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Keywords: Mars, Atmosphere, EMM, Emirates Mars Infrared Spectrometer, Off-axis Detectors.Introduction: The Emirates Mars Mission (EMM) Emirates Mars InfraRed Spectrometer (EMIRS) instrument is a Fourier Transform Infrared (FTIR) spectrometer designed to observe the Martian disk, with the primary scientific objective of determining the three-dimensional thermal state of the lower atmosphere and its diurnal variability on sub-seasonal timescales [1].EMIRS uses a 3x3 array of deuterated L-alanine doped triglycine sulfate (DLaTGS) pyroelectric detectors [1], however, following the integration of the EMIRS electronics with the optical and mechanical hardware it was observed that the performance of the off-axis (non-central) detectors of the array were lower than expected [1]. Investigations into the performance of these off-axis detectors has so far yielded inconclusive root causes. As EMIRS could meet its primary science objective with the on-axis (central) detector and was subject to a pressing instrument schedule, a project level decision was made to forgo any additional investigation and instead rely on the on-axis detector [1][2].Method: In this study we present a comparison of observations captured by EMIRS from the off-axis detectors against the on-axis detector. The comparison is performed via a top-down and bottom-up pathway approach using the EMM Science Team processing pipeline. The top-down pathway focuses on the effects of the pre-processing steps on the detector interferograms, whereas the bottom-up approach compares calibrated radiances derived from the pipeline with and without applying the pre-processing steps [3] [4]. Correction of these issues will expand the retrieval derived products by a factor of five.Results: The top-down comparison shows differences in terms interferogram amplitude and phase error between on and off-axis detectors. We assess the feasibility of correction, then apply correction methods to a subset of EMIRS observations, and propose the root cause of the issues. This study is presented along with the generation of a joint dataset of near-mutual EMIRS and EXI (Emirates eXploration Imager) observations [5].Acknowledgements: The authors would like to acknowledge support by a Joint Research Agreement between the Mohammed Bin Rashid Space Centre (MBRSC) and the National Space Science and Technology Center (NSSTC), UAE University (UAEU).References: [1] Edwards, C. S., et al. (2021). Space Science Reviews (2021) 217:77.[2] Amiri, H.E. S., et al. (2022). Space Science Reviews (2022) 218:4.[3] Forman, M. L., et al. (1966). J. Opt. Soc. Am. 56(1), 59–63.[4] Christensen, V.E., et al. (2018). Space Science Reviews (2018), 215:87.[5] Jones, A. R., et al. (2021). Space Science Reviews (2021) 217:81.

Mars dust storms are an interdisciplinary field of research. They impact the entry-descent-landing operations of spacecraft, the energy production by the solar panels of Mars rovers and landers, and others. As can be foreseen, dust storms are also critical for the future human exploration of Mars. Dust storm research is directly aligned with the Emirates Mars Mission (EMM) science objective on the lower atmosphere, and with the science objective of correlating the lower and upper atmosphere [1,2]. First results of EMM dust storm research were reported in [3].EMM has a high-altitude orbit and provides data products for studies of the Mars atmosphere and surface with a near-hemispheric view. Moreover, EMM can provide information on dust storm activity every few hours or less. EMM observed multiple dust storms during the primary mission, including a large regional dust storm in Sep. and Oct. 2022.The focus of this presentation are unique dust storm observations by the EMM camera EXI [4]. We study a subset of dust storms, which is of particular interest to our research. The formation and growth of dust storms is followed at a (sub-)hourly time scale. This includes results on the dust storm morphology, wind direction, wind speed, surface dust lifting, etc.. Based on that, the implications for the physics and dynamics of dust storms are considered.[1] Amiri, H.E.S., Brain, D., Sharaf, O. et al. The Emirates Mars Mission. Space Sci Rev 218, 4 (2022). https://doi.org/10.1007/s11214-021-00868-x[2] Almatroushi, H., AlMazmi, H., AlMheiri, N. et al. Emirates Mars Mission Characterization of Mars Atmosphere Dynamics and Processes. Space Sci Rev 217, 89 (2021). https://doi.org/10.1007/s11214-021-00851-6[3] Gebhardt, C., Guha, B. K., Young, R. M. B., & Wolff, M. J. (2022). A frontal dust storm in the northern hemisphere at solar longitude 97—An unusual observation by the Emirates Mars mission. Geophysical Research Letters, 49, e2022GL099528. https://doi.org/10.1029/2022GL099528[4] Jones, A.R., Wolff, M., Alshamsi, M. et al. The Emirates Exploration Imager (EXI) Instrument on the Emirates Mars Mission (EMM) Hope Mission. Space Sci Rev 217, 81 (2021). https://doi.org/10.1007/s11214-021-00852-5

The light-toned sedimentary layers that outcrop widely throughout Mars’ Southern Highlands have long been an enigma in uncovering the climatic history of Mars. Although these units seem to contain unique records of fluctuating surface conditions, the role of water in their formation is debated. A distinctive property of many such deposits is their elevated thermal inertia relative to that of surrounding materials. This temperature-controlling trait is often interpreted to indicate induration resulting from aqueous processes. However, prevalent erosional landforms suggest that the deposits host much weaker materials than neighboring units. We address this apparent contradiction by disentangling the relationships between thermal inertia, mineralogy, and erosion susceptibility and by quantifying the cohesion of layered deposits in the Arabia Terra region. We demonstrate that variations in dust cover associated with relative erodibility and eolian abrasion can be inconspicuous controls on apparent thermal inertia. We ultimately find that these deposits are not as cohesive as would be expected from a high water-to-rock ratio setting either during or after deposition. If water-rich surface conditions existed in the region after the Noachian, these deposits suggest they may have only been intermittent and fleeting.

The Emirates Mars Mission (EMM) – Hope Probe – was developed to understand Mars atmospheric circulation, dynamics, and processes through characterization of the Mars atmosphere layers and its interconnections enabled by a unique high-altitude (19,970 km periapse and 42,650 km apoapse) low inclination orbit that will offer an unprecedented local and seasonal time coverage over most of the planet. EMM has three scientific objectives to (A) characterize the state of the Martian lower atmosphere on global scales and its geographic, diurnal and seasonal variability, (B) correlate rates of thermal and photochemical atmospheric escape with conditions in the collisional Martian atmosphere, and (C) characterize the spatial structure and variability of key constituents in the Martian exosphere. The EMM data products include a variety of spectral and imaging data from three scientific instruments measuring Mars at visible, ultraviolet, and infrared wavelengths and contemporaneously and globally sampled on both diurnal and seasonal timescale. Here, we describe our strategies for addressing each objective with these data in addition to the complementary science data, tools, and physical models that will facilitate our understanding. The results will also fill a unique role by providing diagnostics of the physical processes driving atmospheric structure and dynamics, the connections between the lower and upper atmospheres, and the influences of these on atmospheric escape.

Data returned from Martian missions have revealed a wide diversity of surface mineralogies, including in geological structures interpreted to be sedimentary or altered by liquid water. These terrains are of great interest because of their potential to document the environment at a time when life may have appeared. Intriguingly, Martian sedimentary rocks show distinctly low thermal inertia values (i.e. 300 - 700 Jm−2K−1s−1/2, indicative of a combination of low thermal conductivity, specific heat capacity, and density). These low values are difficult to reconcile with their competent bedrock morphologies, whereas hundreds of bedrock occurrences, interpreted as volcanic in origin, have been mapped globally and display thermal inertia values > 1200 Jm−2K−1s−1/2. Bedrock thermal inertia values are generally assumed to be driven by their bulk thermal conductivity, which in turn is controlled by their micro- and macro-physical properties (i.e., degree and style of cementation in the case of detritic rocks, horizontal fractures and layering, etc.), and not by their density (well-known from terrestrial analog measurements, and with modest variability) or specific heat capacity (generally uncharacterized for non-basaltic materials below room temperature). In this paper, we demonstrate that specific heat capacity cannot be a potential cause for the differential thermophysical behavior between magmatic and sedimentary rocks through a series of experimental Cp(T) measurements at 100–350 K using differential scanning calorimetry. The results on 20 Martian-relevant minerals investigated in this work indicate that these materials exhibit very similar specific heats, ranging from 0.3–0.7 Jg−1K−1 at 100 K to 0.6–1.7 Jg−1K−1 at 350 K. When used in a Martian thermal model, this range of Cp values translate to very small surface temperature differences, indicating that uncertainty in composition (and its effect on the specific heat) is not a noticeable source of thermal inertia variability for indurated units on Mars. We therefore conclude that the low thermal inertia value of sedimentary rocks compared to magmatic/volcanic rocks is likely due to their low apparent bulk conductivity, which bears information on their internal physical structure. Future work combining the analysis of thermal observations acquired at various local times and seasons will help further characterize this heterogeneity.

The surface of Mars has been well mapped and characterized, yet the subsurface — the most likely place to find signs of extant or extinct life and a repository of useful resources for human exploration — remains unexplored. In the near future this is set to change.

International audience; Fine scale (submillimeter to centimeter) depositional and diagenetic features encountered during the Curiosity rover's traverse in Gale crater provide a means to understand the geologic history of Vera Rubin ridge (VRR). VRR is a topographically high feature on the lower north slope of Aeolis Mons, a 5 km high stratified mound within Gale crater. We use high spatial resolution images from the Mars Hand Lens Imager (MAHLI) as well as grain sizes estimated with the Gini index mean score technique that uses ChemCam Laser Induced Breakdown Spectroscopy (LIBS) chemical data to constrain the postdepositional history of the strata exposed on this ridge. MAHLI images were used to examine the color, grain size, and style of lamination of the host rocks, as well as to explore the occurrence of nodules, diagenetic crystals, pits, and a variety of dark gray iron rich features. This survey revealed abundant and widespread diagenetic features within the rocks exposed on VRR and demonstrated that rock targets estimated to be coarser generally contain more diagenetic features than those estimated to have finer grains, which indicate that grain size may have influenced the degree and type of diagenesis. A subset of rocks within VRR are gray in color and exhibit the highest proportion of diagenetic features. We suggest that these targets experienced a different diagenetic history than the other rocks on VRR and hypothesize that redistribution and recrystallization of iron within specific intervals may have resulted in both the gray color and the abundance of dark gray iron rich diagenetic features.

International audience

The Emirates Mars Mission Emirates Mars Infrared Spectrometer (EMIRS) will provide remote measurements of the martian surface and lower atmosphere in order to better characterize the geographic and diurnal variability of key constituents (water ice, water vapor, and dust) along with temperature profiles on sub-seasonal timescales. EMIRS is a FTIR spectrometer covering the range from 6.0-100+ μm (1666-100 cm−1) with a spectral sampling as high as 5 cm−1 and a 5.4-mrad IFOV and a 32.5×32.5 mrad FOV. The EMIRS optical path includes a flat 45° pointing mirror to enable one degree of freedom and has a +/- 60° clear aperture around the nadir position which is fed to a 17.78-cm diameter Cassegrain telescope. The collected light is then fed to a flat-plate based Michelson moving mirror mounted on a dual linear voice-coil motor assembly. An array of deuterated L-alanine doped triglycine sulfate (DLaTGS) pyroelectric detectors are used to sample the interferogram every 2 or 4 seconds (depending on the spectral sampling selected). A single 0.846 μm laser diode is used in a metrology interferometer to provide interferometer positional control, sampled at 40 kHz (controlled at 5 kHz) and infrared signal sampled at 625 Hz. The EMIRS beamsplitter is a 60-mm diameter, 1-mm thick 1-arcsecond wedged chemical vapor deposited diamond with an antireflection microstructure to minimize first surface reflection. EMIRS relies on an instrumented internal v-groove blackbody target for a full-aperture radiometric calibration. The radiometric precision of a single spectrum (in 5 cm−1 mode) is −8 W cm−2 sr−1/cm−1 between 300 and 1350 cm−1 over instrument operational temperatures ($\Delta $ Δ T @ 250 K). The absolute integrated radiance error is < 2% for scene temperatures ranging from 200-340 K. The overall EMIRS envelope size is 52.9×37.5×34.6 cm and the mass is 14.72 kg including the interface adapter plate. The average operational power consumption is 22.2 W, and the standby power consumption is 18.6 W with a 5.7 W thermostatically limited, always-on operational heater. EMIRS was developed by Arizona State University and Northern Arizona University in collaboration with the Mohammed bin Rashid Space Centre with Arizona Space Technologies developing the electronics. EMIRS was integrated, tested and radiometrically calibrated at Arizona State University, Tempe, AZ.

This paper provides an overview of the Curiosity rover's exploration at Vera Rubin ridge and summarizes the science results. Vera Rubin ridge (VRR) is a distinct geomorphic feature on lower Aeolis Mons (informally known as Mt. Sharp) that was identified in orbital data based on its distinct texture, topographic expression, and association with a hematite spectral signature. Curiosity conducted extensive remote sensing observations, acquired data on dozens of contact science targets, and drilled three outcrop samples from the ridge, as well as one outcrop sample immediately below the ridge. Our observations indicate that strata composing VRR were deposited in a predominantly lacustrine setting and are part of the Murray formation. The rocks within the ridge are chemically in family with underlying Murray formation strata. Red hematite is dispersed throughout much of the VRR bedrock, and this is the source of the orbital spectral detection. Gray hematite is also present in isolated, gray‐colored patches concentrated towards the upper elevations of VRR, and these gray patches also contain small, dark Fe‐rich nodules. We propose that VRR formed when diagenetic event(s) preferentially hardened rocks, which were subsequently eroded into a ridge by wind. Diagenesis also led to enhanced crystallization and/or cementation that deepened the ferric‐related spectral absorptions on the ridge, which helped make them readily distinguishable from orbit. Results add to existing evidence of protracted aqueous environments at Gale crater and give new insight into how diagenesis shaped Mars’ rock record.

Extraformational sediment recycling (old sedimentary rock to new sedimentary rock) is a fundamental aspect of Earth's geological record; tectonism exposes sedimentary rock, whereupon it is weathered and eroded to form new sediment that later becomes lithified. On Mars, tectonism has been minor, but two decades of orbiter instrument-based studies show that some sedimentary rocks previously buried to depths of kilometers have been exposed, by erosion, at the surface. Four locations in Gale crater, explored using the National Aeronautics and Space Administration's Curiosity rover, exhibit sedimentary lithoclasts in sedimentary rock: At Marias Pass, they are mudstone fragments in sandstone derived from strata below an erosional unconformity; at Bimbe, they are pebble-sized sandstone and, possibly, laminated, intraclast-bearing, chemical (calcium sulfate) sediment fragments in conglomerates; at Cooperstown, they are pebble-sized fragments of sandstone within coarse sandstone; at Dingo Gap, they are cobble-sized, stratified sandstone fragments in conglomerate derived from an immediately underlying sandstone. Mars orbiter images show lithified sediment fans at the termini of canyons that incise sedimentary rock in Gale crater; these, too, consist of recycled, extraformational sediment. The recycled sediments in Gale crater are compositionally immature, indicating the dominance of physical weathering processes during the second known cycle. The observations at Marias Pass indicate that sediment eroded and removed from craters such as Gale crater during the Martian Hesperian Period could have been recycled to form new rock elsewhere. Our results permit prediction that lithified deltaic sediments at the Perseverance (landing in 2021) and Rosalind Franklin (landing in 2023) rover field sites could contain extraformational recycled sediment., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

Hyperspectral unmixing is an important remote sensing task with applications including material identification and analysis. Characteristic spectral features make many pure materials identifiable from their visible-to-infrared spectra, but quantifying their presence within a mixture is a challenging task due to nonlinearities and factors of variation. In this paper, spectral variation is considered from a physics-based approach and incorporated into an end-to-end spectral unmixing algorithm via differentiable programming. The dispersion model is introduced to simulate realistic spectral variation, and an efficient method to fit the parameters is presented. Then, this dispersion model is utilized as a generative model within an analysis-by-synthesis spectral unmixing algorithm. Further, a technique for inverse rendering using a convolutional neural network to predict parameters of the generative model is introduced to enhance performance and speed when training data is available. Results achieve state-of-the-art on both infrared and visible-to-near-infrared (VNIR) datasets, and show promise for the synergy between physics-based models and deep learning in hyperspectral unmixing in the future.

We revisit the idea of ‘terraforming’ Mars — changing its environment to be more Earth-like in a way that would allow terrestrial life (possibly including humans) to survive without the need for life-support systems — in the context of what we know about Mars today. We want to answer the question of whether it is possible to mobilize gases present on Mars today in non-atmospheric reservoirs by emplacing them into the atmosphere, and increase the pressure and temperature so that plants or humans could survive at the surface. We ask whether this can be achieved considering realistic estimates of available volatiles, without the use of new technology that is well beyond today’s capability. Recent observations have been made of the loss of Mars’s atmosphere to space by the Mars Atmosphere and Volatile Evolution Mission probe and the Mars Express spacecraft, along with analyses of the abundance of carbon-bearing minerals and the occurrence of CO2 in polar ice from the Mars Reconnaissance Orbiter and the Mars Odyssey spacecraft. These results suggest that there is not enough CO2 remaining on Mars to provide significant greenhouse warming were the gas to be emplaced into the atmosphere; in addition, most of the CO2 gas in these reservoirs is not accessible and thus cannot be readily mobilized. As a result, we conclude that terraforming Mars is not possible using present-day technology.

We investigated the area to the northwest of the Isidis impact basin (hereby referred to as “NW Isidis”) using thermal infrared emission datasets to characterize and quantify bulk surface mineralogy throughout this region. This area is home to Jezero crater and the watershed associated with its two deltaic deposits in addition to NE Syrtis and the strong and diverse visible/near-infrared spectral signatures observed in well-exposed stratigraphic sections. The spectral signatures throughout this region show a diversity of primary and secondary surface mineralogies, including olivine, pyroxene, smectite clays, sulfates, and carbonates. While previous thermal infrared investigations have sought to characterize individual mineral groups within this region, none have systematically assessed bulk surface mineralogy and related these observations to visible/near-infrared studies. We utilize an iterative spectral unmixing method to statistically evaluate our linear thermal infrared spectral unmixing models to derive surface mineralogy. All relevant primary and secondary phases identified in visible/near-infrared studies are included in the unmixing models and their modeled spectral contributions are discussed in detail. While the stratigraphy and compositional diversity observed in visible/near-infrared spectra are much better exposed and more diverse than most other regions of Mars, our thermal infrared analyses suggest the dominance of basaltic compositions with less observed variability in the amount and diversity of alteration phases. These results help to constrain the mineralogical context of these previously reported visible/near-infrared spectral identifications. The results are also discussed in the context of future in situ investigations, as the NW Isidis region has long been promoted as a region of paleoenvironmental interest on Mars.

The composition of two dune fields, Ogygis Undae and the NE–SW trending dune field in Gale crater (the “Bagnold Dune Field” and “Western Dune Field”), were analyzed using thermal emission spectra from the Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) and the Mars Odyssey Thermal Emission Imaging System (THEMIS). The Gale crater dune field was used as a baseline as other orbital compositional analyses have been conducted, and in situ sampling results will soon be available. Results from unmixing thermal emission spectra showed a spatial variation between feldspar mineral abundances and pyroxene mineral abundances in Ogygis Undae. Other datasets, including nighttime thermal inertia values, also showed variation throughout the dune field. One explanation proposed for this variation is a bimodal distribution of two sand populations. This distribution is seen in some terrestrial dune fields. The two dune fields varied in both mineral types present and in uniformity of composition. These differences point to different source lithologies and different distances travelled from source material. Examining these differences further will allow for a greater understanding of aeolian processes on Mars.

Daytime and nighttime thermal infrared observations acquired by the ASTER and MODIS instruments onboard the NASA Terra spacecraft have produced a dataset that can be used to map thermophysical properties across large regions, which have implications on surface processes, thermal environments and habitat suitability for desert species. ASTER scenes acquired between 2004 and 2012 are combined using new mosaicking and data-fusion techniques to produce a map of daytime and nighttime land surface temperature with coverage exclusive of the effects of clouds and weather. These data are combined with Landsat 7 visible imagery to generate a consistent map of apparent thermal inertia (ATI), which is related to the presence of exposed bedrock, rocks, fine-grained sediments and water on the surface. The resulting datasets are compared to known geomorphic units and surface types to generate an interpreted mechanical composition map of the entire Mojave Desert at 100 m per pixel that is most sensitive to large clast size distinctions in grain size distribution.