioned as having the payload capacity and qualities needed for human Mars missions, utilizing the Orion capsule. One of the challenges for Mars habitats is maintaining the climate, especially the right temperature in the right places. Electronic devices and lights generate heat that rises in the air, even as there are extreme temperature fluctuations outside. One idea for a Mars habitat is to use a Martian cave or lava tube, and an inflatable air-lock was proposed by Caves of Mars Project for making use of such a structure. The idea of living in lava tubes has been suggested for their potential to provide increased protection from radiation, temperature fluctuation, Martian sunlight, etc. An advantage of living underground is that it avoids the need to create a radiation shield above ground. Another idea is to use robots to construct the base in advance of human's arrival. The use of living plants or other living biologicals to aid in the air and food supply if desired can have major impact on the design. Using a reduced-pressure greenhouse could reduce the structural demands of maintaining air pressure, but require the relevant plants to survive at that lower pressure. It is questioned how low of pressure a plant could survive in and still be useful. A Mars habitat may need to focus on keeping a certain type of plant alive, for example, as part of supporting its inhabitants. NASA's Caves of Mars study suggested the following food and food production characteristics:

Rapid growth survival in low light wide pH range high nutrition minimal waste The study noted two plants, duckweed (Lemna minor) and water fern (Azolla filiculoides), as particularly suitable, and they grow on the surface of water. The Mars habitat would have to support the conditions of these food sources, possibly incorporating elements from greenhouse design or farming. Historically, space missions tend to have a set amount of rations like Skylab, replenished with resupply from Earth. Using plants to affect the atmosphere and even enhance food supply was experimented with the 2010s aboard the International Space Station. Another issue is waste management. On Skylab all waste was put in a big tank; on Apollo and the Space Shuttle urine could be vented out into space or pushed away in bags to re-enter Earth's atmosphere. Considerations for maintaining the environment in a closed system included, removal of carbon dioxide, maintaining air pressure, supply of oxygen, temperature and humidity, and stopping fires. Another issue with closed system is keeping it free from contamination from emissions from different materials, dust, or smoke. One concern on Mars is the effect of the fine dust of the Martian soil working its way into the living quarters or devices. The dust is very fine and accumulates on solar panels, amongst other surfaces.

Relevant technologies

Some possible areas of needed technology or expertise:

3D Printing Mars atmospheric entry Caves of Mars Project Mars Excursion Module Aerospace engineering Space capsule Plants in space

Context A Mars habitat is often conceived as part of an ensemble of Mars base and infrastructure technologies. Some examples include Mars EVA suits, Mars rover, aircraft, landers, storage tanks, communication structures, mining, and Mars-movers (e.g. Earth-moving equipment). A Mars habitat might exist in the context of a human expedition, outpost, or colony on Mars.

Air

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