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NASA NTRS2000

Ground-Based Measurements of Stratospheric Composition from Mt. Barcroft, California

The MkIV is an FTIR spectrometer designed and built at JPL in the 1980's for remote sensing the composition of the Earth's atmosphere by solar absorption spectrometry. Optically, MkIV is very similar to the JPL ATMOS instrument, which flew three times on the Space Shuttle. Both use double-passed configurations with a KBr beamsplitter and compensator, in order to cover the mid-infrared. The main advantage of the MkIV is that it uses two detectors in parallel, a HgCdTe photoconductor for the long wavelengths and an InSb photodiode for the short wavelengths, allowing the entire 650 to 5650/cm region to be measured simultaneously. At a 10 kHz sampling rate, each 130 cm OPD interferogram takes 3 minutes to acquire. This paper describes how the MkIV instrument was adapted for remote operation from the Barcroft site, where the harsh winter conditions make access difficult. Some of the main technical challenges will be discussed including, (i) operation from solar panels and batteries, (ii) cooling the detectors with LN2, (iii) instrument control and monitoring over a cellular phone, and (iv) data storage, processing and analysis. Finally, MkIV spectra measured from Barcroft are compared with those measured from JPL to highlight the advantages of the higher altitude site.

Toon, G. C.↗
NASA NTRS2008

2003 Mars Exploration Rover Mission: Robotic Field Geologists for a Mars Sample Return Mission

The Mars Exploration Rover (MER) Spirit landed in Gusev crater on Jan. 4, 2004 and the rover Opportunity arrived on the plains of Meridiani Planum on Jan. 25, 2004. The rovers continue to return new discoveries after 4 continuous Earth years of operations on the surface of the red planet. Spirit has successfully traversed 7.5 km over the Gusev crater plains, ascended to the top of Husband Hill, and entered into the Inner Basin of the Columbia Hills. Opportunity has traveled nearly 12 km over flat plains of Meridiani and descended into several impact craters. Spirit and Opportunity carry an integrated suite of scientific instruments and tools called the Athena science payload. The Athena science payload consists of the 1) Panoramic Camera (Pancam) that provides high-resolution, color stereo imaging, 2) Miniature Thermal Emission Spectrometer (Mini-TES) that provides spectral cubes at mid-infrared wavelengths, 3) Microscopic Imager (MI) for close-up imaging, 4) Alpha Particle X-Ray Spectrometer (APXS) for elemental chemistry, 5) Moessbauer Spectrometer (MB) for the mineralogy of Fe-bearing materials, 6) Rock Abrasion Tool (RAT) for removing dusty and weathered surfaces and exposing fresh rock underneath, and 7) Magnetic Properties Experiment that allow the instruments to study the composition of magnetic martian materials [1]. The primary objective of the Athena science investigation is to explore two sites on the martian surface where water may once have been present, and to assess past environmental conditions at those sites and their suitability for life. The Athena science instruments have made numerous scientific discoveries over the 4 plus years of operations. The objectives of this paper are to 1) describe the major scientific discoveries of the MER robotic field geologists and 2) briefly summarize what major outstanding questions were not answered by MER that might be addressed by returning samples to our laboratories on Earth.

Ming, Douglas W.↗
NASA NTRS1999

Titan

With a launch in December 2001, Space Infrared Telescope Facility (SIRTF) can observe Titan in the interval after Infrared Space Observatory (ISO) but before the onset of observations by Cassini. By virtue of its broad spectral coverage in the thermal infrared, 10-180 micron, its moderately high spectral resolution, approaching lambda/delta lambda=600 over part of this wavelength range, and the very high sensitivity of its helium- cooled detectors, the Infrared Spectrometer (IRS) and MIPS on SIRTF can address several issues raised through earlier observations by the Voyager IRIS experiment and by ISO. These include, for example, a better characterization of the vertical distribution of water in Titan's middle and upper atmospheres and the discovery of new compounds, such as allene or proprionitrile. This talk will address the temperature- and composition-sounding capabilities of SIRTF, particularly in the context of how they will complement Cassini observations and aid in their planning.

Flasar, F. M.↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Future Missions to the Moon

This document contained the following topics: A Miniature Mass Spectrometer Module; SELENE Gamma Ray Spectrometer Using Ge Detector Cooled by Stirling Cryocooler; Lunar Elemental Composition and Investigations with D-CIXS X-Ray Mapping Spectrometer on SMART-1; X-Ray Fluorescence Spectrometer Onboard the SELENE Lunar Orbiter: Its Science and Instrument; Detectability of Degradation of Lunar Impact Craters by SELENE Terrain Camera; Study of the Apollo 16 Landing Site: As a Standard Site for the SELENE Multiband Imager; Selection of Targets for the SMART-1 Infrared Spectrometer (SIR); Development of a Telescopic Imaging Spectrometer for the Moon; The Lunar Seismic Network: Mission Update.

Source record↗
NASA NTRS2004

Reflectance Experiment Laboratory (RELAB) Description and User's Manual

Spectroscopic data acquired in the laboratory provide the interpretive foundation upon which compositional information about unexplored or unsampled planetary surfaces is derived from remotely obtained reflectance spectra. The RELAB is supported by NASA as a multi-user spectroscopy facility, and laboratory time can be made available at no charge to investigators who are in funded NASA programs. RELAB has two operational spectrometers available to NASA scientists: 1) a near- ultraviolet, visible, and near-infrared bidirectional spectrometer and 2) a near- and mid- infrared FT-IR spectrometer. The overall purpose of the design and operation of the RELAB bidirectional spectrometer is to obtain high precision, high spectral resolution, bidirectional reflectance spectra of earth and planetary materials. One of the key elements of its design is the ability to measure samples using viewing geometries specified by the user. This allows investigators to simulate, under laboratory conditions, reflectance spectra obtained remotely (i.e., with spaceborne, telescopic, and airborne systems) as well as to investigate geometry dependent reflectance properties of geologic materials. The Nicolet 740 FT-IR spectrometer currently operates in reflectance mode from 0.9 to 25 Fm. Use and scheduling of the RELAB is monitored by a 4-member advisory committee. NASA investigators should direct inquiries to the Science Manager or RELAB Operator.

Pieters, Carle M.↗
NASA NTRS2004

Comparison of Landsat-7 Enhanced Thematic Mapper Plus (ETM+) and Earth Observing One (EO-1) Advanced Land Imager

We compare images from the Enhanced Thematic Mapper Plus (ETM+) sensor on Landsat-7 and the Advanced Land Imager (ALI) instrument on Earth Observing One (EO-1) over a test site in Rochester, New York. The site contains a variety of features, ranging from water of varying depths, deciduous/coniferous forest, and grass fields, to urban areas. Nearly coincident cloud-free images were collected one minute apart on 25 August 2001. We also compare images of a forest site near Howland, Maine, that were collected on 7 September, 2001. We atmospherically corrected each pair of images with the Second Simulation of the Satellite Signal in the Solar Spectrum (6S) atmosphere model, using aerosol optical thickness and water vapor column density measured by in situ Cimel sun photometers within the Aerosol Robotic Network (AERONET), along with ozone density derived from the Total Ozone Mapping Spectrometer (TOMS) on the Earth Probe satellite. We present true-color composites from each instrument that show excellent qualitative agreement between the multispectral sensors, along with grey-scale images that demonstrate a significantly improved ALI panchromatic band. We quantitatively compare ALI and ETM+ reflectance spectra of a grassy field in Rochester and find < or equal to 6% differences in the visible/near infrared and approx. 2% differences in the short wave infrared. Spectral comparisons of forest sites in Rochester and Howland yield similar percentage agreement except for band 1, which has very low reflectance. Principal component analyses and comparison of normalized difference vegetation index histograms for each sensor indicate that the ALI is able to reproduce the information content in the ETM+ but with superior signal-to-noise performance due to its increased 12-bit quantization.

Pedelty, Jeffrey A.↗
NASA NTRS2016

Mid and Thermal Infrared Remote Sensing at the Jet Propulsion Laboratory

The mid and thermal infrared (MTIR) for the Earth surface is defined between 3 and 14µm. In the outer solar system, objects are colder and their Planck response shifts towards longer wavelengths. Hence for these objects (e.g. icy moons, polar caps, comets, Europa), the thermal IR definition usually stretches out to 50µm and beyond. Spectroscopy has been a key part of this scientific exploration because of its ability to remotely determine elemental and mineralogical composition. Many key gas species such as methane, ammonia, sulfur, etc. also have vibrational bands which show up in the thermal infrared spectrum above the background response. Over the past few decades, the Jet Propulsion Laboratory has been building up a portfolio of technology to capture the MTIR for various scientific applications. Three recent sensors are briefly reviewed: The airborne Hyperspectral thermal emission spectrometer (HyTES), the ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) and Mars Climate Sounder (MCS)/DIVINER. Each of these sensors utilize a different technology to provide a remote sensing product based on MTIR science. For example, HyTES is a push-brooming hyperspectral imager which utilizes a large format quantum well infrared photodetector (QWIP). The goal is to transition this to a new complementary barrier infrared photodetector (CBIRD) with a similar long wave cut-off and increased sensitivity. ECOSTRESS is a push-whisk Mercury Cadmium Telluride (MCT) based high speed, multi-band, imager which will eventually observe and characterize plant/vegetation functionality and stress index from the International Space Station (ISS) across the contiguous United States (CONUS). MCS/DIVINER utilizes thermopile technology to capture the thermal emission from the polar caps and shadow regions of the moon. Each sensor utilizes specific JPL technology to capture unique science. similar long wave cut-off and increased sensitivity. ECOSTRESS is a push-whisk Mercury Cadmium Telluride (MCT) based high speed, multi-band, imager which will eventually observe and characterize plant/vegetation functionality and stress index from the International Space Station (ISS) across the contiguous United States (CONUS). MCS/DIVINER utilizes thermopile technology to capture the thermal emission from the polar caps and shadow regions of the moon. Each sensor utilizes specific JPL technology to capture unique science.

Johnson, William R.↗
NASA NTRS1999

Investigating the Martian Environment with the Mars Global Surveyor Thermal Emission Spectrometer

The Thermal Emission Spectrometer (TES) onboard Mars Global Surveyor (MGS) is being used to investigate the surface and atmosphere of Mars and the martian moons Phobos and Deimos. As such, it builds upon infrared observations obtained by previous spacecraft, e.g.. Mariner 9 and Viking Orbiters. The objectives of the TES experiment are: (1) determine and map surface minerals. rocks. and ices; (2) study the atmospheric dust composition. particle size, and spatial and temporal distribution; (3) investigate condensate clouds, CO2 and H2O, location. temperature, and height; (4) investigate polar cap deposits, e.g., growth, retreat, and energy balance; (5) measure the thermo-physical properties of surface materials; and (6) characterize the atmospheric structure and dynamics. The TES instrument is based upon a Michelson interferometer and collects data in the 1700-200 per cm region (about 6-50 micron at 5 or 10 per cm resolution. There are also broad-band bolometric (4.5100 microns and solar reflectance (0.3-2.7 microns) channels. The TES was designed to have a noise equivalent spectral radiance of 1.2 x l0(exp -8) per W per square cm per sr per cm corresponding to a signal-to-noise ratio of 490 at 1000 per cm (10 mm) for a 270 K scene and preflight data suggest a radiometric accuracy of about 1.2 x 10(exp -8) per W per square cm per sr per cm. In-flight observations indicate a small systematic calibration offset of about 1.2 x 10(exp -7) per W per square cm per sr per cm is present in the TES data. MGS achieved Mars orbital insertion September 11, 1997, and entered the initial aerobraking phase. MGS should have reached a circular orbit by early 1998. However, structural damage to one solar panel occurred during its deployment in the cruise phase and ultimately required an assessment of the extent of the damage and a much slower aerobraking period. This has delayed reaching the final circular orbit until March 1999. TES and the other MGS science instruments began operating just after orbital insertion and continued to obtain data until November 1998 when the TES was turned off to reduce power consumption on the spacecraft. TES data obtained during orbits 2 to 53 have previously been published and clearly illustrate the variety of scientific questions that can be addressed with them.

Roush, T. L.↗
NASA NTRS2016

Physical State and Distribution of Materials at the Surface of Pluto from New Horizons LEISA Imaging Spectrometer

From Earth based observations Pluto is known to be the host of N2, CH4 and CO ices and also a dark red material. Very limited spatial distribution information is available from rotational visible and near-infrared spectral curves obtained from hemispheric measurements. In July 2015 the New Horizons spacecraft reached Pluto and its satellite system and recorded a large set of data. The LEISA spectro-imager of the RALPH instruments are dedicated to the study of the composition and physical state of the materials composing the surface. In this paper we report a study of the distribution and physical state of the ices and non-ice materials on Pluto's illuminated surface and their mode and degree of mixing. Principal Component analysis as well as various specific spectral indicators and correlation plots are used on the first set of 2 high resolution spectro-images from the LEISA instrument covering the whole illuminated face of Pluto at the time of the New Horizons encounter. Qualitative distribution maps have been obtained for the 4 main condensed molecules, N2, CH4, CO, H2O as well as for the visible-dark red material. Based on specific spectral indicators, using either the strength or the position of absorption bands, these 4 molecules are found to indicate the presence of 3 different types of ices: N2-rich:CH4:CO ices, CH4-rich(:CO:N2?) ices and H2O ice. The mixing lines between these ices and with the dark red material are studied using scatter plots between the various spectral indicators. CH4 is mixed at the molecular level with N2, most probably also with CO, thus forming a ternary molecular mixture that follows its phase diagram with low solubility limits. The occurrence of a N2-rich - CH4-rich ices mixing line associated with a progressive decrease of the CO/CH4 ratio tells us that a fractionation sublimation sequence transforms one type of ice to the other forming either a N2-rich - CH4-rich binary mixture at the surface or an upper CH4-rich ice crust that may hide the N2-rich ice below. The strong CH4-rich - H2O mixing line witnesses the subsequent sublimation of the CH4-rich ice lag left behind by the N2:CO sublimation (N spring-summer), or a direct condensation of CH4 ice on the cold H2O ice (S autumn). The weak mixing line between CH4-containing ices and the dark red material and the very sharp spatial transitions between these ices and this non-volatile material are probably due to thermal incompatibility. Finally the occurrence of a H2O ice - red material mixing line advocates for a spatial mixing of the red material covering H2O ice, with possibly a small amount intimately mixed in water ice. From this analysis of the different materials distribution and their relative mixing lines, H2O ice appears to be the substratum on which other ices condense or non-volatile organic material is deposited from the atmosphere. N2-rich ices seem to evolve to CH4-dominated ices, possibly still containing traces of CO and N2, as N2 and CO sublimate away. The spatial distribution of these materials is very complex. The high spatial definition of all these composition maps, as well as those at even higher resolution that will be soon available, will allow us to compare them with Pluto's geologic features observed by LORRI panchromatic and MVIC multispectral imagers to better understand the geophysical processes in action at the surface of this astonishingly active frozen world.

Schmitt, B.↗
NASA NTRS2010

Multi-decade Measurements of the Long-Term Trends of Atmospheric Species by High-Spectral-Resolution Infrared Solar Absorption Spectroscopy

Solar absorption spectra were recorded for the first time in 5 years with the McMath Fourier transform spectrometer at the US National solar Observatory on Kitt Peak in southern Arizona, USA (31.91 N latitude, 111.61 W longitude, 2.09 km altitude). The solar absorption spectra cover 750-1300 and 1850-5000 cm(sup -1) and were recorded on 20 days during March-June 2009. The measurements mark the continuation of a long-term record of atmospheric chemical composition measurements that have been used to quantify seasonal cycles and long-term trends of both tropospheric and stratospheric species from observations that began i 1977. Fits to the measured spectra have been performed, and they indicate the spectra obtained since return to operational status are nearly free of channeling and the instrument line shape function is well reproduced taking into account the measurement parameters. We report updated time series measurements of total columns for six atmospheric species and their analysis for seasonal cycles and long-term trends. An sn example, the time series fit shows a decrease in the annual increase rate i Montreal-Protocol-regulated chlorofluorocarbon CCL2F2 from 1.51 plus or minus 0.38% yr(sup -1) at the beginning of the time span to -1.54 plus or minus 1.28 yr(sup -1) at the end of the time span, 1 sigma, and hence provides evidence for the impact of those regulations on the trend.

Rinsland, Curtis P.↗
NASA NTRS1990

High-Resolution Imaging Spectrometer

Earth resources observed in greater detail. High-Resolution Imaging Spectrometer, undergoing development for use in NASA's Earth Observing System, measures reflectance of Earth's surface in visible and near-infrared wavelengths. From an orbit around Earth, instrument scans surface of Earth in 200 wavelength bands simultaneously. Produces images enabling identification of minerals in rocks and soils, important algal pigments in oceans and inland waters, changes in spectra associated with biochemistry of plant canopies, compositions of atmospheric aerosols, sizes of grains in snow, and contamination of snow by impurities that absorb visible light.

Dozier, Jeff↗
NASA NTRS1993

Multiorder etalon sounder (MOES) development and test for balloon experiment

The Fabry-Perot interferometer (FPI), with its high throughput and high spectral resolution has been used in the remote-sensing measurements of the earth's atmospheric composition, winds, and temperatures. The most recent satellite instruments include the Fabry-Perot interferometer flown on the Dynamics Explorer-2 (DE-2), the High Resolution Doppler Imager (HRDI), and the Cryogenic Limb Array Etalon Spectrometer (CLAES) flown on the Upper Atmosphere Research Satellite (UARS). These instruments measure the Doppler line profiles of the emission and absorption of certain atmospheric species (such as atomic oxygen) in the visible and infrared spectral region. The successful space flight of DE-FPI, HRDI, and CLAES on UARS demonstrated the extremely high spectral resolution and ruggedness of the etalon system for the remote sensing of earth and planetary atmospheres. Recently, an innovative FPI focal plane detection technique called the Circle-to-Line Interferometer Optical (CLIO) system was invented at the Space Physics Research Laboratory. The CLIO simplifies the FPI focal plane detection process by converting the circular rings or fringes into a linear pattern similar to that produced by a conventional spectrometer, while retaining the throughput advantage of the etalon interferometer. The combination of FPI and CLIO allows the development of more sensitive Fabry-Perot interferometers in the infrared for the remote sensing of the lower atmospheres of Earth and possibly other planets. The Multiorder Etalon Sounder (MOES), a combination of the rugged etalon and the CLIO, compares very favorably to other space-borne optical instruments in terms of performance versus complexity. The new instrument is expected to be rugged, compact, and very suitable for an operational temperature and moisture sounder. With this technique, the contamination of radiance measurements by emissions of other gases is also minimized. At the Space Physics Research Laboratory (SPRL), the MOES concept and laboratory experiments were worked on for the past several years. Both theoretical studies and laboratory prototype experiments showed that MOES is very competitive compared with other high resolution sounders in terms of complexity and performance and has great potential as a compact and rugged high resolution atmospheric temperature and trace species sounder from the polar platform or the geostationary platform. The logical next step is to convert our laboratory prototype to a balloon instrument, so that field test of MOES can be carried out to prove the feasibility and capability of this new technology. Some of the activities related to the development of MOES for a possible balloon flight demonstration are described. Those research activities include the imaging quality study on the CLIO, the design and construction of a MOES laboratory prototype, the test and calibration of the MOES prototype, and the design of the balloon flight gondola.

Hays, Paul B.↗
NASA NTRS2005

Extracting Compositional Variation from THEMIS Data for Features with Large Topography on Mars Via Atmospheric Equalization

We have developed a means of equalizing the atmospheric signature in Mars Odyssey Thermal Emission Imaging System (THEMIS) infrared data over regions with large topography such as the Valles Marineris (VM). This equalization allows for the analysis of compositional variations in regions that previously have been difficult to study because of the large differences in atmospheric path length that result from large changes in surface elevation. Specifically, our motivation for this study is to examine deposits that are small at the scales observable by the Thermal Emission Spectrometer (TES) onboard Mars Global Surveyor, but which are more readily resolved with THEMIS.

Anderson, F. S.↗
NASA NTRS1996

A Comparison of Cloud Microphysical and Optical Properties during TOGA-COARE

The impact of cirrus clouds on climate is an issue of research interest currently. Whether cirrus clouds heat or cool the Earth-atmosphere system depends on the cloud shortwave albedo and infrared reflectance and absorptance. These in turn are determined by the size distribution, phase, and composition of particles in the clouds. The TOGA-COARE campaign presented an excellent opportunity to study cirrus clouds and their influence on climate. In this campaign, a microphysics instrument package was flown aboard the DC-8 aircraft at medium altitudes in cirrus clouds. This package included a 2D Greyscale Cloud Particle Probe, a Forward Scattering Spectrometer Aerosol Probe, and an ice crystal replicator. At the same time the ER-2 equipped with a radiation measurement system flew coordinated flight tracks above the DC-8 at very high altitude. The radiation measurement made were short and long wave fluxes, as well as narrowband fluxes, both upwelling and downwelling. In addition LIDAR data is available. The existence of these data sets allows for a the comparison of radiation measurement with microphysical measurements. For example, the optical depth and effective radius retrieved from the ER-2 radiation measurements can be compared to the microphysical data. Conversely, the optical properties and fluxes produced by the clouds can be calculated from the microphysical measurements and compared to those measured aboard the ER-2. The assumptions required to make these comparisons are discussed. Typical microphysical results show a prevalence of micron-sized particles, in addition to the cloud particles that exceed 100 mm. The large number of small particles or "haze" cause the effective cloud radii to shift to smaller sizes, leading to changes in optical parameters.

Strawa, A. W.↗
NASA NTRS1992

AVIRIS study of Death Valley evaporite deposits using least-squares band-fitting methods

Minerals found in playa evaporite deposits reflect the chemically diverse origins of ground waters in arid regions. Recently, it was discovered that many playa minerals exhibit diagnostic visible and near-infrared (0.4-2.5 micron) absorption bands that provide a remote sensing basis for observing important compositional details of desert ground water systems. The study of such systems is relevant to understanding solute acquisition, transport, and fractionation processes that are active in the subsurface. Observations of playa evaporites may also be useful for monitoring the hydrologic response of desert basins to changing climatic conditions on regional and global scales. Ongoing work using Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data to map evaporite minerals in the Death Valley salt pan is described. The AVIRIS data point to differences in inflow water chemistry in different parts of the Death Valley playa system and have led to the discovery of at least two new North American mineral occurrences. Seven segments of AVIRIS data were acquired over Death Valley on 31 July 1990, and were calibrated to reflectance by using the spectrum of a uniform area of alluvium near the salt pan. The calibrated data were subsequently analyzed by using least-squares spectral band-fitting methods, first described by Clark and others. In the band-fitting procedure, AVIRIS spectra are fit compared over selected wavelength intervals to a series of library reference spectra. Output images showing the degree of fit, band depth, and fit times the band depth are generated for each reference spectrum. The reference spectra used in the study included laboratory data for 35 pure evaporite spectra extracted from the AVIRIS image cube. Additional details of the band-fitting technique are provided by Clark and others elsewhere in this volume.

Crowley, J. K.↗
NASA NTRS1985

Spectroscopy of Moses Rock dike using remote sensing

Zeiss IR-photographs, NS0001 (TM simulator) and airborne imaging spectrometer (AIS) data were obtained for the Moses Rock kimberlite dike in southern Utah to identify and characterize the distinctive mafic mineralogy of the dike as well as the surrounding sedimentary rocks. The Zeiss and NS001 images provide information on the regional setting and allow units of the dike to be distinguished from the sediments. The AIS data are narrow images obtained in 128 near-infrared channels and provide characterizing information on the surface composition through. Three distinct spectroscopic units were found which have been tentatively identified as serpentized olivine-bearing soils found in the dike and two types of gypsum bearing soils found in the surrounding sedimentary soils.

Mustard, J. F.↗
NASA NTRS1988

Automatic mineral map generation procedure from imaging spectrometer data

An airborne imaging spectrometer collected data for 128 wave length channels covering from near to short wavelength infrared across a 320 m swath, to help obtain a mineral map of an area based on reflectance spectral signatures of the area. Minerals have distinctive crystal structures and chemical contents which can be identified by their light absorption characteristics, and an optimized automatic mineral map generation procedure for imaging spectrometer data was developed. The procedure generates two types of mineral maps, a mineral distribution map showing spatial layout of various minerals and a mineral composition map showing the percentage composition of a selected mineral.

Lee, M.↗
NASA NTRS2022

Nested Dust Shells Around the Wolf–Rayet Binary WR 140 Observed With JWST

Massive colliding-wind binaries that host a Wolf–Rayet (WR) star present a potentially important source of dust and chemical enrichment in the interstellar medium. However, the chemical composition and survival of dust formed from such systems is not well understood. The carbon-rich Wolf–Rayet binary WR 140 presents an ideal astrophysical laboratory for investigating these questions, given its well-defined orbital period and predictable dust-formation episodes every 7.93 years around periastron passage. We present observations from our Early Release Science programme (ERS 1349) with the James Webb Space Telescope Mid-Infrared Instrument (MIRI) Medium-Resolution Spectrometer and Imager that reveal the spectral and spatial signatures of nested circumstellar dust shells around WR 140. MIRI medium-resolution spectroscopy of the second dust shell and Imager detections of over 17 shells formed throughout approximately the past 130 years confirm the survival of carbonaceous dust grains from WR 140 that are probably carriers of ‘unidentified infrared’-band features at 6.4 and 7.7 μm. The observations indicate that dust-forming carbon-rich Wolf–Rayet binaries can enrich the interstellar medium with organic compounds and carbonaceous dust.

massive stars↗