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The Systems Integration, Modeling and Analysis (SIMA) element1 of the National Aeronautics and Space Administration (NASA) Advanced Life Support (ALS) Project conducts on-going studies to determine the most efficient means of achieving a human mission to Mars. Life support for the astronauts constitutes an extremely important part of the mission and will undoubtedly add significant mass, power, volume, cooling and crew time requirements to the mission. Equivalent system mass (ESM) is the sum of these five parameters on an equivalent mass basis and can be used to identify potential ways to reduce the overall cost of the mission. SIMA has documented several reference missions in enough detail to allow quantitative studies to identify optimum ALS architectures. The Mars Dual Lander Mission, under consideration by the Johnson Space Center (JSC) Exploration Office, is one of those missions.

Use of the local resources on Mars could reduce the cost of life support significantly. Theoretically, Closed Ecological Systems (CES) isolated from surroundings and functioning on the basis of a closed cycle of matter transformation are the most reliable systems for life support in open space or on the surface of non-terrestrial bodies such as the Moon or Mars. But these systems require a relatively high initial mass (which is a critical factor in space flight) in comparison to supply-based systems. In addition CESs are a useful scientific abstraction though they have never been reached in reality. To minimize the cost of life support on Mars, we need to find scenarios and technologies such as a Martian Greenhouse (MG) which are based on use of the planet’s indigenous sources of energy and materials (natural illumination, carbon dioxide, water, nutrient elements for plants in the planetary soil). Our initial analysis shows that such approaches are possible and cost effective.

To effectively develop advanced life support technologies to support humans on future missions into space, the requirements for these missions must first be defined. How many people will go? Where will they go? What risks must be protected against? Since NASA does not officially establish new exploration programs until authorized by Congress, there are no program requirements documents or list of “planned missions” to refer to. Therefore, technology developers must look elsewhere for information on how and where their development efforts and concepts may be used. This paper summarizes the development of several sources designed to help Advanced Life Support researchers working to extend a human presence in space.

The technology selected for waste processing has a major effect on system closure and mission equivalent system mass (ESM). In particular, recovery of the water content of solid waste can make the difference between a mission being water poor and water rich. Potential alternative sources of water that need to be considered would include recovery of water from carbon dioxide reduction, and in situ resources. This paper looks at a range of waste-processing scenarios and calculated system ESM impacts related to these options. The lowest ESM approach is generally storage or dumping. However, other issues also need to be considered. Processing may be driven by requirements such as the need to recover commodities like water, prevent release of toxic gases into the spacecraft environment, planetary protection requirements, and interface loads.

Clothing supply has been examined for historical, current, and planned missions. For STS, crew clothing is stowed on the orbiter and returned to JSC for refurbishment. On Mir, clothing was supplied and then disposed of on Progress for incineration on re-entry. For ISS, the Russian laundry and 75% of the US laundry is placed on Progress for destructive re-entry. The rest of the US laundry is stowed in mesh bags and returned to earth in the Multi Purpose Logistics Module (MPLM) or in the STS middeck. For previous missions, clothing was supplied and thrown away. Supplying clothing without washing dirty clothing will be costly for long-duration missions. An on-board laundry system may reduce overall mission costs, as shown in previous, less accurate, metric studies. Some design and development of flight hardware laundry systems has been completed, such as the SBIR Phase I and Phase II study performed by UMPQUA Research Company for JSC in 1993.

This paper addresses the effect of waste processing on advanced life support (ALS) system design. Waste processing is a critical component of an advanced life support system. It must take all life support system wastes and either convert them into useful products or into a form in which they can be discarded. Waste can be treated as soon as it is produced, stored as is, or processed into an intermediate form for further treatment. The decisions made will affect the cost-effectiveness of the system. Strategies must be developed to meet waste processing requirements for specific mission scenarios.

The relationship between the duration and location of a manned space mission and significant life support resource costs is considered. These costs include mass, pressurized volume, energy, cooling and manpower. They are converted to common mass units (equivalent mass), and the probable range of values addressed. R&D and fabrication costs are hard to estimate and are not considered here, nor are any political constraints. With high equivalencies (e.g., cheap power), the relative effect of equipment mass is increased and in consequence the cost-effectiveness of bioregenerative life support rises dramatically.

New information is presented on conceptual designs of bioregenerative life support systems, with subsystems defined, sizes estimated, and configurations developed.1 Components are sized by comparison with design data from Spacelab, the space station, commercial practice, and research on new technologies. Designs were developed on a Microstation CAD system, importing existing models such as space station modules where available. Layouts consider component mass and power as well as connections and access requirements. In addition, current efforts in the NASA CELSS Breadboard Facility (CBF) at Kennedy Space Center are described, which may validate some of these design concepts. Design optimization for the next-generation Breadboard Facility is discussed.

Exploration missions are expected to reach the 100-day class by Spiral 3, 1000-day class for Spiral 4, and perhaps longer for later spirals. Depending on the equivalencies achieved, bioregenerative life support can offer cost effectiveness as well as autonomy for 1000-day class missions, and will need to be demonstrated in space on Spiral 3 missions to support application to the longer missions. Several other technologies can also reduce the cost of life support in space by factors in the single digits, or perhaps even an order of magnitude. However, these improvements will not come easily, requiring advances in both life support technology and mission infrastructure. Equivalencies (infrastructure cost factors) are recommended for the 2020 to 2030 timeframe anticipated for Spirals 3 and 4. Cost effectiveness of several life support related technologies are assessed, and a life support metric is calculated based on this data.

The ALS Metric is the predominant tool for predicting the cost of ALS systems. Metric goals for the ALS Program are daunting, requiring a threefold increase in the ALS Metric by 2010. Compounding the problem is the slow rate new ALS technologies reach the maturity required for consideration in the ALS Metric and the slow rate at which new configurations are developed. This limits the search space and potentially gives the impression of a stalled research and development program. Without significant increases in the state of the art of ALS technology, the ALS goals involving the Metric may remain elusive. A paper previously presented at his meeting entitled, “Managing to the metric: An approach to optimizing life support costs.” A conclusion of that paper was that the largest contributors to the ALS Metric should be targeted by ALS researchers and management for maximum metric reductions.

Three distinct food system paradigms have been envisioned for long-term space missions. The Skylab, Mir and ISS food systems were based on single-serving prepackaged foods, ready to rehydrate and heat. Bioregenerative food systems, derived from crops grown and processed at the planetary station, have been studied at JSC and KSC. The US Antarctic Program’s Amundsen-Scott South Pole Base uses the third paradigm: bulk packaged food ingredients delivered once a year and used to prepare meals on the station. The packaged food ingredients are supplemented with limited amounts of fresh foods received occasionally during the Antarctic summer, trace amounts of herb and salad crops from the hydroponic garden, and some prepackaged ready to eat foods, so the Pole system is actually a hybrid system; however, it is worth studying as a bulk packaged food system because of the preponderance of bulk packaged food ingredients used.

Work defining advanced life support (ALS) technologies and evaluating their applicability to various long-duration missions has continued. Time-dependent and time-invariant costs have been estimated for a variety of life support technology options, including International Space Station (ISS) environmental control and life support systems (ECLSS) technologies and improved options under development by the ALS Project. These advanced options include physicochemical (PC) and bioregenerative (BIO) technologies, and may in the future include in-situ-resource utilization (ISRU) in an attempt to reduce both logistics costs and dependence on supply from Earth. PC and bioregenerative technologies both provide possibilities for reducing mission equivalent system mass (ESM). PC technologies are most advantageous for missions of up to several years in length, while bioregenerative options are most appropriate for longer missions. ISRU can be synergistic with both PC and bioregenerative options.

Equivalent System Mass (ESM) is the basis of the Advanced Life Support Research and Technology Development metric for measurement of progress of the Advanced Life Support (ALS) Project under the Advanced Human Support Technology (AHST) Program. ESM may be used to evaluate a system or technology based upon its mass, volume, power, cooling and manpower requirements. The ESM metric as defined in the ALS Research and Technology Development Metric Baseline is International Space Station (ISS) technology ESM divided by the ALS technology ESM for a specified mission. This paper discusses various theoretical and practical issues behind application of ESM to systems as well as to individual technologies. Difficulties that might be encountered by researchers in application of the metric are addressed. It is crucial that ALS researchers be proficient in assessing technologies and/or systems of interest with ESM, to minimize the chance of misapplication of the approach.

This paper applies an equivalent system mass (ESM) approach to life support (LS) for a number of mission scenarios, including a manned Mars mission, ISS, and closed chamber tests on the ground. Supply, physicochemical- (PC) and bioregeneration, and in situ resource utilization (ISRU) have been considered. Credible mass equivalencies are derived for a number of missions, and resulting distributions of ESM among the various subsystems are identified for different mission assumptions. Preliminary recommendations are made for cost-effective hybrid scenarios using the four approaches identified above.

The main principles of artificial atmospheric design for a Martian Greenhouse (MG) are described based on: 1. Cost-effective approach to MG realization; 2. Using in situ resources (e.g. CO2, O2, water); 3. Controlled greenhouse gas exchange by using independent pump in and pump out technologies. We show by mathematical modeling and numerical estimates based on reasonable assumptions that this approach for Martian deployable greenhouse (DG) implementation could be viable. A scenario of MG realization (in terms of plant biomass/photosynthesis, atmospheric composition, and time) is developed. A list is given of technologies (natural water collection, MG inflation, oxygen collection and storage, etc.) that are used in the design. The conclusions we reached are: 1. Initial stocks of oxygen and water probably would be required to initiate plant germination and growth; 2. Active control of MG ventilation could provide proper atmospheric composition for each period of plant growth; 3.

Plants can be grown in space to support human life, providing food, and regenerating water and air. Various groups have demonstrated that plants can support human life on the ground, and that plants can grow in space. One would suppose that plants are also able to support human life in space, though obviously it would be a good idea to demonstrate that ability before committing to a mission requiring bioregeneration. However, plant growth in space requires that we provide the necessary conditions for growth, and this might require not only providing water and fertilizer as we do in terrestrial agriculture, but also a controlled environment and lighting. This would make crops much more costly than we are accustomed to on Earth, where the majority of crops are grown outside and where natural sunlight is generally adequate. On the other hand, providing food, air, and water in space by any other means is also costly.