Being able to extract oxygen and produce Methane from the Mars atmosphere would greatly enhance colonization missions to Mars. Here we review how the obviously technical feasible technology would likely scale.
Basis for Scaling in Zubrin Analysis
The masses and power requirements of the S-E and Z-E systems in the 0.5 kg per day production rate are known with considerable accuracy from the experimental work done at Lockheed Martin and the University of Arizona. Power requirements for larger systems can also be estimated with confidence, since with all subsystems except controls, power requirement will increase linearly with production rate. Mass of sorption pump systems are estimated to increase by a factor of four for every factor of 10 increase in output rate. This is based upon a relative decrease in parasitic mass as the total sorption pump system becomes larger.
Mass of the chemical synthesis gear is assumed to be linear with respect to the roughly ~0.3 kg of actual chemical reactors contained within the 3 kg mass of the chemical reactor system required for the 0.5 kg per day production rate. This is based upon the author’s knowledge of the details of the Lockheed – Martin S-E system (0.1 kg Sabatier reactor + 0.2 kg of solid polymer electrolyte contained within the ~3 kg chemical synthesis subsystem) and reports from K.R. Sridhar of the University of Arizona of ~0.3 kg of actual Z – E cells within a ~0.5 kg per day output unit there. Control system mass and power is estimated to scale up by a factor of two for every factor of 10 increase in output.
Mass of lines and valves for all systems except the Z-E are assumed to scale up by factor of 3 for every factor of 10 increase in output. For the Z-E system, a factor of 5 increase in mass for every factor of 10 increase in output is assumed. This is because the Z-E system is composed of large numbers of small tubes. As the system scales up, more and more manifolds are required. This contrasts unfavorably with the other systems, which can simply employ larger reactor vessels as output rates are increased. Refrigerator mass is assumed to increase by a factor of four for every factor of 10 increase in output. This is based upon scaling observed in existing Stirling cycle
They have examined the technologies required to enable Mars In-Situ Resource Utilization (ISRU) because their understanding of Mars resources has changed significantly in the last five years as a result of recent robotic missions to the red planet. Two major developments,
(1) confirmation of the presence of near-surface water in the form of ice in very large amounts at high latitudes by the Phoenix Lander and
(2) the likely existence of water at lower latitudes in the form of hydrates or ice in the top one meter of the regolith, have the potential to change ISRU technology selection.
A brief technology assessment was performed for the most promising Mars atmospheric gas processing techniques: Reverse Water Gas Shift (RWGS) and Methanation (aka Sabatier), as well as an overview of soil processing technology to extract water from Martian soil.
The goal of this work is the development of new processes useful for future manned space missions, in the framework of the so-called ISRU (In-Situ Resource Utilization) and ISFR (In-Situ Fabrication and Repair) concepts. Specifically, the approach to ISRU will focus on technologies necessary to extract consumables for human life-support system replenishment while ISFR is aimed to satisfy other human needs particularly related to the Fabrication Technologies, the Repair & Non Destructive Evaluation Technologies and the Habitat Structures. After a introductory chapter, in the framework of ISRU and ISFR applications, a novel recently patented process based on the occurrence of Self-propagating High temperature Synthesis (SHS) reactions potentially exploitable for the in-situ fabrication of construction materials in Lunar and Martian environments is described. The mixtures to be reacted by SHS are prepared taking advantage of the composition of lunar and martian regoliths. Lunar regolith simulant JSC-1A, Martian regolith JSC-1A, and Mojave martian regolith simulant are considered. In addition, Aluminum is used as reducing agent for all systems examined, whereas ilmenite and iron oxides, namely ematite are added to the initial mixtures to be reacted in order to increase their exothermicity. It should be noted that both ilmenite and iron oxides are anyhow present in significant quantities on Moon and Mars, respectively. The effect of starting mixture compositions on the self-propagating behaviour is examined under different gas pressures of the environment (atmospheric or vacuum) and gravity level (terrestrial or microgravity) and the optimal experimental conditions are identified for each system investigated. The obtained products are characterized in view of their possible utilization as building materials. The final purpose is to allow manned space missions to extract and utilize in-situ resources necessary for human survival without being equipped with huge amount of supplies and to utilize specific technologies to repair Lunar and/or Martian platforms also using in-situ materials, otherwise transported from the Earth. As it is apparent, the possibility to increase mission-time and economic aspects represents the main direct consequences.
During the early phases of human Mars exploration, in-situ resource utilization (ISRU) will lower costs, expand capabilities, and serve as an enabling technology for establishing permanent colonies. Martian atmospheric resources can be used to provide consumables such as fuel, oxidant, breathable air, and water that are critical for early human missions. Martian atmospheric carbon dioxide and imported hydrogen can be used, for example, as feedstock for the catalytic production of oxygen, methane, methanol, water and other propellants (Zubrin, 1991, 1996, 1997, 1998, Zubrin, Meyer, McMillen 1998, Meyer 1989, 1981). These processes utilize catalytic reactors containing small amounts of iron, nickel and other suitable catalysts, plus gas selective membranes, electrolysis, and other easily implemented gas separation techniques. Waste carbon monoxide from carbon dioxide reduction processes together with hydrogen can be combined to produce other liquid and gaseous fuels and chemical compounds. Excess heat from an exothermic Sabatier reaction can be diverted to minimize heat requirements in endothermic processes such as the reverse water-gas shift reaction. Valuable synergies can be realized by integrating various processes. Oxygen and fuel production processes can be combined so the thermal and material wastes of one process can be utilized by the other thus forming a unique Martian “chemical refinery” that features internal hydrogen recycling and production of a purified carbon monoxide intermediate by-product. Turbines can also be used to recover mechanical energy from high-pressure waste gas and systems can share common hardware and feedstock systems. Chemical feedstock, power, heat and mechanical energy are utilized efficiently and conserved in the design of these robust Martian atmospheric refineries whose technologies may also find applications in industrial waste utilization technology on Earth
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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