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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Deployment and Performance of the NASA D3R During the GPM OLYMPEx Field Campaign

The NASA D3R was successfully deployed and operated throughout the NASA OLYMPEx field campaign. A differential phase based attenuation correction technique has been implemented for D3R observations. Hydrometeor classification has been demonstrated for five distinct classes using Ku-band observations of both convection and stratiform rain. The stratiform rain hydrometeor classification is compared against LDR observations and shows good agreement in identification of mixed-phase hydrometeors in the melting layer.

Sea measurements↗
NASA NTRS1989

Flight set 360T004 (STS-30) field joint protection system, volume 7

The Redesigned Solid Rocket Motors (RSRM) of the Space Transportation System have three field joints that are protected by the Joint Protection Systems (JPS). The igniter heater was mounted on the igniter flange. This report documents the performance of the JPS and igniter heaters on the pad and the post-flight condition of the JPS components. All observations that were written up as Squawks and/or Problem Reports are also discussed. The primary heaters performed satisfactorily and maintained the field joint temperatures within the required temperature range. A secondary heater failed Dielectric Withstanding Voltage (DWV) test during the joint closeout prior to launch. This heater was not used, however, since the primary heater functioned properly. Post-test inspection revealed that pin A of the heater power cable was shorted to the connector shell. Design changes have been implemented to resolve the heater power cable problem. All field joint assemblies met all of the performance requirements.

Hale, Elgie↗
NASA NTRS1975

Variational optimization analysis of temperature and moisture advection in a severe storm environment

Horizontal wind components, potential temperature, and mixing ratio fields associated with a severe storm environment in the south central U.S. were analyzed from synoptic upper air observations with a nonhomogeneous, anisotropic weighting function. Each data field was filtered with variational optimization analysis techniques. Variational optimization analysis was also performed on the vertical motion field and was used to produce advective forecasts of the potential temperature and mixing ratio fields. Results show that the dry intrusion is characterized by warm air, the advection of which produces a well-defined upward motion pattern. A corresponding downward motion pattern comprising a deep vertical circulation in the warm air sector of the low pressure system was detected. The axes alignment of maximum dry and warm advection with the axis of the tornado-producing squall line also resulted.

Mcfarland, M. J.↗
NASA NTRS2003

Mars Redox Chemistry: Atacama Desert Soils as a Terrestrial Analog

The motivation for this work is to perform quantitative site characterizations of soil chemical processes to allow further development and field validation of the Mars Oxidant Instrument (MOI). The MOI is an in situ survey instrument designed to establish the presence of reactive chemical species in the martian soil, dust, or atmosphere, and to provide detailed reaction model system measurements to enable comprehensive Earthbased study. Functioning as a survey instrument, MOI tests the broad range of hypotheses explaining the reactivity of the martian surface material that have been put forth since the Viking experiments. This work is currently being carried out under the NASA ASTEP funded AstroBioLab (Jeffery Bada, PI). A second objective is to use Atacama field and Viking data to perform comparative studies, with the goal of furthering the understanding of the formation mechanisms and properties of martian oxidants.

Quinn, R. C.↗
NASA NTRS1990

Flight Set 360L006 STS-34 field joint protection system, thermal protection system, and systems tunnel components, volume 4

The performance of the thermal protection system, field joint protection system, and systems tunnel components of Flight Set 360L006, are documented, as evaluated by postflight hardware inspection. The condition of both motors was similar to previous flights. Sixteen aft edge hits were noted on the ground environment instrumentation thermal protection system. Each hit left a clean substrate, indicating that the damage was caused by nozzle severance debris and/or water impact. No National Space and Transporation System debris criteria for missing thermal protection system were violated. One 5.0 by 1.0 in. unbond was observed on the left hand center field joint K5NA closeout and was elevated to an in-flight anomaly (STS-34-M-4) by the NASA Ice/Debris team. Aft edge damage to the K5NA and an associated black streak indicate that burning debris from the nozzle severance system was the likely cause of the damage. Minor divots caused by debris were seen on previous flights, but this is the first occurrence of a K5NA unbond. Since the unbond occurred after booster separation there is no impact on flight safety and no corrective actions was taken. The right hand center field joint primary heater failed the dielectric withstanding voltage test after joint closeout. The heater was then disabled by opening the circuit breaker, and the redundant heater was used. The redundant heater performed nominally during the launch countdown. A similar condition occurred on Flight 4 when a secondary joint heater failed the dielectric withstanding voltage test.

Wilkinson, J. P.↗
NASA NTRS2010

Mercury Toolset for Spatiotemporal Metadata

Mercury (http://mercury.ornl.gov) is a set of tools for federated harvesting, searching, and retrieving metadata, particularly spatiotemporal metadata. Version 3.0 of the Mercury toolset provides orders of magnitude improvements in search speed, support for additional metadata formats, integration with Google Maps for spatial queries, facetted type search, support for RSS (Really Simple Syndication) delivery of search results, and enhanced customization to meet the needs of the multiple projects that use Mercury. It provides a single portal to very quickly search for data and information contained in disparate data management systems, each of which may use different metadata formats. Mercury harvests metadata and key data from contributing project servers distributed around the world and builds a centralized index. The search interfaces then allow the users to perform a variety of fielded, spatial, and temporal searches across these metadata sources. This centralized repository of metadata with distributed data sources provides extremely fast search results to the user, while allowing data providers to advertise the availability of their data and maintain complete control and ownership of that data. Mercury periodically (typically daily) harvests metadata sources through a collection of interfaces and re-indexes these metadata to provide extremely rapid search capabilities, even over collections with tens of millions of metadata records. A number of both graphical and application interfaces have been constructed within Mercury, to enable both human users and other computer programs to perform queries. Mercury was also designed to support multiple different projects, so that the particular fields that can be queried and used with search filters are easy to configure for each different project.

Wilson, Bruce E.↗
NASA NTRS1989

ARISTOTELES: A European approach for an Earth gravity field recovery mission

Under contract of the European Space Agency a system study for a spaceborne gravity field recovery mission was performed, covering as a secondary mission objective geodetic point positioning in the cm range as well. It was demonstrated that under the given programmatic constraints including dual launch and a very tight development schedule, a six months gravity field mission in a 200 km near polar, dawn-dusk orbit is adequate to determine gravity anomalies to better than 5 mgal with a spatial resolution of 100 x 100 km half wavelength. This will enable scientists to determine improved spherical harmonic coefficients of the Earth gravity field equation to the order and degree of 180 or better.

Benz, R.↗
NASA NTRSDate not supplied

Trajectory Design Considerations for Low Lunar Orbit to Near Rectilinear Halo Orbit Transfers

NASA’s Artemis program plans to use a Near-Rectilinear Halo Orbit (NRHO) to stage assets for a lunar exploration campaign. While the proximity operations in the NRHO are simple and very similar to flat-space dynamics, the far-field ren-dezvous has considerations that are non-intuitive, especially to those that may be steeped in the dynamics of rendezvous in Keplerian orbits. This paper will discuss some key drivers to the delta-V performance of far-field rendezvous from Low Lunar Orbit to the Gateway space station in its 9:2 resonant south-ward NRHO.

NRHO↗
NASA NTRS2008

Performance of a Cylindrical Hall-Effect Thruster with Magnetic Field Generated by Permanent Magnets

While Hall thrusters can operate at high efficiency at kW power levels, it is difficult to construct one that operates over a broad envelope down to 100W while maintaining an efficiency of 45- 55%. Scaling to low power while holding the main dimensionless parameters constant requires a decrease in the thruster channel size and an increase in the magnetic field strength. Increasing the magnetic field becomes technically challenging since the field can saturate the miniaturized inner components of the magnetic circuit and scaling down the magnetic circuit leaves very little room for magnetic pole pieces and heat shields. An alternative approach is to employ a cylindrical Hall thruster (CHT) geometry. Laboratory model CHTs have operated at power levels ranging from the order of 50 Watts up to 1 kW. These thrusters exhibit performance characteristics which are comparable to conventional, annular Hall thrusters of similar size. Compared to the annular Hall thruster, the CHT has a lower insulator surface area to discharge chamber volume ratio. Consequently, there is the potential for reduced wall losses in the channel of a CHT, and any reduction in wall losses should translate into lower channel heating rates and reduced erosion. This makes the CHT geometry promising for low-power applications. Recently, a CHT that uses permanent magnets to produce the magnetic field topology was tested. This thruster has the promise of reduced power consumption over previous CHT iterations that employed electromagnets. Data are presented for two purposes: to expose the effect different controllable parameters have on the discharge and to summarize performance measurements (thrust, Isp, efficiency) obtained using a thrust stand. These data are used to gain insight into the thruster's operation and to allow for quantitative comparisons between the permanent magnet CHT and the electromagnet CHT.

Polzin, Kurt A.↗
NASA NTRS2003

Simulation of the Flow Field Associated with a Rocket Thruster Having an Attached Panel

Two-dimensional inviscid and viscous numerical simulations are performed to predict the flow field induced by a H2-O2 rocket thruster and to provide insight into the heat load on the articles placed in the hot gas exhaust of the thruster under a variety of operating conditions, using the National Combustion Code (NCC). The simulations have captured physical details of the flow field, such as the plume formation and expansion, formation of the shock waves and their effects on the temperature and pressure distributions on the walls of the apparatus and the flat panel. Comparison between the computed results for 2-D and adiabatic walls and the related experimental measurements for 3-D and cooled walls shows that the results of the simulations are consistent with those obtained from the related rig tests.

Davoudzadeh, Farhad↗
NASA NTRS1981

Crop classification using airborne radar and LANDSAT data

Airborne radar data acquired with a 13.3 GHz scatterometer over a test-site near Colby, Kansas were used to investigate the statistical properties of the scattering coefficient of three types of vegetation cover and of bare soil. A statistical model for radar data was developed that incorporates signal-fading and natural within-field variabilities. Estimates of the within-field and between-field coefficients of variation were obtained for each cover-type and compared with similar quantities derived from LANDSAT images of the same fields. The classification accuracy provided by LANDSAT alone, radar alone, and both sensors combined was investigated. The results indicate that the addition of radar to LANDSAT improves the classification accuracy by about 10; percentage-points when the classification is performed on a pixel basis and by about 15 points when performed on a field-average basis.

Ulaby, F. T.↗
NASA NTRS2004

NASA Ground-Truthing Capabilities Demonstrated

NASA Research and Education Network (NREN) ground truthing is a method of verifying the scientific validity of satellite images and clarifying irregularities in the imagery. Ground-truthed imagery can be used to locate geological compositions of interest for a given area. On Mars, astronaut scientists could ground truth satellite imagery from the planet surface and then pinpoint optimum areas to explore. These astronauts would be able to ground truth imagery, get results back, and use the results during extravehicular activity without returning to Earth to process the data from the mission. NASA's first ground-truthing experiment, performed on June 25 in the Utah desert, demonstrated the ability to extend powerful computing resources to remote locations. Designed by Dr. Richard Beck of the Department of Geography at the University of Cincinnati, who is serving as the lead field scientist, and assisted by Dr. Robert Vincent of Bowling Green State University, the demonstration also involved researchers from the NASA Glenn Research Center and the NASA Ames Research Center, who worked with the university field scientists to design, perform, and analyze results of the experiment. As shown real-time Hyperion satellite imagery (data) is sent to a mass storage facility, while scientists at a remote (Utah) site upload ground spectra (data) to a second mass storage facility. The grid pulls data from both mass storage facilities and performs up to 64 simultaneous band ratio conversions on the data. Moments later, the results from the grid are accessed by local scientists and sent directly to the remote science team. The results are used by the remote science team to locate and explore new critical compositions of interest. The process can be repeated as required to continue to validate the data set or to converge on alternate geophysical areas of interest.

Lopez, Isaac↗
NASA NTRS1984

European retrievable carrier (Eureca) and evolutionary space carrier for microgravity, Earth observation and technology demonstration

The Spacelab relatively short stay-time in orbit has led to consideration of the European Retrievable Carrier (EURECA) concept as a reusable carrier. The EURECA concept is a free-flying carrier of experiments which is launched and recovered by the space shuttle. It is commensurate with the size of payloads that can be economically developed in Europe and combines the advantages of Spacelab (high mass and power capability, recovery) with those of a free flyer (extended operating time in a non-polluted environment). The launch of the first EURECA mission is scheduled for October 1987. The Eureca spacecraft will be deployed from the Shuttle cargo bay in orbit, will operate in a free-flying mode for about six months, and will then be retrieved, together with its payloads, returned to Earth by the Space Shuttle and prepared for the next mission. The first mission of EURECA is dedicated to research in the fields of life sciences and material sciences. The experimental hardware of the first mission consist of a variety of processin chambers for crystal growth and equipment for biological investigations viz plant growth and protein crystallization, and there is the possibility to perform experiments in the field of exobiology.

Mory, R.↗
NASA NTRS1990

Technical Evaluation Motor no. 5 (TEM-5)

Technical Evaluation Motor No. 5 (TEM-5) was static test fired at the Thiokol Corporation Static Test Bay T-97. TEM-5 was a full scale, full duration static test fire of a high performance motor (HPM) configuration solid rocket motor (SRM). The primary purpose of TEM static tests is to recover SRM case and nozzle hardware for use in the redesigned solid rocket motor (RSRM) flight program. Inspection and instrumentation data indicate that the TEM-5 static test firing was successful. The ambient temperature during the test was 41 F and the propellant mean bulk temperature (PMBT) was 72 F. Ballistics performance values were within the specified requirements. The overall performance of the TEM-5 components and test equipment was nominal. Dissembly inspection revealed that joint putty was in contact with the inner groove of the inner primary seal of the ignitor adapter-to-forward dome (inner) joint gasket; this condition had not occurred on any previous static test motor or flight RSRM. While no qualification issues were addressed on TEM-5, two significant component changes were evaluated. Those changes were a new vented assembly process for the case-to-nozzle joint and the installation of two redesigned field joint protection systems. Performance of the vented case-to-nozzle joint assembly was successful, and the assembly/performance differences between the two field joint protection system (FJPS) configurations were compared.

Cook, M.↗
NASA NTRS1992

Orbiting Space Interferometer (OSI): A first generation space interferometer

The technical requirements and performance of a first generation space interferometer is discussed. The performance of an interferometer, sensitivity, field of view, dynamic range, astrometric accuracy, etc, in space is set by what cannot be achieved for a ground-based instrument. For the Orbiting Space Interferometer (OSI), the nominal performance parameters are 20 mag sensitivity, field of view of approximately 500*500 pixels, a 1000:1 dynamic range in the image with one milliarcsec resolution, and an astrometric accuracy of 0.1 milliarcsec for wide angle astrometry and 10 microarcsec accuracy for narrow field astrometry (few degrees). OSI is a fully phased interferometer where all critical optical paths are controlled to 0.05 wavelengths. The instrument uses two guide interferometers locked on bright stars several degrees away to provide the spacecraft attitude information needed to keep the fringes from the faint science object stable on the detector.

Shao, Michael↗