High Resolution Imaging Science Experiment Research Articles

A global map of gullied hillslopes on Mars

The distribution of gullies on Mars has been used to support different modes of formation involving CO2, H2O or entirely dry processes. We mapped the extent of gullied hillslope using a global mosaic of ConTeXt camera (CTX) at 6 m/pixel and High Resolution Imaging Science Experiment (HiRISE) browse products at ~3 m/pixel. Our new globalcatalog of gullied hillslopes allows for quantitative, area-based analysis of gullies both at global and regional scale, which was not possible with point-based or more localized previous datasets. We analyzed aspect and gradient information derived from MOLA topography for every mapped gullied hillslope. We have confirmed the trends identified in previous works, which are that the mean gradient of gullied hillslopes is lower than 30°, the angle of repose of dry material on Mars, and that the preferred aspect of gullied hillslopes is latitude-dependent, with a shift between pole-facing to equator-facing happening around 40° in both hemispheres. We established a hierarchy of factors that can explain the global distribution of gullied hillslopes: Latitude is the strictest control because gullies are constrained between 26°-83°S and 28°-76°N. The availability of steep slopes is a strong control over gully distribution, and we observed that gullied hillslopes aspect reflects the orientation of large regional reliefs, which implies that hillslope aspect is less of a factor than the hillslope gradient in explaining gully distribution. We analyzed the correlation of gully distribution with a subsurface water ice consistency map, and we found that gullies are preferentially distributed on areas with some ground ice rather than no ice at all. We identified for the first time a bias toward an east-facing trend for southern hemisphere gullies poleward of ~40° of latitude. We also linked our gullied hillslopes dataset with a global crater morphometry dataset: 63% of the gullied area on Mars is found in craters, and we find that the area covered by gullies in a given crater is positively correlated with the depth and diameter ratio of this crater.Our observations point toward a complex interplay between local slope, insolation, and thermal properties of the substrate to explain the spatial distribution of the current population of gullies. Finally, we have assessed the very high resolution (sub-meter) imagery coverage of gullies to be 36% and that the repeated coverage reaches 21% of gullies, hence this would need expanding to better understand the spatial trends in active gullies.

A Mars Local Terrain Matching Method Based on 3D Point Clouds

To address the matching challenge between the High Resolution Imaging Science Experiment (HiRISE) Digital Elevation Model (DEM) and the Mars Orbiter Laser Altimeter (MOLA) DEM, we propose a terrain matching framework based on the combination of point cloud coarse alignment and fine alignment methods. Firstly, we achieved global coarse localization of the HiRISE DEM through nearest neighbor matching of key Intrinsic Shape Signatures (ISS) points in the Fast Point Feature Histograms (FPFH) feature space. We introduced a graph matching strategy to mitigate gross errors in feature matching, employing a numerical method of non-cooperative game theory to solve the extremal optimization problem under Karush–Kuhn–Tucker (KKT) conditions. Secondly, to handle the substantial resolution disparities between the MOLA DEM and HiRISE DEM, we devised a smoothing weighting method tailored to enhance the Voxelized Generalized Iterative Closest Point (VGICP) approach for fine terrain registration. This involves leveraging the Euclidean distance between distributions to effectively weight loss and covariance, thereby reducing the results’ sensitivity to voxel radius selection. Our experiments show that the proposed algorithm improves the accuracy of terrain registration on the proposed Curiosity landing area’s, Mawrth Vallis, data by nearly 20%, with faster convergence and better algorithm robustness.

Inferred wind speed and direction during the descent and landing of Perseverance on Mars

Perseverance successfully parachuted into Jezero crater close to its western rim on a Martian spring afternoon. In situ observations of the wind conditions during the parachute and powered descent are unavailable. These observations are important for characterising the Planetary Boundary Layer (PBL) and to better constrain atmospheric conditions in Jezero crater.We infer the winds during Perseverance's parachute descent from an altitude of 12 km down to 2 km by fitting a trajectory model to the reconstructed trajectory data published by the M2020 Entry, Descent and Landing team. Below 2 km altitude we infer the winds by analysing a High Resolution Imaging Science Experiment (HiRISE) image of the landing site that was obtained about one sol after the landing.Our inferred wind speed and direction profile indicate high speed winds at an altitude of 7 km blowing from the east and at 3 km blowing from the southwest. Below an altitude of 2 km, the winds are inferred to be easterlies. The heat shield impact on the surface was observed by Perseverance's Lander Vision System Camera (LCAM). Afterwards, ejecta clouds were observed moving towards the north of the impact site. These observations, together with the orientation of the parachute canopy on the surface, suggest near-surface winds at the time were southerlies.We have inferred the wind speed and direction during Perseverance's descent that are consistent with its horizontal motion as revealed by trajectory data and HiRISE image. Comparisons with atmospheric models suggest the high speed winds could be related to topographic forcing. This study provides constraints for atmospheric modelling and advances the characterisation of winds in Jezero crater, focusing on the vertical structure of the complex wind field present in the crater.

Paleoenvironmental significance of Fe/Mg phyllosilicate and sulfate deposits in Mikumi crater, northern Meridiani Planum, Mars

The region of Meridiani Planum on Mars retains the evidence of multiple surface and near-surface aqueous processes that span from the Noachian to the Hesperian. This makes it an interesting spot for better understanding the characteristics and the evolution of Mars’ aqueous environment between these two fundamental epochs. Here we investigate the mineralogy, stratigraphy, and morphology of the Noachian–Hesperian sedimentary materials that fill a 16-km-wide crater named Mikumi, located in the northern part of Meridiani Planum. The analysis was carried out combining observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), the High Resolution Imaging Science Experiment (HiRISE), and the Context Imager (CTX). About 20–30 meters, on average, of Fe/Mg phyllosilicate-rich rocks and a thick sequence (75 m) of both mono- and polyhydrated Mg sulfates are detected on the crater floor. Both layers postdate the impact event. Most of the hydrated terrains are extensively polygonally fractured, suggesting the possible action of water-related processes such as desiccation and hydro fracturing on the sediments. Stratigraphic analysis clearly shows that Fe/Mg phyllosilicates were deposited on top of the sulfate sequence, meaning that they are younger than sulfates. This can have interesting implications on paleoclimatic studies of Mars as it shows that a simple timeline going from a clay-rich Noachian to a sulfate-rich Hesperian oversimplifies the evolution of Mars’ mineralogy and related aqueous environment at the Noachian–Hesperian boundary.

Novel quantitative methods to enable multispectral identification of high-purity water ice exposures on Mars using high resolution imaging science experiment images

Reliable detection and characterization of water ice on the Martian surface is pivotal to not only understand its present and past climate, but to also provide valuable information on in-situ resource availability and distribution for future human exploration missions. Ice-rich features are currently identified with visible/near-IR (VNIR), thermal IR and radar data. However, their coarse spatial scale sometimes limits confident characterization of small (i.e., meter-scale) icy exposures resulting from recent activity like new impacts. Water ice bearing materials possess weaker spectral characteristics at wavelengths shorter than ~1030 nm that may be resolved by VNIR imaging instruments like the High Resolution Imaging Science Experiment (HiRISE) and the Colour and Stereo Surface Imaging System (CaSSIS). Our study assesses the spectral capability of HiRISE colour observations to help distinguish high purity water ice exposures from ice-poor materials. We report detailed methodologies for reliable colour characterization of icy surface using unfiltered HiRISE images. We present the first quantitative approach to uniquely characterize high-purity ice-rich materials through spectral shape and spectral parameterization methods at high spatial resolution (~50 cm/pixel). We also present three spectral parameters to aid detection of pure water ice features, while also providing statistical constraints to enable a quantitative interpretation scheme. Our methods are observed to work well in characterizing and separating ice-rich features uniquely from ice-poor and ferrous materials. However, we do observe that these methods have a lower grain size detection limit of ~250–300 μm, and may not be able to uniquely separate frosts from ground ice exposures. We also apply these methods to better constrain the composition of bright materials exposed by recent impacts identified in previous surveys, where substantial evidence for ice-bearing materials was previously unavailable. Overall, our work proposes HiRISE colour-based methods as a novel approach for high-resolution multispectral characterization of ice-rich features on the Martian surface, which is of particular value since the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) has ceased operations.

Silica‐Bearing Mounds and Strata in the Southwest Melas Basin, Valles Marineris, Mars: Evidence for a Hydrothermal Origin

AbstractA small basin on the Southwest (SW) margin of Melas Chasma in Valles Marineris, Mars, hosts a variety of previously identified sedimentary fans and layered strata hypothesized to have been formed by one or more paleolakes. This basin also contains light‐toned layered mounds that have distinct spectral absorption bands consistent with amorphous hydrated silica (e.g., opal). While the general morphology and mineralogy of these features and the basin itself have been previously characterized, the formation mechanism of the hydrated silica features and their temporal relationships with the proposed paleolake remain to be determined. We use Compact Reconnaissance Imaging Spectrometer for Mars visible through short‐wave infrared reflectance spectra (0.35–2.65 μm) and High Resolution Imaging Science Experiment digital terrain models and images to analyze the stratigraphic location and morphology of the opaline silica‐bearing features in the SW Melas basin. We find that the basin hosts fourteen high‐relief “mounds,” eight low‐relief “patches,” and two extended layers within the sedimentary strata that are light‐toned, fractured, and often exhibit hydrated silica‐like spectral signatures. We hypothesize that the mounds are spring deposits formed by sub‐aerial hydrothermal activity, while the patches and layers correspond to sub‐lacustrine hydrothermal activity. The varied elevations of the mounds and patches indicate at least one fluctuation of lake level in the basin during its history. The combination of contemporaneous hydrothermal and lacustrine activity to form silica‐cemented sedimentary deposits in a nutrient‐rich subaqueous environment would have been conducive to forming and preserving biosignatures in the SW Melas basin.

Limits on polygonal organization of boulders in the Martian northern lowlands

Polygonal terrain on Mars can form via thermal contraction and subsequent fracturing of the permafrost layer and covers much of the surface poleward of ∼60°. In similar terrains on Earth, seasonal freeze-thaw processes create a range of diverse landforms, including several in which clasts on the surface congregate into sorted circles and polygons. In the Martian northern lowlands, several investigations into boulder patterns have come to differing conclusions on whether analogous organization of clasts is present on Mars, whether there is an association between boulders and polygonal fracture margins, and what periglacial process may cause such organization in the modern environment that does not support seasonal melt. To address this discrepancy, we identify and measure boulders in the Martian northern lowlands with the Martian Boulder Automatic Recognition System (MBARS) and assess boulder spatial patterns to determine if boulders are organized into the margins of underlying fracture polygons. Sixty (60) Images from the High-Resolution Imaging Science Experiment (HiRISE) camera aboard the Mars Reconnaissance Orbiter (MRO) with priorly identified and measured polygons make up our survey, in which MBARS characterized 20 million boulders. We find that boulder patterns are not random across the northern lowlands and tend to be clustered with varying intensity. However, analysis of boulder pairwise distances shows that boulders are not generally organized into the 5–10 m polygonal patterns expected from an alignment of boulders to fracture margins. The lack of widespread polygonal organization of boulders indicates that processes responsible for the modern fracture polygons cannot organize meter-scale boulders towards their margins. This greatly reduces the likelihood of any terrestrial-like freeze-thaw organization occurring since the formation of the modern polygonal terrain in the Martian northern lowlands. Isolated instances of boulder patterns consistent with polygonal organization are found at the northern end of our survey. These instances could indicate a restriction of boulder-organizing processes only to the near-polar terrains but are better explained as selective preservation of paleo-organization. Plain language summaryWe have abundant evidence that the near-polar terrains on Mars have water ice buried at or very near the surface, much like on Earth. As this ice-rich surface cools in the winter, regularly spaced, roughly hexagonal cracks appear forming so-called “polygonal terrain”. In similar permafrost-dominated terrains on Earth, the presence of liquid water near the surface can cause rocks on the surface to be pushed outward during freezing. This eventually leads to the formation of stone circles or stone piles outlining the polygons, often forming large networks of sorted polygons. Using high-resolution images of Mars, we can see boulders as small as 1 m across, and it has been suggested that these boulders might also be organized into the edges of polygons on Mars. This raised the question: did these patterns form through Earth-like, wet processes? Or is there a way to make these patterns without liquid water? To answer this question, we surveyed sixty (60) images of Mars and used the Martian Boulder Automatic Recognition System (MBARS) to identify and measure the boulders in each image, totaling 20 million boulders. We determined that the boulders are not organized into a polygonal pattern, except in a few rare cases. Because the boulders are not organized, it is unlikely that any Earth-like wet processes or an unknown dry process is pushing boulders towards the edges of the fracture polygons. In the few places we do see this organization, it might be a pattern formed sometime in Mars' past when liquid water could exist at or near the surface.

A High‐Resolution Digital Terrain Model Mosaic of the Mars 2020 Perseverance Rover Landing Site at Jezero Crater

AbstractWe demonstrate the capabilities of a published MADNet monocular height estimation network in producing a refined digital terrain model (DTM) mosaic at 50 cm/pixel resolution for the Mars 2020 Perseverance rover landing site in Jezero crater on Mars. Our approach utilizes the publicly available Mars 2020 Terrain Relative Navigation (TRN) High‐Resolution Imaging Science Experiment (HiRISE) Digital Terrain Model (DTM) mosaic, which was originally created by the United States Geological Survey (USGS) Astrogeology Science Centre. Our resultant HiRISE MADNet DTM mosaic is strictly matched with the original HiRISE TRN DTM and orthoimage mosaics. These mosaics are themselves co‐aligned with the USGS TRN Context Camera (CTX) based DTM and orthoimage mosaics, as well as the ESA/DLR/FUB (European Space Agency/German Aerospace Center/Free University Berlin) High Resolution Stereo Camera (HRSC) level 5 DTM and orthoimage mosaics. In this paper, we provide a brief description of the technical details, and present both visual and quantitative assessments of the refined MADNet HiRISE Jezero DTM mosaic product. This DTM product is now publicly available at http://dx.doi.org/10.17169/refubium-38359.

Insights into the interaction between defrosting seasonal ices and gully activity from CaSSIS and HiRISE observations in Sisyphi Cavi, Mars

Martian gullies are surface features, typically composed of an alcove, a channel and a depositional apron. They have been extensively studied since their first observations in the 2000s and were initially attributed to the action of liquid water. Later studies highlighted that their activity is spatially and temporally correlated with the seasonal presence of surface CO2 ice, suggesting a link between seasonal frost and gully activity. However, the exact mechanisms leading to gully formation are still under debate. Establishing whether or not gullies are formed by liquid water has important implications for Mars recent climate and habitability. Here, we study the evolution of seasonal frost and its connection to gully activity in Sisyphi Cavi, located in the southern circumpolar region (68°S - 74°S; 345°E − 5°E). The high latitude of this site allows for detailed temporal monitoring, owing to the high frequency imaging by spacecraft in polar orbits, largely unavailable for other martian gullies, hence this site has the potential to reveal new insights on gullies in general. In particular, we used repeat images from MRO HiRISE (Mars Reconnaissance Orbiter, High Resolution Imaging Science Experiment) and TGO CaSSIS (Trace Gas Orbiter, Colour and Stereo Surface Imaging System). Our findings show that the general timing and characteristics of the defrosting patterns in Sisyphi Cavi follow seasonal patterns that are consistent from year to year. The timing of the start of defrosting and its temporal evolution are controlled by the overall orientation of the host hillslope, with equator-facing slopes defrosting before pole-facing ones and the steepest pole-facing slopes defrosting last. Gully alcoves defrost before channels and aprons located on the same hillslope independent of the orientation of the hillslope likely because the aprons have a lower thermal inertia than the alcoves that counteracts the orientation effect, which on pole-facing slopes would mean the alcoves should defrost last. We observe the presence of seasonal and ephemeral dark spots and flows which are interpreted to be a result of sediment deposition on top of the seasonal ice deposits, triggered by basal sublimation. Our observations suggest that the appearance of dark spots and dark flows can be spatially correlated with surface roughness, including presence of boulders, contrasts in material types, irregular lobes/levees and braiding caused by gully activity, and therefore could be used to help detect recently active gullies on Mars in areas with seasonal frost without the need of repeat imaging. Finally, we propose that presently observed gully activity in Sisyphi Cavi is driven by defrosted material flowing on to a frosted apron. We infer that the presence of a frosted apron could be common precursor for this type gully activity. We note that this activity only involves the mobilisation of loose materials and we have not observed any erosion of the wall rock present in Sisyphi Cavi.

Characterization of aqueous alteration and formation of salty exposures at Ius Chasma, Mars

Intriguing outcrops in Ius Chasma provide a window into past aqueous processes in Valles Marineris, Mars. Hydrous sulfate minerals are abundant throughout this region, but one area in Ius Chasma includes phyllosilicates, opal, and additional materials with unusual spectral features. This study at Geryon Montes, an east-west horst that divides Ius Chasma into a northern and southern canyon, exploits recent advances in image calibration and feature extraction techniques for analysis of hyperspectral images acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Specifically, a unique spectral “doublet” feature with absorptions at 2.21–2.23 and 2.26–2.28 μm is isolated at the border of phyllosilicate-bearing and sulfate-bearing regions in Ius Chasma and surveyed to characterize outcrops that may represent a changing climate on Mars. We document and map three distinct forms of this “doublet” material in relation to phyllosilicates and opal. Analyses of compositional maps derived from CRISM overlain on High Resolution Stereo Camera (HRSC) and High Resolution Imaging Science Experiment (HiRISE) imagery has revealed the presence of these hydrated outcrops along the wall rocks below a breach in the Geryon Montes, bordering a canyon containing abundant hydrated sulfates. Our investigation supports formation of these unique alteration phases through acid alteration of ancient smectites in the wall rock as the sulfate brine overflowed the south canyon of Ius Chasma at the breach in Geryon Montes and penetrated the deeper northern canyon.

Seasonal low albedo streaks at the edge of the Martian south polar layered deposits

Low Albedo Streaks (LAS) are narrow dark streaks observed at the edges of the South Polar Layered Deposits (SPLD) on Mars. We investigate the seasonal morphology, surface topography of LAS-rich areas using monochrome and multiband images from both the High Resolution Imaging Science Experiment (HiRISE) and the Color and Stereo Surface Imaging System (CaSSIS). We complement the image analysis with spectral data from the Compact Reconnassiance Imaging Spectrometer (CRISM). In addition, we analyze the thermal environment of LAS-rich areas with data from a Martian global climatological model. Our analysis suggests that streaks (i) originate from similar scarps and outcrops on the edge of layered structures at the end of local winter during different Martian years, (ii) lengthening in spring forming sinuous branches on terrain with rippled ridges, and (iii) eventually fade leaving distinguishable bright deposits within the streaked area. The surface topography analysis indicates that streaks advance on slopes between 4° and 34°, while the dust flows emanated from mass-wasting scars propagate on the slope steeper than 20°. Our spectral data analysis suggests that pyroxene- or basaltic-bearing materials are deposited on the surface mainly composed of dust by LAS. Thermal analysis indicates that LAS are active when the surface temperature rises from 145.5 K to 162 K, fading when the temperature increases suddenly and significantly. Finally, we evaluate several possible mechanisms to explain the formation of LAS. LAS might be formed by liquids, and such liquids might be brines. However, the presence of salts with lower eutectic temperatures seems to be necessary for the existence of brine on the Martian surface, and should be investigated at the target area in the future.

The high-resolution imaging science experiment (HiRISE) in the MRO extended science phases (2009–2023)

The Mars Reconnaissance Orbiter has been orbiting Mars since 2006 and has acquired >80,000 HiRISE images with sub-meter resolution, contributing to over 2000 peer-reviewed publications, and has provided the data needed to enable safe surface landings in key locations by several rovers or landers. This paper describes the changes to science planning, data processing, and analysis tools since the initial Primary Science Phase in 2006–2008. These changes affect the data used or requested by the community and how they should interpret the data. There have been a variety of complications to the dataset over the years, such as gaps in monitoring due to spacecraft and instrument issues and special events like the arrival of new landers or rovers on Mars or global dust storms. The HiRISE optics have performed well except for a period when temperature uniformity was perturbed, reducing the resolution of some images. The focal plane system now has 12 rather than 14 operational detectors. The first failure (2011) was a unit at the edge of the swath width, reducing image width by 10% rather than creating a gap. The recent (2023) failure was in the middle of the swath. An unusual problem with the analog-to-digital conversion of the signal (resulting in erroneous data) has worsened over time; mitigation steps so far have preserved full-resolution imaging over all functional detectors. Soon, full-resolution imaging will be narrowed to a subset of the detectors and there will be more 2 × 2 binned data. We describe lessons received for future very high-resolution orbital imaging. We continue to invite all interested people to suggest HiRISE targets on Mars via HiWish, and to explore the easy-to-use publicly available images.

Insight from the Noachian-aged fractured crust to the volcanic evolution of Mars: A case study from the Thaumasia graben and Claritas Fossae

Although most of the large volcanic landforms on Mars have been extensively studied, this is not the case for kilometer-sized landforms whose origin remains uncertain and which might provide important insights into the evolution of Martian volcanism. Previously, different populations of small-scale putative scoria cone volcanoes have been described in Tharsis, specifically in areas where the heavily fractured crust of the Noachian- and Hesperian-age escaped Amazonian resurfacing by younger lava flows. Therefore, we decided to explore a region of old fractured crust in Tharsis, Claritas Fossae, to search for signs of local-scale volcanic activity. Here, we present the results of a mapping campaign focused on the morphological and spectral properties of small-scale constructional mounds in the Noachian-age Claritas Fossae region that was affected by Hesperian- to early Amazonian-aged fracturing. By using data from Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE), we mapped 39 mounds superimposed on the ancient crust and determined their morphological and morphometrical properties. The majority of the mounds are elongated (WNW- trending) with steep flanks and without associated flow units. The general appearance of studied edifices is consistent with a volcanic origin and their shapes suggest that they have been emplaced by effusion of viscous, volatile poor lavas incapable of significant flow. In addition, a spectral investigation utilizing the data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) reveal that some of the mounds showed evidence for high concentrations of low-calcium pyroxenes (LCP). Based on the relative stratigraphy, we demonstrate that volcanic activity is responsible for their formation and postdates the main N-S-trending fracturing of the Claritas Fossae, suggesting the formation of a volcanic field in the period spanning through the Late Hesperian and the Early Amazonian. However, morphological evidence such as well-preserved volcanic fissures and fresh-appearing slopes of some of the edifices might suggest even younger age. Among the mapped edifices, we found a well-preserved circular-shaped cone with a short-distance flow-like unit spreading from a caldera-like structure that challenges a scenario in which all the edifices are old. Such relatively young ages of volcanic activity combined with LCP-rich compositions might have critical implications for understanding the temporal evolution of magma compositions on Mars. Moreover, the observed shapes and spectral characteristics of the studied edifices appear to be quite different from other volcanic fields of similar geological settings observed so far on Mars. Therefore, we underline the importance of studying old and heavily fractured terrains that escaped later resurfacing by widespread younger lava flows, in order to search for evidence of small-scale volcanism and better understand local Martian magmatic systems.

Dendritic ridges in Antoniadi basin, Mars: Fluvial or volcanic landforms?

Antoniadi basin displays dark-toned dendritic ridges previously interpreted as inverted fluvial channels. Detailed observations of these dark-toned ridges as well as the geological units in the central region of Antoniadi basin are provided emphasizing images from the Colour and Stereo Surface Imaging System (CaSSIS), the High Resolution Stereo Camera (HRSC) and the High Resolution Imaging Science Experiment (HiRISE) instruments. Results show that the dark-toned ridges are part of the most recent geological unit as they overlie, and thus postdate all plains of the central Antoniadi basin, which is Early Amazonian based on its crater size-frequency distribution. Our observations of the dark-toned ridges are not consistent with inverted fluvial channels: they do not widen in the expected downstream direction, they display a rubbly texture and lack layering at high resolution, and have lobes with local levees in place of channel heads. In addition, the branched ridges are more mafic in composition and display a relatively higher thermal inertia than their surroundings. This suite of characteristics is better explained by volcanic flows developed as distributary channels rather than fluvial tributary channels. The occurrence of dikes in the east and west of the studied region supports that these flows were formed by lava, perhaps a'a like flows as suggested by the rubbly texture, but with an unusually high degree of digitation. Alternatively, such a geometry could be explained by the emplacement of the lava along pre-existing fluvial valleys, but neither the underlying topography, nor two nearby older craters, exhibit signs of fluvial erosion.

Mars mud volcanoes in color: A new approach to the study of subsurface sediment mobilization

Mud volcanism has been proposed to explain the formation of morphologically diverse edifices across the surface of Mars. Previous global compositional analysis of surface features on Mars, such as pitted cones and knobs, interpreted as mud volcanoes using Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) targeted data revealed consistent water hydration signatures associated with these landforms (Dapremont and Wray, 2021b). However, no definitive identifications of specific minerals known to comprise mud volcanism materials on Earth (e.g., phyllosilicates, carbonates, sulfates) were identified. Here, we take advantage of an alternative methodology involving a quantitative color band ratio technique using blue-green (BG), red (RED), and infrared (IR) reflectance data sourced from the High Resolution Imaging Science Experiment (HiRISE) camera to determine if any additional mineralogical information about proposed Martian mud volcanoes could be acquired. Across Mars in the three distinct study regions of Valles Marineris, Terra Sirenum, and Arabia Terra, proposed mud materials consistently plot with ferric laboratory and Mars surface reference minerals. In Terra Sirenum, HiRISE color data point clusters acquired from mounds attributed to mud volcanism plot overtop the Fe-smectite reference mineral nontronite. We show that HiRISE color data can be used as a complementary mineralogical investigation tool applied to the study of surface materials on Mars and demonstrate the value of HiRISE color ratios for comparative planetology.

The internal structure of a debris-covered glacier on Mars revealed by gully incision

Viscous flow features (VFFs) in Mars' mid latitudes are analogous to debris-covered glaciers on Earth. They have complex, often curvilinear patterns on their surfaces, which probably record histories of ice flow. As is the case for glaciers on Earth, patterns on the surfaces of VFFs are likely to reflect complexities in their subsurface structure. Until now, orbital observations of VFF-internal structures have remained elusive. We present observations of internal structures within a small, kilometer-scale VFF in the Nereidum Montes region of Mars' southern mid latitudes, using images from the Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) instruments on Mars Reconnaissance Orbiter. The VFF-internal structures are revealed by a gully incision, which extends from the VFF headwall to its terminus and intersects curvilinear undulations and a crevasse field on the VFF surface. Near to the VFF terminus, the curvilinear VFF-surface undulations connect to the VFF-internal layers, which are inclined and extend down to the VFF's deep interior, and possibly all the way to the bed. Similar structures are common near to the termini of glaciers on Earth; they form under ice flow compression where ice thins and slows approaching the ice margin, and ice flow is forced up towards the surface. We performed 3D ice flow modeling which supports this analogy, revealing that the inclined VFF-internal structures, and associated curvilinear structures on the VFF surface, are located in a zone of strong ice flow compression where ice flow deviates upwards away from the bed. The inclined VFF-internal structures we observe could represent up-warped VFF-internal layering transported up to the surface from the VFF's deep interior, or thrust structures representing debris transport pathways between the VFF's bed and its surface. Our observations raise numerous considerations for future surface missions targeting Mars' mid-latitude subsurface ice deposits. Inclined layers formed under flow compression could reduce the requirement for high-cost, high-risk deep drilling to address high-priority science questions. They could allow futures missions to (a) access ice age sequences for palaeoenvironmental reconstruction via shallow sampling along transects of ice surfaces where layers of progressively older age outcrop, and/or (b) access samples of ice/lithics transported to shallow/surface positions from environments of astrobiological interest at/near glacier beds. However, our observations also raise considerations for potential drilling hazards associated with structural complexities and potential dust/debris layers within subsurface ice deposits on Mars. They highlight the importance of characterizing VFF-surface structures, and their relationships to VFF-internal structure and ice flow histories ahead of ice access missions to Mars.

Bedding Scale Correlation on Mars in Western Arabia Terra

AbstractLayered rocks in the Arabia Terra region of Mars preserve a record of the planet's ancient climate. However, the exact formation mechanism of these rhythmically layered deposits is currently unknown. We previously proposed two distinct regionally correlative units of the Arabia Terra layered deposits based on their bedding thicknesses, orientation, and morphology from High Resolution Imaging Science Experiment stereo observations. For this work, we selected two adjacent craters in Arabia Terra, Sera and Jiji, for further study to test the proposed stratigraphic correlation. We constructed vertical stratigraphic sections of the deposits from dip‐corrected bed thickness measurements and local stratigraphic correlations. We found that individual beds maintain a consistent thickness over kilometer scales but are somewhat variable at the basin scale. Each crater exhibited strata with a thinning‐upward trend that terminated at terraces with inconsistent bedding, possibly indicating an equilibrium elevation for the formation mechanism. We also identified a probable stratigraphic correlation between basins using the similarities in bedding characteristics and patterns of measurable differences in bed‐to‐bed thicknesses, indicating synchronous strata. The planar bedding and uniform thickness of the beds within the deposits are consistent with airfall deposition over a prolonged geologic period. This process likely occurred under comparably dry conditions relative to the previously proposed depositional and diagenetic formation mechanisms.

Morphology of the north-western wall of Eos Chaos, Valles Marineris: Evidence for glaciation during late Amazonian high obliquity

Glacial landforms have been reported from various regions on Mars; most notably from the mid-to-high latitude regions. We studied Eos Chaos, located towards the eastern boundary of Valles Marineris, for the possible glacial processes occurring in the low-latitude areas on Mars. A thorough investigation of the morphology of the north-western wall of Eos Chaos was carried out using planetary datasets such as context camera (CTX) and High-resolution Imaging Science Experiment (HiRISE) images from NASA's Mars Reconnaissance Orbiter (MRO) mission and Mars Color Camera (MCC) images from ISRO's Mars Orbiter Mission-1 (MOM-1). We identified various geomorphological features that may have resulted from diverse geological processes. The glacial processes are manifested by the morphological features such as tongue-shaped lobate flows, alternative dark and light strata (~10-15 m thick), light-toned fragmented sediments, kettle lake-like structures, surface striations, sublimation hollows, and pit and knob structures. The flow features correspond to three stages of evolution: developing (~0.3 km length), intermediate size (1.5 km length), and mature (~15 km length). These three stages culminated in developing a model depicting the evolution of the glacial landforms of the region based on morphological features. We deduce that the glacial landforms of the region were formed during episodes of higher planetary spin axis obliquity during the late Amazonian.

Automated Detection of Multitype Landforms on Mars Using a Light-Weight Deep Learning-Based Detector

Intification of geological salient landforms is a primary requirement for spacecraft motion estimation and obstacle avoidance. As a large volume of high-resolution images are acquired by the Mars reconnaissance orbiter, growing number of approaches are proposed to develop automated approaches to detect a particular landform on Mars. However, most existing objective detection models are limited to sliding window-based and morphology-based algorithms, which require complicated preprocessing operations and can hardly be generalized to detecting different types of landforms. In this article, we aimed at developing a multitype landform detection system based on a light-weight deep learning framework, which has a quite small model size but presents excellent performance. This specific deep learning-based framework is named as mini shot multibox detector (SSD), by downsizing and modifying the existing single SSD. In the mini-SSD, some components are further optimized to adapt to this domain specific problem. A pretraining strategy is well-designed and merged into the entire model training process. In the performance evaluation tests, the proposed framework was trained and tested on images with different scales collected from different locations in high resolution imaging science experiment database. Results demonstrate that the introduced Adam optimizer and pretraining strategy can form positive effective to both model training and inference performance. The proposed framework and strategy combination outperforms the original SSD300, faster R-CNN, and YOLO series models as well as all state-of-the-art sliding window-based detectors in the field, namely AdaBoost with LBP features, AdaBoost with Haar features, and support vector machines with histogram of oriented gradient (HOG) features, in two different testing sets. Additionally, it shows high resilience on detecting target landforms in different environments with various sizes and shapes from the qualitative analysis, and can be generalized as a tool for relevant applications.

A Polygonal Terrain on Southern Martian Polar Cap: Implications for Its Formation Mechanism

Polygonal terrains on a Martian southern polar cap have been observed in high-resolution images by the Mars Orbiter Camera. However, their formation mechanism is enigmatic due to the lack of constraints from their geometric and physical properties. Here we proposed a series of recognition procedures on an image of polygonal terrain located at Australe Scopuli taken by a High-Resolution Imaging Science Experiment. Then, we quantitatively analyzed the areas, orientations and polygon edge densities (~0.10 to ~0.06 in different subregions) of the polygonal terrain. Based on the recognition results, three elevation-related subregions can be distinguished according to the distributions of polygon size and orientation. The two side subregions distribute relatively small and relatively large polygons, respectively. The middle subregion can be regarded as an intermediate zone along the slope (~1°). The intermediate zone is squeezed by the surrounding polygons, indicating a possible uplift or subsidence on previous or present Mars. This paper found a possible formation mechanism of the polygonal terrain located at the south pole of Mars, suggesting that polar-ice-cap polygons are formed during the process of lateral sliding gravity-driven plastic creep and the deformation of ice, with the polygon boundaries being reshaped during the alignment at high slopes and partially compressed at low slopes. These properties and possible formation mechanisms could provide more constraints on understanding ancient and/or present climates on Mars.