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| Responsible NASA Official:
Mike Kincaid |
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Final Project
Megan K.
Legislator: Carlos F. Truan, Senator
The Martian Greenhouse
With its thin atmosphere and unbearably cold temperatures, the fourth planet from the Sun, Mars, is unable to support any type of plant life. Upcoming missions to Mars will require an adequate environment in which various plants will be grown and eventually processed into food. It is through the Martian Greenhouse structure that this idea will become a reality.
Aside from being pressurized, the modular building must be able to be easily constructed as well as maintained. Inflatable technology is currently the most appealing option to engineers, yet it is still in its early stages. An inflatable habitat would allow “significantly more space with only a minimal increase in dimensions.” This is a major advantage in that it permits a larger payload size and a greater weight to be brought on board. Because it will lead to a huge cost reduction, the inflatable habitat is without a doubt an attractive option. The exterior of the greenhouse will be composed of extremely high strength steal, in order to reflect harmful solar rays and protect the interior from meteor impacts. All the seams will be properly welded to insure an airtight seal. Frames, made of a non-conducting material, will be strategically placed on the structure’s exterior. This will serve the purpose of both leveling the building and of keeping it from coming in contact with the cooler temperatures of the Martian regolith. This individual habitat can in time be connected to others of the sort through the use of tubular tunnels; however, the main focus right now is to construct the first.
In order to properly maintain healthy living plants, many things must be taken into consideration. For one, temperature is a vital necessity in the growth of each type of plant. Therefore, a temperature sensor will be placed on each tray, guaranteeing that the plants will not be too hot or too cold. A pressure sensor will be mounted on the ceiling of the greenhouse and will guarantee that all of the filters are clean and free from debris. Another critical element is the proper usage of the humidity controls. Ranging from –40 degrees Celsius to 85 degrees Celsius, the humidity sensor will detect flaws in the release of humidity for each tray. If corrections must be made, the sensor will then send a message to the controls, thereby correcting the mistake. An oxygen monitoring system will be operated to determine if the oxygen within the habitat is at a stable and precise number, while the carbon dioxide and nitrogen sensor works to maintain the numbers of the carbon dioxide and nitrogen.
In order to efficiently grow space crops, a hydroponic fluid and control system must be utilized to produce a hydroponic solution for the plants. A hydroponic solution is a mixture of water and necessary nutrients that any plant will need to stay healthy while in the Martian Greenhouse. The production of this solution is fairly simple, as it only involves the mixing of water from the water storage tank and nutrients, which come from of decomposed plants and minerals. Several of the macronutrients in the solution include: Iron sulfate, Copper sulfate, Zinc sulfate, Manganese sulfate, Boric acid, Magnesium sulfate, Calcium nitrate, Potassium nitrate, and Potassium phosphate. Once the fluid is created, it then travels to the circulation system, where it is distributed amongst each tray in the greenhouse. The trays are all connected by tubular structure (not shown in my model). Once one tray is filled up, the solution begins to flow to the next, and so on, until each tray is maximized with its nutrients. The left over will be directed to the water purification system where it will eventually be cleaned through the use of a boiler and sent back to the main water system. Within the greenhouse, a series of condensers will be used to collect the excess humidity. This water will be also transported to the purification system. However, if the humidity falls to an extremely small number, humidifiers will be used to add humidity to the greenhouse.
The atmosphere control systems of the greenhouse were designed primarily to maintain acceptable ranges of oxygen and carbon dioxide ranges for human and plant life. Humans need both proper air and a healthy diet in order to survive on Mars. Their diet should consist of about 4898 calories per person per day. To help them stay healthy and obtain the right nutrients, a wide variety of plants will be grown in the greenhouse. Some specifics that will eventually be grown are: soybeans, wheat, white potatoes, carrots, spinach, cabbage, lettuce, tomatoes, peanuts, dry beans, sweet potatoes, celery, green onions, strawberries, peppers, herbs, rice, peas, snap beans, beets, radishes, and broccoli. Several plants will require different growth environments than others. For example- wheat, white potatoes, lettuce, radish and strawberries can be grown in the first chamber with a temperature of 16-20 degrees Celsius, with a relative humidity of 65%. The second chamber would consist of rice, soybean, sweet potatoes, peanuts, and tomatoes growing at temperatures of 22-26 degrees Celsius. The humidity of chamber two would also be at 65%.
The source of light for the Martian Greenhouse will not be solar radiation that is transmitted through the use of fiber optics. Maybe sometime in the future it will be; however, as of right now, high pressure sodium laps will be set up on each wall of the greenhouse in order to give the plants the energy they need to survive.
Harvesting and storing crops is currently under extensive research. Harvesting requires both machine processing and manual labor. The manual labor is mainly pertained to those crops, which bruise rather easily, such as salad plants. Methods including refrigeration, canning, and dehydration will be sued in storing the products. Within the processing area of the habitat will be a workbench, in which astronauts can use to work on while harvesting and storing the plants. This can also be an area to place harvesting tools on when not in use.
Although the Martian greenhouse is a long way from actually being constructed on the surface of the planet, the ideas for the building process are coming rapidly with the advancing of technologies. With this in mind, it is almost certain that we will see the first Martian Greenhouse within our lifetime.
Sources:
How Stuff Works
http://www.howstuffworks.com/eden2.htm
Lanius, Roger. NASA and the Exploration of Space. Stewart, Tabori, & Chang: New York. 1998.
Magic
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Last Updated: 09/07/01