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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Earth resources sensing technology - 24-channel multispectral sensor system development.

Description of the technology applied to a 24-channel multispectral scanner developed as a tool to investigate the portion of the electromagnetic spectrum between 0.34 and 13.0 microns. Energy reflected or emitted from the terrain and system calibration sources is collected by the scan mirror, reflected into the collecting optics, and brought to focus in a plane containing a square aperture. A dichroic optical element splits the energy which passes through the aperture into two wavelength bands in which wavelengths are greater than and less than 2.0 microns, respectively. These two wavelength bands are dispersed spectrally by two grating spectrometers. The energy from 24 distinct spectral intervals is transformed into electrical signals by 24 detector/preamplifier combinations. These signals then become the inputs to a video processor in an airborne electronics console.

Kessel, J. E.↗
NASA NTRS1983

Nimbus-6 and -7 Earth Radiation Budget (ERB) sensor details and component tests

Construction details and operating characteristics are described for the thermopile (used in the solar and fixed-Earth channels) and the pyroelectric detector (used in the Earth-scanning channels) carried on the Nimbus 6 and the Nimbus 7 satellites for gathering Earth radiation budget data. Properties of the black coating for the detectors, and sensor testing and calibration are discussed.

Soule, H. V.↗
NASA NTRS1986

Inversion of SAGE II measurements

Stratospheric aerosol data acquired by the seven channels of the SAGE II passive radiometer system are first converted to atmospheric slant path transmission (SPT) values before deriving inversion values. The sun-pointing configuration permits bypassing calibration equipment required by other instruments and also furnishes high resolution vertical profile data. The retrieval techniques for quantifying the amounts of aerosol, water vapor, NO2 and O3, the species to which the SAGE II sensors are tuned, are summarized, along with methods for estimating the uncertainty in the calculations.

Chu, W. P.↗
NASA NTRS1988

Pilot-aided modulation for narrow-band satellite communications

This paper discusses a number of tone-aided modulation techniques which have been studied as part of the Mobile Satellite Experiment (MSAT-X) Program. In all instances tone(s) are inserted into data-free portions of the transmit spectrum and used by the receiver to sense the amplitude and frequency/phase distortions introduced by the channel. The receiver then uses this information in a feedforward manner to lessen the effect of the distortions on the data detection performance. Particular techniques discussed are the Tone Calibration Technique (TCT), the Dual Tone Calibrated Technique (DTCT), Transparent Tone-In-Band (TTIB), and Dual-Tone Single Sideband (DTSSB).

Saulnier, Gary J.↗
NASA NTRS1993

Radio metric errors due to mismatch and offset between a DSN antenna beam and the beam of a troposphere calibration instrument

Two components of the error of a troposphere calibration measurement were quantified by theoretical calculations. The first component is a beam mismatch error, which occurs when the calibration instrument senses a conical volume different from the cylindrical volume sampled by a Deep Space Network (DSN) antenna. The second component is a beam offset error, which occurs if the calibration instrument is not mounted on the axis of the DSN antenna. These two error sources were calculated for both delay (e.g., VLBI) and delay rate (e.g., Doppler) measurements. The beam mismatch error for both delay and delay rate drops rapidly as the beamwidth of the troposphere calibration instrument (e.g., a water vapor radiometer or an infrared Fourier transform spectrometer) is reduced. At a 10-deg elevation angle, the instantaneous beam mismatch error is 1.0 mm for a 6-deg beamwidth and 0.09 mm for a 0.5-deg beam (these are the full angular widths of a circular beam with uniform gain out to a sharp cutoff). Time averaging for 60-100 sec will reduce these errors by factors of 1.2-2.2. At a 20-deg elevation angle, the lower limit for current Doppler observations, the beam-mismatch delay rate error is an Allan standard deviation over 100 sec of 1.1 x 10(exp -14) with a 4-deg beam and 1.3 x 10(exp -l5) for a 0.5-deg beam. A 50-m beam offset would result in a fairly modest (compared to other expected error sources) delay error (less than or equal to 0.3 mm for 60-sec integrations at any elevation angle is greater than or equal to 6 deg). However, the same offset would cause a large error in delay rate measurements (e.g., an Allan standard deviation of 1.2 x 10(exp -14) over 100 sec at a 20-deg elevation angle), which would dominate over other known error sources if the beamwidth is 2 deg or smaller. An on-axis location is essential for accurate troposphere calibration of delay rate measurements. A half-power beamwidth (for a beam with a tapered gain profile) of 1.2 deg or smaller is desired for calibration of all types of radio metrics. A water-vapor radiometer calibration beam of this size with very low sidelobes would require a clear aperture antenna with a diameter of at least 1.5 m if the primary water vapor sensing channel were in the 20-22 GHz range.

R P Linfield↗
NASA NTRS1993

A Study of Saturn's E-Ring Particles Using the Voyager 1 Plasma Wave Instrument

The flyby of Voyager 1 at Saturn resulted in the detection of a large variety of plasma waves, e.g., chorus, hiss, and electron cyclotron harmonics. Just before the outbound equator crossing, at about 6.1 R(sub s), the Voyager 1 plasma wave instrument detected a strong, well-defined low-frequency enhancement. Initially it was suggested that plasma waves might be responsible for the spectral feature but more recently dust was suggested as at least a partial contributor to the enhancement. In this report we present evidence which supports the conclusion that dust contributes to the low-frequency enhancement. A new method has been used to derive the dust impact rate. The method relies mainly on the 16-channel spectrum analyzer data. The few wide band waveform observations available (which have been used to study dust impacts during the Voyager 2 ring plane crossing) were useful for calibrating the impact rate from the spectrum analyzer data. The mass and, hence, the size of the dust particles were also obtained by analyzing the response of the plasma wave spectrum analyzer. The results show that the region sampled by Voyager 1 is populated by dust particles that have rms masses of up to few times 10(exp -11) g and sizes of up to a few microns. The dust particle number density is on the order of 10(exp -3) m(exp 3). The optical depth of the region sampled by the spacecraft is 1.04 x 10(exp -6). The particle population is centered about 2500 km south of the equatorial plane and has a north-south thickness of about 4000 km. Possible sources of these particles are the moons Enceladus and Tethys whose orbits lie within the E-ring radial extent. These results are in reasonable agreement with photometric studies and numerical simulations.

Tsintikidis, D.↗
NASA NTRS1995

Study of dust in the vicinity of Dione using the Voyager 1 plasma wave instrument

The flyby of Voyager 1 at Saturn yielded the detection of a large variety of plasma waves, for example, chorus, hiss, and electron cyclotron harmonics. Just before the outbound equator crossing, the Voyager 1 plasma wave instrument detected a strong, well-defined low-frequency enhancement in signal levels. Initially, it was thought that this enhancement was due to plasma waves, but more recently it was suggested that dust impacts might be at least partial contributors. In this report we present evidence that dust impacts are partly responsible for the low-frequency enhancement. A new method of analysis which relies mainly on the 16-channel spectrum analyzer has been used to derive the dust impact rate. The available wideband waveform observations (which have been used previously to study dust impacts) were useful for calibrating the impact rate from the spectrum analyzer data. The mass and hence size of the dust particles were also obtained by analyzing the response of the plasma wave spectrum and analyzer. The results show that the region sampled by Voyager 1 is populated by dust particles that have rms masses of up to a few times 10(exp -11) g and sizes of up to a few microns. The dust particle number density is of the order of 10(exp -3)/cu m. The optical depth of the region sampled by the spacecraft is approximately 10(exp -6). The particle population is centered at 2470 (+/- 150) km south of the equatorial plane and has a north-south FWHM (full-width, half-maximum) thickness of 4130 (+/- 450) km. The dust may be part of the E ring or a localized ringlet assoicated with Dione.

Tsintikidis, D.↗
NASA NTRS1997

Automated Test Systems for Toxic Vapor Detectors

The NASA Toxic Vapor Detection Laboratory (TVDL) at the Kennedy Space Center (KSC), Florida, has been using Personal Computer based Data Acquisition and Control Systems (PCDAS) for about nine years. These systems control the generation of toxic vapors of known concentrations under controlled conditions of temperature and humidity. The PCDAS also logs the test conditions and the test article responses in data files for analysis by standard spreadsheets or custom programs. The PCDAS was originally developed to perform standardized qualification and acceptance tests in a search for a commercial off-the-shelf (COTS) toxic vapor detector to replace the hydrazine detectors for the Space Shuttle launch pad. It has since become standard test equipment for the TVDL and is indispensable in producing calibration standards for the new hydrazine monitors at the 10 part per billion (ppb) level. The standard TVDL PCDAS can control two toxic vapor generators (TVG's) with three channels each and two flow/temperature/humidity (FIFH) controllers and it can record data from up to six toxic vapor detectors (TVD's) under test and can deliver flows from 5 to 50 liters per minute (L/m) at temperatures from near zero to 50 degrees Celsius (C) using an environmental chamber to maintain the sample temperature. The concentration range for toxic vapors depends on the permeation source installed in the TVG. The PCDAS can provide closed loop control of temperature and humidity to two sample vessels, typically one for zero gas and one for the standard gas. This is required at very low toxic vapor concentrations to minimize the time required to passivate the sample delivery system. Recently, there have been several requests for information about the PCDAS by other laboratories with similar needs, both on and off KSC. The purpose of this paper is to inform the toxic vapor detection community of the current status and planned upgrades to the automated testing of toxic vapor detectors at the Kennedy Space Center.

Mattson, C. B.↗
NASA NTRS1997

Automated Test Systems for Toxic Vapor Detectors

The NASA Toxic Vapor Detection Laboratory (TVDL) at the Kennedy Space Center (KSC), Florida, has been using Personal Computer based Data Acquisition and Control Systems (PCDAS) for about nine years. These systems control the generation of toxic vapors of known concentrations under controlled conditions of temperature and humidity. The PCDAS also logs the test conditions and the test article responses in data files for analysis by standard spreadsheets or custom programs. The PCDAS was originally developed to perform standardized qualification and acceptance tests in a search for a commercial off-the-shelf (COTS) toxic vapor detector to replace the hydrazine detectors for the Space Shuttle launch pad. It has since become standard test equipment for the TVDL and is indispensable in producing calibration standards for the new hydrazine monitors at the 10 part per billion (ppb) level. The standard TVDL PCDAS can control two toxic vapor generators (TVG's) with three channels each and two flow/ temperature / humidity (FTH) controllers and it can record data from up to six toxic vapor detectors (TVD's) under test and can deliver flows from 5 to 50 liters per minute (L/m) at temperatures from near zero to 50 degrees Celsius (C) using an environmental chamber to maintain the sample temperature. The concentration range for toxic vapors depends on the permeation source installed in the TVG. The PCDAS can provide closed loop control of temperature and humidity to two sample vessels, typically one for zero gas and one for the standard gas. This is required at very low toxic vapor concentrations to minimize the time required to passivate the sample delivery system. Recently, there have been several requests for information about the PCDAS by other laboratories with similar needs, both on and off KSC. The purpose of this paper is to inform the toxic vapor detection community of the current status and planned upgrades to the automated testing of toxic vapor detectors at the Kennedy Space Center.

Mattson, C. B.↗
NASA NTRS2009

Multiplexed Colorimetric Solid-Phase Extraction

Multiplexed colorimetric solid-phase extraction (MC-SPE) is an extension of colorimetric solid-phase extraction (C-SPE) an analytical platform that combines colorimetric reagents, solid phase extraction, and diffuse reflectance spectroscopy to quantify trace analytes in water. In CSPE, analytes are extracted and complexed on the surface of an extraction membrane impregnated with a colorimetric reagent. The analytes are then quantified directly on the membrane surface using a handheld diffuse reflectance spectrophotometer. Importantly, the use of solid-phase extraction membranes as the matrix for impregnation of the colorimetric reagents creates a concentration factor that enables the detection of low concentrations of analytes in small sample volumes. In extending C-SPE to a multiplexed format, a filter holder that incorporates discrete analysis channels and a jig that facilitates the concurrent operation of multiple sample syringes have been designed, enabling the simultaneous determination of multiple analytes. Separate, single analyte membranes, placed in a readout cartridge create unique, analyte-specific addresses at the exit of each channel. Following sample exposure, the diffuse reflectance spectrum of each address is collected serially and the Kubelka-Munk function is used to quantify each water quality parameter via calibration curves. In a demonstration, MC-SPE was used to measure the pH of a sample and quantitate Ag(I) and Ni(II).

Gazda, Daniel B.↗
NASA NTRS2016

Towards a Radar/Radiometer Mode on the Dual-Frequency, Dual-Polarized, Doppler Radar (D3R) System

The dual-­frequency, dual-­polarized, Doppler radar (D3R) system was developed in support of the ground validation segment of the Global Precipitation Measurement (GPM) mission. Although its main purpose is to provide active, Ku/Ka­‐band, dual­‐polarized measurements of precipitation, the design presents an opportunity to study its operation in an active/passive mode. The opportunity arises from use of solid-­state transmitters employing a multi­‐frequency waveform and receiving system. Typically, a sequence of three pulses separated in frequency is transmitted to achieve its radar sensitivity and minimum range. However, one of the three pulses can be disabled with a tolerable decrease in sensitivity and its receive channel can be repurposed to support passive measurements. This work focuses on progress in the characterization of the Ku-­band H polarized passive channel operating simultaneously with two active as a step towards the provision of brightness temperatures along with the other radar derived products. The methodology developed will be applied to the V polarized channel and Ka­‐band subsystem in the near future. The study consists on the analysis of the antenna performance, receiver architecture, transfer function and achievable number of independent samples, calibration method and preliminary observation analysis. All within the context of the instrument's current configuration and possible future improvements.

radar↗
DOE OSTI2021

Evaluating the ProtoDUNE-SP Detector Performance to Measure a 6 GeV/c Positive Kaon Inelastic Cross Section on Argon

The ProtoDUNE Single-Phase Liquid Argon Time Projection Chamber \\ (ProtoDUNE-SP LArTPC) is a prototype for the Deep Underground Neutrino Experiment (DUNE), a future long-baseline neutrino oscillation experiment. Based at the CERN Neutrino Platform, ProtoDUNE-SP LArTPC collected data from a charged test beam in the fall of 2018. It then took data of cosmic-ray muons from November 2018 to the summer of 2020. The main goals of the prototype were to measure parameters related to charged particle passage in argon and evaluate the performance of the detector to inform future DUNE Far Detector development. The test beam provided kaons, pions, muons, protons, and electrons to the detector. These particles represent common final state particles in neutrino interactions, therefore providing information to DUNE on modeling charged particles in argon for its neutrino physics program. In addition to neutrino physics, DUNE has proposed an analysis using the DUNE Far Detector module to set limits for proton decay through the decay channel $p\rightarrow K^++\bar{\nu}$. This measurement would require information on kaons in argon, providing ProtoDUNE-SP LArTPC another opportunity to aid DUNE. This thesis describes the calibration of ProtoDUNE-SP and its detector performance, which serves as a benchmark for the performance of the DUNE Far Detector modules. A specific calibration highlighted is the evaluation of the liquid argon purity in the detector. These measurements use cosmic-ray muons reconstructed in the detector that are calibrated and matched to data from scintillator strips external to the TPC, known as the Cosmic Ray Tagger (CRT). The thesis will discuss the algorithms to match the data between the ProtoDUNE-SP LArTPC and the CRT and discuss the liquid argon purity measurements using one of the algorithms. Data sets of calibrated tracks measured the liquid argon contamination as consistently below 100 ppt oxygen equivalent. After these discussions on the ProtoDUNE-SP LArTPC detector, the thesis will present an evaluation of the inclusive inelastic, sometimes referred to as a reactive, cross section on argon of kaons from the ProtoDUNE-SP test beam with an average momentum of 6 GeV/c.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS2002

On-Orbit Performance Verification and End-to-End Characterization of the TDRS-H Ka-Band Communications Payload

In June 2000, NASA launched the first of three next generation Tracking and Data Relay Satellites (TDRS-H) equipped with a Ka-band forward and return service capability. This Ka-band service supports forward data rates up to 25 Mb/sec using the 22.55 - 23.55 GHz space-to-space allocation. Return services are supported via channel bandwidths of 225 and 650 MHz for data rates up to 800 Mb/sec (QPSK) using the 25.25 - 27.5 GHz space-to-space allocation. As part of NASA's acceptance of the TDRS-H spacecraft, an extensive on-orbit calibration, verification and characterization effort was performed to ensure that on-orbit spacecraft performance is within specified limits. This process verified the compliance of the Ka-band communications payload with all performance specifications and demonstrated an end-to-end Ka-band service capability. This paper summarizes the results of the TDRS-H Ka-band communications payload on-orbit performance verification and end-to-end service characterization. Performance parameters addressed include Effective Isotropically Radiated Power (EIRP), antenna Gain-to-System Noise Temperature (G/T), antenna gain pattern, frequency tunability and accuracy, channel magnitude response, and Ka-band service Bit-Error-Rate (BER) performance.

Toral, Marco↗
NASA NTRS2000

Validation of Ocean Color Remote Sensing Data using a Moored Databuoy

NASA's Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) aims to measure global ocean color from space to within 5% to provide insights into fundamental ocean processes. SeaWiFS must be backed by comprehensive calibration and validation programs if the mission is to achieve this. In situ measurements of normalized water-leaving radiance (L(sub wn)) made simultaneously with satellite measurements can complement on-orbit methods of tracking changes in the calibration of the satellite radiometer and allow end-to-end vicarious validation of the remotely-sensed data. A moored optical databuoy was developed at Plymouth Marine Laboratory, UK to measure L(sub wn) in the western English Channel. Tests indicate that the buoy is capable of measuring spectral incident irradiance with less than 10% error and water-leaving radiance with less than 20% error; these errors are reduced by averaging and show no bias. There were 24 match-ups with good quality SeaWiFS data at the buoy site during the ten months of deployment within the period May 1997 and September 1998. The differences between the buoy and SeaWiFS measurements of L(sub wn) were found to be variable and often large. The root-mean-square (RMS) differences varied from 102% at 412 nm to 50% at 555 nm. The RMS differences in measurements of L(sub wn) could be reduced to less than 18% by a combination of increasing the calibration coefficients of SeaWiFS by between 0.2 and 4.3% in the visible bands and by tuning the extrapolation of aerosol radiances from the near infrared to the visible wavelengths. These results imply that the monitoring of the absolute calibration of the SeaWiFS bands is imperfect and errors remain in the extrapolation of aerosol radiances for atmospheric correction.

Lavender, Samantha↗
NASA NTRS1985

Energy calibration of the fly's eye detector

The methods used to calibrate the Fly's eye detector to evaluate the energy of EAS are discussed. The energy of extensive air showers (EAS) as seen by the Fly's Eye detector are obtained from track length integrals of observed shower development curves. The energy of the parent cosmic ray primary is estimated by applying corrections to account for undetected energy in the muon, neutrino and hadronic channels. Absolute values for E depend upon the measurement of shower sizes N sub e(x). The following items are necessary to convert apparent optical brightness into intrinsical optical brightness: (1) an assessment of those factors responsible for light production by the relativistic electrons in an EAS and the transmission of light thru the atmosphere, (2) calibration of the optical detection system, and (3) a knowledge of the trajectory of the shower.

Baltrusaitis, R. M.↗
NASA NTRS2023

Level-1 Calibration Assessment of Spire’s LEMUR-2 GNSS-R Ocean Normalized Bistatic Radar Cross Section Estimates

An assessment of the ocean surface Level-1 Normalized Bistatic Radar Cross Section products provided by the two batch 1 ‘LEMUR-2’ GNSS-R receivers of Spire, Inc. is reported. The analysis uses datasets extending from DOY 345, 2020 to DOY 329, 2021. Initial assessments indicate a highly consistent overall inter-channel response with mean NBRCS differences estimated to be at the 1.00% level over a 7-12 m/s ECMWF reference wind speed range. Efforts to validate the observation systems’ aggregate response relative to ≈3 million co-located CYGNSS measurements suggest a highly complementary behavior with an overall NBRCS correlation of 79.03% highlighting the potential utility of ‘LEMUR-2’ measurements for ocean surface wind sensing and related applications. Non-physical NBRCS dependencies on various Level-1 calibration variables, also observed with GNSS-R previous systems, are nonetheless noted and are explored in detail.

Mohammad M. Al-Khaldi↗
NASA NTRS2002

On-Orbit Performance Verification and End-To-End Characterization of the TDRS-H Ka-band Communications Payload

In June 2000, NASA launched the first of three next generation Tracking and Data Relay Satellites (TDRS-H) equipped with a Ka-band forward and return service capability. This Ka-band service supports forward data rates of up to 25 Mb/sec using the 22.55-23.55 GHz space-to-space allocation. Return services are supported via channel bandwidths of 225 and 650 MHz for data rates up to at least 800 Mb/sec using the 25.25 - 27.5 GHz space-to-space allocation. As part of NASA's acceptance of the TDRS-H spacecraft, an extensive on-orbit calibration, verification and characterization effort was performed to ensure that on-orbit spacecraft performance is within specified limits. This process verified the compliance of the Ka-band communications payload with all performance specifications, and demonstrated an end-to-end Ka-band service capability. This paper summarizes the results of the TDRS-H Ka-band communications payload on-orbit performance verification and end-to-end service characterization. Performance parameters addressed include antenna gain pattern, antenna Gain-to-System Noise Temperature (G/T), Effective Isotropically Radiated Power (EIRP), antenna pointing accuracy, frequency tunability, channel magnitude response, and Ka-band service Bit-Error-Rate (BER) performance.

Toral, Marco↗
NASA NTRS1975

Computerized processing of data from Interkosmos-7 and Interkosmos-8 satellite experiments

Computerized data processing problems are analyzed using telemetry data received from Intercosmos-7 and Intercosmos-8 satellites. Problems related to the restoration of measurement data in the form of piecewise continuous and smooth calibrated functions of time and problems encountered in the scientific interpretation of the experimental results are considered. Curve smoothing is discussed in the case of distinct assignments of calibration levels, synchronization, and synchronization checks over time. A proposal is presented for checking a piecewise linear function providing a simple method for the elimination of isolated values due to channel failures and the separation of individual intervals.

Pfau, H.↗