Greenhouse Structural Design
The type of greenhouse structure that might be used for strawberry plant production on Mars vary from small automatically deployed structures with a small number of plants for research purposes to larger structures that would be used to grow plants to feed human colonies on the Mars.
Structure requirements will vary accordingly to different size and purpose of the greenhouse; however function of the greenhouse will be same to produce the plants successfully. To determine loads is the first step in the greenhouse structural design. Dead loads will be considerably less than Earth because of less Martian gravity (0.38 of the Earth gravity). The density of Mars atmosphere is 0.01 that of Earth, so the wind loads are expected to be small on the deployable Martian greenhouse. However in the major storm conditions, the fast air velocity combined with lower Martian gravity can create a risk of uplifting or overturning of light greenhouse structures. The wind loads on the structure can be calculated from the following relation.
Inflatable greenhouse structures with curved geometry are focus of different studies for Lunar and Martian use.
Inflatable structures are a type of tensile structure which includes tents and other structures fabricated using membranes as structural elements. Membranes only carry tensile loads in the plane of the shell or fabric and cannot carry compressive or bending loads. The main load on this Martian greenhouse will be imposed by the internal pressure while gravity and wind loads will be smaller. The greenhouse wall must be thin, transparent and light weight with good strength against different stresses. Furthermore design must provide itself to being stored in a folded configuration and then automatically deployed into its functional configuration. The wall material must also be capable of being folded and be able to be automatically unfolded into the functional configuration. The curved shape of the Martian greenhouse seems more effective because its lower surface area to volume ratios which might be beneficial when considering the heat loss through the wall surfaces but it might also be of disadvantage when considering the light collection.
The underground structures seem more effective, safe and durable with multiple advantages of shielding the plants and colonists against harmful radiations, supporting the structures, moderating the environmental variations present on Mars surface and providing the shirt- sleeve environment with an atmosphere of 101.3 kPa to the colonists in which they can work normally without their space suits. This type of greenhouse might be installed at a depth of 4 m below the Martian surface. It must provide the enough floor space for irrigation, heating, electrical and other greenhouse related systems. Some structures of been shown below get a clear idea of the discussion.