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NASA NTRS1999

Mars Global Surveyor TES Results: Observations of Atmospheric Dust During Mapping

The Mars Global Surveyor entered mapping orbit around Mars in March 1999. Infrared spectra returned by the Thermal Emission Spectrometer (TES) are very well suited for monitoring column-integrated infrared dust opacity. A global view of dust opacity is possible on a daily basis allowing the detailed study of the evolution of dust storms and the seasonal trend of the background dust opacity. Information about the vertical distribution of dust in the atmosphere can be obtained by examination of TES spectra taken in a limb-viewing geometry. We report here on 1) the observed horizontal distribution of dust aerosols and their evolution with time during the mapping phase of the Mars Global Surveyor mission so far (roughly covering northern hemisphere summer and early fall), and 2) the vertical distribution of dust aerosols as determined from TES spectra taken in the limb-viewing geometry.

Smith, Michael D.↗
NASA NTRS2000

Separation of Atmospheric and Surface Spectral Features in Mars Global Surveyor Thermal Emission Spectrometer (TES) Spectra

We present two algorithms for the separation of spectral features caused by atmospheric and surface components in Thermal Emission Spectrometer (TES) data. One algorithm uses radiative transfer and successive least squares fitting to find spectral shapes first for atmospheric dust, then for water-ice aerosols, and then, finally, for surface emissivity. A second independent algorithm uses a combination of factor analysis, target transformation, and deconvolution to simultaneously find dust, water ice, and surface emissivity spectral shapes. Both algorithms have been applied to TES spectra, and both find very similar atmospheric and surface spectral shapes. For TES spectra taken during aerobraking and science phasing periods in nadir-geometry these two algorithms give meaningful and usable surface emissivity spectra that can be used for mineralogical identification.

Smith, Michael D.↗
NASA NTRS1999

Mars Global Surveyor Thermal Emission Spectrometer (TES) Observations of Dust Opacity During Aerobraking and Science Phasing

The Mars Global Surveyor (MGS) arrived at Mars in September 1997 near Mars southern spring equinox and has now provided monitoring of conditions in the Mars atmosphere for more than half a Mars year. The large majority of the spectra taken by the Thermal Emission Spectrometer (TES) are in a nadir geometry (downward looking mode) where Mars is observed through the atmosphere. Most of these contain the distinct spectral signature of atmospheric dust. For these nadir-geometry spectra we retrieve column-integrated infrared aerosol (dust) opacities. TES observations during the aerobraking and science-phasing portions of the MGS mission cover the seasonal range L(sub s)=184 deg - 28 deg. Excellent spatial coverage was obtained in the southern hemisphere. Northern hemisphere coverage is generally limited to narrow strips taken during the periapsis pass but is still very valuable. At the beginning of the mission the 9-(micron)meter dust opacity at midsouthern latitudes was low (0.15-0.25). As the season advanced through southern spring and into summer, TES observed several regional dust storms (including the Noachis dust storm of November 1997) where peak 9-(micron)meter dust opacities approached or exceeded unity, as well as numerous smaller local storms. Both large and small dust storms exhibited significant changes in both spatial coverage and intensity over a timescale of a day. Throughout southern spring and summer the region at the edge of the retreating southern seasonal polar ice cap was observed to be consistently more dusty than other latitudes.

Smith, Michael D.↗
NASA NTRS2001

The TES Hematite-Rich Region in Sinus Meridiani: A Proposed Landing Site for the 2003 Rover

The Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor (MGS) mission has identified an accumulation of crystalline hematite (alpha-Fe2O3) that covers an area with very sharp boundaries approximately 350 by 750 km in size centered near 2 S latitude between 0 and 8 W longitude (Sinus Meridiani). The depth and shape of the hematite fundamental bands in the TES spectra show that the hematite is relatively coarse grained (greater than 5-10 micrometers). The spectrally-derived areal abundance of hematite varies with particle size from approximately 10% for particles greater than 30 micrometers in diameter to 40-60% for unpacked 10 micrometer powders. The hematite in Sinus Meridiani is thus distinct from the fine-grained (diameter less than 5-10 micrometers), red, crystalline hematite considered, on the basis of visible and near-IR data, to be a minor spectral component in Martian bright regions. A global map of the hematite abundance has been constructed using TES data from the MGS mapping mission.

Christensen, Philip R.↗
NASA NTRS2003

Reconciling the MOLA, TES, and Neutron Observations of the North Polar CO2 Mass Budget on Mars

There are now three independent observations of the CO2 polar cap mass budget of Mars' north polar cap. The first is based elevation changes detected by the Mars Orbiter Laser Altimeter (MOLA) on the Mars Global Surveyor (MGS). The second is based on MGS Thermal Emission Spectrometer (TES) broadband observations of the solar and infrared radiation fields at the top of the atmosphere. The third is based on neutron counts measured by the neutron spectrometer (NS) on Odyssey. If one assumes a cap density of 910 kg/cu m, then the peak mass loading poleward of 85 N inferred from the MOLA data is approx. 1090 kg/sq m, which compares to approx. 1150 kg/sq m inferred from TES for the same region, and 700 kg/sq m from the NS data. TES and MOLA are in good agreement, but are about 60% higher than the NS data. Is there a way to reconcile these discrepancies?

Haberle, Robert M.↗
NASA NTRS2003

Analysis of MGS TES Data over Acidalia Planitia and Cydonia Mensae: Compositional Evidence for Hydrovolcanic Activity?

For this study, Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) emissivity data for Acidalia Planitia and Cydonia Mensae (Figure 1) were assembled and used to examine the surface mineralogy of these areas. Analyzing TES data for high latitude locales such as Acidalia presents a challenge since the surface temperatures over these regions is inherently lower than for equatorial locales. In this report, analyses of TES data are described and results are evaluated for potential compositional evidence for hydrovolcanic activity in Acidalia and Cydonia.

Farrand, W. H.↗
NASA NTRS1995

Experimental Results From the Thermal Energy Storage-1 (TES-1) Flight Experiment

The Thermal Energy Storage (TES) experiments are designed to provide data to help researchers understand the long-duration microgravity behavior of thermal energy storage fluoride salts that undergo repeated melting and freezing. Such data, which have never been obtained before, have direct application to space-based solar dynamic power systems. These power systems will store solar energy in a thermal energy salt, such as lithium fluoride (LiF) or a eutectic of lithium fluoride/calcium difluoride (LiF-CaF2) (which melts at a lower temperature). The energy will be stored as the latent heat of fusion when the salt is melted by absorbing solar thermal energy. The stored energy will then be extracted during the shade portion of the orbit, enabling the solar dynamic power system to provide constant electrical power over the entire orbit. Analytical computer codes have been developed to predict the performance of a spacebased solar dynamic power system. However, the analytical predictions must be verified experimentally before the analytical results can be used for future space power design applications. Four TES flight experiments will be used to obtain the needed experimental data. This article focuses on the flight results from the first experiment, TES-1, in comparison to the predicted results from the Thermal Energy Storage Simulation (TESSIM) analytical computer code.

Jacqmin, David↗
NASA NTRS2006

Implementation of Cloud Retrievals for Tropospheric Emission Spectrometer (TES) Atmospheric Retrievals: Part 1. Description and Characterization of Errors on Trace Gas Retrievals

We develop an approach to estimate and characterize trace gas retrievals in the presence of clouds in high spectral measurements of upwelling radiance in the infrared spectral region (650-2260/cm). The radiance contribution of clouds is parameterized in terms of a set of frequency-dependent nonscattering optical depths and a cloud height. These cloud parameters are retrieved jointly with surface temperature, emissivity, atmospheric temperature, and trace gases such as ozone from spectral data. We demonstrate the application of this approach using data from the Tropospheric Emission Spectrometer (TES) and test data simulated with a scattering radiative transfer model. We show the value of this approach in that it results in accurate estimates of errors for trace gas retrievals, and the retrieved values improve over the initial guess for a wide range of cloud conditions. Comparisons are made between TES retrievals of ozone, temperature, and water to model fields from the Global Modeling and Assimilation Office (GMAO), temperature retrievals from the Atmospheric Infrared Sounder (AIRS), tropospheric ozone columns from the Goddard Earth Observing System (GEOS) GEOS-Chem, and ozone retrievals from the Total Ozone Mapping Spectrometer (TOMS). In each of these cases, this cloud retrieval approach does not introduce observable biases into TES retrievals.

aerosols↗
NASA NTRS2007

Alternative Optimizations of X-ray TES Arrays: Soft X-rays, High Count Rates, and Mixed-Pixel Arrays

We are developing arrays of superconducting transition-edge sensors (TES) for imaging spectroscopy telescopes such as the XMS on Constellation-X. While our primary focus has been on arrays that meet the XMS requirements (of which, foremost, is an energy resolution of 2.5 eV at 6 keV and a bandpass from approx. 0.3 keV to 12 keV), we have also investigated other optimizations that might be used to extend the XMS capabilities. In one of these optimizations, improved resolution below 1 keV is achieved by reducing the heat capacity. Such pixels can be based on our XMS-style TES's with the separate absorbers omitted. These pixels can added to an array with broadband response either as a separate array or interspersed, depending on other factors that include telescope design and science requirements. In one version of this approach, we have designed and fabricated a composite array of low-energy and broad-band pixels to provide high spectral resolving power over a broader energy bandpass than could be obtained with a single TES design. The array consists of alternating pixels with and without overhanging absorbers. To explore optimizations for higher count rates, we are also optimizing the design and operating temperature of pixels that are coupled to a solid substrate. We will present the performance of these variations and discuss other optimizations that could be used to enhance the XMS or enable other astrophysics experiments.

Kilbourne, C. A.↗
NASA NTRS2007

Materials Development for Auxiliary Components for Large Compact Mo/Au TES Arrays

We describe our current fabrication process for arrays of superconducting transition edge sensor microcalorimeters, which incorporates superconducting Mo/Au bilayers and micromachined silicon structures. We focus on materials and integration methods for array heatsinking with our bilayer and micromachining processes. The thin superconducting molybdenum bottom layer strongly influences the superconducting behavior and overall film characteristics of our molybdenum/gold transition-edge sensors (TES). Concurrent with our successful TES microcalorimeter array development, we have started to investigate the thin film properties of molybdenum monolayers within a given phase space of several important process parameters. The monolayers are sputtered or electron-beam deposited exclusively on LPCVD silicon nitride coated silicon wafers. In our current bilayer process, molybdenum is electron-beam deposited at high wafer temperatures in excess of 500 degrees C. Identifying process parameters that yield high quality bilayers at a significantly lower temperature will increase options for incorporating process-sensitive auxiliary array components (AAC) such as array heat sinking and electrical interconnects into our overall device process. We are currently developing two competing technical approaches for heat sinking large compact TES microcalorimeter arrays. Our efforts to improve array heat sinking and mitigate thermal cross-talk between pixels include copper backside deposition on completed device chips and copper-filled micro-trenches surface-machined into wafers. In addition, we fabricated prototypes of copper through-wafer microvias as a potential way to read out the arrays. We present an overview on the results of our molybdenum monolayer study and its implications concerning our device fabrication. We discuss the design, fabrication process, and recent test results of our AAC development.

Finkbeiner, F. m.↗
NASA NTRS2007

Indium Hybridization of Large Format TES Bolometer Arrays to Readout Multiplexers for Far-Infrared Astronomy

The advance of new detector technologies combined with enhanced fabrication methods has resulted in an increase in development of large format arrays. The next generation of scientific instruments will utilize detectors containing hundreds to thousands of elements providing a more efficient means to conduct large area sky surveys. Some notable detectors include a 32x32 x-ray microcalorimeter for Constellation-X, an infrared bolometer called SAFIRE to fly on the airborne observatory SOFIA, and the sub-millimeter bolometer SCUBA-2 to be deployed at the JCMT which will use more than 10,000 elements for two colors, each color using four 32x40 arrays. Of these detectors, SCUBA-2 is farthest along in development and uses indium hybridization to multiplexers for readout of the large number of elements, a technology that will be required to enable the next generation of large format arrays. Our current efforts in working toward large format arrays have produced GISMO, the Goddard IRAM Superconducting 2-Millimeter observer. GISMO is a far infrared instrument to be field tested later this year at the IRAM 30 meter telescope in Spain. GISMO utilizes transition edge sensor (TES) technology in an 8x16 filled array format that allows for typical fan-out wiring and wire-bonding to four 1x32 NIST multiplexers. GISMO'S electrical wiring is routed along the tops of 30 micron walls which also serve as the mechanical framework for the array. This architecture works well for the 128 element array, but is approaching the limit for routing the necessary wires along the surface while maintaining a high fill factor. Larger format arrays will benefit greatly from making electrical connections through the wafer to the backside, where they can be hybridized to a read-out substrate tailored to handling the wiring scheme. The next generation array we are developing is a 32x40 element array on a pitch of 1135 microns that conforms to the NIST multiplexer, already developed for the SCUBA-2 instrument This architecture will utilize electrical connections that route from the TES to the support frame and through the wafer. The detector chip will then be hybridized to the NIST multiplexer via indium bump bonding. In our development scheme we are using substrates that allow for diagnostic testing of electrical continuity across the entire array and we are testing our process to minimize or eliminate any contact resistance at metal interfaces. Our goal is hybridizing a fully functional 32x40 array of TES bolometers to a NIST multiplexer. The following work presents our current progress toward enabling this technology.

Miller, Timothy M.↗
NASA NTRS2005

The EOS AURA Tropospheric Emission Spectrometer (TES): Status of the Program

This slide presentation is a programmatic overview covering some of the highlights of the mission and serve as an introduction to the accompanying presentations at the workshop. It reviews the goals and the products of the TES experiment, a simplified chemistry of ozone in both the stratosphere and troposphere, a description of the instrument, and the TES operational modes. Included are graphs showing some of the results of TES analysis of the key constituents of the tropospheric chemistry and the inter-regional transport.

Fourier Transform Infrared (FTIR)↗
NASA NTRS2006

Processing TES Level-2 Data

TES Level 2 Subsystem is a set of computer programs that performs functions complementary to those of the program summarized in the immediately preceding article. TES Level-2 data pertain to retrieved species (or temperature) profiles, and errors thereof. Geolocation, quality, and other data (e.g., surface characteristics for nadir observations) are also included. The subsystem processes gridded meteorological information and extracts parameters that can be interpolated to the appropriate latitude, longitude, and pressure level based on the date and time. Radiances are simulated using the aforementioned meteorological information for initial guesses, and spectroscopic-parameter tables are generated. At each step of the retrieval, a nonlinear-least-squares- solving routine is run over multiple iterations, retrieving a subset of atmospheric constituents, and error analysis is performed. Scientific TES Level-2 data products are written in a format known as Hierarchical Data Format Earth Observing System 5 (HDF-EOS 5) for public distribution.

Poosti, Sassaneh↗
NASA NTRS2011

Development of a Real-Time Pulse Processing Algorithm for TES-Based X-Ray Microcalorimeters

We report here a real-time pulse processing algorithm for superconducting transition-edge sensor (TES) based x-ray microcalorimeters. TES-based. microca1orimeters offer ultra-high energy resolutions, but the small volume of each pixel requires that large arrays of identical microcalorimeter pixe1s be built to achieve sufficient detection efficiency. That in turn requires as much pulse processing as possible must be performed at the front end of readout electronics to avoid transferring large amounts of data to a host computer for post-processing. Therefore, a real-time pulse processing algorithm that not only can be implemented in the readout electronics but also achieve satisfactory energy resolutions is desired. We have developed an algorithm that can be easily implemented. in hardware. We then tested the algorithm offline using several data sets acquired with an 8 x 8 Goddard TES x-ray calorimeter array and 2x16 NIST time-division SQUID multiplexer. We obtained an average energy resolution of close to 3.0 eV at 6 keV for the multiplexed pixels while preserving over 99% of the events in the data sets.

Tan, Hui↗
NASA NTRS2012

Study of the Dependency on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in an AC bias configuration. For x-ray photons at 6 keV the pixel shows an x-ray energy resolution Delta E(sub FWHM) = 3.7 eV, which is about a factor 2 worse than the energy resolution observed in an identical DC-biased pixel. In order to better understand the reasons for this discrepancy we characterized the detector as a function of temperature, bias working point and applied perpendicular magnetic field. A strong periodic dependency of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recently observed weak-link behaviour of a TES microcalorimeter.

Gottardi, L.↗
NASA NTRS2013

Direct Top-down Estimates of Biomass Burning CO Emissions Using TES and MOPITT Versus Bottom-up GFED Inventory

In this study, we utilize near-simultaneous observations from two sets of multiple satellite sensors to segregate Tropospheric Emission Spectrometer (TES) and Measurements of Pollution in the Troposphere (MOPITT) CO observations over active fire sources from those made over clear background. Hence, we obtain direct estimates of biomass burning CO emissions without invoking inverse modeling as in traditional top-down methods. We find considerable differences between Global Fire Emissions Database (GFED) versions 2.1 and 3.1 and satellite-based emission estimates in many regions. Both inventories appear to greatly underestimate South and Southeast Asia emissions, for example. On global scales, however, CO emissions in both inventories and in the MOPITT-based analysis agree reasonably well, with the largest bias (30%) found in the Northern Hemisphere spring. In the Southern Hemisphere, there is a one-month shift between the GFED and MOPITT-based fire emissions peak. Afternoon tropical fire emissions retrieved from TES are about two times higher than the morning MOPITT retrievals. This appears to be both a real difference due to the diurnal fire activity variations, and a bias due to the scarcity of TES data.

bias↗
NASA NTRS2016

Parametric Characterization of TES Detectors Under DC Bias

The X-ray integrated field unit (X-IFU) in European Space Agency's (ESA's) Athena mission will be the first high-resolution X-ray spectrometer in space using a large-format transition-edge sensor microcalorimeter array. Motivated by optimization of detector performance for X-IFU, we have conducted an extensive campaign of parametric characterization on transition-edge sensor (TES) detectors with nominal geometries and physical properties in order to establish sensitivity trends relative to magnetic field, dc bias on detectors, operating temperature, and to improve our understanding of detector behavior relative to its fundamental properties such as thermal conductivity, heat capacity, and transition temperature. These results were used for validation of a simple linear detector model in which a small perturbation can be introduced to one or multiple parameters to estimate the error budget for X-IFU. We will show here results of our parametric characterization of TES detectors and briefly discuss the comparison with the TES model.

X-ray Integral Field↗
NASA NTRS2019

Design of Magnetic Shielding and Field Coils for a TES X-Ray Microcalorimeter Test Platform

The performance of transition-edge sensors (TES) and their SQUID multiplexed readouts is very sensitive to ambient magnetic field and its fluctuations. In order to run ground experiments on thousands of X-ray TES microcalorimeters with a small uniform ambient magnetic field (< 1 μT, with a uniformity < 0.1 μT), we need a very low ambient field to be trapped into the superconducting magnetic shields. We have designed a sub-Kelvin test platform to reach these specifications. For this purpose, we modeled a new design for the shielding consisting of a series of different mu-metal and superconducting shields, including a niobium shield at 50 mK, a cryoperm (A4K) shield at 3 K, and a mu-metal shield at 300 K. A magnetic field coil is used to vary the local perpendicular magnetic field over the TES array. To optimize this field, we have studied a number of different field-coil designs and the impact of the different shield geometries, in order to reach the required field uniformity.

Miniussi, Antoine R.↗