Search Results

The National Aeronautics and Space Administration's (NASA) planned future missions set stringent demands on the design of the Portable Life Support System (PLSS), requiring dramatic reductions in weight, decreased reliance on supplies and greater flexibility for Extravehicular Activity (EVA) duration and objectives. Use of regenerable systems that reduce weight and volume of the space suit life support system is of critical importance to NASA, both for low orbit operations and for long duration manned missions. The carbon dioxide and humidity control unit in the existing PLSS design is relatively large, since it has to remove and store eight hours worth of carbon dioxide (CO2). If the sorbent regeneration can be carried out during the EVA with a relatively high regeneration frequency, the size of the sorbent canister and weight can be significantly reduced.

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.

The control of trace contaminants on the International Space Station (ISS) is carried out by a combination of activated carbon absorption and catalytic oxidation. The carbon bed absorbs most hydrocarbons, chloro and chlorofluorocarbons (CHCs and CFCs) while the catalytic oxidizer removes compounds such as methane, ethylene, ethane, and carbon monoxide that cannot be absorbed by the charcoal bed. Unfortunately, the Space Station catalyst of 0.5% palladium on alumina does not effectively oxidize CHCs and CFCs, and in fact is powerfully poisoned by them (Wright et al. 1996). Thus, even though the charcoal bed has little affinity for CFCs and CHCs, it must be sized to completely remove these compounds in order to protect the crew and prevent poisoning of the catalytic oxidizer. TDA Research Inc. (TDA), under contract to NASA-JSC, has designed, built, and tested an all-catalytic trace contaminant control system (TCCS) to be used in Phase III of the Early Human Testing Program.

The possibility and consequences of a fire on board a spacecraft and the subsequent effects of the resultant toxic gases and smoke on the crew, equipment and mission is an ever-present hazard for the National Aeronautics and Space Administration (NASA). The necessity to remove these contaminants in the presence of high levels of humidity and carbon dioxide has prompted the development of a new prototype atmospheric filter (smoke eater) that can scrub acid gases, basic gases, and carbon monoxide from a spacecraft atmosphere in a post-fire event to a concentration below one half the Spacecraft Maximum Allowable Concentration (SMAC) levels. TDA Research, Inc. (TDA) is developing an advanced smoke eater to remove combustion byproducts. The material makeup of the smoke eater will also be applicable to spacecraft evacuation masks and the shipboard atmospheric revitalization system.

The objective of this SBIR Phase I project was to identify catalysts that are active for ammonia conversion and are also selective for nitrogen and water. Our approach to the problem was centered on the development of a bifunctional catalyst, which could separate adsorbed oxygen and nitrogen atoms, thereby reducing NOx formation. The results of our project demonstrated that our approach was successful. We prepared a group of catalysts and tested them for ammonia oxidation activity. We identified a catalyst formulation that was active for ammonia oxidation at low temperatures in the presence of water and produced very little NOx. We used kinetic data to generate a rate model that predicts 100% ammonia conversion in the full-scale system at a temperature 50°C lower than the current design.

A safe, effective means to control solid waste is a critical need on long-term space missions. With current waste models, 1300 kg of waste occupying a volume 20 m3 will be generated in a 180-day mission to 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 was to develop a low temperature oxidation process to convert waste cleanly and rapidly to carbon dioxide and water. In this Small Business Innovative Research (SBIR) Phase I project, TDA Research Inc. (TDA) conducted tests to measure the rates of oxidation using ozone with five model waste components.

The current Extravehicular Mobility Unit (EMU) system provides thermal control using a sublimator to reject both the heat produced by the astronaut's metabolic activity as well as the heat produced by the Portable Life Support Unit (PLSS). This sublimator vents up to eight pounds of water each Extravehicular Activity (EVA). If this load could be radiated to space, the amount of water that would need to be sublimated could be greatly reduced. There is enough surface area on the EMU that almost all of the heat can be rejected by radiation. Radiators, however, reject heat at a relatively constant rate, while the astronaut generates heat at a variable rate. To accommodate this variable heat load, NASA is developing a new freeze tolerant radiator where the tubes can selectively freeze to “turn down” the radiator and adjust to the heat rejection requirement. This radiator design significantly reduces the amount of expendable water needed for the sublimator.

As manned spacecraft travel farther from Earth, the cost of delivering the payloads to space increases dramatically. For example the cost of delivering a payload to low Earth orbit currently is about $10,000/lb. On the other hand the cost of delivering a payload to Mars may be up to 40 times greater and therefore missions to deep space place a strong emphasis on reducing launch weight and eliminating resupply requirements. The Vapor Phase Catalytic Ammonia Removal (VPCAR) system, which is being developed to purify water, is an example of this focus. In addition to having a lower launch weight than the Water Recycle System (WRS) currently used on the International Space Station, it also has no resupply requirements. A key step in the VPCAR system is the catalytic oxidation of ammonia and volatile hydrocarbons to benign compounds such as carbon dioxide, water, and nitrogen. Currently platinum-based commercial oxidation catalysts are being used for these reactions.

Incineration is a promising method for converting biomass and human waste into CO2 and H2O during extended planetary exploration. During incineration, however, small amounts of NOx and SO2 are produced and must be removed. TDA Research, Inc. (TDA) has developed a safe and effective process to remove NOx and SO2 from waste incinerator product gas streams. In our process, NO is oxidized into NO2 with high selectivity. The NO2 is then removed by wet scrubbing with a weak base to form an innocuous water solution of nitrates and nitrites. SO2 will be removed by a packed bed containing a basic sorbent developed at TDA. As part of an SBIR Phase II project, TDA is to design and construct a pilot-scale effluent cleaning system to be coupled with an existing waste incinerator at NASA Ames Research Center. The effluent from this incinerator may contain fly ash, SO2, unburned hydrocarbons, CO, and NOx.

Incineration is a promising method for converting biomass and human waste into CO2 and H2O during extended planetary exploration. During incineration, small amounts NOX and SO2 are produced and must be removed. TDA has developed a NOX control process that is safe and effective and does not require addition of NH3, which is commonly used in selective catalytic reduction of NOx. In our process, NO is catalytically oxidized to NO2 which is then removed by wet scrubbing with a weak base to form an innocuous water solution of nitrates and nitrites. We plan to integrate our catalytic NO oxidation process into a complete gas cleaning system that will remove NOX, SO2, particulate material, CO and unburned organic compounds.

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.