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Two separate experimental rigs used in tests on NASA and Zero-G Corporation aircrafts flying low-gravity trajectories, and in the NASA 2.2 Second Drop Tower have been developed to test the functioning of the Flexible Membrane Commode (FMC) concept under reduced gravity conditions. The first rig incorporates the flexible, optically opaque membrane bag and the second rig incorporates a transparent chamber with a funnel assembly for evacuation that approximates the size of the membrane bag. Different waste dispensers have been used including a caulking gun and flexible hose assembly, and an injection syringe. Waste separation mechanisms include a pair of wire cutters, an iris mechanism, as well as discrete slug injection. The experimental work is described in a companion paper. This paper focuses on the obtained results and analysis of the data.

Designers of future space vehicles envision simplifying the Atmosphere Revitalization (AR) system by combining the functions of trace contaminant (TC) control and carbon dioxide removal into one swing-bed system. Flow rates and bed sizes of the TC and CO2 systems have historically been very different. There is uncertainty about the ability of trace contaminant sorbents to adsorb adequately in a high-flow or short bed length configurations, and to desorb adequately during short vacuum exposures. This paper describes preliminary results of a comparative experimental investigation into adsorbents for trace contaminant control. Ammonia sorbents and low temperature catalysts for CO oxidation are the foci. The data will be useful to designers of AR systems for Constellation. Plans for extended and repeated vacuum exposure of ammonia sorbents are also presented.

In February 2004 NASA released “The Vision for Space Exploration.” The goals outlined in this document include extending the human presence in the solar system, culminating in the exploration of Mars. A key requirement for this effort is to identify a safe and effective method to process waste. Methods currently under consideration include incineration, microbial oxidation, pyrolysis, drying, and compaction. Although each has advantages, no single method has yet been developed that is safe, recovers valuable resources including oxygen and water, and has low energy and space requirements. Thus, the objective of this work is to develop a low temperature oxidation process to convert waste cleanly and rapidly to carbon dioxide and water. Previously, TDA Research, Inc. demonstrated the potential of a low temperature dry oxidation process using ozone in a small laboratory reactor.

In February 2004 NASA released “The Vision for Space Exploration.” The important goals outlined in this document include extending human presence in the solar system culminating in the exploration of Mars. Unprocessed waste poses a biological hazard to crew health and morale. The waste processing methods currently under consideration include incineration, microbial oxidation, pyrolysis and compaction. Although each has advantages, no single method has yet been developed that is safe, recovers valuable resources including oxygen and water, and has low energy and space requirements. Thus, the objective of this project is to develop a low temperature oxidation process to convert waste cleanly and rapidly to carbon dioxide and water. In the Phase I project, TDA Research, Inc. demonstrated the potential of a low temperature oxidation process using ozone. In the current Phase II project, TDA and NASA Ames Research Center are developing a pilot scale low temperature ozone oxidation system.

Pyrolysis processing of solid waste in space will inevitably lead to carbon formation as a primary pyrolysis product. The amount of carbon depends on the composition of the starting materials and the pyrolysis conditions (temperature, heating rate, residence time, pressure). Many paper and plastic materials produce almost no carbon residue upon pyrolysis, while most plant biomass materials or human wastes will yield up to 20-40 weight percent on a dry, as-received basis. In cases where carbon production is significant, it can be stored for later use to produce CO2 for plant growth. Alternatively it can be partly gasified by an oxidizing gas (e.g., CO2, H2O, O2) in order to produce activated carbon. Activated carbons have a unique capability of strongly absorbing a great variety of species, ranging from SO2 and NOx, trace organics, mercury, and other heavy metals.

This paper describes the initial results of applying two machine-learning-based unsupervised anomaly detection algorithms, Orca and GritBot, to data from two rocket propulsion testbeds. The first testbed uses historical data from the Space Shuttle Main Engine. The second testbed uses data from an experimental rocket engine test stand located at NASA Stennis Space Center. The paper describes four candidate anomalies detected by the two algorithms.

Pyrolysis is a very versatile waste processing technology which can be tailored to produce a variety of solid liquid and/or gaseous products. The main disadvantages of pyrolysis processing are: (1) the product stream is more complex than for many of the alternative treatments; (2) the product gases cannot be vented directly into the cabin without further treatment because of the high CO concentrations. One possible solution is to combine a pyrolysis step with catalytic oxidation (combustion) of the effluent gases. This integration takes advantage of the best features of each process, which is insensitivity to product mix, no O2 consumption, and batch processing, in the case of pyrolysis, and simplicity of the product effluent stream in the case of oxidation. In addition, this hybrid process has the potential to result in a significant reduction in Equivalent System Mass (ESM) and system complexity.

One of the major problems associated with solid waste processing technologies is effluent contaminants that are released in gaseous forms from the processes. This is a concern in both biological as well as physicochemical solid waste processing. Carbon dioxide (CO2), the major gas released, does not present a serious problem and there are currently in place a number of flight-qualified technologies for CO2 removal. However, a number of other gases, in particular NOx, SO2, NH3, and various hydrocarbons (e.g. CH4) do present health hazards to the crew members in space habitats. In the present configuration of solid waste processing in the International Space Station (ISS), some of these gases are removed by the Trace Contaminant Control System (TCCS), demands a major resupply. Reduction of the resupply can be effective by using catalyst impregnated carbon nanotubes. For example, NO decomposition to N2 and O2 is thermodynamically favored.

Pyrolysis is a technology that can be used on future space missions to convert wastes to an inert char, water, and gases. The gases can be easily vented overboard on near term missions. For far term missions the gases could be directed to a combustor or recycled. The conversion to char and gases as well as the absence of a need for resupply materials are advantages of pyrolysis. A major disadvantage of pyrolysis is that it can produce tars that are difficult to handle and can cause plugging of the processing hardware. By controlling the heating rate of primary pyrolysis, the secondary (cracking) bed temperature, and residence time, it is possible that tar formation can be minimized for most biomass materials. This paper describes an experimental evaluation of two versions of pyrolysis reactors that were delivered to the NASA Ames Research Center (ARC) as the end products of a Phase II and a Phase III Small Business Innovation Research (SBIR) project.

Pyrolysis is a very versatile waste processing technology which can be tailored to produce a variety of solid, liquid, and/or gaseous products. The main disadvantages of pyrolysis processing are: (1) the product stream is more complex than for many of the alternative treatments; (2) the product gases cannot be vented directly into the cabin without further treatment because of the high CO concentrations. One possible solution is to combine a pyrolysis step with catalytic oxidation (combustion) of the effluent gases. This integration takes advantage of the best features of each process. The advantages of pyrolysis are: insensitivity to feedstock composition, no oxygen consumption, and batch operation. The main advantage of oxidation is the simplicity and consistency of the product stream. In addition, this hybrid process has the potential to result in a significant reduction in Equivalent System Mass (estimated at 10-40%) and system complexity.

Of the many competing technologies for resource recovery from solid wastes for long duration manned missions such as a lunar or Mars base, incineration technology is one of the most promising and certainly the most well developed in a terrestrial sense. Various factors are involved in the design of an optimum fluidized bed incinerator for inedible biomass. The factors include variability of moisture in the biomass, the ash content, and the amount of fuel nitrogen in the biomass. The crop mixture in the waste will vary; consequently the nature of the waste, the nitrogen content, and the biomass heating values will vary as well. Variation in feed will result in variation in the amount of contaminants such as nitrogen oxides that are produced in the combustion part of the incinerator. The incinerator must be robust enough to handle this variability. Research at NASA Ames Research Center using the fluidized bed incinerator has yielded valuable data on system parameters and variables.

The Spacelab Life Sciences 2 (SLS-2) mission became NASA's longest duration Shuttle mission, lasting fourteen days, when Columbia landed on November 1, 1993. Located within the Spacelab were a total of 48 laboratory rats which were housed in two Research Animal Holding Facilities (RAHFs) developed by the Space Life Sciences Payloads Office (SLSPO) at Ames Research Center. In order to properly maintain the health and well-being of these important research animals, sufficient quantities of food and water had to be available for the duration of the mission. An Inflight Refill Unit was developed by the SLSPO to replenish the animals' drinking water inflight using the Shuttle potable water system in the middeck galley as the source of additional water. The Inflight Refill Unit consists of two major subsystems, a Fluid Pumping Unit (FPU) and a Collapsible Water Reservoir (CWR).

A high fidelity, direct-interface, fusible heat sink for cooling astronauts during extravehicular activity was constructed and tested. The design includes special connectors that allow the coolant loop to be directly connected to the fusible material, in this case water. Aspects tested were start-up characteristics, cooling rate, and performance during simulated heat loads. A simplified math model was used to predict the effect of increasing the effective thermal conductivity on heat sink freezing rate. An experiment was designed to measure the effective thermal conductivity of a water/Aluminum foam system, and full gravity tests were conducted to compare the freezing rates of water and water/foam systems. This paper discusses the results of these efforts.

The short takeoff and landing capabilities that characterize the performance of powered-lift aircraft are dependent on engine thrust and are, therefore, severely affected by loss of an engine. This paper shows that the effects of engine loss on the short takeoff and landing performance of powered-lift aircraft can be effectively mitigated by cross-shafting the engine fans in a twin-engine configuration. Engine-out takeoff and landing performances are compared for three powered-lift aircraft configurations: one with four engines, one with two engines, and one with two engines in which the fans are cross-shafted. The results show that the engine-out takeoff and landing performance of the cross-shafted two-engine configuration is significantly better than that of the two-engine configuration without cross-shafting.

Propulsion system sizing for mechanical flap and externally blown flap aircraft is demonstrated. Included in this study is the effect of various levels of noise suppression on the aircraft final design characteristics. Both aircraft are sized to operate from a 3000 ft runway and perform the same mission. For each aircraft concept, propulsion system sizing is demonstrated for two different engine cycles-one having a fan pressure ratio of 1.5 and a bypass ratio of 9 and the other having a fan pressure ratio of 1.25 and a bypass ratio of 17.8. The results presented include the required thrust to weight ratio, wing loading, resulting gross weight and direct operating costs as functions of the engine noise level for each combination of engine cycle and aircraft concept.