The Emirates Mars Mission (EMM) has a unique opportunity to observe the surface of Deimos, the smaller and outermost of the two moons of Mars. The origins of both Phobos and Deimos remain debated largely due to lack of available observations. The elliptical orbit of the EMM spacecraft, designed to provide comprehensive coverage of the martian atmosphere, allows for campaigns to periodically observe the moon. The slight adjustment of the orbit to move into a resonance with Deimos permits nominal science to continue. The campaign began in August of 2022 by undertaking a series of maneuvers to enable several flybys each stepping in and progressively attaining a closer distance to Deimos. Here, we will present the images collected by EXI of the targeted flyby (e.g., the flyby wherein the spacecraft achieves its closest distance to the moon). Observations for each flyby will include an initial image set at the start of the approach (red/green/blue/320 nm/260 nm), red images will be acquired at 1 min intervals during the approach, and when the spacecraft is at the closest point to Deimos a red/green/blue image set at full resolution, as well as a 320 nm image binned at 2×2 pixels, will be acquired. As the spacecraft leaves Deimos, the reverse observation strategy will be employed. These observations will help constrain the short-wavelength spectral properties and further characterize the geomorphology of this relatively understudied martian moon.

How to cite: Osterloo, M., Edwards, C., Fisher, C., Jeppesen, C., Wolff, M., Jones, A., Knavel, J., Pilinski, E., Tomso, C., Shuping, R., Deighan, J., and Al Matroushi, H.: First observations of Deimos from the Emirates eXploration Imager (EXI), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9313, https://doi.org/10.5194/egusphere-egu23-9313, 2023.

We present the initial views of the surface of Mars’ outer moon Deimos as observed by the Emirates Mars InfraRed Spectrometer (EMIRS), a Fourier transform infrared spectrometer observing from 6-50 µm with a spectral sampling of up to 5 cm^-1. The primary science goal of the Emirates Mars Mission (EMM) is to study the variability in Mars’ atmosphere. As part of a coordinated campaign, the EMM spacecraft has adjusted its orbit into a resonance with Deimos, where it will periodically fly by the moon. Beginning the spring of 2023, EMIRS will collect numerous thermal infrared spectra of Deimos’ surface with a spatial resolution ranging from ~1-10 km. These observations will be the best-resolved infrared views of Deimos to date. Our planned observations achieve nearly complete global coverage of the surface, and span a range of local solar times, enabling investigations of both compositional and thermophysical properties. We will discuss these observations and initial findings. 

How to cite: Smith, N., Edwards, C., Osterloo, M., Christensen, P., Anwar, S., Pilinski, E., Wren, P., Noss, D., Rios, K., Dickenshied, S., Al Matroushi, H., Deighan, J., Parker, J., and Sharaf, O.: The Observations of Deimos from the Emirates Mars Infrared Spectrometer (EMIRS), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10291, https://doi.org/10.5194/egusphere-egu23-10291, 2023.

The Emirates Mars Mission (EMM) Hope probe launched on 20 Jul 2020 and entered Mars orbit on 9 Feb 2021, carrying a payload of 3 complementary instruments to characterize the global atmosphere across the full range of altitudes (surface to exosphere) at diurnal and seasonal timescales.  The unique, high-altitude orbit of the Hope probe (19,970 km periapse, 42,650 km apoapse altitude, 25 deg inclination, 54.5-hour period) that enables its synoptic view of the red planet also brings the spacecraft across the orbit of Mars’ outermost moon, Deimos.  The Hope trajectory was slightly modified by two maneuvers in Aug 2022 and Jan 2023 that will allow the surface of Deimos to be observed in a series of flybys in Feb-Mar 2023.  Here we present preliminary results from the Emirates Mars Ultraviolet Spectrometer (EMUS), an imaging spectrograph with a wavelength range of 100-170 nm and a field of view of 10.75 x 0.18 deg (using the high-resolution slit position).  We will derive the absolute reflectance of the surface, search for any compositionally distinct spectral features (e.g. carbon, polycyclic aromatic hydrocarbons, water ice), and examine any spatial heterogeneity across the surface.

How to cite: Holsclaw, G., Deighan, J., Chaffin, M., Al Matroushi, H., Lillis, R., Fillingim, M., England, S., Jain, S., Lootah, F., Al Mazmi, H., Bershenyi, G., Pilinski, E., Teil, T., Parker, J., and Sharaf, O.: The First Observations of Deimos by the Emirates Mars Ultraviolet Spectrometer (EMUS), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10186, https://doi.org/10.5194/egusphere-egu23-10186, 2023.

Observations of clouds on Mars have long been studied to understand activity and the Martian water cycle. The Martian volcanoes have been shown to have associated cloud formations such as the Aphelion Cloud Belt (ACB) (Wolff et al., 2022), Orographic Clouds (Benson et al., 2006), and Perihelion Cloud Trails (Clancy et al., 2021). Previous studies provide insights into how these clouds appear and contribute to the atmosphere. The objective of this study is to provide a catalog of the life cycle of clouds observed by Emirates eXploration Imager (EXI) spatially (longitude, latitude) and temporally (Solar Longitude (Ls), local time) using the following wavelength channels 635nm (red), 546nm (green), 437nm (blue) and 320nm (ultraviolet which can be used to retrieve the water ice optical depth). To undertake this study, we identified the volcanic region (Olympus Mons and Arsia Mons) as the study region due to cloud presence in the area throughout the Martian year.  EXI is a camera on board the Emirates Mars Mission (EMM) – Hope Probe. EXI acquires 12-megapixel images and has sufficient radiometric calibration for detailed scientific analysis (Jones et al., 2021). It was developed to better understand several critical constituents (e.g., dust, water ice clouds, etc) geographic and diurnal distribution in the lower atmosphere (Jones et al., 2021). We will present the results of our database for clouds for Mars year 36.

Benson, J., James, P., Cantor, B., & Remigio, R. (2006). Interannual variability of water ice clouds over major martian volcanoes observed by MOC. Icarus, 184(2), 365–371. https://doi.org/10.1016/j.icarus.2006.03.014

Clancy, R. T., Wolff, M. J., Heavens, N. G., James, P. B., Lee, S. W., Sandor, B. J., Cantor, B. A., Malin, M. C., Tyler, D., & Spiga, A. (2021). Mars perihelion cloud trails as revealed by MARCI: Mesoscale topographically focused updrafts and gravity wave forcing of high altitude clouds. Icarus, 362, 114411. https://doi.org/10.1016/j.icarus.2021.114411

Jones, A. R., Wolff, M., Alshamsi, M., Osterloo, M., Bay, P., Brennan, N., Bryant, K., Castleman, Z., Curtin, A., DeVito, E., Drake, V. A., Ebuen, D., Espejo, J., Farren, J., Fenton, B., Fisher, C., Fisher, M., Fortier, K., Gerwig, S., . . . Yaptengco, J. L. (2021). The Emirates Exploration Imager (EXI) Instrument on the Emirates Mars Mission (EMM) Hope Mission. Space Science Reviews, 217(8). https://doi.org/10.1007/s11214-021-00852-5

Wolff, M. J., Fernando, A., Smith, M. D., Forget, F., Millour, E., Atwood, S. A., Jones, A. R., Osterloo, M. M., Shuping, R., Al Shamsi, M., Jeppesen, C., & Fisher, C. (2022). Diurnal Variations in the Aphelion Cloud Belt as Observed by the Emirates Exploration Imager (EXI). Geophysical Research Letters, 49(18). https://doi.org/10.1029/2022gl100477

How to cite: Yousuf, M., Osterloo, M., and Edwards, C.: Diurnal and seasonal variations of clouds in the Tharsis Montes region of Mars using the Emirates eXploration Imager (EXI) observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5359, https://doi.org/10.5194/egusphere-egu23-5359, 2023.

The Emirates Mars Mission (EMM) has returned an abundance of whole disk images of Mars at visible wavelengths. Clouds and hazes are evident at the limb of the planet in many of these images, offering an opportunity to determine the vertical distribution of clouds on Mars over the course of a Martian year. However, there are challenges in determining the height of limb clouds due to uncertainty in the location of the Martian surface in the images. This uncertainty comes primarily from small uncertainties in the pointing of the instrument, coupled with the fact that the surface can be difficult to identify in the images due to the opacity of the atmosphere at low altitudes. With a typical pixel spanning roughly 5 km on the limb, the uncertainties in cloud height can be large.

Here we present an algorithm for automatically detecting limb clouds and hazes in Emirates eXploration Imager (EXI) observations, while simultaneously detecting the location of the surface. The algorithm considers straight line ‘transects’ through the images that extend from space to the disk of the planet. The inflection point in the recorded intensity along the transect (i.e. from ‘space’ where the intensity is small, to ‘Mars’ where the intensity is large) is used to determine the location of the surface. The transect is also used to infer the presence of detached clouds, as well as surface hazes. The heights and thicknesses of clouds and hazes can be extracted from the transects. We will present the algorithm, as well as a comparison of how the results of the algorithm compare to manual analysis of EXI images. We will highlight where the algorithm does well and where it has difficulty, and how the algorithm might be used to analyze other planetary datasets.

How to cite: Rothman, M., Almansoori, A., Brain, D., and Wolff, M.: Automated Detection of Limb Clouds and Hazes by the Emirates Mars Mission (EMM) Emirates eXploration Imager (EXI), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10766, https://doi.org/10.5194/egusphere-egu23-10766, 2023.

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

How to cite: Gebhardt, C., Guha, B. K., Young, R. M. B., Wolff, M. J., and Edwards, C. S.: The physics and dynamics of selected dust storms in the EMM primary mission, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3053, https://doi.org/10.5194/egusphere-egu23-3053, 2023.

Montabone et al., 2015 and 2020, [1, 2] have developed an iterative, weighted, running mean methodology to grid the available retrievals of atmospheric column dust optical depth (CDOD) from multi-annual and multi-instrument spacecraft observations at Mars. The application of this methodology has produced daily gridded maps of CDOD from Martian Year (MY) 24 through 35, using Mars Global Surveyor/Thermal Emission Spectrometer and Mars Odyssey/Thermal Emission Imaging System nadir observations, as well as the estimates of this quantity from Mars Reconnaissance Orbiter/Mars Climate sounder (MRO/MCS) limb observations. Given the lack of dust observations at certain times and locations, the daily gridded maps have missing values at some grid points. Kriging spatial interpolation has been used to produce regular maps that are useful as multiannual dust scenarios for model simulations, and for the Mars Climate Database (MCD) statistics [3].

We have now adapted this methodology to include CDOD retrievals from Emirates Mars Mission/Emirates Mars Infrared Spectrometer (EMM/EMIRS) nadir observations in MY 36 [4]. The specificity of EMIRS spatial and temporal coverage as well as the extended nature of its footprint are taken into account when carrying out the gridding. We will present a cross-comparison of maps obtained using only EMIRS retrievals and maps obtained using only MCS retrievals, in the attempt to understand what is the best approach to produce a MY 36 dust scenario that makes the best use of both instruments. We will particularly focus on the evolution of large-scale dust storms in MY 36.

References: [1] Montabone, L., et al. (2015) Icarus 251, pp. 65-95, doi: 10.1016/j.icarus.2014.12.034 ; [2] Montabone, L., et al. (2020) J. Geophys. Res. - Planets, doi: 10.1029/2019JE006111 ; [3] http://www-mars.lmd.jussieu.fr (Publicly available dust gridded maps can be currently found up to MY 35 by clicking on the “climatologies of Martian atmospheric dust” link under “Martian dust Climatology”) ; [4] Smith, M.D., et al. (2022) Geophys. Res. Lett. 49, Issue 15, doi: 10.1029/2022GL099636

How to cite: Montabone, L., Kleinboehl, A., Smith, M., Edwards, C., Forget, F., Kass, D., Millour, E., and Stcherbinine, A.: Reconstructing Martian Year 36 column dust optical depth maps using EMM/EMIRS and MRO/MCS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10341, https://doi.org/10.5194/egusphere-egu23-10341, 2023.

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.

How to cite: Cann, G. H., Young, R. M. B., Edwards, C. S., Smith, M. D., and Wolff, M. J.: Expanding the Emirates Mars Infrared Spectrometer (EMIRS) Science Dataset using EMIRS off-axis detectors, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11146, https://doi.org/10.5194/egusphere-egu23-11146, 2023.

The Emirates Mars Ultraviolet Spectrometer (EMUS) onboard the Emirates Mars Mission (EMM) observes the Martian dayglow at ultraviolet wavelengths (100-170 nm). EMUS disk observations show unexpected variations in atomic hydrogen, atomic oxygen, and carbon monoxide disk emissions. These variations display local time and hemispheric asymmetry and are observed in approximately 25% of the disk images. England et al. (2022; doi:10.1029/2022GL099611) suggested that the spatial structure, occurrence, and spectral characteristics of these variations are associated with changes in composition and photoelectron flux. Using a similar EMUS data set, Chaffin et al. (2022; doi:10.1029/2022GL099881) reported the first observations of neutral atmosphere auroral emission on the Martian dayside, which is not a new type of aurora but another observable form of proton aurora, and suggested that solar wind deposition is responsible for exciting the auroral emission. We further investigate these two potential drivers of the unexpected variations in EMUS disk observations using data from the Imaging Ultraviolet Spectrograph (IUVS), the Solar Wind Ion Analyzer (SWIA), the SupraThermal And Thermal Ion Composition (STATIC) instrument, and a magnetometer (MAG), all onboard NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. We use vertical profiles of densities and temperatures retrieved from limb scan observations by IUVS to identify signatures of dynamics that correlate with unexpected variations in EMUS disk observations. We use measurements from all of the instruments to categorize and characterize EMUS observations in order to determine how changes in composition and solar wind deposition produce unexpected variations in the Martian ultraviolet dayglow.

How to cite: Evans, J. S., Chaffin, M., Deighan, J., Jain, S., Correira, J., Soto, E., Al Matroushi, H., Al Mazmi, H., England, S., Fillingim, M., Holsclaw, G., Lillis, R., and Lootah, F. and the MAVEN Team Members: Dayside auroral emission induced by proton deposition observed by EMM EMUS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8656, https://doi.org/10.5194/egusphere-egu23-8656, 2023.

Discrete aurorae are produced by charged particle precipitation (mostly electrons) into the upper atmosphere. Electron impact causes electronic excitations of atoms and molecules in the atmosphere, whose deexcitation releases ultraviolet photons. Discrete aurora was first discovered as an ultraviolet glow coming from “magnetic umbrellas” in the southern hemisphere. These are strong crustal magnetic field regions on Mars, which are remnants of a global field that decayed billions of years ago. Both Mars Express (Bertaux et al., 2005) and MAVEN (Schneider et al., 2021) have observed cases of discrete aurora events using their limb viewing observations. Emirates Mars Mission (EMM) provides the first synoptic (or disk) images of discrete aurora at Mars (Lillis et al., 2022), thanks to its large orbit and high sensitivity UV spectrograph.

Using observations from Emirates Mars Ultraviolet Spectrometer (EMUS) onboard EMM, the geographic, local time and seasonal distributions of FUV discrete aurora in oxygen auroral emissions (130.4 nm and 135.6 nm) are investigated. Interesting local time asymmetry is observed in the aurora occurrence rates, brightnesses and emission line ratios. More aurora occurrence is observed during pre-midnight (dusk) as compared to post-midnight (dawn). Strong radial crustal field regions (SCFR) have aurora mostly during dusk, and not during dawn. Aurora also tend to occur more in open magnetic field regions away from SCFR. Brighter aurora is observed in the southern hemisphere during dusk, while in the northern hemisphere during dawn. Low brightness ratio [O I 130.4 nm/O I 135.6 nm] is observed in SCFR, but higher ratio in regions away from SCFR in the southern hemisphere. Also, the occurrence rate is found to be enhanced during the perihelion season as compared to the aphelion season. Statistical analysis of the dependence of discrete aurora on observation geometry, upstream solar wind and interplanetary magnetic field conditions will also be presented.

References:

[1] Bertaux, JL., Leblanc, F., Witasse, O. et al. (2005). Discovery of an aurora on Mars. Nature, 435, 790–794, https://doi.org/10.1038/nature03603.

[2] Schneider, N. M., Milby, Z., Jain, S. K., Gérard, J.-C., Soret, L., Brain, D. A., et al. (2021). Discrete aurora on Mars: Insights into their distribution and activity from MAVEN/IUVS observations. Journal of Geophysical Research: Space Physics, 126, https://doi.org/10.1029/2021JA029428.

[3] Lillis, R. J., Deighan, J., Brain, D., Fillingim, M., Jain, S., Chaffin, M., et al. (2022). First synoptic images of FUV discrete aurora and discovery of sinuous aurora at Mars by EMM EMUS. Geophysical Research Letters, 49, https://doi.org/10.1029/2022GL099820.

How to cite: Chirakkil, K., Lillis, R., Deighan, J., Chaffin, M., Jain, S., Brain, D., Fillingim, M., Raghuram, S., Evans, S., Holsclaw, G., Al Matroushi, H., England, S., Al Mazmi, H., Ramstad, R., Halekas, J., Espley, J., Xu, S., Fang, X., Schneider, N., and Curry, S.: Seasonal and Local Time Dependence of Martian FUV Discrete Aurora Observed by EMM EMUS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11360, https://doi.org/10.5194/egusphere-egu23-11360, 2023.

One of the primary objectives of the Emirates Mars Mission (EMM) is to study the seasonal variation of the upper atmosphere of Mars and associated changes in the escape of atmosphere to space. Here we present a preliminary analysis of the oxygen population in the inner exosphere (1.06-1.6 Martian radii) with nearly-contiguous sampling across all Martian seasons from early MY 36 to early MY 37. This oxygen is thought to be a non-thermal photochemically generated population driven by solar EUV, which can produce energetic atoms with sufficient velocity to escape Mars’ gravity. The observations are made by measuring the atomic oxygen emission at 130.4 nm using the Emirates Mars Ultraviolet Spectrometer (EMUS). We compare the brightness of the exospheric oxygen population with the thermospheric population ( < 1.06 Mars radii, or < 200 km) and find that the exosphere is much more responsive to seasonal variations in solar energy input. The seasonal variations cannot be explained by modulations in solar irradiance at 130.4 nm alone, and are consistent with the expectation that the extended oxygen exosphere at Mars is generated by a photochemical source.

How to cite: Deighan, J., Chaffin, M., Chirakkil, K., Al Matroushi, H., Lillis, R., Fillingim, M., England, S., Jain, S., Holsclaw, G., Lootah, F., Al Mazmi, H., Raghuram, S., Eparvier, F., Thiemann, E., Chamberlin, P., and Curry, S.: Seasonal Variation of the Martian Inner Hot Oxygen Exosphere Observed by EMM/EMUS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4712, https://doi.org/10.5194/egusphere-egu23-4712, 2023.

Atomic hydrogen and oxygen are the dominant species in the Martian exosphere. Atomic hydrogen is essentially produced from the dissociation of H₂O, whereas, hot oxygen atoms are populated by non-thermal processes such as the dissociative recombination of O₂⁺ with electrons in the Martian ionosphere. The study of these species helps to understand the evolution of the Martian atmosphere and more specifically the history of water on Mars.  The Emirates Mars Ultraviolet Spectrometer (EMUS), one of the primary instruments onboard the Emirates Mars Mission (EMM), has been observing atomic hydrogen and oxygen in the Martian exosphere over the Mars Year 36. We present the analysis of the cross-exospheric observations by the EMUS for hydrogen Lyman series and oxygen 130.4 nm emissions and their seasonal variability. The EMUS cross-exospheric observations cover the tangent altitude starting from 130 km to more than 35,000 km above the disk (see Fig. 1), with most of the observations below 25,000 km. The observations show that when Mars moved from perihelion to aphelion, the hydrogen emission line intensities increase by an order of magnitude or more whereas, for oxygen, it is an increment by a factor of about 2 at larger altitudes. Based on these observations, we also discuss the retrieval of densities, temperature, and the estimation of escape fluxes of hydrogen and oxygen species by applying 3D hydrogen ballistic corona and 3D Monte Carlo particle transport models, respectively.

Figure 1: The EMM-observed cross-exosphere emission intensity profiles of atomic hydrogen and oxygen during Mars Year 36

How to cite: Raghuram, S., Chirakkil, K., Deighan, J., Chaffin, M., Jain, S., Lillis, R., Gacesa, M., Fillingim, M. O., Brain, D., Thiemann, E., Eparvier, F., Holsclaw, G., England, S., Evans, S., Lootah, F. H., Al Mazmi, H. A., Curry, S., and Al Matroushi, H. R.: Seasonal variability of atomic hydrogen and oxygen in the EMM/EMUS cross-exospheric observations during Mars year 36, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13324, https://doi.org/10.5194/egusphere-egu23-13324, 2023.

We present scattering cross sections for O(³P), C(³P), and H colliding with a CO₂ molecule at collision energies between 0.1 and 5 eV. The kinetics, transport, and energy relaxation associated with collisions between fast atoms and thermal background atomic and molecular species are of fundamental interest for escape processes in the Martian atmosphere. Two of three primary objectives of the Emirates Mars Mission are related to hydrogen and oxygen escape processes and the collision cross sections are used in the models needed to interpret the observations by the EMUS and EMIRS instruments.

In this work, the collision cross sections have been computed using first principles electronic potential energy surfaces constructed in reduced dimensionality for the lowest-energy asymptotes corresponding to the ground states of the interacting pairs. For the three systems, namely C(³P)-CO₂, O(³P)-CO₂, and H-CO₂, velocity-dependent elastic, rotationally inelastic, and corresponding differential cross sections and derived quantities, including the momentum-transfer cross sections, were constructed. In all cases, the CO₂ molecule was modeled using the rigid-rotor approximation, and the collisions were treated as non-reactive. The cross sections were calculated from the first principles (no external parameters) by solving quantum-mechanical coupled channel equations following the approach of Arthurs-Dalgarno, with the coupled-state approximation^1,2.

We estimate the impact of the collision cross sections impact on the O, C, and H escape rates at Mars using simple 1D transport models and find significant differences compared to the values in the literature. In the transport model, we used the altitude density profiles taken from NASA’s MAVEN mission. In case of all three energetic atoms, the inelastic cross sections are found to be a significant part of the total cross sections. In case of O escape, we obtain a larger escape flux closer to the estimates based on the MAVEN measurements. We find that that O+CO flux affects the O escape more significantly than expected³, due to its effects on the available energetic O flux. We expect a similar effect to be present not only at Mars but at all CO₂-rich planets due to the O-CO-CO₂ photochemistry. The impact on C escape is inconclusive, suggesting that the accounted mechanisms of photochemical escape of C are not sufficient to explain the missing carbon at Mars^4,5. Please insert your abstract HTML here.

How to cite: Gacesa, M., Krishnan, B. M., Chaluvalappil, S. V., and Alraie, M.: Scattering cross sections for O(3P), C(3P), and H colliding with a CO2 molecule for planetary aeronomy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13860, https://doi.org/10.5194/egusphere-egu23-13860, 2023.

The formation of water ice clouds can significantly influence the Martian climate, although the Martian atmosphere contains low water vapor concentrations compared to terrestrial levels. The lower Martian atmosphere exhibits three global water ice cloud systems: Aphelion cloud belt (ACB), polar hoods (PHs), and orographic clouds. These clouds are associated with topography, solar heating, global atmospheric circulation, wave activity, and local convection. An appreciable amount of research has been conducted on the first two regimes (ACB and PHs) and very little attention has been given to the third regime (orographic clouds). In general, orographic clouds are observed in northern Spring and summer since they are associated with the major Martian volcanoes. Water ice optical depths provided by the Emirates Exploration Imager (EXI) of the Emirate Mars Mission (EMM) will be used to investigate seasonal and diurnal variations of such clouds in the Tharsis volcanic region: Ascraeus Mons, Pavonis Mons, Arsia Mons, and Olympus Mons. Additionally, context will be provided using the meteorological fields from the Mars PCM (Mars Planetary Climate Model led by Laboratoire de Meteorologie Dynamique Paris, France). This study provides a general picture of how Martian water ice clouds correlate with Mars PCM's meteorological variables: water ice optical depth, atmospheric temperature, meteorological winds, and water vapor mixing ratio. 

How to cite: Fernando, A., Wolff, M., and Forget, F.: Seasonal and Diurnal Variations of Orographic Clouds on Mars with EMM/EXI observations and the Mars Planetary Climate Model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3932, https://doi.org/10.5194/egusphere-egu23-3932, 2023.