Martian Terrain Research Articles

Prescribed Performance-Based Powered Descent Guidance for Step-Shaped Hazardous Terrains

The planetary powered descent guidance problem for step-shaped hazardous terrains is investigated in this article based on prescribed performance function (PPF) methodology. Initially, the distances between the lander and step-shaped terrains around the landing site have been formulated in a new form boundaryfunction using PPF, in which a new step-shaped boundary PPF is specifically designed to constrain the lateral motion. Furthermore, a fixed-time convergent PPF is chosen to coordinate the vertical motion. Next, to avoid the collision with step-shaped terrains and planetary surface, a feedback guidance algorithm is proposed based on the backstepping method. Considering a large guidance gain is beneficial for the lander to move away from the boundary PPF, but excessive control acceleration will be generated when the landing error is large. To solve this problem, an adaptive guidance gain is designed using Gaussian function. Finally, the feasibility and effectiveness of the proposed algorithm have been verified through typical numerical simulations inspired by realistic Martian terrains. Moreover, this attempt using PPF methodology here can be easily reformulated to adjust the powered descent problem with collision avoidance for a flat surface or glide-slope constraint.

The Basal Detectability of an Ice‐Covered Mars by MARSIS

AbstractThe detection of anomalously strong relative basal reflectivity beneath the Martian South Polar Layered Deposits (SPLD) from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) has led to hypotheses suggesting the presence of basal materials such as liquid water. Here, we propose a forward approach to assess whether such a high signal could be produced by a Martian terrain currently exposed at the surface without liquid water. We convert existing MARSIS surface reflectivity measurements into a basal reflectivity as if it were overlaid by an SPLD‐like ice deposit. 0.3%–2% of the surface could produce basal reflections of magnitude similar to the SPLD measurements in the assumption of a 10% impure ice. An ice loss tangent 0.01 is required to prevent any of the current Martian surface from producing a bright SPLD‐like basal reflection. The detected bright terrains are gathered within volcanic constructs of diverse geologic epoch.

A Stepwise Domain Adaptive Segmentation Network With Covariate Shift Alleviation for Remote Sensing Imagery

Semantic segmentation for remote sensing images (RSI) is critical for the Earth monitoring system. However, the covariate shift between RSI datasets under different capture conditions cannot be alleviated by directly using the unsupervised domain adaptation (UDA) method, which negatively affects the segmentation accuracy in RSI. We propose a stepwise domain adaptive segmentation network with covariate shift alleviation (Cov-DA) for RSI parsing to solve this issue. Specifically, to alleviate domain shift generated by different sensors, both the source and target domains are projected into a colorspace with normalized distribution through an elaborate colorspace mapping unified module (CMUM). The color distributions of these two domains tend to be more uniform. Furthermore, in the target domain, the multistatistics joint evaluation module (MJEM) is proposed to capture different statistical characteristics of subscenarios for selecting plain scenarios regarded as high-confidence segmentation results to assist the further improvement of segmentation performance. In addition, a pyramid perceptual attention module (PPAM) containing omnidirectional features without computational burdens is added to our network for effectively enhancing the multiscale feature capture ability. In the cross-city DA experiments based on the International Society for Photogrammetry and Remote Sensing (ISPRS) and aerial benchmarks, the superiority of our algorithm is significantly demonstrated. Furthermore, we release a large-scale Martian terrain dataset noted as “Mars-Seg” containing 5 K images with pixel-level accurate annotations regarding issues, such as the lack of semantic segmentation datasets for unknown scenes.

Optimal Path-Planning With Random Breakdowns

We propose a model for path-planning based on a single performance metric that accurately accounts for the the potential (spatially inhomogeneous) cost of breakdowns and repairs. These random breakdowns happen at a known (also spatially inhomogeneous) rate and can be one of two types: total, which halt all movement until an in-place repair is completed, or partial, after which movement continues in a damaged state. We use the framework of piecewise-deterministic Markov processes to describe the optimal policy for all starting locations. We also introduce an efficient numerical method that uses hybrid value-policy iterations to solve the resulting system of Hamilton-Jacobi-Bellman PDEs. Our method is illustrated through a series of computational experiments that highlight the dependence of optimal policies on the rate and type of breakdowns, with one of them based on Martian terrain data near Jezero Crater.

Biosignatures Associated with Organic Matter in Late Paleoproterozoic Stromatolitic Dolomite and Implications for Martian Carbonates.

The documentation of biosignatures in Precambrian rocks is an important requirement in the search for evidence of life on other ancient planetary surfaces. Three major kinds of biosignatures are crucially important: primary microbial sedimentary textures, diagenetic organomineral assemblages, and stable isotope compositions. This study presents new petrographic, mineralogical, and organic geochemical analyses of biosignatures in dolomitic stromatolites from the Pethei Group (N.W.T., Canada) and the Kasegalik Formation of the Belcher Group (Nunavut, Canada). Both are approximately contemporary late Paleoproterozoic stromatolite-bearing dolomitic units deposited after the Great Oxidation Event. Micro-Raman and optical microscopy are used to identify and characterize possible diagenetic biosignatures, which include close spatial association of diagenetic materials (such as ferric-ferrous oxide and anatase) with disseminated organic matter (OM), dolomitic groundmass textures, and mineralized balls. Many of these petrographic relationships point to the oxidation of OM either biotically or abiotically in association with iron reduction and chemically oscillating reactions. Oxidation of OM in these stromatolites is consistent with the widespread oxidation of biomass during the late Paleoproterozoic Shunga-Francevillian Event. Biosignatures identified in this study are also compared with possible carbonate outcrops on Mars, and thereby contribute a basis for comparison with potential biosignatures in ancient martian terrains. Similarities are drawn between the paleoenvironments of the studied units to the Isidis and Chryse planitia as locations for potential extraterrestrial dolomitic stromatolites.

Fractal analysis of the martian landscape: A study of kilometre-scale topographic roughness

Natural and engineered surfaces can be modelled as fractal objects described by a non-integer dimension (i.e., their fractal dimension). This approach has been used extensively to characterize surface complexity in terms of rugosity or roughness. In this paper, the local fractal dimension is proposed as a means of mapping the spatial variability of the surface roughness of the Martian landscape. The local fractal dimension complements measures of topographic roughness proposed by other authors and provides new images of the Martian surface texture at the kilometric scale that can be used to interpret geological events, geological processes and geological formations. It can also assist in geological mapping and in the detection and prioritisation of sites that merit further exploration. Mars Orbiter Laser Altimeter data were used to characterize the kilometre-scale terrain roughness of Mars. The procedure is general and can also be applied to digital elevation models with higher resolution (for example, digital elevation models generated by stereo-pair HiRISE images) to assess roughness at the metric scale. Sixteen test sites were selected and used to illustrate the patterns of the spatial variability of landscape roughness (local fractal dimension maps) at the kilometric scale. The results show that the mean of the local fractal dimension ranges from 2.036 in Argyre Planitia to 2.403 at the North Pole. The results also show that the mean roughness values of the Martian landscapes are less than those of the Earth's continents. Basically, the roughness of the Martian terrain at the kilometric scale depends, inter alia, on the number of kilometric-scale landforms present on the terrain. It is thus logical that the local fractal dimension is higher on Earth, a geologically active planet, than on Mars. Only the North Pole test site (an area larger than the North polar ice cap) shows a roughness histogram similar to those of terrestrial sites. The abundance of information embedded in the spatial variability patterns in the roughness maps provides a significant resource for planetary geology research.

A Review of the Phyllosilicates in Gale Crater as Detected by the CheMin Instrument on the Mars Science Laboratory, Curiosity Rover

Curiosity, the Mars Science Laboratory (MSL) rover, landed on Mars in August 2012 to investigate the ~3.5-billion-year-old (Ga) fluvio-lacustrine sedimentary deposits of Aeolis Mons (informally known as Mount Sharp) and the surrounding plains (Aeolis Palus) in Gale crater. After nearly nine years, Curiosity has traversed over 25 km, and the Chemistry and Mineralogy (CheMin) X-ray diffraction instrument on-board Curiosity has analyzed 30 drilled rock and three scooped soil samples to date. The principal strategic goal of the mission is to assess the habitability of Mars in its ancient past. Phyllosilicates are common in ancient Martian terrains dating to ~3.5–4 Ga and were detected from orbit in some of the lower strata of Mount Sharp. Phyllosilicates on Earth are important for harboring and preserving organics. On Mars, phyllosilicates are significant for exploration as they are hypothesized to be a marker for potential habitable environments. CheMin data demonstrate that ancient fluvio-lacustrine rocks in Gale crater contain up to ~35 wt. % phyllosilicates. Phyllosilicates are key indicators of past fluid–rock interactions, and variation in the structure and composition of phyllosilicates in Gale crater suggest changes in past aqueous environments that may have been habitable to microbial life with a variety of possible energy sources.

Space Mining Robot Prototype for NASA Robotic Mining Competition Utilizing Systems Engineering Principles

The 2017 National Aeronautics and Space Ad-ministration (NASA) Robotic Mining Competition (RMC) is an outstanding opportunity for engineering students to imple-ment all the knowledge and experience that they gained in the undergraduate years, in building a robot that will provide an intellectual insight to NASA, to develop innovative robotic excavation concepts. For this competition, multiple universities from all over the U.S. will create teams of students and faculty member to design and build a mining robot that can traverse, mine, excavate at least 10 kg of regolith, then deposit it in a bin in the challenging simulated Martian terrain. Our team’s goal is to improve on our current design, and overcome DustyTRON 2.0’s limitations by analyzing them and implementing new engineering solutions. The process to improve this system will enable our team members to learn mechanical, electrical, and software engineering. DustyTRON 3.0 is divided into three sub-teams, namely, Mechanical, Circuitry, Software sub-teams. Mechanical team focused on solving the mechanical structure, robot mobility, stability and weight distribution. Circuitry team focused on the electrical components such as batteries, wiring, and motors. The Software team focused on programming the NVidia TK1, Arduino controller, and cameras integration. This paper will outline the detailed work following systems engineering principles to complete this project, from research, to design process and robot building compete at the Kennedy Space Center. Only 54 teams were invited to participate from allover the US and DustyTRON team represented the state of Texas and placed the 29th and awarded the “Innovative Design” award.

Ecocide and Empire in Jeanette Winterson’s The Stone Gods

ABSTRACT This article argues that Jeanette Winterson enciphers The Stone Gods with allusions to Rapa Nui’s colonial history. Specifically, Winterson’s speculative sections re-enact a forty-year interval (1868–1914) in Rapa Nui’s colonial past that saw the island’s partition into a penal labour camp and leper colony, as well as the islanders’ defeated bid for indigenous sovereignty. In effect, Winterson double-maps Rapa Nui’s colonial entanglements with Scottish-Tahitian and Scottish-Chilean corpocracies onto a terraformed Mars and biodiverse Venus to concretise the transhistorical and supranational scope of the Anthropocene. In so doing, Winterson cites Rapa Nui’s example to caution readers against redirecting available resources towards a techno-escapist solution to advanced climate change. Ultimately, The Stone Gods displaces Rapa Nui’s historical ruination onto Martian terrain to generate an affective sense of contemporary ecological and climatological precarity as inextricable from, and co-extensive with, an ecocidal fiction of Empire that can be revised.

A Review of Soil Dynamics in Traction Studies

As the world population increases more than ever before and increasing demand on food, feed and fiber, and security, the number of off-the-road vehicles is rapidly increasing for agriculture, forestry, military, mining and construction industries. Many researchers have studied and still investigating traction as it relates off-road vehicles and publications abound especially from developed countries of Europe, America and others. In our generation scientists are trying to put robotic vehicles on the lunar and Martian terrains. This trend makes the study of soil dynamics in traction a sine qua non in our tertiary and research institutions. In Nigeria there is a dearth of publications in this specialized area of study. This is a review paper and the purpose is to highlight some of the studies that have been conducted over the years, with a view to enlightening, encouraging, stimulating and challenging would be researchers. Trends in the development of soil bin with single wheel testers were reviewed including tractive and transport devices used in them. Traction parameters including motion resistance, measurement and data acquisition systems, traction predictive equations including wheel numeric and mobility numbers were also reviewed. Efforts made in the development of soil bin for soil dynamics research and further research interest at the Federal University of Technology, Akure (FUTA) were highlighted.

NASA Robotic Mining Competition

The sky’s the limit, so the saying goes, yet humankind is trying to make a footprint on our neighbor Mars. Because of Mars distance from Earth, NASA would like to develop a mechanism to help astronauts to collect water crystals found below the sandy Martian regolith. As a result, they task the Robotic Mining Competition (RMC) teams to design a robot that can steer through a simulated Martian terrain, collect gravel (simulated water crystals) located under the regolith material (BP-1), and bring the gravel back to the collection bin. The RMC teams must work cooperatively in order to design and build such a robot, and to out-compete all their competitors. New solutions are being developed from colleges and universities all over the country to discover new mechanisms that can collect water crystals through a mining robot. These students have taken their skills from their schools, their internships, and clubs to apply their theory and design to develop these new mechanisms. From this program, these students created outreach programs to encourage science, technology, engineering, and mathematics to local communities by volunteering through mentorship programs and after-school activities.

The use of GIS, mapping, and immersive technologies in the CanMars Mars Sample Return analogue mission; advantages for science interpretation and operational decision-making

The CanMars Mars Sample Return (MSR) analogue mission was a high-fidelity rover campaign conducted over a total of five weeks in November 2015 and November 2016. The analogue mission team consisted of a Mission Control Team located at the University of Western Ontario (Western) in London, Ontario, Canada, and a Field Team including the Mars Exploration Science Rover (MESR) platform conducting in situ field operations in the desert north of Hanksville, Utah, USA. This location served as an analogue martian terrain for the duration of the CanMars mission campaign. The main science goal of the mission was to explore the field area using the MESR platform in order to locate and sample geologic materials best suited for identifying evidence for the existence of past or extant life. The CanMars analogue mission necessitated the organization and interpretation of several remote sensing datasets to provide regional morphological and compositional context for the lithological units observed by the rover in the operational field area. These tasks were given to the GIS (Geographic Information Systems) and Mapping team, a sub-team of the Mission Control Team located at Western. These remote sensing datasets were intended to be used as analogues for remote sensing data currently available for the Martian surface and included a HiRISE equivalent full colour Quickbird-2 satellite image (60 cm/pixel), a HiRISE/CTX approximating DEM (5 m/pixel horizontal resolution and a vertical accuracy on the order of 4 m or less), and CRISM and THEMIS equivalent visible to thermal infrared spectral images from Landsat-8 and ASTER (15–90 m/pixel). The GIS and Mapping Team used these datasets in concert with a range of additional derived data products (e.g., hillshade, slope, spectral and thermal inertia maps, etc.). This information was analyzed to create interpreted geomorphological maps of the operational field area. A major goal of the GIS and Mapping Team was to provide valuable contextual information to the Science and Planning Teams pertaining to the rover's position and the characteristics of the surrounding landscape and geology. The GIS and Mapping Team made use of geographic information systems including ArcMap and ArcScene to create a detailed database of geologic and geographic information as well as to derive additional geospatial data products. Additionally, the CanMars analogue missions provided an ideal setting to test the use of immersive virtual reality (VR) technology to aid scientists with both data and image interpretation as they conducted remote field operations. This included the development and implementation of immersive versions of the 360° panoramic images taken by the rover and an interactive immersive VR terrain model of the rover landing site and surrounding area. In the inherently time-sensitive role of interpreting data before sending the rover platform its next set of commands, the immersive technologies became important tools to facilitate a rapid understanding of the rover's location and orientation was well as the geologic and topographic setting of the surrounding region. These immersive products provided a first-person experience of the rover's surroundings that aided in the discussion and decision-making efforts of the CanMars team.

An Instrument Anomaly in the Mars Exploration Rover Pancam 1,009‐nm Filter (R7): Characterization, Simulation, Correction, and Preliminary Verification

During pre‐flight calibration of the panoramic camera (Pancam) instrument on board the Mars Exploration Rovers MER A (Spirit) and MER B (Opportunity), a discrepancy was noted between 11‐band spectra extracted from Pancam images of the camera's radiometric calibration target and reflectance spectra obtained with a spectrometer. This discrepancy was observed in the longest‐wavelength filter of the camera (the longpass R7 filter with system λeff = 1,009 nm) and consisted of a reduction in contrast between bright and dark regions. Here we describe and characterize this effect. We propose that the effect arises because long‐wavelength photons close to the silicon band‐gap at 1,100 nm are allowed through the R7 filter, pass through the bulk charge‐coupled device, scatter from the backside, pass through the charge‐coupled device again, and are registered in a pixel other than the pixel through which they originally entered. Based on this hypothesis we develop a model capable of accurately simulating the effect, and correct for it. We present preliminary results from testing this correction on preflight, as well as in‐flight, images. The effect is small, but in some specific cases in small regions of high contrast, the effect is significant. In in‐flight images of Martian terrain we observed the signal in dark shadows to be artificially inflated by up to ∼ 33% and analysis of early‐mission calibration target images indicated that the reduced contrast due to the artifact is equivalent to >100 DN (full well = 4095 DN) for a hypothetical perfectly dark pixel.

Safe Exploration and Optimization of Constrained MDPs Using Gaussian Processes

We present a reinforcement learning approach to explore and optimize a safety-constrained Markov Decision Process(MDP). In this setting, the agent must maximize discounted cumulative reward while constraining the probability of entering unsafe states, defined using a safety function being within some tolerance. The safety values of all states are not known a priori, and we probabilistically model them via aGaussian Process (GP) prior. As such, properly behaving in such an environment requires balancing a three-way trade-off of exploring the safety function, exploring the reward function, and exploiting acquired knowledge to maximize reward. We propose a novel approach to balance this trade-off. Specifically, our approach explores unvisited states selectively; that is, it prioritizes the exploration of a state if visiting that state significantly improves the knowledge on the achievable cumulative reward. Our approach relies on a novel information gain criterion based on Gaussian Process representations of the reward and safety functions. We demonstrate the effectiveness of our approach on a range of experiments, including a simulation using the real Martian terrain data.

Dioctahedral Phyllosilicates Versus Zeolites and Carbonates Versus Zeolites Competitions as Constraints to Understanding Early Mars Alteration Conditions

AbstractWidespread occurrence of Fe,Mg‐phyllosilicates has been observed on Noachian Martian terrains. Therefore, the study of Fe,Mg‐phyllosilicate formation, in order to characterize early Martian environmental conditions, is of particular interest to the Martian community. Previous studies have shown that the investigation of Fe,Mg‐smectite formation alone helps to describe early Mars environmental conditions, but there are still large uncertainties in terms of pH range, oxic/anoxic conditions, etc. Interestingly, carbonates and/or zeolites have also been observed on Noachian surfaces in association with the Fe,Mg‐phyllosilicates. Consequently, the present study focuses on the dioctahedral/trioctahedral phyllosilicate/carbonate/zeolite formation as a function of various CO2 contents (100% N2, 10% CO2/90% N2, and 100% CO2), from a combined approach including closed system laboratory experiments for 3 weeks at 120°C and geochemical simulations. The experimental results show that as the CO2 content decreases, the amount of dioctahedral clay minerals decreases in favor of trioctahedral minerals. Carbonates and dioctahedral clay minerals are formed during the experiments with CO2. When Ca‐zeolites are formed, no carbonates and dioctahedral minerals are observed. Geochemical simulation aided in establishing pH as a key parameter in determining mineral formation patterns. Indeed, under acidic conditions dioctahedral clay minerals and carbonate minerals are formed, while trioctahedral clay minerals are formed in basic conditions with a neutral pH value of 5.98 at 120°C. Zeolites are favored from pH ≳ 7.2. The results obtained shed new light on the importance of dioctahedral clay minerals versus zeolites and carbonates versus zeolites competitions to better define the aqueous alteration processes throughout early Mars history.

Liquid water inferred on present-day Mars

Researchers have identified the spectral signatures of hydrated minerals on sloping Martian terrain.

Dynamic modeling and mobility analysis of the transforming roving–rolling explorer (TRREx) as it Traverses Rugged Martian Terrain

All planetary surface exploration missions thus far have employed traditional rovers with a rocker-bogie suspension. These rovers can navigate moderately rough and flat terrain, but are not designed to traverse rugged terrain with steep slopes. The fact is, however, that the most scientifically interesting missions require exploration platforms with capabilities for navigating such types of rugged terrain. This issue motivates the development of new kinds of rovers that take advantage of the latest advances in robotic technologies to traverse rugged terrain efficiently. This work analyzes one such rover concept called the Transforming Roving–Rolling Explorer (TRREx) that is principally aimed at addressing the above issue. Biologically inspired by the way the armadillo curls up into a ball when threatened, and the way the golden wheel spider uses the dynamic advantages of a sphere to roll down hills when escaping danger, the TRREx rover can traverse like a traditional 6-wheeled rover over conventional terrain, but can also transform itself into a sphere, when necessary, to travel down steep inclines, or navigate rough terrain. This paper investigates the mobility of the TRREx when it is in its rolling mode, i.e. when it is a sphere and can steer itself through actuations that shift its center of mass to achieve the desired direction of roll. A mathematical model describing the dynamics of the rover in this spherical configuration is presented, and actuated rolling is demonstrated through computer simulation. Parametric analyzes that investigate the rover’s mobility as a function of its design parameters are also presented. This work highlights the contribution of the spherical rolling mode to the enhanced mobility of the TRREx rover and how it could enable challenging surface exploration missions in the future.

Assessing the Spectral Sensitivity of Martian Terrains to Iron Oxide Variations Using the SPLITS Model

The mineralogy and environmental history of Mars are being extensively studied through remote sensing observations paired with laboratory and in situ experiments. A significant portion of these experiments is being devoted to the identification and mapping of different iron oxides present in the Martian terrains. Among these compounds, goethite has been an object of great interest since its occurrence can be interpreted as mineralogical evidence of past aqueous activity on those landscapes. Although such experiments can provide valuable information regarding the presence of these minerals, the scope of the resulting observations may be hindered by logistics and cost-related constraints. We believe that predictive computer simulations can be employed to mitigate some of these constraints and contribute to the generation and validation of hypotheses in this area. Accordingly, we propose the use of SPLITS (Spectral Light Transport Model for Sand) in investigations involving the spectral signatures of iron-bearing regions of Mars. In this paper, we initially demonstrate the predictive capabilities of the SPLITS model in this context through qualitative comparisons of modeled results with actual observations and measured data. Using the resulting modeled reflectance curves as our baseline data, we then perform a series of controlled computational experiments to investigate how variations on goethite and hematite content affect the spectral responses of Martian sand-textured soils.

An assessment of the impact of local processes on dust lifting in martian climate models

Simulation of the lifting of dust from the planetary surface is of substantially greater importance on Mars than on Earth, due to the fundamental role that atmospheric dust plays in the former’s climate, yet the dust emission parameterisations used to date in martian global climate models (MGCMs) lag, understandably, behind their terrestrial counterparts in terms of sophistication. Recent developments in estimating surface roughness length over all martian terrains and in modelling atmospheric circulations at regional to local scales (less than O(100km)) presents an opportunity to formulate an improved wind stress lifting parameterisation. We have upgraded the conventional scheme by including the spatially varying roughness length in the lifting parameterisation in a fully consistent manner (thereby correcting a possible underestimation of the true threshold level for wind stress lifting), and used a modification to account for deviations from neutral stability in the surface layer. Following these improvements, it is found that wind speeds at typical MGCM resolution never reach the lifting threshold at most gridpoints: winds fall particularly short in the southern midlatitudes, where mean roughness is large. Sub-grid scale variability, manifested in both the near-surface wind field and the surface roughness, is then considered, and is found to be a crucial means of bridging the gap between model winds and thresholds. Both forms of small-scale variability contribute to the formation of dust emission ‘hotspots’: areas within the model gridbox with particularly favourable conditions for lifting, namely a smooth surface combined with strong near-surface gusts. Such small-scale emission could in fact be particularly influential on Mars, due both to the intense positive radiative feedbacks that can drive storm growth and a strong hysteresis effect on saltation. By modelling this variability, dust lifting is predicted at the locations at which dust storms are frequently observed, including the flushing storm sources of Chryse and Utopia, and southern midlatitude areas from which larger storms tend to initiate, such as Hellas and Solis Planum. The seasonal cycle of emission, which includes a double-peaked structure in northern autumn and winter, also appears realistic. Significant increases to lifting rates are produced for any sensible choices of parameters controlling the sub-grid distributions used, but results are sensitive to the smallest scale of variability considered, which high-resolution modelling suggests should be O(1km) or less. Use of such models in future will permit the use of a diagnosed (rather than prescribed) variable gustiness intensity, which should further enhance dust lifting in the southern hemisphere in particular.

Minimum effective area for high resolution crater counting of martian terrains

The acquisition of high-resolution imagery for the surface of Mars has enabled mapping of spatially limited (order of <103km2) landforms such as alluvial fans, deltas, and lacustrine deposits that are targets for exploration due to their association with liquid water. It is essential for our understanding of the planet’s geologic and climate history therefore to place these landforms within the global chronostratigraphic context. Here, we analyze both the statistical variability in the cratering pattern as well as the influence of small crater resurfacing on crater counting small landforms. We identified and counted craters (diameter (D)>200m) on four type terrains using Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) imagery that span the Noachian, Hesperian, and Amazonian epochs. The counts from each location include a region covering 10,000km2, ten 1000km2 subsets of that larger area, and approximately one hundred 100km2 samples. The data demonstrate significant variation in the crater size frequency and derived model ages across a single terrain type for the 100km2 samples. The crater size frequency at this area scale varies across a single, uniform geologic unit by up to a factor of 2–3 on the four different terrains. At 1000km2, the local pattern variations that are relevant at the 100km2 scale become less important and the age variations are tighter. In all four terrain cases, the 10,000km2 and 1000km2 samples capture distinct crater populations (km-sized craters) that formed before and after resurfacing event(s). However, due to the relatively high mean distance between km-sized craters, the 100km2 size area samples more commonly than not exclude a statistically significant sample at the kilometer size range, masking important information about the pre-resurfacing history of the terrain. We therefore suggest that due to the effect of pattern variability in cratering over 100km2 and the susceptibility of smaller craters to resurfacing, crater counts derived from small area samples are suspect to major uncertainties.