The Mars 2020 Perseverance rover landing site is located within Jezero crater, a  $\sim50~\mbox{km}$ diameter impact crater interpreted to be a Noachian-aged lake basin inside the western edge of the Isidis impact structure. Jezero hosts remnants of a fluvial delta, inlet and outlet valleys, and infill deposits containing diverse carbonate, mafic, and hydrated minerals. Prior to the launch of the Mars 2020 mission, members of the Science Team collaborated to produce a photogeologic map of the Perseverance landing site in Jezero crater. Mapping was performed at a 1:5000 digital map scale using a 25 cm/pixel High Resolution Imaging Science Experiment (HiRISE) orthoimage mosaic base map and a 1 m/pixel HiRISE stereo digital terrain model. Mapped bedrock and surficial units were distinguished by differences in relative brightness, tone, topography, surface texture, and apparent roughness. Mapped bedrock units are generally consistent with those identified in previously published mapping efforts, but this study’s map includes the distribution of surficial deposits and sub-units of the Jezero delta at a higher level of detail than previous studies. This study considers four possible unit correlations to explain the relative age relationships of major units within the map area. Unit correlations include previously published interpretations as well as those that consider more complex interfingering relationships and alternative relative age relationships. The photogeologic map presented here is the foundation for scientific hypothesis development and strategic planning for Perseverance’s exploration of Jezero crater.

Both NASA's VERITAS and ESA's EnVision missions to Venus incorporate a Venus Emissivity Mapper (VEM) to characterize the surface and distinguish basalt from more felsic rock types. Though Venus' optically dense atmosphere makes direct observations of the surface challenging, five windows in the CO2 spectrum near 1 mu m will be exploited by the VEM instrument. In preparation for these missions, an analog of the VEM instrument (VEMulator2.0) was constructed for field measurements. It was used in a two-week field campaign at Venus-analog sites in Iceland in August 2023 as part of a VERITAS field campaign to collect multi-frequency reflectance measurements of volcanic rocks of varying age and surface conditions, as well as to measure emission from recently erupted lava with hot spots up to similar to 400 degrees C. The goal of the work was to train scientists and to help assess the capability of the VEM instrument to detect differences in surface composition in a wide variety of volcanic rocks in the field with the limited spectral information provided by six bands. In addition, samples of the imaged regions were collected to be analyzed in detail at the Planetary Spectroscopy Laboratory at DLR in Berlin. Comparing field and laboratory spectra gives insights into the efficacy and limitations of the analog instrument. This paper describes the emulator design and calibration procedure as well as first results from field and laboratory measurements.

The delta deposits in Jezero crater contain sedimentary records of potentially habitable conditions on Mars. NASA’s Perseverance rover is exploring the Jezero western delta with a suite of instruments that include the RIMFAX ground penetrating radar, which provides continuous subsurface images that probe up to 20 meters below the rover. As Perseverance traversed across the contact between the Jezero crater floor and the delta, RIMFAX detected a distinct discontinuity in the subsurface layer structure. Below the contact boundary are older crater floor units exhibiting discontinuous inclined layering. Above the contact boundary are younger basal delta units exhibiting regular horizontal layering. At one location, there is a clear unconformity between the crater floor and delta layers, which implies that the crater floor experienced a period of erosion before the deposition of the overlying delta strata. The regularity and horizontality of the basal delta sediments observed in the radar cross sections indicate that they were deposited in a low-energy lake environment.

Introduction: NASA's Perseverance Rover is exploring the Jezero Crater carrying the RIMFAX ground penetrating radar. RIMFAX has acquired a continuous subsurface radar image at 10 cm intervals along the rover’s > 25 km long ground track across the crater floor and fan, probing depths of >30 m below the rover, Figure 1. RIMFAX provides subsurface context for better understanding the depositional environments of the geological units that the rover has examined on the crater floor and the fan thus far. The Mars 2020 mission objectives are to seek signs of ancient life on Mars and cache a set of samples for possible return to Earth by a follow-on mission, [1]. An important part of the mission is to document the geological settings the cached samples are collected from. The Radar Imager of the Mars’ Subsurface Experiment is a gated FMCW radar operating in the frequency band of 150 – 1200 MHz. The antenna is a slotted bow tie antenna 70 cm above the surface. The typical center frequency of the reflected signal at 10–15-meter depth is 400 Mhz. RIMFAX collects soundings in three operating modes (surface, shallow and deep) every 10 cm along the rover’s traverse path, [2]. Figure 1 Orbital context maps of the RIMFAX observations in Jezero Crater. Orbital High Resolution Imaging Science Experiment (HiRISE) color base map showing the path (pale white lines) of the Perseverance rover. RIMFAX Radar Data: In the Margin Unit RIMFAX images several strong dipping layers that get horizontal at depth resembling clinoforms, Figure 2. The location of these reflecting layers is picked from the RIMFAX radargrams giving interface points in depth and location of the different layers. Figure 2 Radargrams give the reflected signal where white is high reflecting amplitude and black low amplitude. The depth axis for this radargram is 35 meters. Geological Modeling: The RIMFAX data can be used to make 3D models of the subsurface. The depth and locations of selected layers are picked from the RIMFAX Marginal Unit radargrams. From these layers, a geological model is made using GemPy, see [4] which employs a universal cokriging interpolation method, [4]. GemPy allows the user to generate complex 3D structural geological models through the interpolation of layer interfaces and orientation measurements and topography. Figure 3 shows a 2D cross section through the GemPy model. Figure 4 shows a map view of the model, indicating locations of outcropping layer boundaries. Figure 5 shows a 3D view of the subsurface layers in relation to surface topography.Figure 3. 2D cross section through the GemPy model from West to East. Non-shaded layers are truncated by surface topography.Figure 4. GemPy model reconstructed geologic map based on the extrapolation of picked layer depths and locations in the RIMFAX radargrams in the Margin Unit (dots). Figure 5. 3D geological model reconstructed from RIMFAX data showing the subsurface dipping layers and where they crop out on the surface. Discussion: The large-scale subsurface structures revealed by the RIMFAX in the Marginal Unit are reminiscent of deltaic clinoforms. Figure 4 shows that Marginal Unit layers are cropping out in complicated patterns that are not apparent in orbital images or topographic maps. Deeper eroded layers are predicted to be cropping out in the wall of Neretva Vallis. Using RIMFAX radar data in conjunction with geological modelling is a powerful tool for studying subsurface structures on Mars. Acknowledgments: The data used in this work are available at the NASA PDS Geosciences Node (https://doi.org/10.17189/1522644). This work was supported by the Research Council of Norway, grant no. 309835.References:[1] Farley et. al. (2021) Space Science Review, [2] Hamran et. al. (2021) Space Science Review, [3] Hamran et. al. (2022) Science Advances, [4] de la Varga et. al. (2019) GemPy, Geosci. Model Dev., 12, 1–32

AbstractThe RIMFAX ground‐penetrating radar (GPR) on Mars2020 Perseverance Rover is the first GPR operated on the Martian surface since February 2021, searching for stratigraphy beneath the Jezero crater. During its operations, GPR detected several strong reflectors extending from the exposed section of the Séitah formation down to depths of 15 m, with derived relative permittivity of ∼9.0 consistent with low‐porosity mafic rocks. We reprocessed all the SHAllow RADar (SHARAD) observations at a higher resolution and combined repeat‐passes coherently and/or incoherently for clutter mitigation. We then examined the bright returns searching for subsurface structures. The reprocessed data did not show any shallow reflectors like those detected by RIMFAX. We investigated possible factors influencing the lack of shallow reflectors in SHARAD radargrams, including the properties of the older volcanic lithologies and the significant variability of subsurface reflectors within the SHARAD km‐wide spatial footprint, which prevents the formation of coherent reflections.

VERITAS is a proposed Discovery mission concept, currently in Step 2 (Phase A), and would launch in 2026. VERITAS addresses one of the most fundamental questions in rocky planetary evolution: why did twin planets follow different evolutionary paths? Venus’ hot lithosphere may be a good analog for early Earth, and could be responsible for the apparent lack of plate tectonics. Determining the factors that lead to the initiation of plate tectonics would inform our predictions for rocky Earth-sized exoplanets. VERITAS answers key questions about Venus’ geologic evolution and searches for current activity and evidence for past or present water.Payload: VERITAS carries two instruments and conducts gravity science. The VISAR X-band [Hensley et al., this meeting] measurements include: 1) a global digital elevation model (DEM) with 250 m postings, 5 m height accuracy, 2) Synthetic aperture radar (SAR) imaging at 30 m horizontal resolution globally, 3) SAR imaging at 15 m resolution > 20% of the surface and 4) surface deformation from RPI at 2 mm precision for at least 12 targeted, potentially active areas. VEM [Helbert et al., this meeting] would produce surface coverage of most of the surface in 6 NIR bands located within 5 atmospheric windows and of 8 atmospheric bands for calibration and water vapor measurements. VERITAS would use Ka-band uplink and downlink to create a global gravity field with 3 mgal accuracy / 160 km resolution.Science: VERITAS looks for the chemical fingerprint of past water in the form of low Fe, high Si rock in the tessera plateaus [Dyar et al. submitted, 2020; Helbert et al., submitted, 2020] and for present day volcanic outgassing of volatiles in the form of near surface water outgassing due to recent or active volcanism. VERITAS uses a variety of approaches to search for present day activity, including 1) tectonic and volcanic cm-scale surface deformation, 2) chemical weathering, 3) thermal emission from recent or active volcanism, 4) topographic or surface roughness changes, and 5) comparisons to past mission data sets.VERITAS constrains rocky planet evolution via: 1) examining the origin of tesserae plateaus -possible continent-like features, 2) assessing the history of volcanism, 3) looking for evidence of prior tectonic or impact features buried by volcanism, and 4) determining the origin of tectonic features such as huge arcuate troughs that have been compared to Earth’s subduction zones.VERITAS gravity data (resolution 160 km, 3x better than avg. Magellan resolution), would enable estimation of elastic thickness (a proxy for thermal gradient) and determination of core size [Mazerico et al. Fall AGU 2019]. Conclusions: VERITAS would create a rich data set of high-resolution topography, imaging, spectroscopy, and gravity. These co-registered data would be on par with those acquired for Mercury, Mars and the Moon that have revolutionized our understanding of these bodies. In addition to answering fundamental science questions, VERITAS’ data would motivate further Venus missions. Active surface deformation would promote a seismic mission. Accurate topography plus surface rock type would optimize targeting of surface or areal missions.Acknowledgements: A portion of this research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. The information presented to about the VERITAS mission concept is pre-decisional and is provided for planning and discussion purposes only.

Introduction: The composition of lava fields on Venus and their alteration state are poorly constrained. The Venus Emissivity Mapper (VEM) [1, 2] on board NASA’s VERITAS [3] and its twin VenSpec-M on ESA’s EnVision will observe the surface of Venus in the NIR range through five atmospheric windows covered by six spectral bands (0.86 to 1.2 µm). These will enable studying the spectral characteristics of the Venusian surface, as well as lava types and possible alteration processes. To prepare for these missions and deepen our understanding of the emissivity spectral characterization of various volcanic rocks, we developed a field camera system analogous to VEM, named “VEMulator2.0” [4], and have undertaken in-situ measurements during the VERITAS expedition in Iceland, early August 2023. We relate these data to emissivity spectra of field samples acquired in the Venus chamber at the Planetary Spectroscopy Laboratory (PSL) of DLR-Berlin [1].Iceland: The vegetation-free, geologically recent basaltic lava fields of Iceland make this area a prime Venus analog [5, 6]. Selected regions of interest for this campaign are [6]: Askja/Holuhraun in the highlands; Fagradalsfjall on the Reykjanes Peninsula. These ROIs offer a wide variety of surface textures, sand cover, and diverse fumarolic deposits, as well as macro- and micro- fractures. Fagadalsfjall is of particular interest for NIR team because of its very fresh lava flows (2021, 2022, and 2023), the still-cooling lava in the subsurface, and the recent fumarolic alteration products on the surface.In-situ NIR data acquisition: The VEMulator2.0 is an in-house built camera system equipped with an InGaAs detector – similar to the VEM flight model – and a filter wheel with six bandpass filters: 860, 910, 990, 1030, 1100, 1200 nm. A simpler version of this set-up had been successfully used in a field campaign in Vulcano, Italy [7]. In Iceland, data were collected in daytime (reflected sunlight) and at nighttime as emittance of the very hot (~100-480°C) lava flow at the active fissure of Litli-Hrutur.Reflectance data. The main goal here is to understand the NIR spectral response of different basaltic surfaces in the spectral range of VEM. The sites were selected based on their surface texture and mineralogy. The goal was to image varying surface textures as well as contacts between different materials, such as sand cover over the 2014-2015 Holuhraun lava field, fumaroles and their deposits of Holuhhraun and Fagradalsfjall, tephra mantled lava flows near Askja, very fresh surfaces of Fagradalsfjall’s 2021-2023 fields, and near surface alteration due to escaping hot gases (including water vapor), exposed via fractures.The imaged sites were scanned by the LiDAR team to obtain a high-resolution (millimeter-scale) DEM of the ROIs. These data will constrain surface geometry [8, 9]. GPS coordinates of the VEMulator location and the imaged targets have been collected, providing cm-scale precision on the camera-target distance. Two calibration targets were used in each imaged scene: one black surface as blackbody, and a gray disc. Both calibration targets were spectrally analyzed in the PSL laboratory before and after the field campaign, thus have known spectra that will help improving our data calibration processes.Emittance data. The main goal here was to collect in-situ emittance of a fresh lava flow in the NIR spectral range of VEM. We imaged the hot lava surface (approximately 100-480°C) of the active vent of Litli-Hrútur where an eruption terminated two days prior to our arrival to obtain in-situ emittance of the basaltic rock at Venus temperature, after sunset. We used a FLIR thermal camera to find the hot spots, in collaboration with colleagues at the Univ. of Iceland. This allowed direct observation of surface temperature and identification of several cracks where hot gases were escaping from the cooling lava. All these collected data will provide detailed spectral information and a deeper understanding of the surface composition of the studied lava flows.Sample collection. We collected samples from every imaged scenery by VEMulator. A total of ~60 kg of samples was transported to DLR in Berlin for post- processing and analyses using reflectance and emittance methods available there. All the samples are carefully labeled and stored in the sample collection laboratory at DLR-Berlin.Laboratory measurements: Bi-directional and hemispherical reflectance spectra from 0.7-2.63 μm were collected using the Bruker Vertex 80V spectrometer at the PSL in DLR-Berlin. The data will be related to the daytime field data to better understand the NIR spectral response of surface material using the six spectral bands. We will collect emissivity measurements using the Venus chamber at PSL, to correlate with the in-situ nighttime data collected from Litli-Hrutur 2023 lava field. In addition, various Icelandic basalt samples will be analyzed in the Venus chamber with the goal to expand our datasets of emissivity spectra of Venus-analog materials as part of the VEM calibration plan [10].Conclusion and future work: In the VERITAS expedition 2023 in Iceland, we collected in-situ NIR data using a Venus Emissivity Mapper (VEM) emulator (VEMulator2.0), and 60 kg of samples of Venus analog materials. The highlight of this work is the data we collected after sunset from the active fissure of Litli-Hrutur in the range of Venus surface temperature. We are currently analyzing the samples at PSL-DLR Berlin using the reflectance and emittance set-ups to correlate the laboratory data with the field data. This work will increase our understanding of emissivity of rock samples in hot temperature and will contribute in the VEM calibration plan.Acknowledgments: SA, SPG, NM, AD received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 871149. GC, EM was supported by NASA Planetary Science Division Research Program through the GSFC GIFT ISFM.References: [1] Helbert, J., et al. (2022) SPIE. [2] Helbert et al. (2024) LPSC 55. [3] Smrekar S. (2022) IEEE Aerospace Conf.. [4] Garland S. et al. (2024) EPSC 2024. [5] Nunes et al. (2023) LPSC 54. [6] Nunes et al. (2024) LPSC 55. [7] Adeli et al. (2023) SPIE. [8] Mazarico et al. (2024) LPSC 55. [9] Cascioli et al. (2024) LPSC 55. [10] Alemanno et al. (2023) SPIE.

In this work we discuss various selected mission concepts addressing Venus evolution through time. More specifically, we address investigations and payload instrument concepts supporting scientific goals and open questions presented in the companion articles of this volume. Also included are their related investigations (observations & modeling) and discussion of which measurements and future data products are needed to better constrain Venus’ atmosphere, climate, surface, interior and habitability evolution through time. A new fleet of Venus missions has been selected, and new mission concepts will continue to be considered for future selections. Missions under development include radar-equipped ESA-led EnVision M5 orbiter mission (European Space Agency 2021 ), NASA-JPL’s VERITAS orbiter mission (Smrekar et al. 2022a ), NASA-GSFC’s DAVINCI entry probe/flyby mission (Garvin et al. 2022a ). The data acquired with the VERITAS, DAVINCI, and EnVision from the end of this decade will fundamentally improve our understanding of the planet’s long term history, current activity and evolutionary path. We further describe future mission concepts and measurements beyond the current framework of selected missions, as well as the synergies between these mission concepts, ground-based and space-based observatories and facilities, laboratory measurements, and future algorithmic or modeling activities that pave the way for the development of a Venus program that extends into the 2040s (Wilson et al. 2022 ).

Summary The Ground Penetrating Radar (GPR) RIMFAX on the NASA Mars 2020 rover Perseverance is the first time a NASA Mars rover has a GPR. The GPR makes it possible to collect information on subsurface structure, physical properties, and composition. RIMFAX has during the first two years of operation on Mars shown that ground penetrating radar is an excellent tool for studying the shallow subsurface of Mars. RIMFAX has imaged layers that outcrop at the surface and make it possible to trace the layers between the outcrops. RIMFAX has revealed the stratigraphic relationship between several geological contacts that would have been difficult to interpret using only surface observations. RIMFAX penetrates and image the subsurface down to approximately 15 meter in the crater floor and down to 20 meter in the deltaic sediments.

The Mars 2020 Perseverance Rover is equipped with the RIMFAX ground penetrating radar instrument which has been continuously surveying the shallow subsurface during the rover's journey. Within the first 379 mission days, we identify hyperbolic patterns in the data, which are thought to be caused by objects such as buried boulders or cavities located in the upper 5 m of the subsurface. To obtain the first detailed estimates of radar wave propagation velocity, we match these scatterer‐generated patterns with theoretical traveltime hyperbolas, which take into account the refraction at the surface. We employ these estimates to derive the average dielectric permittivity and bulk rock density of the volume above the scatterer source. The parameters compare well with those obtained through orbital radar measurements and those measured by other instruments onboard the Perseverance Rover. Our findings are consistent with a subsurface dominated by solid rock and mafic material.

The Radar Imager for Mars Subsurface Experiment instrument has conducted the first rover-mounted ground-penetrating radar survey of the Martian subsurface. A continuous radar image acquired over the Perseverance rover’s initial ~3-kilometer traverse reveals electromagnetic properties and bedrock stratigraphy of the Jezero crater floor to depths of ~15 meters below the surface. The radar image reveals the presence of ubiquitous strongly reflecting layered sequences that dip downward at angles of up to 15 degrees from horizontal in directions normal to the curvilinear boundary of and away from the exposed section of the Séitah formation. The observed slopes, thicknesses, and internal morphology of the inclined stratigraphic sections can be interpreted either as magmatic layering formed in a differentiated igneous body or as sedimentary layering commonly formed in aqueous environments on Earth. The discovery of buried structures on the Jezero crater floor is potentially compatible with a history of igneous activity and a history of multiple aqueous episodes.

Dipole antennas are well known and are used for a variety of applications in many different shapes and forms. Wide-band planar dipole antennas, in particular, have been developed, designed and implemented in the past and have shown promising RF performance. In this paper, we describe a particular style of a wide-band planar dipole antenna that is being developed over a wide range of frequencies for a variety of scientific applications on Earth, the Moon and beyond. Aside from the appealing RF performance, this antenna element also lends itself to being easily folded and stowed on a small satellite and deployed once in space, making it very useful in applications where large apertures or low frequency/long wavelength antennas need to be deployed from a small platform (compared to the wavelength).

The subsurface of Mars has the potential to harbor existing deposits of liquid water, which are of great interest both scientifically (in the search for life) and as resources for future astronauts living on the red planet. However, the depth to a potential subsurface aquifer may be kilometers deep, which is well beyond what current surface or orbital approaches can sur-vey while also confirming the unique signature for liquid water. Inspired by critical technology for exploring deep aquifers on Earth, we are developing the Transient H2O Reconnaissance (TH 2 OR) instrument at NASA's Jet Propulsion Laboratory (JPL). TH2OR operates on the principle of transient electro-magnetics (TEM), which leverages induction and electromotive force to induce a current in a subsurface water body using a loop-shaped antenna that provides both transmit and receive functions when placed on the surface. On Mars, TEM may be even more effective given the relative dryness of the subsurface compared to a more conductive, saline, liquid, water body on Earth. However, to probe deep within the subsurface (below 5 km) a large enclosed antenna is needed - specifically, a 100-m diameter effective loop or a shape with roughly equivalent area that can transmit at low frequencies (kHz-Hz). The deployment of a large-scale structure on the surface is complicated by the fact that the transmit wire must be both lightweight and robust to contact with the surface. Further, TH2OR may be delivered to the surface by a non-mobile vehicle, so it is desired that the deployment can be activated from a static location. This paper provides an overview of the deployment trade study, focusing on our current, favored approach, using a projectile wire launcher. Building on past approaches in the literature, we have developed and fielded an Earth-based, gas-projectile prototype for launching a triangle-shaped antenna onto analogue terrain. Our results compare simulated launch performance to actual field tests conducted under Earth gravity and pressure conditions. We discuss how Earth performance maps to a prospective Mars deployment under reduced gravity and pressure. We also pro-vide lessons learned and next steps towards the development of an integrated TH 2 OR instrument for finding water on Mars.

Deep understanding of planetary habitability requires identifying key factors that govern the surface environment over time. Venus is the ultimate control case for understanding how Earth developed and maintained conditions suited to life. Venus very likely had elements essential to habitability such as past surface water and a dynamo. Tectonism and volcanism, which create chemical disequilibrium, very likely persist today. What caused Earth and Venus to diverge down different evolutionary paths? VERITAS would create foundational, co-registered data sets of high-resolution topography, imaging, spectroscopy, and gravity, on par with those available for Mercury, Mars, and the Moon. VERITAS would answer outstanding fundamental questions about the evolution of Earth's twin. The VERITAS payload consists of the Venus Interferometric Synthetic Aperture Radar (VISAR) and the Venus Emissivity Mapper (VEM), plus a gravity science investigation. VISAR is an X-band radar that provides: 1) a global digital elevation model (DEM) with 250-m postings and 6-m height accuracy, 2) Synthetic aperture radar (SAR) imaging at 30-m horizontal resolution globally, 3) SAR imaging at 15-m resolution for $> \boldsymbol{25\%}$ of the surface, and 4) surface deformation from repeat pass interferometry (RPI) with 2-cm vertical precision for $> \boldsymbol{12} \boldsymbol{(\sim 200\ \mathrm{x}\ 200\ \text{km})}$ targeted areas. VEM covers $\boldsymbol{ > 70\%}$ of the surface in six near-infrared (NIR) bands sensitive to iron composition located within five atmospheric windows, plus eight atmospheric bands for calibration and water vapor measurements. VEM would provide near-global maps of mafic to felsic rock type and will search for active and recent volcanism. VERITAS would use two-way Ka-band uplink and downlink from a low circular orbit $\boldsymbol{(< 250\ \text{km})}$ to create a global gravity field with 3-mGal accuracy of 155-km resolution (degree and order 123). An onboard technology demonstration, the Deep Space Atomic Clock (DSAC-2), may support radio science and navigation with one-way tracking. VERITAS data would enable estimation of elastic thickness (a proxy for thermal gradient) and density differences due to subsurface structures, as well as constraining interior structure, including core size and state. Lockheed Martin builds the spacecraft. VISAR is built by JPL, with the Italian Space Agency (ASI) providing the low power electronics. ASI also provides transponders and a high gain antenna for the telecom system. CNES provides the Ka-band traveling wave tube amplifiers (TWTA). The German Space Agency (DLR) provides VEM and contributes algorithms for VISAR ground and onboard data processing.

Primary author: Suzanne Smrekar Jet Propulsion Laboratory/California Institute of Technology, Pasadena CA ; Co-authors: Jeff Andrews-Hanna (U.AZ), Doris Breuer (DLR Berlin), Paul Byrne (NCSU), Debra Buczkowski (JHU/APL), Bruce Campbell (Nat. Air Space Museum), A. Davaille (CNRS/U. Paris-Saclay), Darby Dyar (Mt. Holyoke/PSI), G. Di Achille (INAF/Astro Obs. Teramo), Caleb Fassett (Marshall), Martha Gilmore (Wesleyan), Robert Grimm (SWRI), Jorn Helbert (DLR Berlin), Scott Hensley (JPL), Robert Herrick (U. Alaska), Luciano Iess (U.Roma), Lauren Jozwiak (JHU/APL), Tiffany Katiaria (JPL), Marco Mastrogiuseppe (U. Roma), Erwan Mazarico (Goddard), Nils Mueller (DLR Berlin), Daniel Nunes (JPL), Joseph O'Rourke (ASU); Patrick McGovern (LPI), Maria Raguso (Caltech), Joann Stock (Caltech), Constantine Tsang (SwRI), Thomas Widemann (Obs. Paris), Jennifer Whitten (Tulane), Thomas Widemann (LESIA), Howard Zebker (Stanford)

Jezero crater hosts a rich variety of geomorphological features, which together record an equally rich geological history. The Mars 2020 Perseverance Rover is exploring Jezero’s varied terrain with the goal of understanding its geological history and its potential for preserving biosignatures. This exploration is naturally multi-faceted, comprising investigations of the materials and structures currently preserved in the crater, using both pre-landing orbital data and observations collected in-situ by Perseverance. Here, we report on investigations of Jezero’s geomorphological lineaments, focusing on fractures and their significance for Jezero’s geological history. Lineaments in general are the surface expressions of structures reflecting either brittle or ductile deformation of the host rock. At Jezero, we have mapped several distinct suites of lineaments that we interpret as brittle fractures. Fractures are important to understand because, in general, they provide conduits for fluid flow; they represent planes of mechanical weakness that can signal bulk mechanical properties of the rocks in which they form; and, on Mars, represent possible sites of astrobiological interest. Using both orbital and in-situ data, we systematically analyze the characteristics of these fractures. We focus on fracture geometry, which can provide critical information about the deformation history of a region, and relative timing, which can provide valuable relative chronological or stratigraphic information. We are particularly interested in the three-dimensional geometry of fractures expressed at the surface. The RIMFAX ground-penetrating radar instrument on the Perseverance Rover provides the opportunity to characterize the subsurface geometry of Jezero’s fractures, thereby adding a critical dimension to the analysis of these features. By documenting fracture morphologies, orientations, scale, spacing, and spatial patterns and interactions, including subsurface information wherever possible, we seek to understand the nature and sequence of deformation in Jezero crater.

The Shallow Radar (SHARAD) instrument on the Mars Reconnaissance Orbiter (MRO) has been operating since 2006, revealing the detailed layered structure of the polar caps, mid-latitude glacial deposits, and a range of volcanic features. Here we address the major sources of change in the effective gain and signal-to-noise ratio of data collected by SHARAD: (1) the altitude and background noise level, (2) the configuration of the solar arrays (SA) and high-gain antenna (HGA), (3) ionospheric attenuation, and (4) the roll angle of MRO. Background noise fluctuations have a range of similar to 5 dB, and electromagnetic interference may significantly affect comparisons among limited bands of the full spectrum. We use the dense spatial coverage of sounder data to define a model for gain as a function of SA and HGA orientations, and demonstrate its predictive capability over a 4-dB range with radargrams collected under different configurations. Ionospheric attenuation as a function of the phase distortion correction used in radargram processing is refined through a larger dataset than available in earlier studies. Gain improvements due to MRO rolls up to 28(o) are also a function of the SA-HGA configuration, such that the maximum span of combined SHARAD gain contributions is about 7 dB. After calibration, Planum Boreum in the north polar layered deposits is similar to 3 dB less reflective than Planum Australe, and multi-band analysis suggests destructive interference occurs in the more densely layered shallow structure of the northern cap. The new calibration model allows targeting of future observations during optimum conditions over features of interest.