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At least 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

The development of an unconventional food regeneration process: Quantifying the nutritional components of a model methylotrophic yeast

A hybrid chemical/biological approach to unconventional food regeneration is discussed. Carbon dioxide and water, the major wastes of human metabolism would be converted to methanol by one of several physiochemical processes available (thermal, photocatalytic, etc.). Methanol is then used to supply carbon and energy for the culture of microorganisms which in turn produce biological useful basic food stuffs for human nutrition. Our work has focused on increasing the carbohydrate levels of a candidate methylotrophic yeast to more nearly coincide with human nutritional requirements. Yeasts were chosen due to their high carbohydrate levels compared to bacteria and their present familiarity in the human diet. The initial candidate yeast studied was a thermotolerant strain of Hansenula polymor pha, DL-1. The quantitative results that permit an evaluation of the overall efficiency in hybrid chemical/biological food production schemes are discussed. A preliminary evaluation of the overall efficiency of such schemes is also discussed.

Petersen, G. R.↗
NASA NTRS1986

Organic S13C values vary slightly with salinity in microbial mats at Guerrero Negro, Baja California Sur, Mexico: Implications for stromatolite S13C values

Stromatolites, layered sedimentary rock structures produced by communities of microorganisms, constitute the most abundant early evidence of life on Earth. Microbial mats, which are found most frequently in hypersaline marine or hot spring environments, serve as useful modern analogs of stromatolitic communities. Biochemical studies of mats were conducted to assist in the interpretations of stromatolites. The data suggest that salinity effects are insufficient by themselves to cause the C-13 differences observed betwwen Precambrain stromatolites and modern microbial mats.

Desmarais, D. J.↗
NASA NTRS1985

Microbial mats and modern stromatolites in Shark Bay, Western Australia

Distribution, external morphology, texture, and microbial composition of microbial mats in Hamelin Pool, Shark Bay, Western Australia, have been studied and reviewed along a composite representative profile starting from the permanently submerged zone, across the zones of periodic flooding, toward permanently emerged land and coastal dunes. The following nine types of algal mats have been recognized: colloform, gelatinous, smooth, pincushion, tufted, mamillate, film, reticulate, and blister. Solar ponds represent a particular environment. The mat types represent microbial communities that are characterized by one or more dominant microorganisms. The colonization and stabilization of loose sediment is carried out by a microbial assemblage of generalists that prepare the ground for later replacement and succession by specialized microflora. Lithification of microbial mats takes place periodically, mainly during the austral summer. This process is destructive for the microbial community but increases the preservation potential of the stromatolitic structures.

Golubic, S.↗
NASA NTRS1985

Physiological considerations for EVA in the Space Station era

The physiological parameters that will affect EMU design and operational scheduling for the Space Station Program are discussed. The system must be designed to safely and effectively handle the increased frequency of extravehicular activity projected for longer flight periods than in the past. In order to minimize the risk of decompression sickness a proper combination of equilibration time to cabin pressure, suit pressure, and prebreathing denitrogenation, is necessary. Effective thermal exchange is projected to be automatically controlled and to have an 8-hr 1000 BTU/hr capability. Physiological changes due to adaptation to weightlessness must be considered in scheduling for their impact on performance/fatigue and in coping with motion sickness. Radiation protection to the limit of 80 rad/quarter must be achieved by scheduling to avoid periodic proton and solar flare exposure, and by additional EMU shielding. Additional EMU considerations are the control of microorganisms and the higher pressure requirement for emergency O2 purge.

Horrigan, D. J., Jr.↗
NASA NTRS1986

Diatoms on earth, comets, Europa and in interstellar space

There exists a close correspondence between the measured infrared properties of diatoms and the infrared spectrum of interstellar dust as observed in the Trapezium nebula and toward the galactic center source GC-IRS 7. Diatoms and bacteria also exhibit an absorbance peak near 2200 A, which is found to agree with the observed ultraviolet absorbance properties of interstellar grains. The observational data are reviewed, and the known properties of diatoms and bacteria are considered. It is suggested that these characteristics are consistent with the concept of a cosmic microbiological system in which these or similar microorganisms might exist on comets, Europa and in interstellar space.

Hoover, R. B.↗
NASA NTRS1986

Results on reuse of reclaimed shower water

The Waste Water Recovery System that has been used in conjunction with a microgravity whole body shower to test a closed loop shower water reclamation system applicable to the NASA Space Station employs a Thermoelectric Integrated Hollow Fiber Membrane Evaporation Subsystem. Attention is given to the suitability of a Space Shuttle soap for such crew showers, the effects of shower water on the entire system, and the purification qualities of the recovered water. The chemical pretreatment of the shower water for microorganism control involved activated carbon, mixed ion exchange resin beds, and iodine bactericide dispensing units. The water was recycled five times, demonstrating the feasibility of reuse.

Verostko, Charles E.↗
NASA NTRS1987

Microbial trace-fossil formation, biogenous, and abiotic weathering in the Antarctic cold desert

In the Antarctic cold desert (Ross Desert), the survival of the cryptoendolithic microorganisms that colonize the near-surface layer of porous sandstone rocks depends on a precarious equilibrium of biological and geological factors. An unfavorable shift of this equilibrium results in death, and this may be followed by formation of trace fossils that preserve the characteristic iron-leaching pattern caused by microbial activity. Similar microbial trace fossils may exist in the geological record. If life ever arose on early Mars, similar processes may have occurred there and left recognizable traces.

Friedmann, E. Imre↗
NASA NTRS1987

Biogeochemistry of dimethylsulfide in a seasonally stratified coastal salt pond

Dimethylsulfide (DMS) is the major volatile reduced organic sulfur compound in the water column of coastal Salt Pond, Cape Cod, MA. DMS concentration and vertical distributions vary seasonally in response to changing biogeochemical processes in the pond. When the pond is thermally stratified in summer, maximum DMS concentrations of up to 60 nmol/l were found in the oxygen-deficient metalimnion. DMS concentrations in the epilimnion (typically 5-10 nmol/l) were always an order of magnitude higher than in the hypolimnion (less than 0.2 nmol/l). The most likely precursor for DMS is algal dimethylsulfoniopropionate (DMSP), which showed vertical profiles similar to those of DMS. Laboratory experiments show that microorganisms in the pond, especially in the metalimnion, are capable of decomposing DMSP to DMS, while photosynthetic sulfur bacteria in the hypolimnion can consume DMS. Estimates of DMS production and consumption in Salt Pond have been made, considering production of DMS in the epilimnion and metalimnion and removal of DMS via gas exchange to the atmosphere, tidal exchange, and microbial consumption in the hypolimnion.

Wakeham, S. G.↗
NASA NTRS1987

Test results of a shower water recovery system

A shower test was conducted recently at NASA-JSC in which waste water was reclaimed and reused. Test subjects showered in a prototype whole body shower following a protocol similar to that anticipated for Space Station. The waste water was purified using reverse osmosis followed by filtration through activated carbon and ion exchange resin beds. The reclaimed waste water was maintained free of microorganisms by using both heat and iodine. This paper discusses the test results, including the limited effectiveness of using iodine as a disinfectant and the evaluation of a Space Station candidate soap for showering. In addition, results are presented on chemical and microbial impurity content of water samples obtained from various locations in the water recovery process.

Verostko, Charles E.↗
NASA NTRS1988

Environmental control medical support team

The activities conducted in support of the Environmental Control and Life Support Team during December 7, 1987 through September 30, 1988 are summarized. The majority of the ongoing support has focused on the ECLSS area. Through a series of initial meetings with the ECLSS team and technical literature review, an initial list of critical topics was developed. Subtasks were then identified or additional related tasks received as action items from the ECLSS group meetings. Although most of the efforts focused on providing MSFC personnel with information regarding specific questions and problems related to ECLSS issues, other efforts regarding identifying an ECLSS Medical Support Team and constructing data bases of technical information were also initiated and completed. The specific tasks are as follows: (1) Provide support to the mechanical design and integration of test systems as related to microbiological concerns; (2) Assist with design of Human Subjects Test Protocols; (3) Interpretation and recommendations pertaining to air/water quality requirements; (4) Assist in determining the design specifications required as related to the Technical Demonstration Program; (5) Develop a data base of all microorganisms recovered from previous subsystem testing; (6) Estimates of health risk of individual microbes to test subjects; (7) Assist with setting limits for safety of test subjects; (8) Health monitoring of test subjects; (9) Assist in the preparation of test plans; (10) Assist in the development of a QA/QC program to assure the validity, accuracy and precision of the analyses; and (11) Assist in developing test plans required for future man in the loop testing.

Crump, William J.↗
NASA NTRS1988

Trace fossils of microbial colonization on Mars: Criteria for search and for sample return

The recent discovery of microbial trace-fossil formation in the frigid Ross Desert of Antarctica suggests that early primitive life on Mars may have left behind similar signatures. These trace fossils are apparent as chemical or physical changes in rock (or sediment) structure (or chemistry) caused by the activity of organisms. Life on Mars, if it ever existed, almost certainly did not evolve above the level of microorganisms, and this should be considered in search for fossil life. For the reasons detailed here, microbial trace fossils seem to be a better and more realistic target for search than would be true microbial fossils (remnants of cellular structures).

Friedmann, E. I.↗
NASA NTRS1988

Test results on re-use of reclaimed shower water: Summary

A microgravity whole body shower (WBS) and waste water recovery systems (WWRS) were evaluated in three separate closed loop tests. Following a protocol similar to that anticipated for the U.S. Space Station, test subjects showered in a prototype whole body shower. The WWRS processes evaluated during the test series were phase change and reverse osmosis (RO). A preprototype Thermoelectric Integrated Hollow Fiber Membrane Evaporation Subsystem phase change process was used for the initial test with chemical pretreatment of the shower water waste input. The second and third tests concentrated on RO technologies. The second test evaluated a dynamic RO membrane consisting of zirconium oxide polyacrylic acid (ZOPA) membranes deposited on the interior diameter of 316L porous stainless steel tubes while the final test employed a thin semipermeable RO membrane deposited on the interior surface of polysulfone hollow fibers. All reclaimed water was post-treated for purity using ion exchange and granular activated carbon beds immediately followed by microbial control treatment using both heat and iodine. The test hardware, controls exercised for whole body showering, types of soaps evaluated, shower subject response to reclaimed water showering, and shower water collection and chemical pretreatment (if required) for microbial control are described. The WWRS recovered water performance and the effectiveness of the reclaimed water post-treatment techniques used for maintaining water purity and microorganism control are compared. Results on chemical and microbial impurity content of the water samples obtained from various locations in the shower water reuse system are summarized.

Verostko, C. E.↗
NASA NTRS1988

Bioisolation on the Space Station

Animal research on the Space Station presents the need for bioisolation, which is here defined as instrumental and operational provisions, which will prevent the exchange of particles greater than 0.3-micron size and microorganisms between crew and animals. Current design principles for the Biological Research Project thus call for: (1) use of specific pathogen-free animals; (2) keeping animals at all times in enclosed habitats, provided with microbial filters and a waste collection system; (3) placing habitats in a holding rack, centrifuge, and workbench, all equipped with particulate and odor filters, (4) washing dirty cage units in an equipment cleaner, with treatment and recycling of the water; (5) designing components and facilities so as to ensure maximal accessibility for cleaning; and (6) defining suitable operational procedures. Limited ground tests of prototype components indicate that proper bioisolation can thus be achieved.

Bonting, Sjoerd L.↗
NASA NTRS1989

Life on Mars - How it disappeared (if it was ever there)

Information available on Mars chemistry suggest that conditions on early Mars may have been suitable for life. This paper examines the possible events that led to the disappearance of life, assuming it existed, from the surface of Mars. The sequence of events leading to life extinction on early Mars assumes the following steps: (1) a decrease of temperature and humidity levels, leading to a selection of microorganisms for tolerance of low temperatures and arid conditions; (2) further deterioration of environment leading to withdrawal of cold-adapted organisms to protected niches under the surface; (3) further cooling producing heavy stresses in these organisms; and (4) further deterioration of the environment resulting in extinction. This sequence of events is considered parallel events documented for the microbial community in the Ross Desert of Antarctica, where TEM examinations of the material detected progressive stages of cell damage and death.

Friedmann, E. Imre↗
NASA NTRS1989

Biological nitrogen fixation under primordial Martian partial pressures of dinitrogen

One of the most striking differences between the conditions on early Mars and earth was a low (18 mb) partial pressure of N2 (pN2) on early Mars, as opposed to 780 mb N2 on earth. To investigate the possibility of biological nitrogen fixation under conditions of early Mars, experiments were carried out on the growth of Azotobacter vinelandii and Azomonas agilis in nitrogen-free synthetic medium under various partial pressures of N2 (ranging from 780 to 0 mb). It was found that, although the biomass, cell number, and growth rate of these bacteria decreased with decreasing pN2 values below pN2 of 400 mb, both microorganisms were capable of growing at pN2 as low as 5 mb (but not at of below 1 mb), indicating that biological fixation of nitrogen could have occurred on primordial Mars.

Klingler, J. M.↗
NASA NTRS1989

Planetary protection issues in advance of human exploration of Mars

The major planetary quarantine issues associated with human exploration of Mars, which is viewed as being more likely to harbor indigenous life than is the moon, are discussed. Special attention is given to the environmental impact of human missions to Mars due to contamination and mechanical disturbances of the local environment, the contamination issues associated with the return of humans, and the planetary quarantine strategy for a human base. It is emphasized that, in addition to the question of indigenous life, there may be some concern of returning to earth the earth microorganisms that have spent some time in the Martian environment. It is suggested that, due to the fact that a robot system can be subjected to more stringent controls and protective treatments than a mission involving humans, a robotic sample return mission can help to eliminate many planetary-quarantine concerns about returning samples.

Mckay, Christopher P.↗
NASA NTRS1990

Utilization of the water soluable fraction of wheat straw as a plant nutrient source

Recovery of water soluble, inorganic nutrients from the inedible portion of wheat was found to be an effective means of recycling nutrients within hydroponic systems. Through aqueous extraction (leaching), 60 percent of the total inorganic nutrient weight was removed from wheat straw and roots, although the recovery of individual nutrients varied. Leaching also removed about 20 percent of the total organic carbon from the biomass. In terms of dry weight, the leachate was comprised of approximately 60 percent organic and 40 percent inorganic compounds. Direct use of wheat straw leachate in static hydroponic systems had an inhibitory effect on wheat growth, both in the presence and absence of microorganisms. Biological treatment of leachate either with a mixed microbial community or the oyster mushroom Pleurotus ostreatus L., prior to use in hydroponic solutions, significantly reduced both the organic content and the inhibitory effects of the leachate. The inhibitory effects of unprocessed leachate appear to be a result of rapidly acting phytotoxic compounds that are detoxified by microbial activity. Leaching holds considerable promise as a method for nutrient recycling in a Controlled Ecological Life Support System (CELSS).

Mackowiak, C. L.↗
NASA NTRS1989

Estimates of the maximum time required to originate life

Fossils of the oldest microorganisms exist in 3.5 billion year old rocks and there is indirect evidence that life may have existed 3.8 billion years ago (3.8 Ga). Impacts able to destroy life or interrupt prebiotic chemistry may have occurred after 3.5 Ga. If large impactors vaporized the oceans, sterilized the planets, and interfered with the origination of life, life must have originated in the time interval between these impacts which increased with geologic time. Therefore, the maximum time required for the origination of life is the time that occurred between sterilizing impacts just before 3.8 Ga or 3.5 Ga, depending upon when life first appeared on earth. If life first originated 3.5 Ga, and impacts with kinetic energies between 2 x 10 the the 34th and 2 x 10 to the 35th were able to vaporize the oceans, using the most probable impact flux, it is found that the maximum time required to originate life would have been 67 to 133 million years (My). If life originated 3.8 Ga, the maximum time to originate life was 2.5 to 11 My. Using a more conservative estimate for the flux of impacting objects before 3.8 Ga, a maximum time of 25 My was found for the same range of impactor kinetic energies. The impact model suggests that it is possible that life may have originated more than once.

Oberbeck, Verne R.↗