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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Synegies Between Visible/Near-Infrared Imaging Spectrometry and the Thermal Infrared in an Urban Environment: An Evaluation of the Hyperspectral Infrared Imager (HYSPIRI) Mission

A majority of the human population lives in urban areas and as such, the quality of urban environments is becoming increasingly important to the human population. Furthermore, these areas are major sources of environmental contaminants and sinks of energy and materials. Remote sensing provides an improved understanding of urban areas and their impacts by mapping urban extent, urban composition (vegetation and impervious cover fractions), and urban radiation balance through measures of albedo, emissivity and land surface temperature (LST). Recently, the National Research Council (NRC) completed an assessment of remote sensing needs for the next decade (NRC, 2007), proposing several missions suitable for urban studies, including a visible, near-infrared and shortwave infrared (VSWIR) imaging spectrometer and a multispectral thermal infrared (TIR) instrument called the Hyperspectral Infrared Imagery (HyspIRI). In this talk, we introduce the HyspIRI mission, focusing on potential synergies between VSWIR and TIR data in an urban area. We evaluate potential synergies using an Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and MODIS-ASTER (MASTER) image pair acquired over Santa Barbara, United States. AVIRIS data were analyzed at their native spatial resolutions (7.5m VSWIR and 15m TIR), and aggregated 60 m spatial resolution similar to HyspIRI. Surface reflectance was calculated using ACORN and a ground reflectance target to remove atmospheric and sensor artifacts. MASTER data were processed to generate estimates of spectral emissivity and LST using Modtran radiative transfer code and the ASTER Temperature Emissivity Separation algorithm. A spectral library of common urban materials, including urban vegetation, roofs and roads was assembled from combined AVIRIS and field-measured reflectance spectra. LST and emissivity were also retrieved from MASTER and reflectance/emissivity spectra for a subset of urban materials were retrieved from co-located MASTER and AVIRIS pixels. Fractions of Impervious, Soil, Green Vegetation (GV) and Non-photosynthetic Vegetation (NPV), were estimated using Multiple Endmember Spectral Mixture Analysis (MESMA) applied to AVIRIS data at 7.5, 15 and 60 m spatial scales. Surface energy parameters, including albedo, vegetation cover fraction, broadband emissivity and LST were also determined for urban and natural land-cover classes in the region. Fractions were validated using 1m digital photography.

Roberts, Dar A.↗
NASA NTRS2013

Space Environmental Testing of the Electrodynamic Dust Shield Technology

NASA's exploration missions to Mars and the moon may be jeopardized by dust that will adhere to surfaces of (a) Optical systems, viewports and solar panels, (b) Thermal radiators, (c) Instrumentation, and (d) Spacesuits. We have developed an active dust mitigation technology, the Electrodynamic Dust Shield, a multilayer coating that can remove dust and also prevents its accumulation Extensive testing in simulated laboratory environments and on a reduced gravity flight shows that high dust removal performance can be achieved Long duration exposure to the space environment as part of the MISSE-X payload will validate the technology for lunar missions.

Calle, Carlos I.↗
NASA NTRS2016

MISTiC Winds, a Micro-Satellite Constellation Approach to High Resolution Observations of the Atmosphere Using Infrared Sounding and 3D Winds Measurements

MISTiC(TM) Winds is an approach to improve short-term weather forecasting based on a miniature high resolution, wide field, thermal emission spectrometry instrument that will provide global tropospheric vertical profiles of atmospheric temperature and humidity at high (3-4 km) horizontal and vertical ( 1 km) spatial resolution. MISTiCs extraordinarily small size, payload mass of less than 15 kg, and minimal cooling requirements can be accommodated aboard a 27U-class CubeSat or an ESPA-Class micro-satellite. Low fabrication and launch costs enable a LEO sunsynchronous sounding constellation that would collectively provide frequent IR vertical profiles and vertically resolved atmospheric motion vector wind observations in the troposphere. These observations are highly complementary to present and emerging environmental observing systems, and would provide a combination of high vertical and horizontal resolution not provided by any other environmental observing system currently in operation. The spectral measurements that would be provided by MISTiC Winds are similar to those of NASA's AIRS that was built by BAE Systems and operates aboard the AQUA satellite. These new observations, when assimilated into high resolution numerical weather models, would revolutionize short-term and severe weather forecasting, save lives, and support key economic decisions in the energy, air transport, and agriculture arenasat much lower cost than providing these observations from geostationary orbit. In addition, this observation capability would be a critical tool for the study of transport processes for water vapor, clouds, pollution, and aerosols. Key remaining technical risks are being reduced through laboratory and airborne testing under NASA's Instrument Incubator Program.

Maschhoff, K. R.↗
NASA NTRSDate not supplied

New Constraints on the Volatile Deposit in Mercury’s North Polar Crater, Prokofiev

There is strong evidence from multi-wavelength, multi-instrument observations and thermal models for the presence of ice and other volatiles in Mercury’s north polar permanently shadowed regions (PSRs)[1-6]. Ground-based radar measurements identified bright regions in some polar craters interpreted to be water ice on or near the surface[1]. The MESSENGER spacecraft found that some radar-bright deposits appeared bright in the optical and near-infrared while others appeared dark[4-6]. The bright regions were interpreted to be exposed surface ice while the dark regions were hypothesized to be complex organic volatile lag deposits overlaying buried ice[3]. One example of the former is in the 112 km diameter crater, Prokofiev, for which the Mercury Dual Imaging System (MDIS) acquired broadband images while in Sun shadow but illuminated by scattered light from the crater walls[5]. These images revealed a relatively high-albedo region spatially correlated with the PSR. Subsequent work[7] found a small offset between the boundary of the radar-bright region and that of the PSR predicted by an illumination model based on the polar digital elevation model (DEM)from the Mercury Laser Altimeter (MLA). Such an offset, if true, could have implications for the ice properties and its delivery and destruction mechanisms. However, the low resolution (1 km/pix) of the polar MLA DEM precluded a definitive conclusion. In the present work, we build new higher-resolution topographic, illumination, and thermal models of Prokofiev to place stronger constraints on its PSR and volatile deposits. We also study the MLA reflectance data in this crater to quantitatively estimate the ice abundance.

Michael K Barker↗
NASA NTRSDate not supplied

Managing Risk for the James Webb Space Telescope Deployment Mechanisms: Enabling First Light

The $10 billion James Webb Space Telescope (JWST) is perhaps the most ambitious astronomy mission in NASA history and is the largest and most powerful space science telescope optimized for infrared detection. It is operating in an L2 Orbit about a million miles away from the earth. This will complement and extend the discoveries of the Hubble Space Telescope. It was so big that it had to fold origami – style to fit in the rocket and open in space.Webb’s 5-layer tennis court sized sunshield assembly(SSA) protects the telescope from the Sun’s thermal radiation enabling instruments to operate about 230degree C below 0. It relayed the first amazing picture of galaxies to the world on 12 July 2022. Webb’s unprecedented infrared sensitivity will peer back in time over 13.5 billion years to see the first galaxies born after the Big Bang.

JWST↗
NASA NTRS1976

Development of thermal control methods for specialized components and scientific instruments at very low temperatures (follow-on)

Many payloads currently proposed to be flown by the space shuttle system require long-duration cooling in the 3 to 200 K temperature range. Common requirements also exist for certain DOD payloads. Parametric design and optimization studies are reported for multistage and diode heat pipe radiator systems designed to operate in this temperature range. Also optimized are ground test systems for two long-life passive thermal control concepts operating under specified space environmental conditions. The ground test systems evaluated are ultimately intended to evolve into flight test qualification prototypes for early shuttle flights.

Wright, J. P.↗
NASA NTRS2018

Thermal Assessment of OSIRIS-REx OVIRS Cryogenic Instrument During Flight System TVAC Test and in Flight

The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) Visible and Infrared Spectrometer (OVIRS) is a cryogenic instrument. At the Outbound Cruise nominal spacecraft attitude, sunlight impinges on several multilayer insulation blankets on the forward deck. It is reflected or scattered to other components on the deck. This solar illumination adds heat load to the OVIRS, and causes its detector temperature to exceed the 105K maximum operating allowable flight temperature limit by 0.8K. During the flight system thermal vacuum test, the solar simulator beam reflected or scattered from the test fixtures to the OVIRS added non-flight heat load. The detector temperature was 9K warmer than that in flight. At those temperatures, the science data was acceptable, despite its quality was not as high as that of 105K or colder.

"OSIRIS-REx; OVIRS; cryogenic instrument; parasiti↗
NASA NTRS1993

Next generation optical instruments and space experiment based on the LDEF thermal control surfaces experiment (S0069)

The Thermal Control Surfaces Experiment (TCSE) was a successful experiment to study the effects of the space environment on thermal control surfaces using in-space optical properties measurements combined with post-flight analyses. The TCSE reflectometer performed well on the LDEF mission demonstrating that a portable compact integrating sphere spectroreflectometer can be built that is rugged and space rated. Since the retrieval of the TCSE package from space, several other instruments have evolved from its pioneering technologies. These are the Optical Properties Monitor (OPM), the Laboratory Portable SpectroReflectometer (LPSR), and the Space Portable SpectroReflectometer (SPSR). These instruments and experiment packages are described.

Wilkes, Donald R.↗
NASA NTRSDate not supplied

Crucial Role of Thermal Gradients in MMS Fluxgate In-Flight Calibration

To meet the science goals of the Magnetospheric Multiscale (MMS) mission, the Fluxgate Magnetometer (FGM) must measure the ambient magnetic field with an accuracy of 0.1 nT. On a typical MMS orbit, the offsets (or zero levels) of the 3-axis FGM can vary by ~0.5 nT (exclusive of periods in Earth shadow). Previous studies have shown that these variations can be characterized as functions of sensor temperature, TS, and can thus be corrected to within 0.2 nT in the spin plane using in-flight calibration techniques (Bromund, et al., 2016, https://ntrs.nasa.gov/citations/20160014711). In that presentation, we noted two significant observations: A distinct function of TS must be used to characterize offsets during shadow: offsets at a given TScan differ by as much as 2 nT in shadow vs sunlight. Offsets change after maneuvers, without a commensurate change in TS . These changes can be as large as 2 nT. We now note a third, related observation: Offsets increase with proximity to the earth even when TS is constant, resulting in variations of ~0.2 nT at 4-5 Earth radii (RE) These effects are evidence that offsets are a multivariate function of TS and another factor, namely: thermal gradients. Due to the spacecraft spin, the Earth and the Sun each provide a relatively constant thermal input onto one instrument face while the opposite face remains in shadow, thus giving rise to thermal gradients. The thermal gradient depend on the orientation of the spin axis relative to the Earth or Sun. We observe that offsets vary by as much as 0.17 nT/degree as a function of the tilt of the spin axis towards the Sun. Thermal input from the Earth is dominated by Outgoing Longwave Radiation (OLR). Due to the proximity to Earth, the inverse proportion of the distance squared is a significant factor in the thermal gradient attributed to Earth OLR. We find that offsets can be corrected to <0.05 nT accuracy near perigee when accounting for these factors using empirically determined constants of proportionality that account for differences in emissivity of the top and bottom faces of the sensor to OLR (as well as other thermal effects). The changes in offset associated with thermal gradient are of the same order of magnitude as effects that were formerly attributed to sensor temperature alone, and thus both parameters are necessary to characterize the FGM offsets.

Kenneth R Bromund↗
NASA NTRS1995

Long-Lived Linear-Motion Suspension For Cryogenic Instrument

Mechanism suspends optical component in cryogenic instrument in such way to allow component to translate smoothly along one axis, without vibration. Bearings located outside cooled instrument chamber for longer life. Thermal isolators separate bearings from cryogenic environment inside instrument chamber.

Packard, Douglas T.↗
NASA NTRS1993

AVIRIS and TIMS data processing and distribution at the land processes distributed active archive center

The U.S. Government has initiated the Global Change Research program, a systematic study of the Earth as a complete system. NASA's contribution of the Global Change Research Program is the Earth Observing System (EOS), a series of orbital sensor platforms and an associated data processing and distribution system. The EOS Data and Information System (EOSDIS) is the archiving, production, and distribution system for data collected by the EOS space segment and uses a multilayer architecture for processing, archiving, and distributing EOS data. The first layer consists of the spacecraft ground stations and processing facilities that receive the raw data from the orbiting platforms and then separate the data by individual sensors. The second layer consists of Distributed Active Archive Centers (DAAC) that process, distribute, and archive the sensor data. The third layer consists of a user science processing network. The EOSDIS is being developed in a phased implementation. The initial phase, Version 0, is a prototype of the operational system. Version 0 activities are based upon existing systems and are designed to provide an EOSDIS-like capability for information management and distribution. An important science support task is the creation of simulated data sets for EOS instruments from precursor aircraft or satellite data. The Land Processes DAAC, at the EROS Data Center (EDC), is responsible for archiving and processing EOS precursor data from airborne instruments such as the Thermal Infrared Multispectral Scanner (TIMS), the Thematic Mapper Simulator (TMS), and Airborne Visible and Infrared Imaging Spectrometer (AVIRIS). AVIRIS, TIMS, and TMS are flown by the NASA-Ames Research Center ARC) on an ER-2. The ER-2 flies at 65000 feet and can carry up to three sensors simultaneously. Most jointly collected data sets are somewhat boresighted and roughly registered. The instrument data are being used to construct data sets that simulate the spectral and spatial characteristics of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument scheduled to be flown on the first EOS-AM spacecraft. The ASTER is designed to acquire 14 channels of land science data in the visible and near-IR (VNIR), shortwave-IR (SWIR), and thermal-IR (TIR) regions from 0.52 micron to 11.65 micron at high spatial resolutions of 15 m to 90 m. Stereo data will also be acquired in the VNIR region in a single band. The AVIRIS and TMS cover the ASTER VNIR and SWIR bands, and the TIMS covers the TIR bands. Simulated ASTER data sets have been generated over Death Valley, California, Cuprite, Nevada, and the Drum Mountains, Utah using a combination of AVIRIS, TIMS, amd TMS data, and existing digital elevation models (DEM) for the topographic information.

Mah, G. R.↗
NASA NTRS1989

Flight motor set 360T004 (STS-30R). Volume 1: System overview

The fourth NASA space shuttle flight incorporating redesigned solid rocket motors began on 4 May 1989. The flight motors were designated 360Q004A (left-hand) and 360H004B (right-hand); the mission was designated STS-30R. Overall engine performance was excellent. The low sample rate data that was available showed exceptional propulsion performance. All ballistic and mass property parameters closely matched the predicted values and were well within the required contract end item specification levels that could be assessed. No strain, vibration, or aft skirt heating environments could be addressed due to developmental flight instrumentation deletion. Infrared readings from the shuttle thermal imager were considered very good when compared with ground environment instrumentation readings taken during both the aborted and the actual countdowns. However, hand-held infrared gun reading/ground environment instrumentation comparisons were considered poor during both countdowns, with the exception of the T - 3 hour timeframe during the actual launch. Postflight inspection again verified superior performance of the insulation, phenolics, metal parts, and seals. All combustion gas was contained by the insulation in the field and case-to-nozzle joints. Inadequate parachute performance on the left-hand booster caused high splashdown loads, which resulted in a displaced nozzle and factory joint weatherseal unbond anomalies. Recommendations were made concerning improved thermal modeling and instruments. The rationale for these recommendations, the dispositions of all anomalies, and complete result details are given.

Ricks, Glenn A.↗
NASA NTRS2011

Validation of the MODIS "Clear-Sky" Surface Temperature of the Greenland Ice Sheet

Surface temperatures on the Greenland Ice Sheet have been studied on the ground, using automatic weather station (AWS) data from the Greenland-Climate Network (GC-Net), and from analysis of satellite sensor data. Using Advanced Very High Frequency Radiometer (AVHRR) weekly surface temperature maps, warming of the surface of the Greenland Ice Sheet has been documented from 1981 to present. We extend and refine this record using higher-resolution Moderate-Resolution Imaging Spectroradiometer (MODIS) data from March 2000 to the present. To permit changes to be observed over time, we are developing a well-characterized monthly climate-data record (CDR) of the "clear-sky" surface temperature of the Greenland Ice Sheet using data from both the Terra and Aqua satellites. We use the MODIS ice-surface temperature (IST) algorithm. Validation of the CDR consists of several facets: 1) comparisons between the Terra and Aqua IST maps; 2) comparisons between ISTs and in-situ measurements; 3) comparisons between ISTs and AWS data; and 4) comparisons of ISTs with surface temperatures derived from other satellite instruments such as the Thermal Emission and Reflection Radiometer. In this work, we focus on 1) and 2) above. Surface temperatures on the Greenland Ice Sheet have been studied on the ground, using automatic weather station (AWS) data from the Greenland-Climate Network (GC-Net), and from analysis of satellite sensor data. Using Advanced Very High Frequency Radiometer (AVHRR) weekly surface temperature maps, warming of the surface of the Greenland Ice Sheet has been documented from 1981 to present. We extend and refine this record using higher-resolution Moderate-Resolution Imaging Spectroradiometer (MODIS) data from March 2000 to the present. To permit changes to be observed over time, we are developing a well-characterized monthly climate-data record (CDR) of the "clear-sky" surface temperature of the Greenland Ice Sheet using data from both the Terra and Aqua satellites. We use the MODIS ice-surface temperature (IST) algorithm. Validation of the CDR consists of several facets: 1) comparisons between the Terra and Aqua IST maps; 2) comparisons between ISTs and in-situ measurements; 3) comparisons between ISTs and AWS data; and 4) comparisons of ISTs with surface temperatures derived from other satellite instruments such as the Thermal Emission and Reflection Radiometer. In this work, we focus on 1) and 2) above. First we provide comparisons between Terra and Aqua swath-based ISTs at approximately 14:00 Local Solar Time, reprojected to 12.5 km polar stereographic cells. Results show good correspondence when Terra and Aqua data were acquired within 2 hrs of each other. For example, for a cell centered over Summit Camp (72.58 N, 38.5 W), the average agreement between Terra and Aqua ISTs is 0.74 K (February 2003), 0.47 K (April 2003), 0.7 K (August 2003) and 0.96 K (October 2003) with the Terra ISTs being generally lower than the Aqua ISTs. More precise comparisons will be calculated using pixel data at the swath level, and correspondence between Terra and Aqua IST is expected to be closer. (Because of cloud cover and other considerations, only a few common cloud-free swaths are typically available for each month for comparison.) Additionally, previous work comparing land-surface temperatures (LSTs) from the standard MODIS LST product and in-situ surface-temperature data at Summit Camp on the Greenland Ice Sheet show that Terra MODIS LSTs are about 3 K lower than in-situ temperatures at Summit Camp, during the winter of 2008-09. This work will be repeated using both Terra and Aqua IST pixel data (in place of LST data). In conclusion, we demonstrate that the uncertainties in the CDR will be well characterized as we work through the various facets of its validation.

Hall, Dorothy K.↗
NASA NTRS2021

Europa Environmental Testing of Thermal Hardware for the Mapping Imaging Spectrometer for Europa (MISE) Instrument

The Europa Clipper spacecraft, scheduled for launch in June 2022, hosts a suite of instruments including the Mapping Imaging Spectrometer for Europa (MISE). MISE is a high-optical through-put pushbroom infrared imaging spectrometer that can collect measurements within Europa’s challenging radiation environment. It is externally mounted to the spacecraft and as a result is exposed to high radiation levels and cold temperatures. The instrument consists of a scan mirror assembly, an optical bench including a Dyson spectrometer and a telescope, and a structure that supports a cryocooler and a radiator. The cryocooler is used to actively cool the focal plane array and the spectrometer. The heat from the cryocooler is rejected through pyrolytic graphite sheet thermal straps to a honeycomb radiator. MISE will implement thermal hardware that will either not be used on other parts of the spacecraft or have a more extreme environment than the spacecraft. As a result, the MISE instrument performed numerous environmental tests on its thermal hardware. This paper discusses the results of the thermal cycling and radiation tests performed on the MISE thermal hardware including a Lockheed Martin Micro1-2 cryocooler, Pyrolytic graphite sheet thermal straps, Annealed pyrolytic graphite K-Core, Rosemount Platinum Resistance Thermometers, Tayco Kapton Thermofoil heaters, Dale Ohm resistors, and aluminum honeycomb and facesheets.

Strong, Patrick↗
NASA NTRS2000

AVHRR-Based Polar Pathfinder Products: Evaluation, Enhancement and Transition to MODIS

Study of the environment has historically been done with observations and measurements in relatively few local areas. While some of these have been done over long time spans, most have not. The NOAA/NASA Pathfinder project was initiated to complement these data sets with satellite data that can provide information over larger spatial areas and longer time spans. The AVHRR Polar Pathfinder (APR) program was part of this project. The APR was to supply data from the NOAA AVHRR instruments that was consistently generated in a format usable to a wide range of scientific investigators. A grant was obtained from the NASA Research Announcement 97-MTPE-03 to evaluate the APP products, to provide any enhancements, and to compare with products from the new MODIS instrument. There was about a two year overlap between the projects, and this validation effort had several impacts on the APP products. The APP products are derived from the instruments aboard 4 NOAA satellites, NOAA-7, 9, 11, and 14. Initial validation efforts compared the thermal calibrations of these instruments, and differences are found. Calibration has undergone many revisions and techniques have changed since the satellites were launched. The first calibration methods were optimized for global ocean temperatures, as this was one of the primary and important uses of the AVHRR instruments. As the APP program started, newer methods that provided more accurate temperature retrievals over a wider range of temperatures were being developed. The calibration of a wider range of temperatures were necessary because of the extremely low values in the polar regions. These methods were also designed so that calibrated data was also consistent between all the NOAA satellites. These newer calibration methods were then adopted primarily because of the initial finding of this validation effort.

Fowler, Charles↗