Relating geologic units and mobility system kinematics contributing to Curiosity wheel damage at Gale Crater, Mars

Curiosity landed on plains to the north of Mount Sharp in August 2012. By June 2016 the rover had traversed 12.9 km to the southwest, encountering extensive strata that were deposited in a fluvial-deltaic-lacustrine system. Initial drives across sharp sandstone outcrops initiated an unacceptably high rate of punctures and cracks in the thin aluminum wheel skin structures. Initial damage was found to be related to the drive control mode of the six wheel drive actuators and the kinematics of the rocker-bogie suspension. Wheels leading a suspension pivot were forced onto sharp, immobile surfaces by the other wheels as they maintained their commanded angular velocities. Wheel damage mechanisms such as geometry-induced stress concentration cracking and low-cycle fatigue were then exacerbated. A geomorphic map was generated to assist in planning traverses that would minimize further wheel damage. A steady increase in punctures and cracks between landing and June 2016 was due in part because of drives across the sharp sandstone outcrops that could not be avoided. Wheel lifetime estimates show that with careful path planning the wheels will be operational for an additional ten kilometers or more, allowing the rover to reach key strata exposed on the slopes of Mount Sharp

The WISDOM Radar: Unveiling the Subsurface Beneath the ExoMars Rover and Identifying the Best Locations for Drilling

The search for evidence of past or present life on Mars is the principal objective of the 2020 ESA-Roscosmos ExoMars Rover mission. If such evidence is to be found anywhere, it will most likely be in the subsurface, where organic molecules are shielded from the destructive effects of ionizing radiation and atmospheric oxidants. For this reason, the ExoMars Rover mission has been optimized to investigate the subsurface to identify, understand, and sample those locations where conditions for the preservation of evidence of past life are most likely to be found. The Water Ice Subsurface Deposit Observation on Mars (WISDOM) ground-penetrating radar has been designed to provide information about the nature of the shallow subsurface over depth ranging from 3 to 10 m (with a vertical resolution of up to 3 cm), depending on the dielectric properties of the regolith. This depth range is critical to understanding the geologic evolution stratigraphy and distribution and state of subsurface H2O, which provide important clues in the search for life and the identification of optimal drilling sites for investigation and sampling by the Rover's 2-m drill. WISDOM will help ensure the safety and success of drilling operations by identification of potential hazards that might interfere with retrieval of subsurface samples

Terrain physical properties derived from orbital data and the first 360 sols of Mars Science Laboratory Curiosity rover observations in Gale Crater

Physical properties of terrains encountered by the Curiosity rover during the first 360 sols of operations have been inferred from analysis of the scour zones produced by Sky Crane Landing System engine plumes, wheel touch down dynamics, pits produced by Chemical Camera (ChemCam) laser shots, rover wheel traverses over rocks, the extent of sinkage into soils, and the magnitude and sign of rover‐based slippage during drives. Results have been integrated with morphologic, mineralogic, and thermophysical properties derived from orbital data, and Curiosity‐based measurements, to understand the nature and origin of physical properties of traversed terrains. The hummocky plains (HP) landing site and traverse locations consist of moderately to well‐consolidated bedrock of alluvial origin variably covered by slightly cohesive, hard‐packed basaltic sand and dust, with both embedded and surface‐strewn rock clasts. Rock clasts have been added through local bedrock weathering and impact ejecta emplacement and form a pavement‐like surface in which only small clasts (<5 to 10 cm wide) have been pressed into the soil during wheel passages. The bedded fractured (BF) unit, site of Curiosity's first drilling activity, exposes several alluvial‐lacustrine bedrock units with little to no soil cover and varying degrees of lithification. Small wheel sinkage values (<1 cm) for both HP and BF surfaces demonstrate that compaction resistance countering driven‐wheel thrust has been minimal and that rover slippage while traversing across horizontal surfaces or going uphill, and skid going downhill, have been dominated by terrain tilts and wheel‐surface material shear modulus values

Visualizing practical knowledge: The Haughton-Mars Project

To improve how we envision knowledge, we must improve our ability to see knowledge in everyday life. That is, visualization is concerned not only with displaying facts and theories, but also with finding ways to express and relate tacit understanding. Such knowledge, although often referred to as "common," is not necessarily shared and may be distributed socially in choreographies for working together—in the manner that a chef and a maitre d’hôtel, who obviously possess very different skills, coordinate their work. Furthermore, non-verbal concepts cannot in principle be inventoried. Reifying practical knowledge is not a process of converting the implicit into the explicit, but pointing to what we know, showing its manifestations in our everyday life. To this end, I illustrate the study and reification of practical knowledge by examining the activities of a scientific expedition in the Canadian Arctic—a group of scientists preparing for a mission to Mar

Science Operations for the 2008 NASA Lunar Analog Field Test at Black Point Lava Flow, Arizona

Surface science operations on the Moon will require merging lessons from Apollo with new operation concepts that exploit the Constellation Lunar Architecture. Prototypes of lunar vehicles and robots are already under development and will change the way we conduct science operations compared to Apollo. To prepare for future surface operations on the Moon, NASA, along with several supporting agencies and institutions, conducted a high-fidelity lunar mission simulation with prototypes of the small pressurized rover (SPR) and unpressurized rover (UPR) (Fig. 1) at Black Point lava flow (Fig. 2), 40 km north of Flagstaff, Arizona from Oct. 19-31, 2008. This field test was primarily intended to evaluate and compare the surface mobility afforded by unpressurized and pressurized rovers, the latter critically depending on the innovative suit-port concept for efficient egress and ingress. The UPR vehicle transports two astronauts who remain in their EVA suits at all times, whereas the SPR concept enables astronauts to remain in a pressurized shirt-sleeve environment during long translations and while making contextual observations and enables rapid (less than or equal to 10 minutes) transfer to and from the surface via suit-ports. A team of field geologists provided realistic science scenarios for the simulations and served as crew members, field observers, and operators of a science backroom. Here, we present a description of the science team s operations and lessons learned

Remote Neutron Spectroscopy on Mars

Remote neutron spectroscopy is an important technique in planetary science that allows for classification of the amount of light elements in a planetary regolith. It is especially suited for studying hydrogen abundances and elements with high thermal neutron absorption cross sections in the top ~1 meter of regolith. The Mars Science Laboratory rover Curiosity carries the first rover based neutron spectrometer Dynamic Albedo of Neutrons (DAN) in Gale crater, Mars. As the DAN instrument operates in passive mode, it is sensitive to neutrons produced through Galactic Cosmic Ray interactions and neutrons generated by the rover\u27s Multi-Mission Radioisotope Thermoelectric Generator. In this work, we develop an appropriate simulation strategy and data analysis methods to interpret passive data from the DAN instrument. Furthermore, the methods are used to estimate water equivalent hydrogen abundances in the shallow regolith of Gale crater along the traverse route of Curiosity from landing to the base of Mt. Sharp. Hydrogen is shown to have large variability on a scale of a few meters, much smaller than the spatial footprint of previous orbital investigations. Strong correlations between WEH content and surface properties are not observed. While in passive operation, DAN also observes diurnal variations in the martian neutron leakage fluxes. These diurnal variations are investigated and shown to possibly be a consequence of a combination of instrumental effects and environmental effects, most notably preferential shielding of alpha particles by the martian atmosphere leading to increased neutron production in the regolith as the surface atmospheric pressure changes throughout the sol

Characterization and mapping of surface physical properties of Mars from CRISM multi-angular data: application to Gusev Crater and Meridiani Planum

The analysis of the surface texture from the particle (grain size, shape and internal structure) to its organization (surface roughness) provides information on the geological processes. CRISM multi-angular observations (varied emission angles) allow to characterize the surface scattering behavior which depends on the composition but also the material physical properties (e.g., grain size, shape, internal structure, the surface roughness). After an atmospheric correction by the Multi-angle Approach for Retrieval of the Surface Reflectance from CRISM Observations, the surface reflectances at different geometries are analyzed by inverting the Hapke photometric model depending on the single scattering albedo, the 2-term phase function, the macroscopic roughness and the 2-term opposition effects. Surface photometric maps are created to observe the spatial variations of surface scattering properties as a function of geological units at the CRISM spatial resolution (200m/pixel). An application at the Mars Exploration Rover (MER) landing sites located at Gusev Crater and Meridiani Planum where orbital and in situ observations are available, is presented. Complementary orbital observations (e.g. CRISM spectra, THermal EMission Imaging System, High Resolution Imaging Science Experiment images) are used for interpreting the estimated Hapke photometric parameters in terms of physical properties. The in situ observations are used as ground truth to validate the interpretations. Varied scattering properties are observed inside a CRISM observation (5x10km) suggesting that the surfaces are controlled by local geological processes (e.g. volcanic resurfacing, aeolian and impact processes) rather than regional or global. Consistent results with the in situ observations are observed thus validating the approach and the use of photometry for the characterization of Martian surface physical properties