Biosphere 2.1
MECE 4343 Thermal Design
Group 7
Date: 04/30/2020
Written By:
Anh Phung, Damian Kao, Aldor Shkurti, Andrew Ibarra, Cristian Castellanos
Abstract
The failed Biosphere 2 project ended 26 years ago. This project has been the only real attempt to create an artificial, materially closed ecological system, and ended in complete failure. This study will analyze all the problems related with technical results of Biosphere 2 closure such as oxygen levels and CO2 concentrations. After the first crew entered Biosphere 2, oxygen levels started to fall and were not close to normal levels. Oxygen levels reached as low as 14.5% after 16 months dropping from an initial of 20.9%. As for CO2 concentration, levels rose as high as 4000ppm from 1000ppm during the two years time frame. In this study, our team will provide solutions that would substantially assist in designing a self-sustaining enclosed biosphere for human habitation on Mars. We hope to achieve this by comparing existing documentation on the workings of Biosphere 2 to more recent ideas for atmosphere regulation in closed systems. The solution is not to create a mini earth, but to instead produce a system that can provide necessities for life sustainably. There have been recent developments with regards to this strategy, such as NASA’s approach to using hydroponic systems [1] to create a self sufficient closed system that provides as well as recycles food and air while using significantly less space, which is key to creating and maintaining cost effective and efficient systems in very remote locations.
Problem Statement
To use the results from the Biosphere 2 experiment in order to assist in designing a self-sustaining enclosed environment, that could efficiently support human life beyond the earth’s biosphere and on Mars for extended periods of time.
Introduction
Biospherics can be defined as the science of energetically open, relatively materially closed life systems that increase their free energy over time (Morowitz, 1979, 1988). Biosphere 2 is a research facility that was constructed in the late 1980s, to study earth’s different ecosystems by trying to replicate them within a confined space of 3 acres. The goal was to provide data for designing methods for long term habilitation in space. Biosphere 2 was a closed system which housed a tropical rain-forest, desert, savannah, and cloud forest ecosystems as well as a coral reef within a miniature ocean. [2]
Eight researchers lived in the biosphere for two years, mostly isolated from the outside world. Their goal was to see if the systems established within the biosphere could sustain itself effectively. However this was not the case, and they came across many issues such as drops in oxygen levels, and increases in carbon dioxide and nitrous oxide [3], which was life threatening and had to be remedied via external sources. Although providing much needed research data, the technology used in Biosphere 2 would not succeed in creating a self sustaining system for living on Mars. Biosphere 2 was technically designed to be a research experiment to understand the many processes that work on earth, therefore duplicating or using an updated version of it will not be a good idea. Changes will have to be made, and duplicating all of earth’s ecosystems will be difficult, especially on another planet such as Mars. Therefore some of the process will have to be replaced with modern technology.
In order to create a more promising solution, NASA considered using hydroponics,[1] which is a method to grow plants without the use of soil, and relies only on water that is infused with essential nutrients. An obvious benefit when using hydroponics to grow plants is the ability to conserve space, as you can stack the plants on multiple levels, each providing artificial light, and a regular stream of nutrient infused water. As the variables related to plant growth using hydroponics are already easy to control, it makes it an ideal option to include into a closed system.
Biosphere 2 - Systems and Processes
On September 26, 1991, a crew of eight healthy “biospherians” entered Biosphere 2 with the intent of surviving in the dome for two years. Food and water are an essential in survival, so the crew spent about a quarter of their time on farming and anything food related [3] (Data on how the crew spent their time in the dome can be seen in Table 1). To grow enough food to eat, the crew spent four hours a day, five days a week on farming. They grew 80 different crops and about 3,000 different species of plants [4]. They also fed the tilapia in rice paddies and looked after livestock for meat. In order to avoid using chemical fertilizers or pesticides within closed systems for growing food, they lived on organic food with a good amount of protein. However their overall calorie intake was not sufficient, and one of the researchers lost 25 pounds. Due to unfortunate growing conditions, the crew was forced to eat upwards of a pound of sweet potatoes a day. Eating too much of the same food that contained beta carotene caused a disconcerting orange hue in their skin.
Table 1. Breakdown of biosphere activity from September 1992 - May 1993 [3]
After several months the crew began to realize that oxygen levels had dropped from 20.9 percent to 14.2 percent, the equivalent of living at a 15,000-feet elevation. It caused half of them to feel sick, and even suffer from sleep apnea. So they had to call an outside medical team to recheck their conditions. Refrigerated trucks were required to come to pump the oxygen into the Biosphere 2. The reason for the reduction of oxygen levels was that the microbes used to enriched the soil produced more carbon dioxide than the amount of oxygen released by the young plants via photosynthesis. The unsealed concrete used in the construction of the biosphere also contributed to absorbing a lot of the oxygen, which was a major design flaw.[3]
The photosynthetic equation CH2O + O2 <---> CO2 + H2O shows that one mole of CO2 is produced for each mole of O2 consumed and the volume of the gas is constant. A big part of Biosphere II was built out of concrete which contains After an investigation analyzing concentration of carbon, concrete and scrubber product on the inside of Biosphere 2, it was confirmed that CO2 from atmosphere was being captured by carbonation of concrete as in Ca(OH)2 + CO2 ---> CaCO3 + H2O on the order of rates of 600kmol(26t) distributed over an area of 15800 m2 concrete. [5] Instead of being used by the plants to produce more O2, CO2 to form water and CaCO3. Oxygen is an important element that holds concrete compound structures. Figure 1 depicts the loss of Oxygen within the biosphere over the course of the experiment. The sudden jump in oxygen levels is when the team had to manually insert oxygen into the biosphere to return it to save levels. Since oxygen loss through concrete was at high levels, using a different material than concrete would be more efficient. The ideal material would be a new cement generation which absorbs CO2 and might even produce O2.
Figure 1. Oxygen concentration in Biosphere 2 over time [5]
Conditions on Mars
The conditions on Mars are significantly different from those on Earth, which pose as greater challenges as the existing improvements to the Biosphere will also have to be tailored to be favorable in the harsher conditions. Compared to Earth, these differences include the planet being half as large and further away from the sun, a greatly reduced planetary core, and a much thinner atmosphere composed mostly of carbon dioxide (compared to nitrogen and oxygen) [6].
The combination of these differences pose as extra challenges for modifications on the Biosphere, especially for an energy source. The distance away from the sun, as well as frequent dust storms, cause solar energy to only be 40% as effective on Earth. The less dense atmosphere and smaller/colder planetary core lead to wind and geothermal energies not being nearly effective enough to serve as plausible solutions. With this obstacle, the recommended energy source is nuclear fuel, and since Mars lacks easily accessible uranium [8] a method of storing and regulating nuclear fuel will have to be integrated into the updated Biosphere design.
In addition to this, Mars’ weaker core and atmosphere causes the planet to be filled with radiation. The sun emits radioactive particles that are heavily reduced by the electromagnetic field around Earth caused by its metal core (the magnetosphere), as well as the dense atmosphere. Since Mars lacks both of these [9], the radiation on Mars is 50 times as much on Earth, which leads to the ground and air being poisonous for Earth’s biological life. One solution is to use the heavy concentration of atmospheric carbon dioxide, along with Mars dirt, to create a frozen “shield” around the dome that would protect it from the radiation. As this would lead to a closed dome with no windows, artificial sunlight and Hydroponics would be necessary for a sustainable environment.
Figure 2. Comparing the atmosphere compositions of Mars and Earth [6]
6. Alternative solutions for a Martian Habitat
i. Designing a ‘better biosphere’
The Biosphere II incorporated a variety of plant, animal and insect species. The rate that some species would not survive was much higher than expected. Majority of the species did not survive. Almost all of the insects included for the intent of pollination plants went extinct. Simultaneously, some species such as ants, cockroaches, and katydids thrived in and threatened every other plant. Hence, to be more efficient, more space and farm production variety it is needed. Different soil preferences and temperatures and humidities would be needed to grow the variety of foods needed. At the same time it is important that crew members that will maintain the plants should be experienced farmers and appropriate fertilizer and disposal options need to be considered. In addition to the enhanced efficiency measures, more land would also be required to cultivate the required crops.
Better building materials would need to be considered, such as light metals, durable polymers, as well as glasses. This would replace the concrete that resulted in oxygen deficiencies in biosphere 2. These solutions would however pose a problem if such a habitat would be built on Mars. Extra cultivable soil, and all the resources that would be needed to tend to it will have to be continuously supplied via spacecraft from Earth. More farm land would also require more construction materials, which only adds to the weight of the cargo. Space transportation is a very expensive procedure, and transport to mars can only be done very rarely. This would spell doom for any astronaut that has to survive on Mars if any delay in supply transport happens, as it would last months. Therefore a much so self sustaining, and compact solution would be required to achieve the goal of creating a habitable biosphere on Mars.
ii. Hydroponics
This method of growing food consists of using a growing medium submerged in nutrient rich water instead of soil. As the plants will no longer need large areas of land, they can be stacked one on top of another to create a ‘vertical farm’, which makes it a perfect option to use in limited spaces. [11] The idea is to use plants and microbes in a self-contained system to recycle waste and regenerate it into air, water, and food. [1] An advantage to using hydroponic systems is the amount of control it has over every step of the growing process. The water and nutrient content can be rotated and adjusted automatically. This forced motion will be essential in a world where the impact of gravity will be different than that is present on Earth.[12] The artificial light that the stacked layers of plants use to photosynthesize, in addition to surrounding temperature and humidity can also be adjusted by sensors to give the plants the perfect growing environment.
In the Biosphere 2 experiment, a large amount of time was spent on agricultural needs. Although time will still need to be allotted for care, hydroponic systems can be heavily automated, which could spare the researchers more time for other duties. The University of Arizona has designed a closed system to solve this very issue. Called the lunar greenhouse chamber, it is a prototype bioregenerative life support system (See Figure 3). Aside from it having the name ‘lunar’, NASA can expect it to work on Mars as well. At 18-foot long, with a 7-foot diameter, it is relatively compact, and compressible to an even smaller form factor for transport. [1] The small size and light weight makes it significantly easier to transport into space, especially given how expensive it is to do so.
Figure 3. The Lunar Greenhouse Chamber design by the University of Arizona[1]
“One unit operating at its full planned potential, Sadler said, could provide 50% of the food, 100% of the air, and 100% of the water that one astronaut needs on either Mars or the moon.”[1] Although it does not produce the required amount of food, outside ideal conditions, it currently does not satisfy the oxygen needs either. One alternative is to use two or more modules per person in order to meet the minimum requirements, but further optimizations could potentially improve the modules’ specifications. As it is now however, it functions well in a closed system, and is self sustainable as depicted in figures 4a through 4c.
The one major issue that will have to be overcome in order to use these modules effectively is the stable generation of electricity. Fortunately, decades of space exploration has given us options to choose from. Large solar farms could be constructed to provide electricity while excess charge could be stored in batteries packs, but given that the solar energy obtained from the surface of Mars is significantly less than that of earth, it would require a larger quantity of solar panels, which would be harder to transport and maintain long term . Small scale nuclear fission generators like the Radioisotope Thermoelectric Generators [13] used on probes could be used for stable long term energy production.
7. Conclusion
Biosphere 2 was and still is a very effective tool to study the earth’s ecosystems themselves, and how they evolve and adapt overtime. Its failings were brought upon by its inability to self-sustain itself, through design flaws, and overly ambitious goals to create a mini earth within itself. Although Biosphere 2 failed to create a fully self sustainable replica of the earth's ecosystems, it taught us that we may not need every single aspect of the earth to be replicated to make a self sustaining system. As long as we focus on providing the necessities effectively, humans will be able to survive in foreign worlds. In order to travel to other plants and reside there for indefinite periods of time, lightweight, compact, durable, and highly self-sufficient methods would have to be implemented. By trying to control many variables, the biosphere itself would have too many variables of its own to manage, making it a very challenging martian habitat. Innovations such as the Lunar Greenhouse Chamber, coupled with stable nuclear generators provide a more feasible lodging for space travellers of the future.
8. References
[1]. Mosher, Dave, and Skye Gould. To survive on Mars, we need a 'technology that replaces what the Earth does.' This tube might be NASA's best hope., Business Insider, 14 May 2018,
www.businessinsider.com/astronaut-plants-air-food-water-life-support-2018-5 .
[2] Vergano, Dan. "Brave New World of Biosphere 2." Science News 150, no. 20 (16 November 1996): 312–313. https://www.encyclopedia.com/science-and-technology/biology-and-genetics/environmental-studies/biosphere-ii-project
[3]. Allen, John, and Mark Nelson. "Biospherics and Biosphere 2, mission one (1991–1993)." Ecological Engineering, vol. 13, 30 Nov. 1997, pp. 15-29, www.researchgate.net/profile/Mark_Nelson9/publication/222488641_Overview_and_Design_Biospherics_and_Biosphere_2_mission_one_1991-1993/links/5b33b9240f7e9b0df5ce24c5/Overview-and-Design-Biosphe .
[4]. Nelson, Mark. Biosphere 2: What Really Happened?, Business Insider, May 2018, www.dartmouthalumnimagazine.com/articles/biosphere-2-what-really-happened .
[5] Dempster, William F. "Biosphere 2 engineering design." Ecological Engineering, vol. 13, 29 Nov. 1997, pp. 31-42, www.ecotechnics.edu/wp-content/uploads/backup/2011/08/Ecol-Eng-1999-Bio-2-Engineering-Design-Dempster.pdf .
[6] "COMPARING THE ATMOSPHERES OF MARS AND EARTH." robotic exploration of mars, European Space Agency, 1 Sept. 2019, www.exploration.esa.int/web/mars/-/60153-comparing-the-atmospheres-of-mars-and-earth .
[7] Stelter, Chris. Mars surface shielding from radiation, Selenian Boondocks, 6 Sept. 2015, www.selenianboondocks.com/2015/09/mars-surface-shielding-from-radiation/ .
[8] Meslin, P Y., et al. "Analysis of Uranium and Thorium Lines in Mars Odyssey Gamma Spectra and Refined Mapping of Atmospheric Radon." 43rd Lunar and Planetary Science Conference, Mar. 2012, www.lpi.usra.edu/meetings/lpsc2012/pdf/2852.pdf .
[9] Vaisberg, O L., et al. "The Structure of Martian Magnetosphere at the Dayside Terminator Region as Observed on MAVEN Spacecraft." Geophysical Research: Space Physics, 23 Mar. 2018, www.arxiv.org/ftp/arxiv/papers/1801/1801.08878.pdf .
[10] Radiation Measurements on Mars, NASA, www.nasa.gov/jpl/msl/mars-rover-curiosity-pia17600.html#.XqtnGqhKiUn .
[11] "Hydroponics." Alternative Farming Systems Information Center, US Department of Agriculture, www.nal.usda.gov/afsic/hydroponics .
[12] Brandit, Rosemary. Lunar Lasers and Cosmic Crops: NASA Funds UArizona Space Exploration Missions, The University of Arizona, 5 Mar. 2020, www.uanews.arizona.edu/story/lunar-lasers-and-cosmic-crops-nasa-funds-uarizona-space-exploration-missions .
[13] Jiang, Mason. An Overview of Radioisotope Thermoelectric Generators, Stanford University, 15 Mar. 2013, http://large.stanford.edu/courses/2013/ph241/jiang1/.
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