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At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS2010

315mJ, 2-micrometers Double-Pulsed Coherent Differential Absorption Lidar Transmitter for Atmospheric CO2 Sensing

The design of a double pulsed, injection seeded, 2-micrometer compact coherent Differential absorption Lidar (DIAL) transmitter for CO2 sensing is presented. This system is hardened for ground and airborne applications. The design architecture includes three continuous wave lasers which provide controlled on and off line seeding, injection seeded power oscillator and a single amplifier operating in double pass configuration. As the derivative a coherent Doppler wind lidar, this instrument has the added benefit of providing wind information. The active laser material used for this application is a Ho: Tm:YLF crystal operates at the eye-safe wavelength. The 3-meter long folded ring resonator produces energy of 130-mJ (90/40) with a temporal pulse length around 220 nanoseconds and 530 nanosecond pulses for on and off lines respectively. The separation between the two pulses is on the order of 200 microseconds. The line width is in the order of 2.5MHz and the beam quality has an M(sup 2) of 1.1 times diffraction limited beam. A final output energy for a pair of both on and off pulses as high as 315 mJ (190/125) at a repetition rate of 10 Hz is achieved. The operating temperature is set around 20 C for the pump diode lasers and 10 C for the rod. Since the laser design has to meet high-energy as well as high beam quality requirements, close attention is paid to the laser head design to avoid thermal distortion in the rod. A side-pumped configuration is used and heat is removed uniformly by passing coolant through a tube slightly larger than the rod to reduce thermal gradient. This paper also discusses the advantage of using a long upper laser level life time laser crystal for DIAL application. In addition issues related to injection seeding with two different frequencies to achieve a transform limited line width will be presented.

Yu, Jirong↗
NASA NTRS2010

Multiple frequency optical mixer and demultiplexer and apparatus for remote sensing

A pulsed laser system includes a modulator module configured to provide pulsed electrical signals and a plurality of solid-state seed sources coupled to the modulator module and configured to operate, responsive to the pulsed electrical signals, in a pulse mode. Each of the plurality of solid-state seed sources is tuned to a different frequency channel separated from any adjacent frequency channel by a frequency offset. The pulsed laser system also includes a combiner that combines outputs from each of the solid state seed sources into a single optical path and an optical doubler and demultiplexer coupled to the single optical path and providing each doubled seed frequency on a separate output path.

Chen, Jeffrey R.↗
NASA NTRS2010

Trace Gas Measurements on Mars and Earth Using Optical Parametric Generation

Trace gases and their isotopic ratios in planetary atmospheres offer important but subtle clues as to the origins of a planet's atmosphere, hydrology, geology, and potential for biology. An orbiting laser remote sensing instrument is capable of measuring trace gases on a global scale with unprecedented accuracy, and higher spatial resolution that can be obtained by passive instruments. We have developed an active sensing instrument for the remote measurement of trace gases in planetary atmospheres (including Earth). The technique uses widely tunable, seeded optical parametric generation (OPG) to measure methane, CO2, water vapor, and other trace gases in the near and mid-infrared spectral regions. Methane is a strong greenhouse gas on Earth and it is also a potential biogenic marker on Mars and other planets. Methane in the Earth's atmosphere survives for a shorter time than CO2 but its impact on climate change can be larger than CO2. Methane levels have remained relatively constant over the last decade around 1.78 parts per million (ppm) but recent observations indicate that methane levels may be on the rise. Increasing methane concentrations may trigger a positive feedback loop and a subsequent runaway greenhouse effect, where increasing temperatures result in increasing methane levels. The NRC Decadal Survey recognized the importance of global observations of greenhouse gases and called for simultaneous CH4, CO, and CO2 measurements but also underlined the technological limitations for these observations. For Mars, methane measurements are of great interest because of its potential as a strong biogenic marker. A remote sensing instrument that can measure day and night over all seasons and latitudes can identify and localize sources of biogenic gas plumes produced by subsurface chemistry or biology, and aid in the search for extra-terrestrial life. It can identify the dynamics of methane generation over time and latitude and identify future lander mission sites for more detailed in-situ analysis. In this paper we report on remote sensing measurements of methane using a high peak power, widely tunable optical parametric generator (OPG) operating at 3.3 micron and 1.65 micron. The OPG is pumped by a passively q-switched single frequency laser (3ns, 5KHz, 50uJ) and seeded by a diode laser. The spectral width of both signal and idler of seeded OPG is nearly Fourier transform limited. The output of seeded OPG is single frequency with high spectral purity and is widely tunable. Both 1650 nm and 3300 nm can be generated with a conversion efficiency of more than 30%. We have demonstrated detection of methane at 3274 nm and 1650 nm in a cell and also performed open path atmospheric measurements of methane at the same wavelengths. Finally, we were able to demonstrate simultaneous detection of methane at 3270.4 nm and CO2 at 1578.2 nm. In this paper we will discuss the OPG performance and atmospheric open path measurement results.

Numata, Kenji↗
NASA NTRS2005

Identifying Objects via Encased X-Ray-Fluorescent Materials - the Bar Code Inside

Systems for identifying objects by means of x-ray fluorescence (XRF) of encased labeling elements have been developed. The XRF spectra of objects so labeled would be analogous to the external bar code labels now used to track objects in everyday commerce. In conjunction with computer-based tracking systems, databases, and labeling conventions, the XRF labels could be used in essentially the same manner as that of bar codes to track inventories and to record and process commercial transactions. In addition, as summarized briefly below, embedded XRF labels could be used to verify the authenticity of products, thereby helping to deter counterfeiting and fraud. A system, as described above, is called an encased core product identification and authentication system (ECPIAS). The ECPIAS concept is a modified version of that of a related recently initiated commercial development of handheld XRF spectral scanners that would identify alloys or detect labeling elements deposited on the surfaces of objects. In contrast, an ECPIAS would utilize labeling elements encased within the objects of interest. The basic ECPIAS concept is best illustrated by means of an example of one of several potential applications: labeling of cultured pearls by labeling the seed particles implanted in oysters to grow the pearls. Each pearl farmer would be assigned a unique mixture of labeling elements that could be distinguished from the corresponding mixtures of other farmers. The mixture would be either incorporated into or applied to the surfaces of the seed prior to implantation in the oyster. If necessary, the labeled seed would be further coated to make it nontoxic to the oyster. After implantation, the growth of layers of mother of pearl on the seed would encase the XRF labels, making these labels integral, permanent parts of the pearls that could not be removed without destroying the pearls themselves. The XRF labels would be read by use of XRF scanners, the spectral data outputs of which would be converted to alphanumeric data in a digital equivalent data system (DEDS), which is the subject of the previous article. These alphanumeric data would be used to track the pearls through all stages of commerce, from the farmer to the retail customer.

Schramm, Harry F.↗
NASA NTRS2016

Comparison of Simultaneous PIV and Hydroxyl Tagging Velocimetry in Low Velocity Flows

Hydroxyl tagging velocimetry (HTV) is a molecular tagging velocimetry (MTV) technique that relies on the photo- dissociation of water vapor into OH radicals and their subsequent tracking using laser-induced fluorescence. At ambient temperature in air, the OH species lifetime is about 50 micro-s. The feasibility of using HTV for probing low- speed flows (a few m/s) is investigated by using an inert, heated gas as a means to increase the OH species lifetime. Unlike particle-based techniques, MTV does not suffer from tracer settling, which is particularly problematic at low speeds. Furthermore, the flow needs to be seeded with only a small mole fraction of water vapor, making it safer for both the user and facilities than other MTV techniques based on corrosive or toxic chemical tracers. HTV is demonstrated on a steam-seeded nitrogen jet at approximately 75 C in the laminar (Umean=3.31 m/s, Re=1,540), transitional (Umean=4.48 m/s, Re=2,039), and turbulent (Umean=6.91 m/s, Re=3,016) regimes at atmospheric pressure. The measured velocity profiles are compared with particle image velocimetry (PIV) measurements performed simultaneously with a second imager. Seeding for the PIV is achieved by introducing micron-sized water droplets into the flow with the steam; the same laser sheet is used for PIV and HTV to guarantee spatial and temporal overlap of the data. Optimizing each of these methods, however, requires conflicting operating conditions: higher temperatures benefit the HTV signals but reduce the available seed density for the PIV through evaporation. Nevertheless, data are found to agree within 10% for the instantaneous velocity profiles and within 5% for the mean profiles and demonstrate the feasibility of HTV for low-speed flows at moderate to high temperatures.

Andre, Matthieu A.↗
NASA NTRS2017

Space Plants for Astronaut Consumption

Growing plants in space will be an essential part of sustaining astronauts during long-range missions. During the summer of 2017, three female NASA interns, have been engaged in research relevant to food production in space, and will present their projects to an all female program known as Girls in STEM camp. Ayla Grandpre, a senior from Rocky Mountain College, has performed data mining and analysis of crop growth results gathered through Fairchild Botanical Gardens program, Growing Beyond Earth. Ninety plants were downselected to three for testing in controlled environment chambers at KSC. Ayla has also managed an experiment testing a modified hydroponics known as PONDS, to grow mizuna mustard greens and red robin cherry tomatoes. Emma Boehm, a senior from the University of Minnesota, has investigated methods to sterilize seeds and analyzed the most common microbial communities on seed surfaces. She has tested a bleach fuming method and an ethanol treatment. Emma has also tested Tokyo bekana Chinese cabbage seeds from four commercial seed vendors to identity differences in germination and growth variability. Lastly, Payton Barnwell, a junior from Florida Polytechnic University has shown that light recipes provided by LEDs can alter the growth and nutrition of 'Outredgeous' lettuce, Chinese cabbage, and Mizuna. The results of her light quality experiments will provide light recipe recommendations for space crops that grown in the Advanced Plant Habitat currently aboard the International Space Station.

VEGGIE↗
NASA NTRS2018

Preparation for Pick-and-Eat Food Production on the International Space Station: Flight Definition for the VEG-04 and VEG-05 Missions

Growth of fresh, nutritious, palatable produce for crew consumption during spaceflight may provide health-promoting, bioavailable nutrients and enhance the dietary experience as we move toward longer-duration missions. Tending plants also may serve as a countermeasure for crew psychological stresses associated with long duration spaceflight. However, requirements to support consistent growth of a variety of high quality, nutritious crops under spaceflight environmental conditions is unknown. This study is exploring the potential to grow plants for food production on the International Space Station (ISS) using the Veggie vegetable production system. Ground testing is underway to compare the impacts of several fertilizer and lighting treatments on growth, quality, and nutritional composition of the leafy green crop mizuna, and the dwarf tomato crop Red Robin when subjected to Veggie ISS environmental conditions. Early testing focused on the leafy crop Tokyo Bekana Chinese cabbage, but ground tests indicated that this plant suffered from stress responses when grown under LEDs and the chronically elevated CO2 levels found on the ISS. Mizuna, a related leafy variety that grows well in the presence of high CO2, and has excellent organoleptic characteristics, was selected as an alternate crop. Tomato crops have been grown using two fertilizer formulations and two pollination techniques, and growth tests using different red:blue lighting environments are underway. Chemical analysis is also being conducted and these data, when coupled with the growth results, will be used to down-select to the two best lighting treatments and best fertilizer treatment for future testing of each crop on the ISS. Additionally, seed-source testing has become important, with mizuna seeds from two different vendors growing very differently. A seed source has been selected, and seed-surface-sanitizing methods have been confirmed for mizuna, but these remain under development for tomato. A crop-handling protocol is also being evaluated to support food safety. All harvests reserve a subset of samples for microbial analysis to determine baseline microbial levels and help establish critical control points for food safety. Testing was initially conducted in hardware analogs of the standard Veggie plant pillows. However, a new Veggie watering system, the Passive Orbital Nutrient Delivery System or PONDS, has been designed and is being prepared for future flight experiments. With the selection of this growth system, ground tests have shifted to analog PONDS systems. Crop tests on ISS, designated VEG-04 for mizuna and VEG-05 for tomato, are planned in 2018 to evaluate any additional impacts of spaceflight on the light and fertilizer conditions down-selected from ground tests. A set of Veggie-specific questions has been developed to characterize the psychological impacts of plant growth and plant-care activities during spaceflight. Organoleptic questionnaires have been developed to assess produce attributes in microgravity taste sessions. These tests for plants growing in the Veggie hardware on ISS will help to mitigate the risk of an inadequate food supply for long duration missions by developing methods and determining hardware requirements to integrate fresh vegetables as a dietary supplement. This research was co-funded by the Human Research Program and Space Biology (MTL1075) in the ILSRA 2015 NRA call.

Veggie↗
NASA NTRS2018

Preparation for Pick-and-Eat Food Production on the International Space Station: Flight Definition for the VEG-04 and VEG-05 Missions

Growth of fresh, nutritious, palatable produce for crew consumption during spaceflight may provide health-promoting, bioavailable nutrients and enhance the dietary experience as we move toward longer-duration missions. Tending plants also may serve as a countermeasure for crew psychological stresses associated with long duration spaceflight. However, requirements to support consistent growth of a variety of high quality, nutritious crops under spaceflight environmental conditions is unknown. This study is exploring the potential to grow plants for food production on the International Space Station (ISS) using the Veggie vegetable production system. Ground testing is underway to compare the impacts of several fertilizer and lighting treatments on growth, quality, and nutritional composition of the leafy green crop mizuna, and the dwarf tomato crop "Red Robin" when subjected to Veggie ISS environmental conditions. Early testing focused on the leafy crop "Tokyo Bekana" Chinese cabbage, but ground tests indicated that this plant suffered from stress responses when grown under LEDs and the chronically elevated CO2 levels found on the ISS. Mizuna, a related leafy variety that grows well in the presence of high CO2, and has excellent organoleptic characteristics, was selected as an alternate crop. Tomato crops have been grown using two fertilizer formulations and two pollination techniques, and growth tests using different red:blue lighting environments are underway. Chemical analysis is also being conducted and these data, when coupled with the growth results, will be used to down-select to the two best lighting treatments and best fertilizer treatment for future testing of each crop on the ISS. Additionally, seed-source testing has become important, with mizuna seeds from two different vendors growing very differently. A seed source has been selected, and seed-surface-sanitizing methods have been confirmed for mizuna, but these remain under development for tomato. A crop-handling protocol is also being evaluated to support food safety. All harvests reserve a subset of samples for microbial analysis to determine baseline microbial levels and help establish critical control points for food safety. Testing was initially conducted in hardware analogs of the standard Veggie plant pillows. However, a new Veggie watering system, the Passive Orbital Nutrient Delivery System or PONDS, has been designed and is being prepared for future flight experiments. With the selection of this growth system, ground tests have shifted to analog PONDS systems. Crop tests on ISS, designated VEG-04 for mizuna and VEG-05 for tomato, are planned in 2018 to evaluate any additional impacts of spaceflight on the light and fertilizer conditions down-selected from ground tests. A set of Veggie-specific questions has been developed to characterize the psychological impacts of plant growth and plant-care activities during spaceflight. Organoleptic questionnaires have been developed to assess produce attributes in microgravity taste sessions. These tests for plants growing in the Veggie hardware on ISS will help to mitigate the risk of an inadequate food supply for long duration missions by developing methods and determining hardware requirements to integrate fresh vegetables as a dietary supplement. This research was co-funded by the Human Research Program and Space Biology (MTL#1075) in the ILSRA 2015 NRA call.

LED light↗
NASA NTRSDate not supplied

On the Use of Liquid Nitrogen Droplets as Flow Tracers in Cryogenic Flow Facilities at NASA Langley Research Center

The injection of liquid nitrogen droplets to cool the gas temperature in cryogenic wind tunnels is discussed as a method of natural seeding for velocimetry-focused, particle-based, laser diagnostics. Historical observations and issues with seeding are presented for both ground-test facilities of interest in this work at NASA Langley: the 0.3-m Transonic Cryogenic Wind Tunnel (TCT) and the National Transonic Facility (NTF). Recent observations of natural seeding with a Rayleigh scattering instrument are presented in the two facilities, which motivated the purposeful use of a pulse-burst laser system to observe the particles directly with a sequentially operated laser sheet for the first time. Time-resolved image sequences of unevaporated liquid nitrogen droplets were readily acquired for tunnel total temperatures of 200 K and below. The preliminary results promote a discussion on the fitness of these natural particles as flow tracers for either a particle image velocimetry or a particle tracking velocimetry instrument in these high-Reynolds-number facilities.

cryogenic wind tunnels↗
NASA NTRSDate not supplied

The maize rough endosperm6 (rgh6) mutant encodes a predicted DEAD-box RNA helicase

Maize rough endosperm (rgh) mutants have defective seeds with a rough, etched, or pitted endosperm surface. Molecular genetic analysis of this mutant class has identified multiple RNA processing proteins critical to endosperm development. We isolated the rgh6 locus from the UniformMu transposon tagging population. Mutant kernels have reduced grain-fill with defective embryos that fail to germinate. Self-pollination of rgh6 heterozygotes produces mutant seeds at frequency consistent with a single recessive mutation. Molecular mapping localized rgh6 to a 60 kbp interval on chromosome 5. PCR analysis of gene models within the fine-map interval identified a Mutator (Mu) transposon insertion within a predicted DEAD-box RNA helicase gene. A second allele of rgh6 was identified from UniformMu population. Reciprocal crosses between rgh6-umu1 and rgh6-umu2 heterozygotes produces mutant seeds at a frequency consistent with a 3:1 ratio indicating these mutants are allelic. Both rgh6-umu1 and rgh6-umu2 have Mu element insertions at the same insertion site within the DEAD-box RNA helicase gene. However, the terminal inverted repeat sequences are polymorphic between the alleles showing the alleles are independent mutations. We conclude that mutation of the DEAD-box RNA helicase causes the rgh6 phenotype. Further characterization of the rgh6 mutant phenotype and biochemical investigation of the RGH6 protein is expected to give further insights on the roles of RNA processing in endosperm development.

maize↗
NASA NTRS1971

Experimental investigation to simulate propellant heating in the nuclear light bulb engine.

Experiments to heat a simulated propellant to high bulk temperatures by the absorption of thermal radiation are discussed. Argon seeded with micron-sized carbon particles was used as the simulated propellant; a 500 kw d-c arc was used as the radiant energy source. Bulk temperatures up to 3860 K were obtained with greater than 95% of the incident radiation absorbed. The arc radiation source, seed dispersal equipment, techniques used to prevent transparent wall coating by the seeds, and calorimetric measurement of bulk temperature are also discussed.

Klein, J. F.↗
NASA NTRS1973

Use of meteorological satellite observations in weather modification programs

The potential value of weather satellite data in field operations of weather modification is appraised. It was found that satellites could play a useful role in operational weather modification projects, particularly in the recognition of treatment opportunities. Satellite cloud photographs and infrared observations appear promising in the identification of treatment opportunities in seeding orographic cloud systems for increased snowpack, in seeding convective clouds for increased rainfall, in identifying hail threats, and in tracking and observing hurricanes as an aid to timing and location of seeding treatments. It was concluded that the potential value of satellite data in the treatment and evaluation phases of operational projects is not as great as in the recognition of treatment opportunity.

Dennis, A. S.↗
NASA NTRS1973

Gas chromatography-mass spectrometry study of sterols from Pinus elliotti tissues.

A comparative study of the sterol components of slash pine (Pinus elliotti) callus tissue cultures, seeds, and seedlings was carried out using GC-MS techniques. Cholesterol, desmosterol, campesterol, stigmasterol, sitosterol and cycloeucalenol were identified in all tissues while lophenol and 24-methylenelophenol were identified in only the seed and seedlings. 24-Ethylidenelophenol was detected in trace concentrations in only the seedlings. Sitosterol was the predominant sterol component, i.e., 80.8, 38.1 and 47.8% of the tissue culture, seed and seedling sterols, respectively.

Laseter, J. L.↗
NASA NTRS1976

Results and progress on the NASA Lewis H2-O2 MHD program

It was found that flame sprayed ceramic coatings on combustion chamber and nozzle walls permit operation with hot walls, thereby eliminating possible problems associated with seed condensation. However, under the conditions of experiment the net heat transfer was unexpectedly increased over that of cold copper walls. Pressure disturbances associated with oblique pressure waves were measured in a MHD channel. These disturbances are due to a rocket-type nozzle which was designed to achieve low weight rather than perfectly parallel flow at the exit. A new nozzle with parallel flow at the exit was designed. Electrical conductivity measurements agreed well with theory except at low combustion pressures and/or high ratios of seed/oxygen mass flows (seed was injected into oxygen flow line). The discrepancy is believed to be the result of poor atomization of the seed at high ratios of seed/oxygen mass flows which results in droplet sizes which do not completely vaporize the combustor.

Smith, J. M.↗
NASA NTRS1976

Results and progress on the NASA Lewis H2-O2 MHD program

A rocket test facility at the NASA Lewis Research Center has been used to develop interelectrode insulating materials, measure heat losses, and determine the fluid dynamic and electrical properties of MHD ducts and the cesium-seeded H2-O2 working fluid. Test results show that flame sprayed ceramic coatings on combustion chamber and nozzle walls permit operation with hot walls, eliminating problems associated with seed condensation; however, the net heat transfer was unexpectedly increased over that of cold copper walls. Pressure disturbances associated with oblique pressure waves were measured in a rocket nozzle designed to achieve low weight rather than perfectly parallel flow at the exit. Electrical conductivity measurements were in good agreement with theory except at low combustion pressures and/or high seed/oxygen mass flow ratios. The discrepancy is thought to result from poor atomization of the seed, producing droplets which do not completely vaporize during their residence time.

Smith, J. M.↗
NASA NTRS1976

Natural precedents to active magnetospheric experiments

Some of the natural analogs of proposed seeding experiments in the magnetosphere are: electric charged particle injections during substorms; lightning-induced whistlers providing wave injections; 'detachment' of plasma from the plasmapause, which is equivalent to light-ion seeding in the outer magnetosphere. In the present paper, the characteristics of some natural precedents to active experiments are reviewed, and their relative advantages and drawbacks are examined. One of these precedents - wave generation in detached plasma regions - is then discussed in some detail; the discussion reveals the generation of ELF electromagnetic noise when the energetic electrons exceed the stably trapped limit, and also indicates that a critical dimension for the seeded volume exists transverse to the geomagnetic field.

Russell, C. T.↗
NASA NTRS1977

Spectroscopic determination of electrical conductivity in an MHD duct from absolute intensity measurements

Measurements of the electrical conductivity in the NASA Lewis cesium seeded, H2-O2 MHD duct made by applying a voltage across the channel from one end electrode to the other, measuring the current, and using the inner electrodes as probes to monitor the voltage distribution along the channel were found to be in good agreement with theory except at low combustion pressures and/or high ratios of seed/oxygen mass flows. To corroborate these measurements and to analyze the possibility of nonuniform seed injection as a cause of the above deviations, a spectroscopic investigation of the plasma conductivity was undertaken. Radial profiles of emission coefficient were obtained from measured transverse profiles of the absolute integrated intensity by Abel inversion. Radial profiles of electrical conductivity were then obtained under two different assumptions. In the first the Cs seed fraction is assumed uniform and equal to the measured flow rate at the time when the temperature and conductivity were obtained. In the second method the local temperature and pressure are taken to be those given by a one-dimensional channel calculation including heat transfer and friction. The results of the two methods are compared to the previously measured conductivity.

Wang, S. Y.↗
NASA NTRS1976

Heat transfer evaluation in a plasma core reactor

Numerical evaluations of heat transfer in a fissioning uranium plasma core reactor cavity, operating with seeded hydrogen propellant, was performed. A two-dimensional analysis is based on an assumed flow pattern and cavity wall heat exchange rate. Various iterative schemes were required by the nature of the radiative field and by the solid seed vaporization. Approximate formulations of the radiative heat flux are generally used, due to the complexity of the solution of a rigorously formulated problem. The present work analyzes the sensitivity of the results with respect to approximations of the radiative field, geometry, seed vaporization coefficients and flow pattern. The results present temperature, heat flux, density and optical depth distributions in the reactor cavity, acceptable simplifying assumptions, and iterative schemes. The present calculations, performed in cartesian and spherical coordinates, are applicable to any most general heat transfer problem.

Smith, D. E.↗