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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Circuits Enhance Scientific Instruments and Safety Devices

Since its founding in 1958, NASA has pioneered the use of different frequencies on the electromagnetic spectrum - including X-ray, microwave, and infrared wavelengths - to gather information about distant celestial bodies. During the 1962 Mariner 2 mission, NASA used microwave radiometers that operated in the range of 15-23 gigahertz (GHz) to assess the surface temperature of Venus and to determine the percentage of water vapor in its atmosphere. Today, there is another area on the spectrum proving uniquely useful to scientists: the terahertz (THz) range, spanning from about 100 GHz-10,000 GHz. (1 THz equals approximately 1,000 GHz.) Terahertz frequencies span the lesser-known gap on the electromagnetic spectrum between microwave radiation and infrared (and visible) light, falling within the spectral range where most simple molecules resonate. This molecular resonance makes terahertz particularly useful for chemical spectroscopy and the remote sensing of specific molecules. In the 1990s, NASA began using frequencies above 300 GHz (more than an order of magnitude higher than the instrumentation on Mariner 2) to perform spectral analysis of molecular clouds and planetary atmospheres. Instruments using these higher frequencies have included the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite (UARS), deployed from 1991-2001, and the Microwave Instrument for the Rosetta Orbiter (MIRO), launched in 2004. With UARS-MLS, NASA used advanced terahertz receivers to measure the emission signatures from atmospheric molecules, providing researchers with valuable data about the changes in the Earth s protective ozone layer. MIRO, set to rendezvous with the comet 67P Churyumov-Gerasimenko in 2014, will use terahertz instrumentation to analyze the comet s dust and gases. Although NASA has been a driving force behind the development of terahertz technology, scientific equipment for terahertz research - including transmitters, receivers, and basic test and measurement equipment - is not widely available, making scientific experiments in this range between traditional electronics and quantum photonics more costly and greatly limiting commercial development in the field. Given NASA s interest in studying distant bodies in space as well as in improving life on Earth, the Agency has collaborated with private industry to develop terahertz technologies.

Source record↗
NASA NTRS1990

Tropical Rainfall Measuring Mission (TRMM) project. VI - Spacecraft, scientific instruments, and launching rocket. Part 3 - The electrically Scanning Microwave Radiometer and the Special Sensor Microwave/Imager

The two microwave radiometers for TRMM are designed to measure thermal microwave radiation upwelling from the earth. The Electrically Scanning Microwave Radiometer (ESMR) scans from 50 deg to the left through nadir to 50 deg to the right in 78 steps with no moving mechanical parts in a band centered at 19.35 GHz. The TRMM concept uses the radar to develop a climatology of rain-layer thickness which can be used for the interpretation of the radiometer data over a swath wider than the radar. The ESMR data are useful for estimating rain intensity only over an ocean background. The Special Sensor Microwave/Imager (SSM/I), which scans conically with three dual polarized channels at 19, 37, and 85 GHz and a single polarized channel at 22 GHz, provides a wider range of rainfall intensities. The SSM/I spins about an axis parallel to the local spacecraft vector and 128 uniformly spaced samples of the 85 GHz data are taken on each scan over a 112-deg scan region simultaneously with 64 samples of the other frequencies.

Wilheit, Thomas T.↗
NASA NTRS1998

Characterization of Thin Film Microstrip Lines on Polyimide

This paper presents an in depth characterization of thin film microstrip (TFMS) lines fabricated on Dupont PI-2611 polyimide. Measured attenuation and effective dielectric constant is presented for TFMS lines with thicknesses from 2.45-7.4 microns and line widths from 5-34.4 microns over the frequency range of 1-110 GHz. The attenuation is separated into conductor and dielectric losses to determine the loss tangent of Dupont PI-2611 polyimide over the microwave frequency range. In addition, the measured characteristics are compared to closed form equations for a and eff from the literature. Based on the comparisons, recommendations for the best dosed form design equations for TFMS are made.

Ponchak, George E.↗
NASA NTRS1980

Some n-p (Hg,Cd)Te photodiodes for 8-14 micrometer heterodyne applications

The results describing the dc and CO2 laser heterodyne characteristics of a three element photodiode array and single element and four element photodiode arrays are presented. The measured data shows that the n(+)-p configuration is capable of achieving bandwidths of 475 to 725 MHz and noise equivalent powers of 3.2 x 10 to the minus 20th power W/Hz at 77 K and 1.0 x 10 to the minus 19th power W/Hz at 145 K. The n(+)-n(-)-p photodiodes exhibited wide bandwidths (approximately 2.0 GHz) and fairly good effective heterodyne quantum efficiencies (approximately 13-30 percent at 2.0 GHz). Noise equivalent powers ranging from 1.44 x 10 to the minus 19th power W/Hz to 6.23 x 10 to the minus 20th power W/Hz were measured at 2.0 GHz.

Shanley, J. F.↗
NASA NTRS2011

Coaxial Cables for Martian Extreme Temperature Environments

Work was conducted to validate the use of the rover external flexible coaxial cabling for space under the extreme environments to be encountered during the Mars Science Laboratory (MSL) mission. The antennas must survive all ground operations plus the nominal 670-Martian-day mission that includes summer and winter seasons of the Mars environment. Successful development of processes established coaxial cable hardware fatigue limits, which were well beyond the expected in-flight exposures. In keeping with traditional qualification philosophy, this was accomplished by subjecting flight-representative coaxial cables to temperature cycling of the same depth as expected in-flight, but for three times the expected number of in-flight thermal cycles. Insertion loss and return loss tests were performed on the coaxial cables during the thermal chamber breaks. A vector network analyzer was calibrated and operated over the operational frequency range 7.145 to 8.450 GHz. Even though some of the exposed cables function only at UHF frequencies (approximately 400 MHz), the testing was more sensitive, and extending the test range down to 400 MHz would have cost frequency resolution. The Gore flexible coaxial cables, which were the subject of these tests, proved to be robust and displayed no sign of degradation due to the 3X exposure to the punishing Mars surface operations cycles.

Ramesham, Rajeshuni↗
DOE OSTI2023

A near magnetic-to-kinetic energy equipartition flare from the relativistic jet in AO 0235 + 164 during 2013–2019

ABSTRACT We present the multiwavelength flaring activity of the blazar AO 0235 + 164 during its recent active period from 2013 to 2019. From a discrete correlation function analysis, we find a significant ($\gt 95~{{\ \rm per\ cent}}$) correlation between radio and gamma-ray light curves with flares at longer wavelengths following flares at shorter wavelengths. We identify a new jet component in 43 GHz Very Long Baseline Array data that was ejected from the radio core on MJD $57246^{+26}_{-30}$ (2015 August 12), during the peak of the 2015 radio flare. From the analysis of the jet component, we derived a Doppler factor of δvar = 28.5 ± 8.4, a bulk Lorentz factor of $\Gamma =16.8^{+3.6}_{-3.1}$, and an intrinsic viewing angle of $\theta _{\rm v}=1.42^{+1.07}_{-0.52}\textrm {~degrees}$. Investigation of the quasi-simultaneous radio data revealed a partially absorbed spectrum with the turnover frequency varying in the range of 10−70 GHz and the peak flux density varying in the range of 0.7−4 Jy. We find the synchrotron self-absorption magnetic field strength to be $B_{\rm SSA}=15.3^{+12.6}_{-14.0}\textrm {~mG}$ at the peak of the 2015 radio flare, which is comparable to the equipartition magnetic field strength of $B_{\rm EQ}=43.6^{+10.6}_{-10.4}\textrm {~mG}$ calculated for the same epoch. Additional analysis of the radio emission region in the relativistic jet of AO 0235 + 164 suggests that it did not significantly deviate from equipartition during its recent flaring activity.

Astronomy & Astrophysics↗
DOE OSTI2023

Tensor-to-scalar ratio forecasts for extended LiteBIRD frequency configurations

LiteBIRD is a planned JAXA-led cosmic microwave background (CMB) B-mode satellite experiment aiming for launch in the late 2020s, with a primary goal of detecting the imprint of primordial inflationary gravitational waves. Its current baseline focal-plane configuration includes 15 frequency bands between 40 and 402 GHz, fulfilling the mission requirements to detect the amplitude of gravitational waves with the total uncertainty on the tensor-to-scalar ratio, δr, down to δr < 0.001. A key aspect of this performance is accurate astrophysical component separation, and the ability to remove polarized thermal dust emission is particularly important. In this paper we note that the CMB frequency spectrum falls off nearly exponentially above 300 GHz relative to the thermal dust spectral energy distribution, and a relatively minor high frequency extension can therefore result in even lower uncertainties and better model reconstructions. Specifically, we compared the baseline design with five extended configurations, while varying the underlying dust modeling, in each of which the High-Frequency Telescope (HFT) frequency range was shifted logarithmically toward higher frequencies, with an upper cutoff ranging between 400 and 600 GHz. In each case, we measured the tensor-to-scalar ratio r uncertainty and bias using both parametric and minimum-variance component-separation algorithms. When the thermal dust sky model includes a spatially varying spectral index and temperature, we find that the statistical uncertainty on r after foreground cleaning may be reduced by as much as 30–50% by extending the upper limit of the frequency range from 400 to 600 GHz, with most of the improvement already gained at 500 GHz. We also note that a broader frequency range leads to higher residuals when fitting an incorrect dust model, but also it is easier to discriminate between models through higher χ 2 sensitivity. Even in the case in which the fitting procedure does not correspond to the underlying dust model in the sky, and when the highest frequency data cannot be modeled with sufficient fidelity and must be excluded from the analysis, the uncertainty on r increases by only about 5% for a 500 GHz configuration compared to the baseline.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2023

Tensor-to-scalar ratio forecasts for extended LiteBIRD frequency configurations

LiteBIRD is a planned JAXA-led cosmic microwave background (CMB) B -mode satellite experiment aiming for launch in the late 2020s, with a primary goal of detecting the imprint of primordial inflationary gravitational waves. Its current baseline focal-plane configuration includes 15 frequency bands between 40 and 402 GHz, fulfilling the mission requirements to detect the amplitude of gravitational waves with the total uncertainty on the tensor-to-scalar ratio, δr , down to δr < 0.001. A key aspect of this performance is accurate astrophysical component separation, and the ability to remove polarized thermal dust emission is particularly important. In this paper we note that the CMB frequency spectrum falls off nearly exponentially above 300 GHz relative to the thermal dust spectral energy distribution, and a relatively minor high frequency extension can therefore result in even lower uncertainties and better model reconstructions. Specifically, we compared the baseline design with five extended configurations, while varying the underlying dust modeling, in each of which the High-Frequency Telescope (HFT) frequency range was shifted logarithmically toward higher frequencies, with an upper cutoff ranging between 400 and 600 GHz. In each case, we measured the tensor-to-scalar ratio r uncertainty and bias using both parametric and minimum-variance component-separation algorithms. When the thermal dust sky model includes a spatially varying spectral index and temperature, we find that the statistical uncertainty on r after foreground cleaning may be reduced by as much as 30–50% by extending the upper limit of the frequency range from 400 to 600 GHz, with most of the improvement already gained at 500 GHz. We also note that a broader frequency range leads to higher residuals when fitting an incorrect dust model, but also it is easier to discriminate between models through higher χ 2 sensitivity. Even in the case in which the fitting procedure does not correspond to the underlying dust model in the sky, and when the highest frequency data cannot be modeled with sufficient fidelity and must be excluded from the analysis, the uncertainty on r increases by only about 5% for a 500 GHz configuration compared to the baseline.

U. Fuskeland↗
NASA NTRS1994

A 1- to 10-GHz downconverter for high-resolution microwave survey

A downconverter was designed, built, and tested for the High Resolution Microwave Survey project. The input frequency range is 1 to 10 GHz with instantaneous bandwidth of 350 MHz and dynamic range of 125 dB/Hz. Requirements were derived for the local oscillators and special design techniques were implemented to achieve the high degree of spectral purity required.

Mcwatters, D.↗
NASA NTRSDate not supplied

2-D Lunar Microwave Radiance Observations From the NOAA-20 ATMS

Reported here are disk-integrated Moon surface microwave brightness temperature (Tb) retrievals covering the frequency range of 23–183 GHz. FullMoon observations obtained from the advanced technology microwave sounder (ATMS) onboard the NOAA-20 satellite during a special spacecraft pitch–maneuver operation forms the basis of the retrievals. Instrument nonlinearity, Earth sidelobe contamination, cosmic background radiation, and reflector thermal emission corrections are applied to the observations to obtain accurate values of the Moon’s Tb at all frequencies. The measured full Moon Tb ranges from ~240 to 293 K with frequency increases from 23 to 183 GHz. A clear frequency trend is detected when the brightness temperature increases.

Hu Yang↗
NASA NTRS1999

The Design and Operation of TMI, a Mechanically-Scanning, Multi-Frequency Microwave Radiometer for the Tropical Rainfall Measurements Mission

The Tropical Rainfall Measurement Mission (TRMM), a joint mission between the U.S. NASA and the Japans NASDA (National Space Development Agency), was successfully launched in November of 1997. On board of the TRMM satellite are two major microwave sensors, a real-aperture radar operating at 13.8 GHz, called the Precipitation Radar (PR), and a microwave radiometer system called TRMM Microwave Imager (TMI). The TMI contains five frequencies, ranging from 10.7 to 85 GHz, is designed to cover a wide dynamic range of rain intensities. The TMI measures the rain from the emission properties while the PR's measurement is based on the scattering of the hydrometeor. The two instruments aboard the same platform provide a complementary and synergistic measurement of precipitation. This paper will focus primarily on the TMI. The advent of microwave sensor technology in recent years, the addition of a new frequency (at 10.7 GHz), as well as the mission design, have enabled the TMI to be a superior instrument for the precipitation measurement. We will provide a description of the instrument together with some of its the design rationales and practical hardware implementation. We will also show the performance of TMI aboard the TRMM and some examples of its data.

Shiue, James C.↗
NASA NTRS2009

Beam Width Robustness of a 670 GHz Imaging Radar

Detection of a replica bomb belt concealed on a mannequin at 4 m standoff range is achieved using a 670 GHz imaging radar. At a somewhat larger standoff range of 4.6 m, the radar's beam width increases substantially, but the through-shirt image quality remains good. This suggests that a relatively modest increase in aperture size over the current design will be sufficient to detect person-borne concealed weapons at ranges exceeding 25 meters.

Cooper, K. B.↗
NASA NTRS1987

VLBI observations of the 3C 111 jet

VLBI observations have been made of the central component of the broad-line radio galaxy 3C 111 at 1.7 GHz and 5.0 GHz. High-dynamic-range maps at both frequencies show a one-sided jet in PA 62 + or - 1 deg but no counterjet. The lower limit to the jet/counterjet ratio is 30:1 at 5 GHz and 15:1 at 1.7 GHz. The jet is initially straight, but beyond 15 marcsec from the core it exhibits small bends or wiggles. Their onset corresponds to a sharp reduction in the rate of intensity falloff along the jet, suggesting that an instability in the jet is causing substantial particle acceleration.

Linfield, Roger↗
NASA NTRS2009

Tests of Low-Noise MMIC Amplifier Module at 290 to 340 GHz

A document presents data from tests of a low-noise amplifier module operating in the frequency range from 290 to 340 GHz said to be the highest-frequency low-noise, solid-state amplifier ever developed. The module comprised a three-stage monolithic microwave integrated circuit (MMIC) amplifier integrated with radial probe MMIC/waveguide transitions and contained in a compact waveguide package, all according to the concepts described in the immediately preceding article and in the referenced prior article, "Integrated Radial Probe Transition From MMIC to Waveguide" (NPO-43957), NASA Tech Briefs Vol. 31, No. 5 (May 2007), page 38. The tests included measurements by the Y-factor method, in which noise figures are measured repeatedly with an input noise source alternating between an "on" (hot-load) condition and an "off" (cold-load) condition. (The Y factor is defined as the ratio between the "on" and "off" noise power levels.) The test results showed that, among other things, the module exhibited a minimum noise figure of about 8.7 dB at 325 GHz and that the gain at that frequency under the bias conditions that produced the minimum noise figure was between about 9 and 10 dB.

Gaier, Todd↗
NASA NTRS1989

32-GHz cryogenically cooled HEMT low-noise amplifiers

The cryogenic noise temperature performance of a two-stage and a three-stage 32 GHz high electron mobility transistor (HEMT) amplifier was evaluated. The amplifiers employ 0.25 micrometer conventional AlGaAs/GaAs HEMT devices, hybrid matching input and output microstrip circuits, and a cryogenically stable dc biasing network. The noise temperature measurements were performed in the frequency range of 31 to 33 GHz over a physical temperature range of 300 K down to 12 K. Across the measurement band, the amplifiers displayed a broadband response, and the noise temperature was observed to decrease by a factor of 10 in cooling from 300 to 15 K. The lowest noise temperature measured for the two-stage amplifier at 32 GHz was 35 K with an associated gain of 16.5 dB, while the three-stage amplifier measured 39 K with an associated gain of 26 dB. It was further observed that both amplifiers were insensitive to light.

Duh, K. H. George↗
NASA NTRS1988

On 32-GHz cryogenically cooled HEMT low-noise amplifiers

The cryogenic noise temperature performance of a two-stage and a three-stage 32 GHz High Electron Mobility Transistor (HEMT) amplifier was evaluated. The amplifiers employ 0.25 micrometer conventional AlGaAs/GaAs HEMT devices, hybrid matching input and output microstrip circuits, and a cryogenically stable dc biasing network. The noise temperature measurements were performed in the frequency range of 31 to 33 GHz over a physical temperature range of 300 K down to 12 K. Across the measurement band, the amplifiers displayed a broadband response, and the noise temperature was observed to decrease by a factor of 10 in cooling from 300 K to 15 K. The lowest noise temperature measured for the two-stage amplifier at 32 GHz was 35 K with an associated gain of 16.5 dB, while the three-stage amplifier measured 39 K with an associated gain of 26 dB. It was further observed that both amplifiers were insensitive to light.

Bautista, J. J.↗
NASA NTRS1986

A study of 35-ghz radar-assisted orbital maneuvering vehicle/space telescope docking

An experiment was conducted to study the effects of measuring range and range rate information from a complex radar target (a one-third scale model of the Edwin P. Hubble Space Telescope). The radar ranging system was a 35-GHz frequency-modulated continuous wave unit developed in the Communication Systems Branch of the Information and Electronic Systems Laboratory at Marshall Space Flight Cneter. Measurements were made over radar-to-target distances of 5 meters to 15 meters to simulate the close distance realized in the final stages of space vehicle docking. The Space Telescope model target was driven by an antenna positioner through a range of azimuth and elevation (pitch) angles to present a variety of visual aspects of the aft end to the radar. Measurements were obtained with and without a cube corner reflector mounted in the center of the aft end of the model. The results indicate that range and range rate measurements are performed significantly more accurately with the cooperative radar reflector affixed. The results further reveal that range rate (velocity) can be measured accurately enough to support the required soft docking with the Space Telescope.

Mcdonald, M. W.↗
NASA NTRS2008

Measurements by a Vector Network Analyzer at 325 to 508 GHz

Recent experiments were performed in which return loss and insertion loss of waveguide test assemblies in the frequency range from 325 to 508 GHz were measured by use of a swept-frequency two-port vector network analyzer (VNA) test set. The experiments were part of a continuing effort to develop means of characterizing passive and active electronic components and systems operating at ever increasing frequencies. The waveguide test assemblies comprised WR-2.2 end sections collinear with WR-3.3 middle sections. The test set, assembled from commercially available components, included a 50-GHz VNA scattering- parameter test set and external signal synthesizers, augmented with recently developed frequency extenders, and further augmented with attenuators and amplifiers as needed to adjust radiofrequency and intermediate-frequency power levels between the aforementioned components. The tests included line-reflect-line calibration procedures, using WR-2.2 waveguide shims as the "line" standards and waveguide flange short circuits as the "reflect" standards. Calibrated dynamic ranges somewhat greater than about 20 dB for return loss and 35 dB for insertion loss were achieved. The measurement data of the test assemblies were found to substantially agree with results of computational simulations.

Fung, King Man↗