Topography Of Mars Research Articles

Pixel-level Terrain Processing of the Martian Surface from Moderate Resolution Images of Tianwen-1

The moderate-resolution camera (MoRIC) of the Tianwen-1 orbiter, China’s first Mars exploration mission, is a frame-imaging scheme color camera. However, generating a precise digital elevation model (DEM) from these images faces challenges due to the presence of featureless and repetitive regions on the Martian surface. Traditional photogrammetric methods often struggle to achieve pixel-level resolution in these areas. To address this, we employ a shape from shading (SFS) algorithm that leverages shading patterns to reconstruct fine-scale terrain details, optimizing photogrammetric initial DEM. This paper presents a novel global bisection search algorithm, based on the Pearson correlation coefficient to determine the smoothing parameter, a crucial element in the SFS process. Comparisons with higher-resolution data from the Mars Express high-resolution stereo camera and Mars Reconnaissance Orbiter CTX images validate our approach, highlighting the potential of SFS to significantly enhance the scientific value of Tianwen-1 MoRIC data by generating high-resolution, three-dimensional maps of Mars.

Mars' North Polar Spiral Trough Migration Paths as Revealed Through 3D Radar Mapping

AbstractWe present observations and maps of Mars' northern polar spiral trough migration paths (TMPs) as revealed through the 3D SHARAD (Shallow Radar) data volume, identify patterns of TMP morphology, and provide interpretations and implications of these TMPs on past climate. This data set provides additional spatial context over traditional 2D data as it allows for radargrams to be taken perpendicular to each trough strike, which minimizes distortion of migration paths due to oblique viewing geometry. Here, we present an expanded survey of trough migration and analysis of surface troughs across the north polar layered deposits. We corroborate many previous observations of trough migration such as: the general poleward and stratigraphically upward migration from the TMP initiation point; the broadly similar depth of trough initiation across the cap; regional variability in TMP morphology; and the presence of buried promontories. Our results support the presence of two generations of troughs, though we cannot confirm that the oldest generation originated deeper than ∼600 m beneath the current surface, as previously reported. Two generations of troughs suggest that climate conditions favorable for initiation of trough migration have occurred at least twice. Trough initiation occurring only in the upper ∼600 m suggests that troughs are relatively recent features in the polar cap, developing after the formation of ∼half the current cap height. The mapped TMPs provide insight into the consistency of Mars' climate during the accumulation of the past few hundred meters of ice by recording the boundary of erosion and accumulation of ice at the troughs.

Seeking sand origins on Mars: Towards testing the volcaniclastic hypothesis globally

Aeolian processes are a dominant cause of Martian surface modification today. Sand is pervasive, even while the contemporary transport of sand at high-threshold wind speeds implies sand breakdown. Thus, detecting the origin(s) of sand on Mars is an important open question in Mars science. One long-standing hypothesis for an origin of Martian sand is as volcaniclastic sediments, either epiclastic (from the breakdown of effusive volcanic rock) or pyroclastic (from explosive sedimentation). Recent analyses identified the most likely pyroclastic unit on Mars, the Medusae Fossae Formation (MFF) – mapped as the Hesperian and Amazonian-Hesperian transitional units (Tanaka et al., 2014) – as an origin of Martian sand, a genesis consistent with inferences from other work. On these bases, we continued in this work to test for a volcaniclastic origin of Martian sand elsewhere on Mars. We inspected the seven units from the global geologic map of Mars interpreted as possibly/partially volcaniclastic and six geographic terrains ascribed as likely volcanogenic in a more recent analysis. Of these units and geographic terrains, potential sand sources (PSSs) were detected only within two locales: 1) the remaining (central and eastern) extent of the MFF, and 2) Arabia Terra. Arabia Terra shows more numerous PSS, commonly characterized as having proximal dune fields. The explosive volcanic history of the region points towards a pyroclastic origin, though the geologic complexity of the region suggests complexity in the provenance of Arabia Terra PSSs. In contrast to PSS identifications in the western MFF, PSSs in the central and eastern MFF were clustered along the contact of the MFF with lava plains, indicating a potential epiclastic sand origin. Thus, these results indicate both pyroclastic and potentially epiclastic origins for sand on Mars. However, these sand origins as detected by this work are confined to limited locales and (for the MFF) in the amount of sand generated. To further evaluate the amount of sand production in these two study regions from volcanogenic processes, spectroscopic analysis of PSSs in comparison with sand deposits would be a means to test first whether the PSSs were indeed generating sand and secondly if that sand were of volcanic origin. Potential sand flux modeling would be a means to establish the source location(s) of the sand. The origin(s) of the pervasive sand on Mars remain(s) to be better understood, for which the work presented here provides a foundation.

A 76-m per pixel global color image dataset and map of Mars by Tianwen-1

A 76-m per pixel global color image dataset and map of Mars by Tianwen-1

Atmosphere-aware photoclinometry for pixel-wise 3D topographic mapping of Mars

High-resolution topographic mapping is essential for scientific investigations and operational exploration of planets, such as Mars. Photoclinometry, which uses light scattered from a surface to reconstruct 3D topography, can retrieve subtle topographic details from monocular images. However, its performance is affected by the atmosphere of Mars, which alters surface reflectance mechanisms due to the scattering and absorption by aerosols. Therefore, specific treatments accounting for these atmospheric effects are needed to enable photoclinometric mapping of Mars. This paper presents a novel photoclinometric approach incorporating a radiative-transfer model of atmospheric scattering effects for pixel-wise 3D reconstruction of the Martian surface. The approach requires a high-resolution image, a corresponding coarse-resolution digital elevation model (DEM), and information of the optical depth as inputs. A radiative transfer model adapted to the Martian atmosphere is used to account for the atmospheric effects. The approach also allows directly adopting optical depth estimates from a global database (e.g., the Mars Climate Database). The approach was validated using different types of Mars orbiter images collected by cameras on-board the Mars Reconnaissance Orbiter and the Tianwen-1 Orbiter. The results indicate that the approach can achieve a geometric accuracy (in terms of root-mean-squared error (RMSE) of the elevation) of approximately 2 pixels of the image resolution and significantly enhances topographic details. In addition, we evaluated the approach using different settings for the optical depths and spatial resolutions of the input DEMs. The results show that overestimating the optical depth leads to overestimation of topographic amplitudes (e.g., deeper craters). On the other hand, underestimating the optical depth by the same amount as overestimation leads to a smaller increase in the RMSE. Moreover, coarsening the resolution of an input DEM increases the RMSE of the photoclinometric results. Nevertheless, photoclinometry improves both the RMSE and the resolution of the input DEM. This new approach serves as an effective means for applying photoclinometry for pixel-wise 3D topographic mapping of the Martian surface. This will facilitate exploitation of the large number of high-resolution monocular images of Mars in 3D topographic mapping of the planet.

Bounding the unknowns of martian crustal heat flow from a synthesis of regional geochemistry and InSight mission data

The thermal evolution of terrestrial planets is primarily modulated by the distribution of heat-producing elements (HPE) within the crust and mantle. Chemical data from Martian meteorites suggest that Mars differentiated early, which led to an early partitioning of incompatible heat-producing elements in the crust. Previous estimates of Martian crustal heat flow that used the bulk regolith abundances of HPEs from the Gamma-Ray Spectrometer (GRS) suite on Mars Odyssey spacecraft have further corroborated this view of Mars, albeit with poorly known crustal column representativeness. Here we couple the GRS-derived chemical maps of Mars with estimates of crustal thickness and density from the InSight lander to revise the estimated Martian crustal heat flow. The mean crustal heat flow values range from 3.0 to 13.9 mW m−2 for the endmember gravity-derived crustal thickness models anchored by constraints from InSight. We also estimate the crustal heat flow from other factors such as the distribution of HPEs with depth and the Uranium content of the crust. Our results suggest that the mean crustal heat flow varies substantially across models, with the highest mean values being associated with higher densities and an increased enrichment of HPEs with depth. Further work is needed to constrain the crustal thickness of Mars, as the largest uncertainties in the estimate of crustal heat flow stem from uncertainty in the crustal thickness estimates, not geochemical variability. The results from this work corroborate previous estimates of a strong fractionation of heat-producing elements into the Martian crust.

Tianwen-1 releasing first colored global map of Mars

Tianwen-1 releasing first colored global map of Mars

Revisiting Atmospheric Features of Mars Orbiter Laser Altimeter Data Using Machine Learning Algorithms

AbstractThe Mars Orbiter Laser Altimeter (MOLA) instrument has been drawing a map of Mars' topography between September 1997 and June 2001. It has also been able to observe clouds during the mission duration, providing data for the low Martian atmosphere for nearly 1.5 Mars years. The Mars Global Surveyor, which carried MOLA, also carried two other instruments that also observed clouds during the same time period (the Mars Orbiter Camera and the Thermal Emission Spectrometer). Combining observations from these three data sets could provide a complete recap of most atmospheric structures during MY24 and MY25. However, previous studies of MOLA data set often had to use stringent detection criteria. Using machine learning clustering methods, we end up finding way more atmospheric returns. Our results are presented in the form of an atmospheric features catalog that we then use to compare MOLA observations with Mars Orbiter Camera and Thermal Emission Spectrometer results, but also with more recent missions. We study the development of recurrent phenomenon in the Martian atmosphere, like the aphelion cloud belt or the south polar hood, but also spontaneous events such as regional dust storms. Methods could be tuned even more finely by using more complex clustering methods or deep learning algorithms to clearly distinguish atmospheric structures.

Discordance analysis on a high-resolution valley network map of Mars: Assessing the effects of scale on the conformity of valley orientation and surface slope direction

Fluvial valleys incised into planetary surfaces display morphologies, geometries and orientations that can be used to understand their controlling processes. Comparisons between valley orientations and topographic surface slope direction have been used to understand how Martian surfaces have evolved (Luo and Stepinski, 2012; Black et al., 2017); however, new insights from terrestrial studies have revealed that the slope needs to be defined on a scale commensurate with the length of valley (Lipp and Roberts, 2020). We propose and test a new map-based framework for interpreting the difference between Martian valley orientation and surface slope direction (discordance) at varying spatial scales. Valleys and inverted channels were manually mapped in a latitudinal strip from pole to pole between 20°E–20°W using High/Super Resolution Stereo Colour Imager images (15 to 25 m per pixel). The orientation of incisional valleys, associated with fluvial activity, were compared with topographic slope direction at varying scales (463 m, 1 km, 10 km and 50 km). High-resolution mapping resulted in ~1.5 times the density (0.02 km/km2 on average) of the previous valley map (Hynek et al., 2010), which raises the possibility that water volumes necessary to carve valleys were greater than previously thought. The distribution of valleys is similar to previous valley maps, however there are areas where valleys were identified that have previously remained undetected in low resolution images. The scale over which one compares valley orientation to surface slope direction has a clear effect on the apparent conformity between Martian valley orientation and topographic slope direction, with smaller valleys conforming more closely with smaller scale topography. To account for scale we perform discordance analysis with the spatial scale of surface slope direction varying based on valley length. When scale is accounted for, there is a greater conformity between valley orientation and surface slope direction, however only ~38% of valleys display conformity, indicating other sources of high discordance. We find that the source of the high values of discordance are likely a result of a combination of valley immaturity, attesting to the arid nature of the Late Noachian – Early Hesperian climate, but also the palaeolake outburst and, possible, subglacial origin of some valley networks. Considering a large proportion of valleys do not display conformity with topography, we suggest that a discordance analysis of the kind reported here is an important preliminary to any hydrodynamic analysis that relies on topographic information.

Deliquescence probability maps of Mars and key limiting factors using GCM model calculations

There may be a chance of small-scale ephemeral liquid water formation on present day Mars, even though the current climate does not support the existence of larger bodies of water. Through a process called deliquescence, hygroscopic salts can enter solution by absorbing water vapor directly from the atmosphere. Due to the absence of in-situ deliquescence experiments so far, the most reliable way to forecast deliquescence is through atmospherical modeling, however, the locations and times when salty liquid water could emerge are not yet well known. In this paper we present our results of likely brine formation on Mars, their proposed locations and seasons, as well as the possible limiting factors. For our calculations we used the data of Laboratoire de M\'et\'eorologie Dynamique Mars General Circulation Model version 5. The results show that from L$_s$ 35$^\circ$ - L$_s$ 160$^\circ$, between 9 PM and 11 PM there is a good chance for calcium perchlorate deliquescence above 30$^\circ$ N, while in this zone the ideal regions are concentrated mostly to Acidalia Planitia and Utopia Planitia between 1 AM and 3 AM. We found that in the Southern Hemisphere, between L$_s$ 195$^\circ$ and L$_s$ 320$^\circ$, there is a noticeable, but weaker band in the vicinity of 60$^\circ$ S, and both Argyre Planitia and Hellas Planitia show some chance for brine formation. According to our statistics the key limiting factor of deliquescence could be relative humidity in most cases. Our results suggest that during summer -- early fall seasons, there could be deliquescence in both hemispheres in specific areas from the late evening until the early morning hours. There are only few studies detailing the geological and temporal distribution of brine formation through deliquescence, thus this work could be used as a good guide for future landing site analysis or in choosing a specific location for further research.

Designing and validation of moderate-resolution cameraof Tianwen-1

<p indent=0mm>China’s first Mars exploration mission Tianwen-1 will achieve Mars orbiting, landing and roving conduct global and comprehensive surveys and perform detailed inspections and surveys of key areas on the surface of Mars. A moderate-resolution camera is installed on the orbiter to image the surface of Mars, draw its global remote sensing image map, and explore the topography, geomorphology, and geological structure of Mars. The moderate-resolution camera is light weight and has a compact integrated design, which mainly comprises optical, focal plane, camera-control, power and interface, camera-support, thermal-control and reference modules. Radiometric, color, and geometric calibrations have been conducted to ensure that the camera accurately acquires the detection data of the surface of Mars. This paper introduces the detection mission, system composition, working principle, ground calibration test and results of the moderate-resolution camera and provides a reference for scientific data processing and applications.

Automated Geological Landmarks Detection on Mars Using Deep Domain Adaptation From Lunar High-Resolution Satellite Images

The diversity in geological characteristics on the planetary surface, such as distribution (density), size, shapes, floor structures, ages, and availability of various input data types such as optical, thermal images, and digital elevation maps pose numerous challenges for detecting geological landmarks (e.g., rockfalls, craters, etc.). Several automatic detection methods are proposed to identify geological landmarks. However, the insufficiency of the labeled dataset is a challenging problem. It requires exceedingly time-consuming and expensive manual annotation. In this article, we use the domain adaptation technique to transfer deep learning from the planetary surface to another (lunar surface into Martian surface). We test the feasibility of transfer learning of the convolutional neural networks in optical images and elevation maps to distinguish landmarks such as rockfalls and craters from the background. The experimental results demonstrate the effectiveness of the proposed method. It achieves high F1-scores compared to the state-of-the-art methods with 58.32<inline-formula><tex-math notation="LaTeX">$\,{\pm}\,$</tex-math></inline-formula>2.3 and 57.51<inline-formula><tex-math notation="LaTeX">$\,{\pm}\,$</tex-math></inline-formula>2.4 in detecting rockfall regions in optical lunar and Martian images. It also achieves 65.32<inline-formula><tex-math notation="LaTeX">$\,{\pm}\,$</tex-math></inline-formula>1.8, 67.39<inline-formula><tex-math notation="LaTeX">$\,{\pm}\,$</tex-math></inline-formula>2.4, 77.37<inline-formula><tex-math notation="LaTeX">$\,{\pm}\,$</tex-math></inline-formula>2.2, and 72.56<inline-formula><tex-math notation="LaTeX">$\,{\pm}\,$</tex-math></inline-formula>2.3 in detecting crater regions in optical images and digital elevation maps of Moon and Mars. This method can be a potential approach to identify landmarks for coming Mars missions.

Water Ice Detection Research in Utopia Planitia Based on Simulation of Mars Rover Full-Polarimetric Subsurface Penetrating Radar

The probe of China’s first Mars exploration mission, Tianwen-1, has been successfully launched. It will carry out scientific exploration on the topography, soil characteristics, water ice, climate, ionosphere, and physical fields of Mars. Different from other rovers landing on the moon and Mars, the Zhurong rover is equipped with a full polarimetric subsurface penetrating radar (FP-SPR) system for the first time. The radar’s mission is to depict the shallow subsurface structure of Mars and search for possible water ice. Therefore, in this paper, a 3D realistic structure model is established and numerically simulated based on the possible subsurface structure of Utopia Planitia (the landing area). Influencing factors such as topographical fluctuations, rocks, water ice, and the variation of dielectric constant of different layers are added to the model. The analysis of the acquired FP-SPR data set shows that the two-dimensional principal component analysis (2D-PCA) method can extract effective reflected signals from the radar data with noise interference and improve the data quality. These clearly imaged targets may be water ice blocks, so the application of 2D-PCA to FP-SPR data increases the imaging quality of suspected water ice targets. The results of this paper are the basis for future processing of the measured FP-SPR data on Mars, which will help to identify more details of subsurface structures.

Tianwen-1 and China's Mars exploration program

About every 26 months, the distance between Earth and Mars reaches a minimum, and that is the best time window for Mars exploration from Earth. In July 2020, three spacecraft started their journey to Mars: the Hope orbiter of the United Arab Emirates, the Tianwen-1 mission of China and the Perseverance rover of the United States’ National Aeronautics and Space Administration (NASA). If all go well, these spacecraft will reach Martian orbit in February 2021 and start their scientific observations.Tianwen-1 is China's first mission to Mars. It includes an orbiter, a lander and a rover. It carries 13 scientific payloads and will investigate the topography, soil composition, water-ice distribution, internal structure, atmospheric environment and physical fields (electromagnetic and gravitational) of Mars. In this interview, we talked with the mission's Chief Scientist Yongxin Pan (潘永信) and Scientific Payload Sub-System Director Chi Wang (王赤) about this scientific mission and China's future plans for Mars exploration.

Linear Transformations and Signal Estimation in the Joint Spatial-Slepian Domain

We develop a framework for generalized linear transformations of the joint spatial-Slepian domain representation of signals on the sphere. Such a representation is enabled by the spatial-Slepian transform on the sphere. We formulate a least-square signal estimation framework for reconstruction of the spherical signal from the modified (transformed) spatial-Slepian representation specified by the spatial-Slepian transformation kernel. We specialize the form of the kernel to present analytical expressions for the multiplicative and convolutive transformations, and use the latter to present illustrations on a Mars topography map.

The global distribution of depositional rivers on early Mars

AbstractSedimentary basins are the archives of ancient environmental conditions on planetary surfaces, and on Mars they may contain the best record of surface water and habitable conditions. While erosional valley networks have been mapped, the global distribution of fluvial sedimentary deposits on Mars has been unknown. Here we generated an eight-trillion-pixel global map of Mars using data from the NASA Context Camera (CTX), aboard the Mars Reconnaissance Orbiter spacecraft, to perform the first systematic global survey of fluvial ridges—exhumed ancient deposits that have the planform shape of river channels or channel belts, but stand in positive relief due to preferential erosion of neighboring terrain. We used large fluvial ridges (&amp;gt;70 m width) as a conservative proxy for the occurrence of depositional rivers or river-influenced depositional areas. Results showed that fluvial ridges are as much as 100 km long, common across the southern highlands, occur primarily in networks within intercrater plains, and are not confined to impact basins. Ridges were dominantly found in Noachian through Late Hesperian units, consistent with cessation of valley network activity, and occurred downstream from valley networks, indicating regional source-to-sink transport systems. These depositional areas mark a globally distributed class of sedimentary deposits that contain a rich archive of Mars history, including fluvial activity on early Mars.

Mars's Red (575–625 nm) Seasonal Approximate Reflectivity Averaged Over Mars Years 24–28 From Mars Orbiter Camera

AbstractThe Mars Global Surveyor spacecraft successfully orbited Mars for over nine Earth years, its instruments returning a plethora of data that still today form important, key data sets in Mars research. A relatively underutilized data set was returned from the Mars Orbiter Camera (MOC), specifically the wide‐angle component (MOC‐WA), despite returning over 150,000 images in “blue” and “red” wavelengths. The median imaging time of day was 14:00, resulting in few shadows, making it difficult to use for geology, while better cameras arrived within a few years. However, the limb‐to‐limb coverage of the MOC‐WA survey images provides an important resource, where the imaging time that was poor for geology is good for measuring reflectivity. To‐date, the only published albedo maps of Mars are from a companion MGS instrument, TES, with wide wavelength coverage and low spatial resolution, and the OMEGA instrument on Mars Express. Modern processing of the MOC‐WA images, presented here, allow for the creation of new reflectivity maps in a narrow wavelength range that can be used for photometric control of other data sets and understanding broad‐scale surface changes on Mars. Four reflectivity maps were made, at cardinal Ls points, averaging images taken within just a week of each Ls but across multiple Mars years. From these maps, several trends are revealed though most have been previously described, including significant differences in seasonal frost cover surrounding each residual polar ice cap, and significant changes across Syrtis Major, Solis Lacus, and the Tharsis volcanoes.

Where to Map? Iterative Rover-Copter Path Planning for Mars Exploration

In addition to conventional ground rovers, the Mars 2020 mission will send a helicopter to Mars. The copter's high-resolution data helps the rover to identify small hazards such as steps and pointy rocks, as well as providing rich textual information useful to predict perception performance. In this paper, we consider a three-agent system composed of a Mars rover, copter, and orbiter. The objective is to provide good localization to the rover by selecting an optimal path that minimizes the localization uncertainty accumulation during the rover's traverse. To achieve this goal, we quantify the localizability as a goodness measure associated with the map, and conduct a joint-space search over rover's path and copter's perceptual actions given prior information from the orbiter. We jointly address where to map by the copter and where to drive by the rover using the proposed iterative copter-rover path planner. We conducted numerical simulations using the map of Mars 2020 landing site to demonstrate the effectiveness of the proposed planner.

The Subjectivity in Identification of Martian Channel Networks and Its Implication for Citizen Science Projects

The Martian surface is incised by numerous valley networks, which indicate the planet experienced sustained widespread flowing water in the past (e.g. Carr in Water on Mars, Oxford University Press, New York, 1996; Phil Trans R Soc A 370:2193–2212, 2012. https://doi.org/10.1098/rsta.2011.0500). Examining the distribution and geometries of these valley networks provides invaluable information about the Martian climate during the period of formation. The recent advancement in high resolution images has provided an opportunity to build upon past valley maps of Mars (Bahia et al. in LPSC 2018, 2018), however, the identification of these valley networks is extremely time-consuming. A citizen science project may aid in reducing this time-consuming process; this project conducts a valley mapping task with participants of varying expertise in valley mapping to determine whether a citizen science project of this kind should be worth pursuing. This was conducted in a region adjacent to Vogel Crater (36.1° S, 10.2° W). Repeated mapping of the area (a repeatability test) found that participants with low experience in valley mapping (22 a-level physics student’s representative of the public) were inconsistent when mapping valleys. Additionally, when comparing the results of participants within this group (a reproducibility test), the majority of reproduced valleys are false positives (i.e. incorrectly traced valleys). These results were consistent with those found for the medium experience group (45 2nd year geology undergraduates). The validated tracings of the low experience group improve upon the number and total length of valleys mapped by previous studies (Hynek et al. in J Geophys Res 115:1–14, 2010). To validate these valleys requires the input of an expert to remove false positives which is less time consuming than manually mapping the images; this may indicate that a citizen science project is worth pursuing. However, to effectively identify the maximum amount of valleys an expert is required.

Payload moderate resolution camera of China's first Mars exploration

China's first Mars exploration mission will carry out comprehensive global surveys of the planet from data collected by instruments carried in orbit and roving on the planet itself. Goals of the mission include detailed inspections and surveys of key areas on the surface of Mars. One of the main scientific payloads installed on the orbiter is the moderate resolution camera. Its mission is to image the surface of Mars sufficiently to produce a global remote sensing image map of the planet, and to explore and record changes to the topography of Mars, including major geological structures, and to advance research on topography and geomorphology in general. The moderate resolution camera uses a lightweight and compact integrated design; its primary components are an optical module, a focal plane module, a camera control module, a power and interface module, a camera support module, a thermal control module, and a reference module. Radiometric calibration, color calibration, and geometric calibration have been carried out to ensure that the camera can acquire sufficient accurate data to complete mission goals. This paper introduces the camera's detection mission, its system composition, and its working principle; it also describes the camera's ground calibration tests and their results, and provides a reference for processing the camera's scientific data and for future applications.