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NASA NTRS2002

Large Format Si:As IBC Array Performance for NGST and Future IR Space Telescope Applications

A mid-IR (5-30micrometer) instrument aboard a cryogenic space telescope can have an enormous impact in resolving key questions in astronomy and cosmology. A space platform's greatly reduced thermal backgrounds (compared to airborne or ground-based platforms), allow for more sensitive observations of dusty young galaxies at high redshifts, star formation of solar-type stars in the local universe, and formation and evolution of planetary disks and systems. The previous generation's largest, in sensitive IR detectors at these wavelengths are 256x256 pixel Si:As Impurity Band Conduction (IBC) devices built by Raytheon Infrared Operations (RIO) for the Space Infrared Telescope Facility/Infrared Array Camera (SIRTF)/(IRAC) instrument. RIO has successfully enhanced these devices, increasing the pixel count by a factor of 16 while matching or exceeding SIRTF/IRAC device performance. NASA-ARC in collaboration with RIO has tested the first high performance large format (1024x 1024) Si:As IBC arrays for low background applications, such as for the middle instrument on Next Generation Space Telescope (NGST) and future IR Explorer missions. These hybrid devices consist of radiation hard SIRTF/IRAC-type Si:As IBC material mated to a readout multiplexer that has been specially processed for operation at low cryogenic temperatures (below 10K), yielding high device sensitivity over a wavelength range of 5-28 micrometers. We present laboratory testing results from these benchmark, devices. Continued development in this technology is essential for conducting large-area surveys of the local and early universe through observation and for complementing future missions such as NGST, Terrestrial Planet Finder (TPF), and Focal Plane Instruments and Requirement Science Team (FIRST).

Ennico, Kimberly↗
NASA NTRS2005

Mercury: First Spectra from 8 to 25 Microns Using MIRSI

Spectral measurements from 8 to 25 microns of Mercury's surface were taken using MIRSI (Mid-InfraRed Spectrometer and Imager) mounted on the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii [1]. Few spectral observations of Mercury have been made between 8 and 14 m and these are the first to be made between 17 and 25 m. The goal for these observations is to measure the emission from Mercury in the Restrahllen Bands in the 8 to 25 micron region in an effort to identify spectral features that may give clues to Mercury s composition. These observations will be compared to previous observations [2] [3] [4], and future observations made with instrumentation on Messenger at other spectral regions [5]. Spectra from the Moon were also obtained with the same instrumentation and telescope during the same observing periods.

Hanna, K. L. Donaldson↗
NASA NTRS2010

Ultra-High Resolution Spectroscopic Remote Sensing: A Microscope on Planetary Atmospheres

Remote sensing of planetary atmospheres is not complete without studies of all levels of the atmosphere, including the dense cloudy- and haze filled troposphere, relatively clear and important stratosphere and the upper atmosphere, which are the first levels to experience the effects of solar radiation. High-resolution spectroscopy can provide valuable information on these regions of the atmosphere. Ultra-high spectral resolution studies can directly measure atmospheric winds, composition, temperature and non-thermal phenomena, which describe the physics and chemistry of the atmosphere. Spectroscopy in the middle to long infrared wavelengths can also probe levels where dust of haze limit measurements at shorter wavelength or can provide ambiguous results on atmospheric species abundances or winds. A spectroscopic technique in the middle infrared wavelengths analogous to a radio receiver. infrared heterodyne spectroscopy [1], will be describe and used to illustrate the detailed study of atmospheric phenomena not readily possible with other methods. The heterodyne spectral resolution with resolving power greater than 1,000.000 measures the true line shapes of emission and absorption lines in planetary atmospheres. The information on the region of line formation is contained in the line shapes. The absolute frequency of the lines can be measured to I part in 100 ,000,000 and can be used to accurately measure the Doppler frequency shift of the lines, directly measuring the line-of-sight velocity of the gas to --Im/s precision (winds). The technical and analytical methods developed and used to measure and analyze infrared heterodyne measurements will be described. Examples of studies on Titan, Venus, Mars, Earth, and Jupiter will be presented. 'These include atmospheric dynamics on slowly rotating bodies (Titan [2] and Venus [3] and temperature, composition and chemistry on Mars 141, Venus and Earth. The discovery and studies of unique atmospheric phenomena will also be described, such as non-thermal and lasing phenomena on Mars and Venus, mid-infrared aurora on Jupiter [5], and results of small body impacts on Jupiter [6]. The heterodyne technique can also be applied for detailed study of the Earth's stratosphere and mesosphere by measuring trace constituent abundances and temporal and spatial variability as well as winds, which provide information of transport. All ground-based measurements will be described as complementary and supporting studies for on-going and future space missions [7] (Mars Express, Venus Express, Cassini Huygens, JUNO, ExoMars Trace Gas Orbiter, and the Europa Jupiter System Mission, an Earth Science Venture Class missions), Proposed instrument and technology development for a space flight infrared heterodyne spectrometer will be described.

Kostiuk, Theodor↗
NASA NTRS2009

On the Nature of the First Galaxies Selected at 350 Micrometers

We present constraints on the nature of the first galaxies selected at 350 micrometers. The sample includes galaxies discovered in the deepest blank-field survey at 350 micrometers (in the Bo6tes Deep Field) and also later serendipitous detections in the Lockman Hole. In determining multiwavelength identifications, the 350 lam position and map resolution of the second generation Submillimeter High Angular Resolution Camera are critical, especially in the cases where multiple radio sources exist and the 24 micrometer counterparts are unresolved. Spectral energy distribution templates are fitted to identified counterparts, and the sample is found to comprise IR-luminous galaxies at 1 < z < 3 predominantly powered by star formation. The first spectrum of a 350 micrometer selected galaxy provides an additional confirmation, showing prominent dust grain features typically associated with star-forming galaxies. Compared to submillimeter galaxies selected at 850 and 1100 micrometers, galaxies selected at 350 micrometers have a similar range of far-infrared color temperatures. However, no 350 micrometer selected sources are reliably detected at 850 or 1100 micrometers. Galaxies in our sample with redshifts 1 < z < 2 show a tight correlation between the far- and mid-infrared flux densities, but galaxies at higher redshifts show a large dispersion in their mid- to far-infrared colors. This implies a limit to which the mid-IR emission traces the far-IR emission in star-forming galaxies. The 350 micrometer flux densities (15 < S(sub 350) < 40 mJy) place these objects near the Herschel/SPIRE 350 micrometer confusion threshold, with the lower limit on the star formation rate density suggesting the bulk of the 350 micrometers contribution will come from less luminous infrared sources and normal galaxies. Therefore, the nature of the dominant source of the 350 micrometers background-star-forming galaxies in the epoch of peak star formation in the universe-could be more effectively probed using ground-based instruments with their angular resolution and sensitivity offering significant advantages over space-based imaging. Key words: galaxies: high-redshift galaxies: starburst infrared: galaxies submillimeter

Khan, Sophia A.↗
NASA NTRS2012

Characterization of Hayabusa II Target Asteroid (162173) 1999 JU3

The Japanese Hayabusa II mission is planned to rendezvous with and return a sample from the near-Earth asteroid (162173) 1999 JU3. Previous mid-infrared studies have constrained the albedo and thermal properties of this object (Muller et al. 2011; Campins et al. 2011; Hasegawa et al. 2008). Visible wavelength spectra from 1999 and 2007 reveal a C-type asteroid that displays pronounced spectroscopic variability around 0.7 microns. Variability in the strength of a 0.7 micron band could be due to heterogeneous concentrations of iron-bearing phyllosilicates across its surface (Vilas 2008). We will present new observations from the favorable 2012 apparition to further characterize this object. In June of 2012 spectroscopic observations were conducted with the LDSS3 and FIRE instruments on the Magellan telescopes at Las Campanas Observatory in Chile. Between April and July of 2012 broadband visible-wavelength photometry was obtained with the Tenagra II telescope in Arizona and with the IMACS, Megacam and LDSS3 instruments on the Magellan telescopes. Our visible and near-infrared spectra confirm a C-type taxonomic classification, but do not show evidence for the presence of a 0.7 micron phyllosilicate band. Our time series of visible spectra cover approximately 60% of the rotational phases of 1999 JU3, but do not display any pronounced variability. We use our new optical light curves, combined with photometry from 2007, to refine a shape model of the asteroid. This shape model provides a means for mapping surface regions accessed by the spectroscopic observations from both 2007 and 2012, and thus to directly address the possibility of surface heterogeneity. This surface map, in conjunction with the newly measured photometric phase curve of the asteroid, will be used to make predictions regarding composition and surface properties that will ultimately be tested upon arrival of the Hayabusa II spacecraft.

Moskovitz, Abe↗
NASA NTRS2004

Background-Limited Infrared-Submillimeter Spectroscopy (BLISS)

The bulk of the cosmic far-infrared background light will soon be resolved into its individual sources with Spitzer, Astro-F, Herschel, and submm/mm ground-based cameras. The sources will be dusty galaxies at z approximately equal to 1-4. Their physical conditions and processes in these galaxies are directly probed with moderate-resolution spectroscopy from 20 micrometers to 1 mm. Currently large cold telescopes are being combined with sensitive direct detectors, offering the potential for mid-far-IR spectroscopy at the background limit (BLISS). The capability will allow routine observations of even modest high-redshift galaxies in a variety of lines. The BLISS instrument's capabilities are described in this presentation.

spectrometers↗
NASA NTRSDate not supplied

PRIMA: The PRobe Far-Infrared Mission for Astrophysics

PRIMA is a far-infrared observatory concept being developed to address timely and fundamental questions about the growths of galaxies and solar systems and their constituents. It will observe the build-up of heavy elements, dust, stars, and black holes in galaxies and their interrelationships, and trace the masses and water contents of protoplanetary disks to probe the growths of solar systems. The majority of observing time will be devoted to Guest Observer programs to enable the astrophysics community to identify and plan the most critical observations, with focused PI programs to address key science with rapid releases of data to inform community planning. PRIMA will have spectral, hyperspectral imaging, and polarimetric capabilities, enabled now for the first time by extraordinary progress in kinetic inductance detector (KID) array technology over the last two decades. The 2.0-meter telescope will be cooled to < 5 K to take maximum advantage of the KID sensitivities. For observations of atomic fine-structure lines, molecular lines, and solid-state emission and absorption bands, R = 200 spectral coverage will range from approximately 25 µm to 200 µm, with a high-resolution mode across the entire band that will have a spectral resolving power of a few thousand at 100 µm. R ~ 10 moderate-resolution (hyperspectral) imaging will range from 25 to 80 µm for rest-frame, mid- and far-infrared spectral energy distribution measurements to probe dust grain composition and disambiguate star formation and active galactic nuclei in galaxies. Polarimetric observations of large areas of Galactic molecular clouds and the Magellanic Clouds from 80 to ~200 µm will bridge between the large-scale polarimetry of the interstellar medium from cosmic microwave background observatories and protostellar disk-scale interferometric observations to probe magnetic fields at the critical scales at which clouds collapse to form stars. An overview of PRIMA’s basic design and capabilities will be presented. Other posters in this session describe PRIMA science, technology, and instrumentation in greater depth.

Jason Glenn↗
NASA NTRS2007

"Constellation-X and JWST: Concurrent X-ray and Infrared Great Observatories"

Great synergy has been enjoyed between NASA's current Great Observatories and we expect that this will continue in the next decade with the concurrent operation of both Constellation-X and JWST. The great increase in sensitivity offered by these two observatories, working in unison, will be required for a number of key science investigations, several of which we describe in this poster. For instance, although >SO% of the cosmic X-ray background is resolved at 2-8 keV in the deepest Chandra surveys, the peak of the cosmic X-ray background remains largely unexplained (at energies of 8-40 keV). There may be a significant population of obscured (perhaps Compton-thick) AGN that produce this part of the extragalactic background radiation, and Constellation-X's large collecting area and spectroscopic capabilities over the 1-40 keV bandpass will allow determination of the nature of the obscuring material. This obscured nuclear emission is expected to be re-emitted at longer wavelengths and hence mid-infrared (MIR) observations can be crucial to reveal obscured AGN emission. However, current photometric observations in the infrared are limited by contamination from star formation, and sensitive, moderate-to-high resolution IR spectroscopy (provided by JWST) will be required. In addition, the two observatories will make great advances in unraveling the nature of the highest redshift AGN (4 < z < 8; and possibly ~ 8dow)n to Seyfert luminosities and will probe the formation and evolution of galaxy groups and clusters (including important cosmological measurements). This poster describes these science areas and briefly touches upon the role of the various Con-X and JWST instruments in these science investigations.

Hornschemeier, Ann↗
NASA NTRS1985

BIG MAC: A bolometer array for mid-infrared astronomy, Center Director's Discretionary Fund

The infrared array referred to as Big Mac (for Marshall Array Camera), was designed for ground based astronomical observations in the wavelength range 5 to 35 microns. It contains 20 discrete gallium-doped germanium bolometer detectors at a temperature of 1.4K. Each bolometer is irradiated by a square field mirror constituting a single pixel of the array. The mirrors are arranged contiguously in four columns and five rows, thus defining the array configuration. Big Mac utilized cold reimaging optics and an up looking dewar. The total Big Mac system also contains a telescope interface tube for mounting the dewar and a computer for data acquisition and processing. Initial astronomical observations at a major infrared observatory indicate that Big Mac performance is excellent, having achieved the design specifications and making this instrument an outstanding tool for astrophysics.

Telesco, C. M.↗
NASA NTRS2005

Satellite Infrared Radiation Measurements Prior to the Major Earthquakes

This work describes our search for a relationship between tectonic stresses and increases in mid-infrared (IR) flux as part of a possible ensemble of electromagnetic (EM) phenomena that may be related to earthquake activity. We present and &scuss observed variations in thermal transients and radiation fields prior to the earthquakes of Jan 22, 2003 Colima (M6.7) Mexico, Sept. 28 .2004 near Parkfield (M6.0) in California and Northern Sumatra (M8.5) Dec. 26,2004. Previous analysis of earthquake events has indicated the presence of an IR anomaly, where temperatures increased or did not return to its usual nighttime value. Our procedures analyze nighttime satellite data that records the general condtion of the ground after sunset. We have found from the MODIS instrument data that five days before the Colima earthquake the IR land surface nighttime temperature rose up to +4 degrees C in a 100 km radius around the epicenter. The IR transient field recorded by MODIS in the vicinity of Parkfield, also with a cloud free environment, was around +1 degree C and is significantly smaller than the IR anomaly around the Colima epicenter. Ground surface temperatures near the Parkfield epicenter four days prior to the earthquake show steady increase. However, on the night preceding the quake, a significant drop in relative humidity was indicated, process similar to those register prior to the Colima event. Recent analyses of continuous ongoing long- wavelength Earth radiation (OLR) indicate significant and anomalous variability prior to some earthquakes. The cause of these anomalies is not well understood but could be the result of a triggering by an interaction between the lithosphere-hydrosphere and atmospheric related to changes in the near surface electrical field and/or gas composition prior to the earthquake. The OLR anomaly usually covers large areas surrounding the main epicenter. We have found strong anomalies signal (two sigma) along the epicentral area signals on Dec 21, five days prior to the Northern Sumatra quake compared to the reference field for December 2001-2004 periods. Our recent results support the hypothesis of a possible relationship between a thermodynamic processes produced by increasing tectonic stress in the Earth's crust and a subsequent electro-chemical interaction between this crust and the atmosphere/ionosphere.

Ouzounov, Dimitar↗
NASA NTRS2009

Infrared Heterodyne Spectroscopy and its Unique Application to Planetary Studies

Since the early 1970's the infrared heterodyne technique has evolved into a powerful tool for the study of molecular constituents, temperatures, and dynamics in planetary atmospheres. Its extremely high spectral resolution (Lambda/(Delta)Lambda/>10(exp 6)) and highly accurate frequency measurement (to 1 part in 10(exp 8)) enabled the detection of nonthermal/natural lasing phenomena on Mars and Venus; direct measurements of winds on Venus, Mars, and Titan; study of mid-infrared aurorae on Jupiter; direct measurement of species abundances on Mars (ozone, isotopic CO2), hydrocarbons on Jupiter, Saturn., Neptune, and Titan, and stratospheric composition in the Earth's stratosphere (O3, CIO, N2O, CO2 ....). Fully resolved emission and absorption line shapes measured by this method enabled the unambiguous retrieval of molecular abundances and local temperatures and thermal structure in regions not probed by other techniques. The mesosphere of Mars and thermosphere of Venus are uniquely probed by infrared heterodyne spectroscopy. Results of these studies tested and constrained photochemical and dynamical theoretical models describing the phenomena measured. The infrared heterodyne technique will be described. Highlights in its evolution to today's instrumentation and resultant discoveries will be presented, including work at Goddard Space Flight Center and the University of Koln. Resultant work will include studies supporting NASA and ESA space missions and collaborations between instrumental and theoretical groups.

Kostiuk, Theodore↗
NASA NTRS2021

Accounting for the photochemical variation in stratospheric NO2 in the SAGE III/ISS solar occultation retrieval

The Stratospheric Aerosol and Gas Experiment (SAGE) III has been operating on the International Space Station (ISS) since mid-2017. Nitrogen dioxide (NO2) number density profiles are routinely retrieved from SAGE III/ISS solar occultation measurements in the middle atmosphere. Although NO2 density varies throughout the day due to photochemistry, the standard SAGE NO2 retrieval algorithm neglects these variations along the instrument’s line of sight by assuming that the number density has a constant gradient within a given vertical layer of the atmosphere. This assumption will result in a retrieval bias for a species like NO2 that changes rapidly across the terminator. In this work we account for diurnal variations in retrievals of NO2 from the SAGE III/ISS measurements, and we determine the impact of this algorithm improvement on the resulting NO2 number densities. The first step in applying the diurnal correction is to use publicly available SAGE III/ISS products to convert the retrieved number density profiles to optical depth profiles. The retrieval is then re-performed with a new matrix that applies photochemical scale factors for each point along the line of sight according to the changing solar zenith angle. In general NO2 that is retrieved by accounting for these diurnal variations is more than 10% lower than the standard algorithm below 30 km. This effect is greatest in winter at high latitudes and generally greater for sunrise occultations than sunset. Comparisons with coincident profiles from the Optical Spectrograph and InfraRed Imager System (OSIRIS) show that NO2 from SAGE III/ISS is generally biased high; however the agreement improves by up to 20% in the mid-stratosphere when diurnal variations are accounted for in the retrieval. We conclude that diurnal variations along the SAGE III/ISS line of sight are an important term to consider for NO2 analyses at altitudes below 30 km.

Stratospheric NO2↗
NASA NTRS1989

The use of aircraft and satellite remote sensing of phytoplankton chlorophyll concentrations in case 2 estuarine waters of the Chesapeake Bay

Two projects using remote sensing of phytoplankton chlorophyll concentrations in the Chesapeake Bay estuary were proposed. The first project used aircraft remote sensing with a compact radiometer system developed at NASA's Goddard Space Flight Center (GSFC), the Ocean Data Acquisition System (ODAS). ODAS includes three radiometers at 460, 490, and 520 nm, an infrared temperature sensor (PRT-5), Loran-C for navigation, and a data acquisition system using a PC and mass storage device. This instrument package can be flown in light aircraft at relatively low expense, permitting regular and frequent flights. Sixteen flights with ODAS were completed using the Virginia Institute of Marine Science's De Havilland 'Beaver'. The goal was to increase spatial and temporal resolution in assaying phytoplankton pigment concentrations in the Chesapeake. At present, analysis is underway of flight data collected between March and July 1989. The second project focused on satellite data gathered with the Nimbus-7 Coastal Zone Color Scanner (CZSC) between late 1978 and mid 1986. The problem in using CZSC data for the Chesapeake Bay is that the optical characteristics of this (and many) coastal and estuarine waters are distinct from those of the open ocean for which algorithms for computing pigment concentrations were developed. The successful use of CZCS data for the estuary requires development of site-specific algorithms and analytical approaches. Of principal importance in developing site-specific procedures is the availability of in-situ data on pigment concentrations. A significant data set was acquired from EPA's Chesapeake Bay Program in Annapolis, Maryland, and clear satellite scenes are being analyzed for which same-day sea truth measurements of pigment were obtained. Both the University of Miami and GSFC Seapak systems are being used in this effort. The main finding to date is an expected one, i.e., the algorithms developed for oceanic waters are inadequate to compute pigment concentrations for the Case 2 waters of the Chesapeake Bay. One reason is the overestimation of aerosol radiances by assuming that water-leaving radiance in Band 4 of CZCS (670 nm) is zero, an assumption that is invalid for the Bay. This prompted any attempts to iterative procedures for estimating the proportion of the Band 4 radiance that is actually attributable to aerosol by estimating the water-leaving component using optical data. A cruise on the Chesapeake the week of 7 August 1989 was conducted to collect additional optical data necessary to this task.

Harding, Lawrence W., Jr.↗
NASA NTRS1999

Quantitative Species Measurements in Microgravity Combustion Flames using Near-Infrared Diode Lasers

Understanding the physical phenomena controlling the ignition and spread of flames in microgravity has importance for space safety as well as for characterizing dynamical and chemical combustion processes which are normally masked by buoyancy and other gravity-related effects. Unfortunately, combustion is highly complicated by fluid mechanical and chemical kinetic processes, requiring the use of numerical modeling to compare with carefully designed experiments. More sophisticated diagnostic methods are needed to provide the kind of quantitative data necessary to characterize the properties of microgravity combustion as well as provide accurate feedback to improve the predictive capabilities of the models. Diode lasers are a natural choice for use under the severe conditions of low gravity experiments. Reliable, simple solid state operation at low power satisfies the operational restrictions imposed by drop towers, aircraft and space-based studies. Modulation wavelength absorption spectroscopy (WMS) provides a means to make highly sensitive and quantitative measurements of local gas concentration and, in certain cases, temperature. With near-infrared diode lasers, detection of virtually all major combustion species with extremely rapid response time is possible in an inexpensive package. Advancements in near-infrared diode laser fabrication technology and concurrent development of optical fibers for these lasers led to their use in drop towers. Since near-infrared absorption line strengths for overtone and combination vibrational transitions are weaker than the mid-infrared fundamental bands, WMS techniques are applied to increase detection sensitivity and allow measurement of the major combustion gases. In the first microgravity species measurement, Silver et al. mounted a fiber-coupled laser at the top of the NASA 2.2-sec drop tower and piped the light through a single-mode fiber to the drop rig. A fiber splitter divided the light into eight channels that directed the laser beam across a methane or propane diffusion jet flame. The light beams were recaptured by a set of gradient index lenses, coupled back into separate fiber optic lines, and transmitted back to detectors and electronics in the instrument package. In these experiments a 6-mm od fiber cable (containing the nine optical fibers) fell with the drop rig. Using separate detection and demodulation channels, spatial and temporal (up to 20 Hz) maps of water vapor and methane concentrations were obtained at differing heights in the flames. While this apparatus was useful from a demonstration standpoint, several drawbacks needed attention before useful scientific measurements could be obtained. First, eight lines of sight are somewhat insufficient for detailing the spatial profiles of the gas. Second, multiple detection channels operating in parallel are both expensive and present a challenge for accurate calibration. As a result, a newer scanning system was developed in our first contract under this program. The primary characteristic of this system is that it contains a single detection channel and achieves "continuous" spatial resolution by scanning the laser beam across the flame region, then directing this beam onto a single detector. Thus spatial measurements are converted to a temporal series of data. The true spatial resolution is limited only by the beam diameter and width of the sweep. In these experiments the beam is focused to about 1-mm diameter and scans across a region up to 4-cm wide.

Silver, Joel A.↗
NASA NTRS1980

Pioneer Saturn

The Pioneer Saturn spacecraft, designated Pioneer 11 until its encounter with Jupiter, is presented, and its trajectory is reported. The 550-pound spin-stabilized spacecraft carries 12 scientific instruments, 11 of which were operational during its encounters with Jupiter and Saturn. After the successful completion of the Pioneer 10 Jupiter fly-by, for which Pioneer 11 was intended as a back-up, the Pioneer 11 spacecraft was committed to a Saturn-bound trajectory, and was sent on a spiral trajectory around Jupiter to approach Saturn. After mid-course maneuvers, the spacecraft arrived at Saturn on September 1, 1979, where it penetrated the ring plane outside of the visible rings, descending from above the ecliptic plane late in the morning quadrant, and making measurements of the planetary magnetosphere and its interaction with the solar wind, infrared radiation and gravitational and atmospheric effects on the radio signal. Pioneer Saturn departed from Saturn slightly above the ring plane, crossing the orbit of Titan 25 hr after Saturn flyby, and became the second spacecraft to escape the solar system.

Dyer, J. W.↗
NASA NTRS2022

Surface Biology and Geology (SBG) Thermal Infrared (TIR) Free -Flyer Concept

Scientists and engineers from the United States and Italy are developing a thermal infrared (TIR) free-flyer concept that forms an essential element of the NASA Surface Biology & Geology (SBG) designated observable and the greater NASA Earth System Observatory (ESO), which also includes observations of aerosols, clouds, convection, and precipitation; mass change; and surface deformation & change.In response to the recommendations from the 2017 National Academies decadal survey for Earth science, NASA initiated the SBG designated observable with five key research and applications focus areas: ecosystems and natural resources, hydrology, weather, climate, and solid Earth. SBG includes spaceborne measurements of hyperspectral imagery in the visible to shortwave infrared (0.4-2.5 um) and multispectral imagery in the mid and thermal infrared (3-12 um) that provide the remote sensing data needed to inform each research and applications area. High-level TIR data products include Earth surface temperature & emissivity, evapotranspiration, substrate composition, volcanic plumes, and high-temperature features. While the science, applications, and technology build on prior mission studies conducted for more than a decade, it has only been recently that a joint team of scientists and engineers from the NASA Jet Propulsion Laboratory (JPL), Agenzia Spaziale Italiana (ASI), Istituto Nazionale Geofisica e Volcanologia (INGV), and the Istituto Nazionale Astrofisica (INAF) have developed a compelling concept for a TIR free-flyer. In this concept, the TIR instrument is an eight-band radiometer. Seven of the bands are between 3 and 12 um with an additional band at 1.65 um. The instrument’s 68.8 deg total viewing angle and the free-flyer’s 665 km operational altitude results in a ground sampling distance (GSD) of <60 m at nadir, produces a swath width of 935 km, and allows for a 2-3-day revisit time. A two-band visible and near infrared (VNIR) camera, with <30 m GSD at nadir and 935 km swath width, will complement the TIR instrument. VNIR high-level data products include top & bottom of atmosphere reflectance and normalized difference vegetation indices (NDVI). The TIR instrument and VNIR camera will be mounted on a PLATiNO+ spacecraft, a multi-application, reconfigurable, and scalable platform. The launcher selected for the TIR free-flyer is the VEGA-C. To maximize the science and applications benefits the SBG-TIR free-flyer team are collaborating with personnel from the ESA Land Surface Temperature Monitoring mission (LSTM) as well individuals from the Thermal Infrared Imaging Satellite for High-resolution Natural resource Assessment (TRISHNA), a joint mission by CNES and ISRO. Pre-Phase A concept studies for the SBG-TIR free-flyer commenced in the spring 2021. This allows for the concept to be refined; for technical risks to be identified and mitigated, as necessary; and strategies for reducing the development schedule to be defined and assessed before conducting a NASA-ASI Mission Concept Review (MCR) in the spring of 2022 and a NASA Key Decision Point-A (KDP-A) as early as the summer of 2022. These are key milestones in being able to launch and begin operating the SBG-TIR free-flyer in the second half of the decade, so that many of the questions posed by the National Academies in the 2017 decadal survey can be answered.

Fabrizia-Buongiorno, Maria↗
NASA NTRS2020

High-resolution Infrared Spectroscopy of Hot Molecular Gas in AFGL 2591 and AFGL 2136: Accretion in the Inner Regions of Disks around Massive Young Stellar Objects

We have performed a high-resolution 4–13 μm spectral survey of the hot molecular gas associated with the massive protostars AFGL 2591 and AFGL 2136, utilizing the Echelon Cross Echelle Spectrograph (EXES) on board the Stratospheric Observatory for Infrared Astronomy, and the iSHELL instrument and Texas EchelonCross Echelle Spectrograph (TEXES) on the NASA Infrared Telescope Facility (IRTF). Here we present the results of this survey with analysis of CO, HCN, C2H2, NH3, and CS, deriving the physical conditions for each species. Also from the IRTF, iSHELL data at 3 μm for AFGL 2591are presented that show HCN and C2H2 in emission. In the EXES and TEXES data, all species are detected in absorption, and temperatures and abundances are found to be high (600 K and 10−6, respectively). Differences of up to an order of magnitude in the abundances of transitions that trace the same ground-state level are measured for HCN and C2H2. The mid-infrared continuum is known to originate in a disk, hence we attribute the infrared absorption to arise in the photosphere of the disk. As absorption lines require an outwardly decreasing temperature gradient, we conclude that the disk is heated in the midplane by viscous heating due to accretion. We attribute the near-IR emission lines to scattering by molecules in the upper layers of the disk photosphere. The absorption lines trace the disk properties at 50 au where high-temperature gasphase chemistry is taking place. Abundances are consistent with chemical models of the inner disk of Herbig disks.

Andrew Barr↗