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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Experiments with optical instruments

Photography was used to document known defects of the periscopic instrument used to check spacecrews in the descent module of the Soyuz T-4. The screen of the altitude control unit was also photographed and revealed glare in the central field of vision. A light filter was installed in the peripheral window to observe the Sun and horizon of the Earth. Checking attitude control by means of polaroids enabled a 5 further advance (500 km) into the zone of shadow. The attitude control unit was used to check the orbital orientation with respect to the vertical during the night segment of flight. A lens screen was used for the emission glow of the atmosphere at an altitude of about 100 km. Docking of the Soyuz T-4 was observed by means of an onboard display, a television camera, and a sighting device. From a distance of about 5 km, the space station could be seen as a bright dot in the sighting device. Docking occurred in shadow.

Savinykh, V.↗
NASA NTRS1995

A final look at LDEF electro-optic systems components

Postrecovery characteristics of LDEF electro-optic components from the GTRI tray are compared with their prelaunch characteristics and with the characteristics of similar components from related experiments. Components considered here include lasers, light-emitting diodes, semiconducting radiation detectors and arrays, optical substrates, filters, and mirrors, and specialized coatings. Our understanding of the physical effects resulting from low earth orbit are described, and guidelines and recommendations for component and materials choices are presented.

Blue, M. D.↗
NASA NTRS2014

IVGEN Post Flight Analysis

The Intravenous Fluid Generation (IVGEN) Experiment was a technology demonstration experiment that purified ISS potable water, mixed it with salt, and transferred it through a sterilizing filter. On-orbit performance was verified as appropriate and two 1.5 l bags of normal saline solution were returned to earth for post-flight testing by a FDA certified laboratory for compliance with United States Pharmacopiea (USP) standards. Salt concentration deviated from required values and an analysis identified probable causes. Current efforts are focused on Total Organic Content (TOC) testing, and shelf life.The Intravenous Fluid Generation (IVGEN) Experiment demonstrated the purification of ISS potable water, the mixing of the purified water with sodium chloride, and sterilization of the solution via membrane filtration. On-orbit performance was monitored where feasible and two 1.5-liter bags of normal saline solution were returned to earth for post-flight testing by a FDA-registered laboratory for compliance with United States Pharmacopeia (USP)standards [1]. Current efforts have been focused on challenge testing with identified [2] impurities (total organic-carbon), and shelf life testing. The challenge testing flowed known concentrations of contaminants through the IVGEN deionizing cartridge and membrane filters to test their effectiveness. One finding was that the filters and DI-resin themselves contribute to the contaminant load during initial startup, suggesting that the first 100 ml of fluid be discarded. Shelf life testing is ongoing and involves periodic testing of stored DI cartridges and membrane filters that are capped and sealed in hermetic packages. The testing is conducted at six month intervals measuring conductivity and endotoxins in the effluent. Currently, the packaging technique has been successfully demonstrated for one year of storage testing. The USP standards specifies that the TOC be conducted at point of generation as opposed to point of consumption. Samples were generated and shipped to an FDA facility however, testing determined that the samples failed the TOC specification with most likely due to leaching from the sample container. Shelf life testing is examining packaging techniques and periodic testing of samples of DI cartridges that are capped and sealed in hermetic packages. Periodic testing of the purified water output will be conducted at six month intervals.

microgravity applications↗
NASA NTRS2004

Spectral Cloud-Filtering of AIRS Data: Non-Polar Ocean

The Atmospheric Infrared Sounder (AIRS) is a grating array spectrometer which covers the thermal infrared spectral range between 640 and 1700/cm. In order to retain the maximum radiometric accuracy of the AIRS data, the effects of cloud contamination have to be minimized. We discuss cloud filtering which uses the high spectral resolution of AIRS to identify about 100,000 of 500,000 non-polar ocean spectra per day as relatively "cloud-free". Based on the comparison of surface channels with the NCEP provided global real time sst (rtg.sst), AIRS surface sensitive channels have a cold bias ranging from O.5K during the day to 0.8K during the night. Day and night spatial coherence tests show that the cold bias is due to cloud contamination. During the day the cloud contamination is due to a 2-3% broken cloud cover at the 1-2 km altitude, characteristic of low stratus clouds. The cloud-contamination effects surface sensitive channels only. Cloud contamination can be reduced to 0.2K by combining the spectral filter with a spatial coherence threshold, but the yield drops to 16,000 spectra per day. AIRS was launched in May 2002 on the Earth Observing System (EOS) Aqua satellite. Since September 2002 it has returned 4 million spectra of the globe each day.

infrared↗
NASA NTRSDate not supplied

Flight Environment HEPA Filter Testing for Lunar Dust Removal Capability

Lunar dust is an abrasive regolith that can cause critical damage to hardware and crew. Its morphology and chemical makeup differs from typical earth dust due to space weathering effects. Current space missions require extensive air filtration of lunar dust to ensure mission success; as such filtration testing is paramount in verifying the dust-removal capabilities of the system. Previous testing at NASA GRC consisted of two stages: testing a flat high efficiency particulate air (HEPA) media sheet at various pressure ranges (Stage 1) and testing a pleated HEPA filter at different humidity and dust levels (Stage 2). This testing was done to buy-down risk when testing the flight-qualification HEPA filter for the proposed Stage 3 test. Stage 3 testing used a flight-ready HEPA filter to measure its performance characteristics to verify programmatic requirements. This included measuring lunar dust loading versus pressure drop performance and establishing a maximum capacity based on the allowable pressure drop, determining the HEPA filter efficiency utilizing two separate methodologies, and assessing if the lunar dust caused the HEPA filter to experience any damage. Additionally, dust removal from the HEPA filter was performed using a vacuum to ascertain if the filter life can be prolonged. These test results will aid the program in verifying programmatic requirements and ensuring risk buydown before this HEPA filter takes flight.

HEPA↗
NASA NTRS1983

Filtering flight data prior to aerodynamic system identification

An algorithm for processing flight-test data to provide state estimates and instrument calibrations for aerodynamic or hydrodynamic system identification by the equation error estimation method is developed and demonstrated on synthesized data. The extended-Kalman-filter algorithm employs a locally level, north-pointing frame of reference, accounts for rotating ellipsoidal earth effects, and estimates sensor bias, scale factors, wind components, and process noise levels by maximum-likelihood parameters. The method is found to be most effective with navigation quality inertial input data. The algorithm is applied to data from a six-degree-of-freedom F-4 aircraft simulation and shown to produce state estimates in good agreement with the simulation values.

Trankle, T. L.↗
NASA NTRS1987

Martin Marietta atomic oxygen Low Earth Orbit (LEO) simulation

An atomic oxygen beam apparatus that produces flux levels and atomic kinetic energy similar to that encountered by spacecraft in low Earth orbit (LEO) is described. The beam apparatus consists of an electric discharge ion source, mass filter, decelerator, and neutralizer. Specific design goals include a 1.3 cm beam diameter, a 5 eV beam energy, and a flux density on the order of 10(15) cm(-2) s(-1). The total fluence will be on the order of 10(19) cm(-2) for an 8 hour test. The neutral oxygen beam will expose various materials contained within a large target chamber. Within the chamber will be a rather complex suite of instrumentation that will allow real-time studies of material mass loss and reactant species spatial distribution. In addition, a UV solar simulator will aid in the understanding of various synergistic effects.

Sjolander, Gary W.↗
NASA NTRS1988

Infrared Remote Sensing Of The Martian Atmosphere

Distributions of temperature dust, vapors, and condensates measured. Report describes design and intended uses of developmental pressure-modulator infrared readimeter, PMIRR, carried aboard Mars Observer spacecraft. Applies remote-sensing techniques used to study atmosphere of Earth. Takes similar measurements from polar orbit around Mars. Nine-channel atmospheric sounder that employs filter and pressure-modulation gas-correlation infrared radiometry.

Mccleese, D. J.↗
NASA NTRS1992

Photometry from space

A brief description of the High Speed Photometer (HSP) of the Hubble Space Telescope is given, in particular the HSP light path, detectors, entrance apertures, and filters. The status of HSP testing to date is reported, and problems encountered with the bright earth and the telescope pointing system are described. The calibration effort for the HSP is well under way. Results of internal (instrument coordinate) aperture locations good to 0.05 arcsec and external (telescope coordinate) locations good to 0.02 arcsec are shown. The effects of spacecraft pointing and jitter on HSP photometry are detailed, and a preliminary measurement of spacecraft jitter with HSP is shown. The aperture calibration effort is verified by accurate pointing of a star to different HSP 1.0 arcsec entrance apertures, and photometric performance of the instrument is shown to be accurate to the 2 percent photon noise of the observations. Future science verification and guaranteed observing time programs are listed. Suggestions are made for future space-based photometers.

Nelson, M. J.↗
NASA NTRS2008

Refractory Ceramic Foams for Novel Applications

Workers at NASA Ames Research center are endeavoring to develop durable, oxidation-resistant, foam thermal protection systems (TPSs) that would be suitable for covering large exterior spacecraft surfaces, would have low to moderate densities, and would have temperature capabilities comparable to those of carbon-based TPSs [reusable at 3,000 F (.1,650 C)] with application of suitable coatings. These foams may also be useful for repairing TPSs while in orbit. Moreover, on Earth as well as in outer space, these foams might be useful as catalyst supports and filters. Preceramic polymers are obvious candidates for use in making the foams in question. The use of these polymers offers advantages over processing routes followed in making conventional ceramics. Among the advantages are the ability to plastically form parts, the ability to form pyrolized ceramic materials at lower temperatures, and the ability to form high-purity microstructures having properties that can be tailored to satisfy requirements. Heretofore, preceramic polymers have been used mostly in the production of such low-dimensional products as fibers because the loss of volatiles during pyrolysis of the polymers leads to porosity and large shrinkage (in excess of 30 percent). In addition, efforts to form bulk structures from preceramic polymers have resulted in severe cracking during pyrolysis. However, because the foams in question would consist of networks of thin struts (in contradistinction to nonporous dense solids), these foams are ideal candidates for processing along a preceramic-polymer route.

Stackpoole, M.↗
NASA NTRS1997

Spatial and Temporal Energy Characterization of Precipitating Electrons for the January 10th, 1997 Magnetic Cloud Event

The January 10-11, 1997 magnetic cloud event provided a rare opportunity to study auroral energy deposition under varying but intense IMF conditions. The Wind spacecraft located about 100 RE upstream monitored the IMF and plasma parameters during the passing of the cloud. The Polar Ultraviolet Imager (UVI) observed the aurora[ precipitation during the first encounter of the cloud with Earth's magnetosphere and during several subsequent substorm events. The UVI has the unique capability of measuring the energy flux and characteristic energy of the precipitating electrons through the use of narrow band filters that distinguish short and long wavelength molecular nitrogen emissions. The spatial and temporal characteristics of the precipitating electron energy will be discussed beginning with the inception of the event at the Earth early January 1 Oth and continuing through the subsidence of auroral activity on January 11th.

Spann, J. F., Jr.↗
NASA NTRS1986

Nonlinear filtering for spacecraft attitude estimation

Nonlinear filtering techniques are applied to spacecraft attitude estimation using quaternion parameterization for the attitude kinematics. By replacing the angular velocity vector by the gyro output vector, a state dependent noise vector is introduced in the seven-dimensional system equations. The resulting conditional probability density function from the Ito differential rule is governed by the Fokker Planck partial differential equation which is approximated by the second order mean and covariance differential equations. In order to minimize computer loading, the covariance propagation is carried out in six-dimensional state space using a matrix transformation. The star tracker data is used to update the covariance matrix in the seven-dimensional space. The algorithm is simulated for an earth pointing spacecraft mission, using Monte Carlo samples of gyro and star measurements. The performance of the second order filter is compared with the extended Kalman Filter through several simulation runs and drift rates have been identified.

Vathsal, S.↗
NASA NTRS1999

Characterization of Infrared Diode Laser Beams and Atmospheric CO Imaging Instrument

During June-August 1997 Dr. Jonathan Miles participated in the ASEE-sponsored summer faculty research program at NASA Langley Research Center (LaRC). The Aerospace Electronic Systems Division (AESD), Sensor Systems Branch (SSB), at NASA LARC had proposed a new mission, GEOstationary TROpospheric Pollution SATellite (GEO TROPSAT), to address critical science questions of tropospheric chemistry. The troposphere is a complex system, comprising "point" and distributed sources of natural and anthropogenic origin; complicated transport processes, both lateral and vertical; and photochemistry driven by UV flux, temperature, atmospheric composition, and other variables. GEO TROPSAT would be implemented about a geostationary Earth orbital (GEO) position at the equator between 600 and 80" West longitude to observe the Americas and large portions of the oceans of either coast. This mission would advance our knowledge of the atmosphere by capturing the wide temporal and spatial variability of tropospheric phenomena which is undetectable from low Earth orbit. A pre-prototype imaging carbon monoxide (CO) imaging system operating within a narrow waveband about 4.7 [Lm was built, demonstrated, and evaluated. This system applies the gas-filter correlation radiometry (GFCR) technique and produces digitized images comprising 4096 pixels, each representing a single CO mixing ratio measurement inferred from radiometric data. Associated tasks accomplished included specification for the next-generation prototype system to operate in the 2.3-@tm waveband; characterization of a 64x64, InSb focal-plane-array (FPA) imager; design, fabrication, and assembly of a filter wheel; and software development. Laboratory evaluation of this system involved imaging of a test cell placed in the path of radiant flux emanating from a blackbody source used to simulate the radiant energy reflected by Earth in real application. The cell was evacuated for system balancing and then charged with measured quantities of CO to provide a means for system characterization. Two related research efforts were undertaken during the term of the study reported here - continued development of an atmospheric CO imaging instrument and characterization of diode-laser beams. Both efforts were successful and are described within the body of this report. A second objective was to provide a means for undergraduate ISAT majors to become involved with the research described, to be afforded the opportunity to learn the technologies associated with the work performed. Two ISAT students gained a comprehensive understanding and interest in missions supported by NASA through direct involvement in this project. Many more students were exposed to these technologies through demonstrations, laboratory tours, and explanations provided in lectures.

Miles, Jonathan J.↗
NASA NTRS1986

Narrow- and broad-band satellite measurements of shortwave radiation - Conversion simulations with a general circulation model

The Oregon State University/Lawrence Livermore National Laboratory general circulation model has been employed as a vehicle for suggesting and exploring various means of converting narrow-band measurements of reflected solar radiation from the earth-atmosphere system to broad-band quantities. For purely illustrative purposes within the model's solar radiation routine, a narrow-band filter function consisting of a square-wave window extending from 0.5 to 0.9 microns is adopted. A limitation of the model, for this sort of endeavor, is that it does not include the wavelength dependence of surface albedos. Nevertheless, the model simulations tend to mimic the calibration of a narrow-band instrument, utilizing reflected solar radiation from the earth-atmosphere system as simultaneously measured by a collocated broad-band instrument; for the model, however, this is done in terms of fluxes, in contrast to instrument-measured radiances. The model results suggest that it might be preferable to perform narrow- to broad-band conversions in terms of planetary albedo (or an equivalent quantity), rather than in terms of reflected fluxes or radiances. Further improvement is achieved if, for instruments that can differentiate between clear and overcast conditions, separate clear and overcast calibrations are performed.

Cess, Robert D.↗
NASA NTRS1976

Computer simulation results of attitude estimation of earth orbiting satellites

Computer simulation results of attitude estimation of Earth-orbiting satellites (including Space Telescope) subjected to environmental disturbances and noises are presented. Decomposed linear recursive filter and Kalman filter were used as estimation tools. Six programs were developed for this simulation, and all were written in the basic language and were run on HP 9830A and HP 9866A computers. Simulation results show that a decomposed linear recursive filter is accurate in estimation and fast in response time. Furthermore, for higher order systems, this filter has computational advantages (i.e., less integration errors and roundoff errors) over a Kalman filter.

Kou, S. R.↗
NASA NTRS1984

Fabrication of glass gas cells for the HALOE and MAPS satellite experiments

The Halogen Occultation Experiment (HALOE) and the Measurement of Air Pollution from Satellites (MAPS) experiment are satellite-borne experiments which measure trace constituents in the Earth's atmosphere. The instruments which obtain the data for these experiments are based on the gas filter correlation radiometer measurement technique. In this technique, small samples of the gases of interest are encapsulated in glass cylinders, called gas cells, which act as very selective optical filters. This report describes the techniques employed in the fabrication of the gas cells for the HALOE and MAPS instruments. Details of the method used to fuse the sapphire windows (required for IR transmission) to the glass cell bodies are presented along with detailed descriptions of the jigs and fixtures used during the assembly process. The techniques and equipment used for window inspection and for pairing the HALOE windows are discussed. Cell body materials and the steps involved in preparing the cell bodies for the glass-to-sapphire fusion process are given.

Sullivan, E. M.↗
NASA NTRS2006

Airborne Dust in Space Vehicles and Habitats

Airborne dust, suspended inside a space vehicle or in future celestial habitats, can present a serious threat to crew health if it is not controlled. During the Apollo missions to the moon, lunar dust brought inside the capsule caused eye irritation and breathing difficulty to the crew when they launched from the moon and re-acquired "microgravity." During Shuttle flights reactive and toxic dusts such as lithium hydroxide have created a risk to crew health, and fine particles from combustion events can be especially worrisome. Under nominal spaceflight conditions, airborne dusts and particles tend to be larger than on earth because of the absence of gravity settling. Aboard the ISS, dusts are effectively managed by HEPA filters, although floating dust in newly-arrived modules can be a nuisance. Future missions to the moon and to Mars will present additional challenges because of the possibility that external dust will enter the breathing atmosphere of the habitat and reach the crew's respiratory system. Testing with simulated lunar and Martian dust has shown that these materials are toxic when placed into the lungs of test animals. Defining and evaluating the physical and chemical properties of Martian dusts through robotic missions will challenge our ability to prepare better dust simulants and to determine the risk to crew health from exposure to such dusts.

James, John↗
NASA NTRS2016

Everglades Ecological Forecasting II: Utilizing NASA Earth Observations to Enhance the Capabilities of Everglades National Park to Monitor & Predict Mangrove Extent to Aid Current Restoration Efforts

Mangroves act as a transition zone between fresh and salt water habitats by filtering and indicating salinity levels along the coast of the Florida Everglades. However, dredging and canals built in the early 1900s depleted the Everglades of much of its freshwater resources. In an attempt to assist in maintaining the health of threatened habitats, efforts have been made within Everglades National Park to rebalance the ecosystem and adhere to sustainably managing mangrove forests. The Everglades Ecological Forecasting II team utilized Google Earth Engine API and satellite imagery from Landsat 5, 7, and 8 to continuously create land-change maps over a 25 year period, and to allow park officials to continue producing maps in the future. In order to make the process replicable for project partners at Everglades National Park, the team was able to conduct a supervised classification approach to display mangrove regions in 1995, 2000, 2005, 2010 and 2015. As freshwater was depleted, mangroves encroached further inland and freshwater marshes declined. The current extent map, along with transition maps helped create forecasting models that show mangrove encroachment further inland in the year 2030 as well. This project highlights the changes to the Everglade habitats in relation to a changing climate and hydrological changes throughout the park.

Kirk, Donnie↗