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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Assessment of Terra MODIS On-Orbit Polarization Sensitivity Using Pseudoinvariant Desert Sites

The Moderate Resolution Imaging Spectroradiometer (MODIS) is currently flying on NASA's Earth Observing System Terra and Aqua satellites, launched in 1999 and 2002, respectively. MODIS reflective solar bands in the visible wavelength range are known to be sensitive to polarized light based on prelaunch polarization sensitivity tests. After about five years of on-orbit operations, it was discovered that the polarization sensitivity at short wavelengths had shown a noticeable increase. In this paper, we examine the impact of polarization on measured top-of-atmosphere (TOA) reflectance based on MODIS Collection-6 L1B over pseudo invariant desert sites. The standard polarization correction equation is used in combination with simulated at-sensor radiances using the second simulation of a satellite signal in the Solar Spectrum, Vector Radiative Transfer Code (6SV). We ignore the polarization contribution from the surface and a ratio approach is used for both 6SV-derived in put parameters and observed TOA reflectance. Results indicate that significant gain corrections up to 25% are required near the end of scan for the 412 and 443 nm bands. The polarization correction reduces the seasonal fluctuations in reflectance trends and mirror side ratios from 30% and 12% to 10% and 5%, respectively, for the two bands. Comparison of the effectiveness of the polarization correction with the results from the NASA Ocean Biology Processing Group shows a good agreement in the corrected reflectance trending results and their seasonal fluctuations.

Wu, Aisheng↗
NASA NTRS1995

Elemental and charge state composition of the fast solar wind observed with SMS instruments on WIND

The elemental composition and charge state distributions of heavy ions of the solar wind provide essential information about: (1) atom-ion separation processes in the solar atmosphere leading to the 'FIP effect' (the overabundance of low First Ionization potential (FIP) elements in the solar wind compared to the photosphere); and (2) coronal temperature profiles, as well as mechanisms which heat the corona and accelerate the solar wind. This information is required for solar wind acceleration models. The SWICS instrument on Ulysses measures for all solar wind flow conditions the relative abundance of about 8 elements and 20 charge states of the solar wind. Furthermore, the Ulysses high-latitude orbit provides an unprecedented look at the solar wind from the polar coronal holes near solar minimum conditions. The MASS instrument on the WIND spacecraft is a high-mass resolution solar wind ion mass spectrometer that will provide routinely not only the abundances and charge state of all elements easily measured with SWICS, but also of N, Mg, S. The MASS sensor was fully operational at the end of 1994 and has sampled the in-ecliptic solar wind composition in both the slow and the corotating fast streams. This unique combination of SWICS on Ulysses and MASS on WIND allows us to view for the first time the solar wind from two regions of the large coronal hole. Observations with SWICS in the coronal hole wind: (1) indicate that the FIP effect is small; and (2) allow us determine the altitude of the maximum in the electron temperature profile, and indicate a maximum temperature of approximately 1.5 MK. New results from the SMS instruments on Wind will be compared with results from SWICS on Ulysses.

Gloeckler, G.↗
NASA NTRS1984

Status of Solar Measurements and Data Reduction for Erb-nimbus 7

The status of the Total Solar Irradiance data obtained using the cavity radiometer aboard the Earth Radiation Budget experiment of the Nimbus 7 satellite is described. The ERB experiment has a number of sensors which measure the radiative fluxes (both shortwave and infrared) leaving the Earth as well as the solar channels. The complexity of the processing of the Earth-flux data, both wide and narrow angle has necessitated a reprocessing effort which produces the final data. Since the solar data is embedded in the same data stream and tape product as the Earth-flux data, it was not generally available in a format convenient for analysis as a separate product. Values for the final data product only are presented and a few remarks concerning the basic features of the data. There is no scientific conclusions presented here other than those directly related to the measurement results. A set of tabulated values is appended.

Hickey, J. R.↗
NASA NTRS1972

Detection of ocean chlorophyll from earth orbit

Calculations were made of the magnitude of the optical signature of ocean chlorophyll available to any remote sensor in earth orbit. It was desired to ascertain whether commercially significant concentrations of chlorophyll-A pigments in the ocean would produce a sufficient optical signal at orbital altitudes to operate optical remote sensors, such as those planned for the earth observatory satellite, on clear and hazy days. It was also desired to explore the effect of solar altitude on these optical signals. The best orientation was desired for the field of view for a remote sensor in orbit in order to optimize its ability to detect ocean chlorophyll.

Duntley, S. Q.↗
DOE OSTI2024

Power generation forecasting for solar plants based on Dynamic Bayesian networks by fusing multi-source information

A Dynamic Bayesian network (DBN) model for solar power generation forecasting in solar plants is proposed in this paper. The key idea is to fuse sensor data, operational indicators, meteorological data, lagged output power information, and model errors for more accurate short-term (e.g., hours) and mid-term (e.g., days to weeks) power generation forecasting. The proposed DBN augments automated data-driven structure learning with expert knowledge encoding using continuous and categorical data given constraints to represent causal relationships within a solar inverter system. Additionally, an error compensation mechanism is proposed to capture temporal fluctuation. The effectiveness of the DBN on solar power generation forecasting was evaluated by rolling window analysis with one-year testing data collected from a local solar plant. The proposed DBN is compared with four state-of-art methods including support-vector regression (SVR), k-nearest neighbors (kNN), artificial neural network (ANN), and long short-term memory (LSTM) models. The result show that the proposed DBN achieves better accuracy in general, and it is not as data-hungry as some neural network-based models. The proposed DBN is also shown to have robust and consistent forecasting power with different forecasting horizons. The accuracy is 92% - 95% from one hour to one week ahead forecasting.

14 SOLAR ENERGY↗
NASA NTRS2018

Assessing the Calibration Differences in the Reflective Solar Bands of Terra MODIS and Landsat-7 Enhanced Thematic Mapper Plus

Long-term data records obtained from Earth observing sensors depend not only onthe calibration accuracy of individual sensors but also on the consistency across instruments andplatforms. Hence, sensor calibration intercomparison plays a vital role for a better understandingof various science products. The Moderate Resolution Imaging Spectroradiometer (MODIS)and enhanced thematic mapper plus (ETM+) on the Terra and Landsat 7 platforms have operatedsuccessfully since their launch, collecting measurements in the reflective solar and infrared partsof the spectrum. Terra MODIS has employed a reflectance-based calibration since beginning itsmission. In the case of ETM+, a radiance-based calibration was employed until recent years,when a reflectance-based calibration was introduced. Being in the AM constellation with lessthan 30 min difference in overpass times, near-simultaneous Earth scene measurements can beeffectively used to assess the calibration differences between the spectrally matching bands ofthese two instruments. The pseudoinvariant calibration sites (PICS) in the North African desertare widely used for on-orbit calibration and validation of satellite sensors. Four PICS from thisregion have been employed to assess the multitemporal reflectance differences. Correction forbidirectional reflectance, spectral response function mismatch, and impacts of atmosphericwater-vapor have been incorporated to provide an assessment of the long-term stability ofeach spectral band and reflectance differences amongst them. Results indicate that the spectralbands of both instruments show a long-term stability to within 2% from 2000 to 2017. Thetop-of-atmosphere reflectances between the two instruments postcorrection agree to within 4%.Also included in this paper is a detailed discussion of various parameters contributing to theuncertainties of this cross-calibration. The techniques presented in this paper can be furtherextended to perform similar intercomparison between Landsat 8 Operational Land Imager, AquaMODIS, and Suomi-NPP VIIRS.

Angal, Amit↗
NASA NTRS1977

Dynamics and control simulation of the Spacelab Experiment Pointing Mount

Computer simulations were developed to evaluate the performance of four Experiment Pointing Mounts (EPM) being considered for Spacelab experiments in the 1980-1990 time frame. The system modeled compromises a multibody system consisting of the shuttle, a mechanical isolation device, the EPM, celestial and inertial sensors, bearings, gimbal torque motors and associated nonlinearities, the experiment payload, and control and estimator algorithms. Each mount was subjected to a common disturbance (shuttle vernier thruster firing and man push off) and command (stellar pointing or solar raster scan) input. The fundamental limitation common to all mounts was found to be sensor noise. System dynamics and hardware nonlinearities have secondary effects on pointing performance for sufficiently high bandwidth.

Marsh, E. L.↗
NASA NTRS1982

Irradiance measurement errors due to the assumption of a Lambertian reference panel

A technique is presented for determining the error in diurnal irradiance measurements that results from the non-Lambertian behavior of a reference panel under various irradiance conditions. Spectral biconical reflectance factors of a spray-painted barium sulfate panel, along with simulated sky radiance data for clear and hazy skies at six solar zenith angles, were used to calculate the estimated panel irradiances and true irradiances for a nadir-looking sensor in two wavelength bands. The inherent errors in total spectral irradiance (0.68 microns) for a clear sky were 0.60, 6.0, 13.0, and 27.0% for solar zenith angles of 0, 45, 60, and 75 deg, respectively. The technique can be used to characterize the error of a specific panel used in field measurements, and thus eliminate any ambiguity of the effects of the type, preparation, and aging of the paint.

Kimes, D. S.↗
NASA NTRSDate not supplied

Research Activities at NASA: “The Hera Astronaut Analog Mission, Astrobee, and the Advanced Composite Solar Sail System”

During this seminar, I will talk about three of the projects I’ve been involved with at NASA in the last few years: - The Human Exploration Research Analog (HERA) is a ground-based astronaut analog mission run at NASA’s JSC in Houston to study and evaluate impacts on the crew due to isolation, remoteness, and confined habitation. NASA scientists use the collected data to develop and verify countermeasures to reduce or mitigate psychological and physiological effects for future Deep Space missions. This simulation was a 45-day trip to Mars’s moon Phobos and back with the goal of performing geological operations with complete communications delays in effect. - Astrobee is a new class of free-flying robots that operates in the interior of the International Space Station (ISS). In addition to being a research platform for microgravity free-flying robotics, Astrobee improves the efficiency of ISS operations by providing flight and payload controllers with a mobile camera and a sensor platform. - NASA is developing new deployable structures and material technologies for solar sail propulsion systems destined for future low-cost deep space missions. NASA’s Advanced Composite Solar Sail System (ACS3) uses composite materials in its novel, lightweight booms that deploy from a Cubesat. Data obtained from ACS3 will guide the design of future larger-scale composite solar sail systems that could be used for several deep space exploration missions

International Space Station↗
NASA NTRS2007

Sensor On-orbit Calibration and Characterization Using Spacecraft Maneuvers

Spacecraft flight operations often require activities that involve different kinds of maneuvers for orbital adjustments (pitch, yaw, and roll). Different maneuvers, when properly planned and scheduled, can also be applied to support and/or to perform on-board sensor calibration and characterization. This paper uses MODIS (Moderate Resolution Imaging Spectroradiometer) as an example to illustrate applications of spacecraft maneuvers for Earth-observing sensors on-orbit calibration and characterization. MODIS is one of the key instruments for NASA's Earth Observing System (EOS) currently operated on-board the EOS Terra and Aqua spacecraft launched in December 1999 and May 2002, respectively. Since their launch, both Terra and Aqua spacecraft have made a number of maneuvers, specially the yaw and roll maneuvers, to support the MODIS on-orbit calibration and characterization. For both Terra and Aqua MODIS, near-monthly spacecraft roll maneuvers are executed for lunar observations. These maneuvers are carefully scheduled so that the lunar phase angles are nearly identical for each sensor's lunar observations. The lunar observations are used to track MODIS reflective solar bands (RSB) calibration stability and to inter-compare Terra and Aqua MODIS RSB calibration consistency. To date, two sets of yaw maneuvers (each consists of two series of 8 consecutive yaws) by the Terra spacecraft and one set by the Aqua spacecraft have been performed to validate MODIS solar diffuser (SD) bi-directional reflectance factor (BRF) and to derive SD screen transmission. Terra spacecraft pitch maneuvers, first made on March 26, 2003 and the second on April 14, 2003 (with the Moon in the spacecraft nadir view), have been applied to characterize MODIS thermal emissive bands (TEB) response versus scan angle (RVS). This is particularly important since the pre-launch TEB RSV measurements made by the sensor vendor were not successful. Terra MODIS TEB RVS obtained from pitch maneuvers have been used in the current LIB calibration algorithm. Lunq observations from pitch maneuvers also provided information to cross-calibrate MODIS with other sensors (MISR and ASTER) on the same platform. We will provide a summary of MODIS maneuver activities and their applications for MODIS calibration and characterization. The results and lessons learned discussed in this paper from MODIS maneuver activities will provide useful insights into future spacecraft and sensor operation.

Xiong, X.↗
DOE OSTI2025

Five Years of Dissolved Oxygen, Temperature, Salinity, Depth, Weather Data from a Transitioning Wetland at Beaver Creek, Washington, USA

Groundwater dissolved oxygen (DO) variability in coastal system remains poorly understood despite its importance for biogeochemical cycling and ecosystem modeling. Here we investigate the temporal variability in groundwater DO and its hydro-climatic drivers across hourly to seasonal timescales in a transitioning wetland at Beaver Creek, Washington, USA. The site is transitioning from a freshwater forest to a brackish tidal wetland following removal of a barrier in 2014 that prevented tides from accessing the freshwater creek. By utilizing novel optical dissolved oxygen instrumentation (Opti O2, LLC) we obtained continuous, high-frequency (5-minute), in-situ measurements of DO from the flood-plain from June 26th, 2019 through September 30th, 2024. This 63 month dataset is comprised of groundwater dissolved oxygen, temperature, water level and salinity timeseries from the floodplain. This dataset also includes rainfall, air pressure, air temperature, and solar radiation data collected with a co-located Campbell ClimaVUE50 weather sensor. All data is contained within a single csv (2019-06-26 to 2024-09-30 Beaver Creek DO, saln, BGS, temp, weather.csv) that can easily be viewed either using software such as Excel or using any text editor.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1978

Solar Energy Reporting

Last year the people of Cleveland, Ohio were troubled by natural gas shortages during one of the coldest winters on record. The severe winter generated a great deal of interest in solar energy as an alternative source of heat. Home owners, home builders and civic officials wanted to know just how much solar energy is available in Cleveland. Now they get a daily report through the city's news media, from information supplied as a community service by NASA's Lewis Research Center. Lewis routinely makes daily measurements of solar energy as part of its continuing research in behalf of the Department of Energy. The measuring device is a sun sensor called a pyranometer (upper photo) located atop a building at the NASA Center. To make the information conveniently available to news media, Lewis developed a Voice Output Integrating Insolometer, an automated system that acquires information from the sun sensor and translates it into a recorded telephone message. The Lewis pyranometer collects sun data for 15 hours daily and measures the total solar energy yield. For reporting to the public, the information is electronically converted to a specific reading. A media representative calling in gets a voice-synthesized announcement of a two or three digit number; the number corresponds to the kilowatt-hours of solar energy that would be available to a typical 500-square-foot solar collector system. Response in Cleveland has been favorable and interest is developing in other parts of the country.

Source record↗
NASA NTRS2017

Overview of SPRITE: Saturn Probe Interior and aTmosphere Explorer Concept

The Saturn PRobe Interior and aTmosphere Explorer (SPRITE) mission concept targets high-priority Planetary Science Decadal Survey science objectives. This mission concept would deliver the SPRITE entry probe into the Saturn atmosphere to obtain in situ measurements of elemental abundances and isotopic ratios, which would help distinguish the role Saturn played in the solar system formation and co-evolution of other planets. An Atmospheric Structure Investigation sensor package on the entry probe would provide in situ measurements of the pressure/temperature and wind structure below the cloud-tops, and a Quadrupole Mass Spectrometer and Tunable Laser Spectrometer suite would determine the composition of Saturn’s atmosphere. The SPRITE mission concept described in this paper uses a solar-powered carrier-relay spacecraft to deliver the battery-powered entry probe to Saturn after a 10-year Venus-Earth-Earth gravity-assist trajectory, and then relays the probe data back to Earth during the carrier-relay spacecraft Saturn flyby. A high-heritage design approach is implemented for the flight elements to minimize technical risk and enable successful return of this high-value science data.

Cuddy, Cavan↗
DOE OSTI2021

LiDAR For Heliostat Optical Assessment (Final Report)

This project has sought to develop new uses for surveying-quality Light Detecting and Ranging (LiDAR) 3D scanning sensors in the automatic/autonomous assessment of optical errors in largescale concentrating solar power heliostat fields. Past experiments have demonstrated the ability of a 3D-LiDAR to acquire highly accurate point cloud measurements across several Sandia NSTTF heliostats. The goal of this project is to expand upon this work to see if and how it can be used in large commercial heliostat fields.

14 SOLAR ENERGY↗
NASA NTRS1979

Multispectral Resource Sampler (MRS): Proof of concept study on atmospheric corrections. Determinations of atmospheric optical parameters using the multispectral resource sampler atmospheric optical

An investigation was performed to determine which mathematical algorithms should be used in the calculation of atmospheric optical parameters using the Multispectral Resource Sampler (MRS) sensor. A simulation of the MRS sensor was performed using a radiative-transfer model. The simulation provides the spectral radiance at the satellite sensor in terms of various atmospheric parameters, such as optical thickness, solar zenith angle, nadir view angle, relative azimuth angle, bi-directional reflectance of the target, background albedo, and wavelength. Atmospheric correction algorithms were also developed for the determination of the total spectral optical thickness of the atmosphere for: (1) homogeneous (horizontal) hazy atmospheres with diffuse targets; (2) inhomogeneous (horizontal) hazy atmospheres with diffuse targets; and (3) homogeneous (horizontal) hazy atmospheres with non-diffuse targets.

Turner, R. E.↗
NASA NTRS1984

Effective bandwidths for Landsat-4 and Landsat-D' multispectral scanner and thematic mapper subsystems

The spectral bands of the Multispectral Scanner and Thematic Mapper subsystems of Landsat-4 and Landsat-D' have been analyzed using a bandwidth normalization technique based on analysis of the moments of the spectral responsitivity curves. The results include the effective wavelength, the bandpass, the wavelength limits, and the normalized responsivity for each spectral channel. In addition, temperature coefficients for TM PF Channel 6 have been derived. The moments normalization method employed yields sensor parameters whose derivation is independent of source characteristics (i.e., incident solar spectral irradiance, atmospoheric transmittance, or ground reflectance). The errors expected using these parameters are lower than those expected using other normalization methods.

Palmer, J. M.↗
NASA NTRS1988

Predicting Roll Angle Of A Spinning Spacecraft

Data for corrections of attitude derived on Earth from secondary measurements. Paper describes how attitude of Pioneer 10 spacecraft controlled since spacecraft lost signal from Sun-sensor signal. Roll calculations in paper yields insight into environment of solar system at great distances.

Smith, M. A.↗
NASA NTRS1990

New high-resolution electrostatic ion mass analyzer using time of flight

The design of a high-resolution ion-mass analyzer is described, which is based on an accurate measurement of the time of flight (TOF) of ions within a region configured to produce a harmonic potential. In this device, the TOF, which is independent of ion energy, is determined from a start pulse from secondary electrons produced when the ion passes through a thin carbon foil at the entrance of the TOF region and at a stop pulse from the ion striking a microchannel plate upon exciting the region. A laboratory prototype instrument called 'VMASS' was built and was tested at the Goddard Space Flight Center electrostatic accelerator, showing a good mass resolution of the instrument. Sensors of the VMASS type will form part of the WIND Solar Wind and Suprathermal Ion experiment, the Soho mission, and the Advanced Composition Explorer.

Hamilton, D. C.↗