Vilmos Steinmann

While fluvial features are plentiful on Mars and offer valuable insights into past surface conditions, the climatic conditions inferred from these valleys, like precipitation and surface runoff discharges, remain the subject of debate. Model-based estimations have already been applied to several Martian valleys, but exploration of the related numerical estimations has been limited. This work applies an improved precipitation-based, steady-state erosion/accumulation model to a Martian valley and compares it to a terrestrial Mars analogue dessert catchment area. The simulations are based on a previously observed precipitation event and estimate the fluvial-related hydrological parameters, like flow depth, velocity, and erosion/accumulation processes in two different but morphologically similar watersheds. Moderate differences were observed in the erosion/accumulation results (0.13/−0.06 kg/m²/s for Zafit (Earth) and 0.01/−0.007 for Tinto B (Mars)). The difference is probably related to the lower areal ratio of surface on Mars where the shield factor is enough to trigger sediment movement, while in the Zafit basin, there is a larger area of undulating surface. The model could be applied to the whole surface of Mars. Using grain size estimation from the global THEMIS dataset, the grain size value artificially increased above that observed, and decreased hypothetic target rock density tests demonstrated that the model works according to theoretical expectations and is useful for further development. The findings of this work indicate the necessity of further testing of similar models on Mars and a better general analysis of the background geomorphological understanding of surface evolution regarding slope angles.

Identifying surface sites with significant astrobiological potential on Mars requires a comprehensive understanding of past geological processes and conditions there, including the shallow subsurface region. Numerical modelling could distinguish between regions dominated by erosion and those characterized by sediment accumulation in ancient wet environments. The target area of Jezero Crater is relatively well explored and thus is an ideal site to evaluate model calculations; however, important works are still missing on expectations related to its shallow subsurface . In this work, the best available approaches were followed, and only surface morphology was considered (supposedly formed by the last fluvial episode). The shallow subsurface became an important target recently, and this model could provide new inputs in this area. Erosion–accumulation models are suitable for terrestrial surface features, but few have been applied to Mars. This work addresses this challenge using the SIMWE (SIMulated Water Erosion) model on the Jezero Crater delta, the landing site of the Perseverance rover. For calculations, the average grain size according to the THEMIS TI data was applied to the target area. The flow depth varied between 1.89 and 34.74 m (average of 12.66 m). The water-filled channel width ranged from 35.3 to 341.42 m. A flow velocity of 0.008–11.6 m/s, a maximum erosion rate of 5.98 g/m²/h, and a deposition 4.07 g/m²/h were estimated. These calculated values are close to the range of estimations from other authors assuming precipitation of 1–20 mm/h and discharges of 60–400 m³/s. The model was able to distinguish between erosion- and accumulation-dominated areas about 1 m above Jezero Crater’s delta that are not visible from above. This model helps to identify the accumulation-dominated areas with the finest grain size with good preservation capability for the shallow but invisible subsurface.

A model-based surface fluvial erosion and deposition approach was adapted to Martian conditions to forecast the potential locations for shallow subsurface sampling by the Rosalind Franklin ExoMars rover at Oxia Planum. While remote and on-site images show only the surface visible features, former fluvial-related accumulation sites might be hidden. During the fluvial activity, most accumulation-related areas are interesting with regard to clay-like sediments, which could adsorb organics effectively—such sites could be identified by modeling. By applying the SIMWE fluvial erosion/deposition model, substantial variability in accumulation and deposition-dominated areas with their specific pattern and spatial distribution could be outlined, indicating that sophisticated targeting of future sampling could use such a model-based approach. At the main valley-like feature, former water flow tracks were identified, as well as deposition-dominated locations, which are the best targets for shallow subsurface sampling. Joint evaluation of safety aspects like slope angle and loose sand dunes with scientific aspects provide the best sampling locations. Such model-based targeting is important as by using only orbital images, these locations could not be identified.

The possibility and feasibility of future drone-based shallow subsurface GPR radar survey for Mars have been examined. Various observations indicate shallower features are present on Mars, could be surveyed ideally from a low altitude flying airborne GPR with survey around 100 MHz transmitted frequency. Although there are uncertainties especially related to the role of iron-oxides – but in general better and deeper penetration is expected for the radar signals than it is characteristic on the Earth. The proposed instrument will be able to explore discontinuities in the underground to measure thickness, volume and stratigraphic sequence.IntroductionThis project aims to evaluate the feasibility and realization of a small mass drone based GPR survey on Mars to support next missions. Range of scientific questions on tectonics, volcanism, climate changes, water and ice could be answered of partly clarified with better knowledge on the shallow subsurface of Mars – all are ideal targets for GPR analysis. The discoveries of shallow subsurface ice on Mars (Dundas et al. 2021, Morgan et al. 2021, Mouginot et al. 2012, Schiff and Gregg 2022), and the mapping of these deposits (Putzing et al. 2023, Morgan et al. 2021), make shallow subsurface region especially important recently. While the top surface is influenced by UV- plus charged particle irradiation, as well as heavily oxidized, the few meters deep region is not influenced by these effected, thus ideal for the acquisition of astrobiology relevant samples.Radar observations are important for Mars and based on the former MARSIS (Jordan et al. 2009, Picardi et al. 2004, Seu et al. 2007) and SHARAD instruments used from orbit, the RIMFAX instrument onboard the Perseverance and RoPeR instrument onboard Zhurong rovers could provide a range of such discoveries. Internal structure of the polar caps (Jawin et al. 2022), thickness so some depositional units (Li et al. 2022), occurrence of buried ice masses (Nerozzi and Holt 2019) have already demonstrated the success of GPR-like technology for Mars.Targets on Mars it is expected that the shallow subsurface consists mainly porous basaltic materials together with various salts beside sedoments. The porous voids if filled by brine or ice could increase electrical conductivity and cause strong radar reflection (Stillman et al. 2022). Porosity exhibits an elevated value at shallow depths in the regolith. Using InSight mission pores are expected to be closed around 9 km depth (Gyalay and Nimmo 2022), and close to the surface the porosity might be up to about 50-60% (Grott et al. 2022). Brines are expected also on Mars, permittivity of salty solutions depends on temperature. Brine mixtures in JSC Mars-1 regolith simulant also show a range of permittivity values depending on temperature and concentration (Kobayashi et al. 2023).Considering the morphology of target features, surveying about HiRISE images the existence of subsurface structures in the top 10-20 m layer. Some examples are indicated in Figure 1.Figure 1: Surface exposed shallow subsurface structures on HiRISE images. First column shows 100 km diameter terrain using THEMIS images for context, second column shows about 4 km diameter part of the HiRISE images, while third column shows 1x1 km magnified section of the images.Required technical parametersAiming the top 1-40 m of the Martian regolith the wavelength range 100-200 MHz is idel. The spatial resolution is expected in the range of meters horizontally (controlled by the pulse frequency and UAV (drone) velocity). Duricrust, hydration-related mineral filled voids and air-filled voids are expected (Spray 2004). Earth based studies showed iron-oxide lower wave velocity, bound water content also has an effect, controlling permittivity (Van Dam et al. 2002).Identification of bulk liquids water might be moderately straightforward (Wu et al. 2019), as it absorbs the radar signal – but could be rare or absent on Mars today. Thus radar signal could penetrate deeper on Mars than in the case of the Earth. The elevated abundance of iron containing minerals on Mars could potentially affect the interpretability of GPR signal by signal attenuation caused of magnetic minerals (Heggy et al. 2001) could still be too provide useful data (Pettinelli et al. 2007).Considering such a “FlyRadar” mission with the technical capabilities listed above, an airborne shallow subsurface radar would provide range of new information on ice content of indurated dunes, internal layering of fluvial deposits, mid- and high latitude ice, former crater lake sediments, lava caves, and subsurface tectonic structures and volcanic plumbing systems, or source region of volcano-ice interaction.ConclusionsDrone based GPR survey on Mars could explore a poorly known domains: large (10-100 km) size area at 1-50 m shallow subsurface, what is and was in close contact with the atmosphere and volatile circulation. Enhanced mobility and accessibility even at rough, steep and dangerous areas are supported by drone-based survey. Rapid mapping of large areal in a short period with repeated observations at different daily and seasonal cycles would provide unique results.For drones there are limitations on the size and weight of the antenna that can be carried, 100 MHz looks to be ideal. Additionally, at these wavelengths, the attenuation of the electromagnetic waves in the Martian subsurface is still acceptable, based on the attenuation at frequencies of SHARAD and MARSIS.AcknowledgementThis work was supported by the FlyRadar EU project (No 101007973). The support from Internal fund from Thales Alenia Space Italia is also acknowledged.ReferencesDundas et al. 2021. JGR 126, e06617.Grott et al. 2021. 52nd LPSC #1237.Gyalay and Nimmo 2022. 53rd LPSC #1633Heggy et al. 2001. Icarus 154, 244–257.Jawin et al. 2022. GRL 49, e99896.Jordan et al. 2009. PSS 57, 1975–1986.Kobayashi et al. 2023. Earth, Planets and Space...

There are many hydrological models for normal terrestrial environments based on precipitation related erosion, but few of them work well in arid and hyper-arid conditions. These extreme arid regions can be good Mars analogue sites to test and model the conditions and laws of precipitation fed runoff and produced erosion on the Red Planet and infer to past periods. The hydrological model we have developed is primarily designed for Martian conditions and has been tested and validated in the Zafit subbasin of the Zin basin of the Negev desert, the eastern part of Israel. The calculated model data were also compared with data from hydrological models and field measurements in the area. Our applied hydrological model without precipitation data is able to estimate the main hydrographic characteristics of the sample area, such as flow discharge, flow velocity, flow depth, and the model is also able to estimate the Formation Timescale (FTS) of some surface features, as well as vertical erosion rates. The model was developed in the open source QGIS software using SAGA and GRASS GIS modules. It uses input variables that can be measured not only under terrestrial conditions but also measured or estimated under Martian conditions, and there are good quality datasets of them. Examples of such variables are the aridity index, which plays an important role in determining the flow discharge, or the density of the rock that makes up the grains, water density, gravity, and grain size classes. The model can be run on any DTM (Digital Terrain Model), the most important constraint being that the linear unit of projection used is defined in SI metres. The hydrological part of the model is complete however under continuous development, and the final model will be complemented by a further developed erosion model to simulate long term surface evolution and change, thus facilitating the understanding of not only terrestrial but also fluvial erosion produced Martian surface changes.

Introduction: Simulating the fluvial activity produced landscape changes on the Earth is difficult and even harder on another planet, like Mars. There are several erosion models (eg. USLE, RUSLE), which can be well used in terrestrial environments, but these models are not able to be applied for Mars. The SIMWE erosion-accumulation model [1] is a good one to simulate fluvial surface modification in a short timescale, because the model uses only physically based parameters, in contrast the most used terrestrial model USLE uses two theoretical parameters (C and P parameters).The SIMWE model was used already in the Martian environment [2] but not properly. This new version of the adopted SIMWE model produced more realistic results for the erosion-accumulation of the analysed valley system. This fluvial valley can be found next to the Palos crater and Tinto Vallis, for this reason called Tinto-B.Data and Methods: To perform the erosion-accumulation model, digital elevation model (DEM) from the High Resolution Stereo Camera (HRSC) with 50 meter/pixel (m/px) resolution and thermal inertia data (TI) from the Thermal Emission Imaging System (THEMIS) with 100 m/px resolution were used. For the erosion-accumulation model the SIMulated Water Erosion Model (SIMWE) was used, which is integrated into GRASS GIS. The tool simulates the erosion-accumulation of a terrain using several physical based parameters, like water depth and shear stress. The estimated maximal flow depth depends on the flow width, which was calculated in SAGA GIS, and the upstream slope, which was calculated in GRASS GIS. To run the model, beside the original DEM, the estimated water depth and the estimated specific volumetric transport [3] were used as transport coefficient. The detachment coefficient depends on the sediment diameter size.The formation timescale [3] was based on the full water depth, which was estimated in SAGA GIS and the already mentioned volumetric sediment transport.Results: The erosion-accumulation model was used in four different durations. The model used 60, 720 and 1440-minutes erosion-accumulation periods. The average water depth used in the simulation was 5.8 meters with an average 3.73 m/s flow velocity. In all cases the accumulation dominates the analysed area.The formation timescale represents how much time (in year) needed to erode the sediment volume, which is represented by the full water depth, to the original surface. The average time of the erosion is 153344 years.Discussion:The model was tested at a longer timescale than 24 hours, but there aren’t any significant differences. To simulate longer time, the 24 hours results were multiplied by 365.25, which represent one terrestrial year and multiplied again with the results of the formation time-scale calculation. These erosion-accumulation results do not represent properly the long time landscape changes, but in shorter times (1000 years) work well.References: [1] Mitasova et al, 2004, Path Sampling Method for Modeling Overland Water Flow, Sediment Transport, and Short Term Terrain Evolution in Open Source GIS; [2] Steinmann et al, 2020, Geomorphological analysis of Tinto-B Vallis on Mars; [3] Kelinhans et al, 2010, Paleoflow reconstruction from fan delta morphology on Mars

Introduction:  Mars’ surface is carved by an array of dendritic valley networks, which are evidence for ancient water cycles and surface run-off on Mars. The majority of these networks appear to have formed during the Late Noachian – Early Hesperian (3.8 to 3.6 Ga) and resemble terrestrial precipitation-fed systems. After this period, other than localised valleys present on the flanks of several volcanoes, valley network formation appears to have rapidly decreased, indicating that Mars’ climate experienced a sudden change from a warm and wet state to hyper aridity. However, a recent analysis of Amazonian – Hesperian aged flat crater-bottom deposits and alluvial fans indicates that localised areas of wettest persisted after the Early Hesperian. By analysing the morphological, morphometric, and paleohydraulic characteristics, and formation timescales of valley networks of different ages, one can gain a better understanding of the evolution of Mars’ aridity.In this study, we aim to perform a detailed analysis of valley networks of differing ages to determine their formation origin and the duration of aqueous activity required to incise their troughs. At present we have performed formation timescale analysis on an Amazonian-Hesperian aged valley network – the results are presented below.Data and Methods: A combination of GIS software packages were used to perform the analysis: SAGA GIS was used to determine full water depth estimates and flow width via the multiply flow direction method; GRASS GIS was used to determine flow accumulation, flow direction, and upstream slope; ArcGIS Pro was used to perform spatially variable drainage area calculations for Hack’s Law and Flint’s Law calculations. Valley networks were initially identified using the Hynek et al. (2010) valley map, and narrowed to different surface ages based on the Tanaka et al. (2014) surface age map. Detailed mapping and morphological analyses of these valleys was performed using Context Camera images (5 m per pixel). High-Resolution Stereo Camera (HRSC) DEMs were used for paleohydraulic and formation timescale analysis. For the formation timescale calculation, the estimated volume (km3) of each pixel was divided by the volumetric transport rate (km3/yr).Initial Results: At present, we have applied the technique to a valley network located north-east of Lowell Crater (49.82 °S 77.16 °W). The source is within a Middle Noachian highland unit, with the majority of the network incising an Amazonian-Hesperian aged impact unit. The valley network has a main valley length of ~123 km, an almost linear profile, and an average slope (dz/dl) of ~ 0.012. Based on a calculated average water velocity of 6.8 m/s and an average 12.25 m water depth, the average formation time for the whole study area is 23235.3 yr (1 sigma standard deviation = 39401.2 yr).Discussion: It is apparent the examined young valley is immature compared to previously examined Late Noachian – Early Hesperian Martian valley networks, which have minimum formation timescales ranging from 105 to 107 years. Applying formation timescale and paleohydraulic calculations to valley networks from a range of ages, we will be able to better understand the evolution of fluvial activity that formed them.