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• Paper reviews operation and parameters of archimedean scroll propulsion systems. • A thorough review of literature on scroll propulsion vehicles is presented. • An emerging application of screw propulsion are uncrewed ground vehicles. This paper provides a comprehensive review of the published literature on screw propulsion for off-road vehicles and amphibious transportation, from its origins in the 18th century to the present day. Additionally, this work describes the basis and elements of an archimedean scroll propulsion mechanism and discusses the most developed dynamic models available in the literature and their limitations. The paper also examines the need for a tested terramechanics dynamic model and explores potential future applications of screw propulsion technology for uncrewed ground vehicles and robotic planetary exploration. [ABSTRACT FROM AUTHOR]

MONOLITh is a bioinspired, untethered crawling soft robot. The body is made from a lightweight reticulated foam that provides passive shape restoration and supports the internally embedded components (motors, battery, wireless controller). DC motors pull tendons attached to an external fabric that distributes forces, and novel differential friction elements enable forward locomotion. This robot is capable of traveling at a maximum speed of 0.1 body lengths/sec, lifting 100% of its body weight, while remaining 95% soft materials by volume. We expect that the design principles and materials used to make this low cost and scalable robot will lead to the development of useful, and commercially viable, terrestrial or extraterrestrial vehicles. [ABSTRACT FROM AUTHOR]

The article offers information on Mars rover, Perseverance of National Aeronautics and Space Administration (NASA). Topics discussed include focus to examine certain minerals to look for the frozen imprint of a magnetic field in Mars; aim to traced the tracks of ancient water across Mars; and information on how levels of atmospheric carbon dioxide and the greenhouse effect on lakes.

As interest in low-cost reusable launch vehicles and extraterrestrial exploration has increased in recent years, soft-landing techniques have become important. A pintle injector can help realize this because it is capable of thrust control. However, research on this topic is very limited, and general optimization design procedures have not been completely established. In particular, no studies have examined orifice adjustment for annular flow, which is important in thrust control. In this study, a new design concept for a pintle injector is presented specifically to improve spray uniformity in a 400 N class engine; this maintains the concentricity of the pintle rod associated with the radial flow's orifice size. The primary focus here was on spray tests that were conducted to obtain the control range of the orifice area for annular flow. Spray characteristics such as spray angle, spray uniformity, and droplet size were analyzed, from which empirical correlations were derived. Finally, the optimum control range for the annular flow's orifice area was estimated from the perspective of atomization performance. This can be of reference to develop an enhanced thrust control system. • New design concept for a pintle injector was introduced to improve uniformity in a 400 N class liquid rocket engine. • Spray tests helped find the control range of the annular flow's orifice area. • An appropriate correlation equation was developed for the parameters. • The control range was estimated using empirical correlations with respect to the degree of atomization. • A database for linear control system design was established. [ABSTRACT FROM AUTHOR]

In recent years, CanSats have become a popular choice in simulated satellite contests. Among CanSat contests, the ARLISS project is the one that uses rockets to launch the CanSat into the sky. ARLISS provides rockets to launch CanSats, which reach an altitude of ∼4,000 m and then drop the rover to the ground using a parachute. However, the rovers of several teams cannot withstand the large acceleration applied during the launch, which damage and make them non-operational. The acceleration applied to the rocket during the launch was measured by multiple teams previously; however, because the CanSat is a small-embedded device, an acceleration sensor with a wide measurement range and a high sampling frequency could not be used. In this study, we measure the acceleration applied to the rover from the launch till it drops on the ground using an acceleration sensor with a wider measurement range, and by acquiring data at a higher sampling frequency than before. The acceleration is found to be larger than that in the conventional measurement when the rocket is launched and it drops to the ground. Further, the descriptions of the technical details of the rover structure that can withstand these impacts, perform accurate measurements, and operate without breakage in ARLISS are provided. [ABSTRACT FROM AUTHOR]

With the increase of planetary exploration missions and thereby the resultant increase of extraterrestrial rovers deployed, their mobility performance meets new challenges. Wheel-soil interaction plays an important role in the movement of these rovers. Our research addresses the study of this interactions in the first moments of the trajectory. The investigations reported so far, focus on long-distance motion (approx. 20-30 cm). However, the authors believe that the firsts interactions are crucial for the future performance of the motion. Here, by means of a device that allows multiple and precise repetitions of a wheel rolling experiment at controlled gravities, we characterize the movement of a wheel on sandy soil, in the gravity of Mars. Our study reveals that gravity influences the performance of the wheel, under these conditions. The experiments show that, as the gravity decreases, the rolling efficiency also decreases. [ABSTRACT FROM AUTHOR]

The article informs that a robotic rover has been deployed in the Atacama Desert in Chile that has recovered subsurface soil samples during a trial mission to find signs of life. It mentions about a string of volcanoes in the Cascades Arc ranging from Mountain Lassen in California to Mountain Baker in Washington. It also mentions about the discovery of a stunning' trove of thousands of fossils on a riverbank in China.

Giorgio Scarpa (1938-2012) was an Italian designer, artist and teacher who worked in bionics, topology and rotational geometry. This article describes Scarpa's bionic model of "Aristotle's lantern"--the mouth of the sea urchin. The technical literature on Echinoidea lacks a detailed study of its remarkable mouth mechanism. Scarpa's model is the only known analysis and physical analogue of the mechanism. It is a striking example of geometrical analysis and craftsmanship, bridging science and art. Built in the early 1970s and described in 1985 in Modelli di Bionica, his model has inspired designs for a biopsy harvester and for a mini-rover to collect soil samples on Mars. [ABSTRACT FROM AUTHOR]

Highlights • Comparison of eleven well-known machine learning algorithms. • Influence of tires, speed, soil, and mounting position of sensors. • Validation by means of a real planetary exploration rover (LATUV rover). • Deep discussion with the lessons learned. Abstract This paper presents a comprehensive comparison of well-known machine learning algorithms for estimating discrete slip events associated with individual wheels in planetary exploration rovers. This analysis is performed with various tuning configurations for each algorithm (55 setups). This research also shows the key role that environment plays in the performance of the learning algorithms: rover speed (0.05–0.25 [m/s]), type of terrain (gravel vs. sand), and tire type (off-road tires vs. smooth tires). These contributions are validated by using a broad data set collected using a planetary rover equipped with proprioceptive sensing. This work not only identifies the best algorithm to be deployed for discrete slip estimation, but it also helps with the selection and the mounting position of the sensing systems to be employed in future robotic planetary missions. [ABSTRACT FROM AUTHOR]

Highlights • Theoretical and experimental research was done for online terrain parameters and resistance force estimation. • Both normal and shear stresses can be expressed linearly using equivalent wheel sinkage. • Terrain's mechanical properties are re-characterized by proposed stiffness and shear strength. • Maximum relative error of the estimated resistance force is less than 7% at steady state. Abstract Wheel-soil interaction mechanics plays a crucial role for wheeled mobile robots (WMR) on rough and deformable terrains such as Martian and Lunar surfaces. Skid terramechanics is an essential component for WMRs and generates resistance force when a WMR brakes or on downhill slopes. The basis of classical terramechanics theories for WMRs – Bekker's normal stress and Janosi's shear stress equations – are so complex that the wheel-soil interaction force/torque equations are not amenable to closed form solutions, which seriously limits the application of terramechanics theories to WMRs. To establish analytical wheel-soil interaction expressions, the normal and shear stresses that can be characterized linearly by the proposed terrain stiffness and shear strength, respectively, are presented in this paper. Terrain stiffness and shear strength can be used to characterize terrain mechanical properties. Compared with the experimental data, the maximum relative error of the resistance forces estimated using these expressions at steady state is less than 7%. These validated expressions can be applied to estimate terrain parameters and resistance force online with high accuracy. Terrain's stiffness and shear strength increase first, and then reach a constant. Before wheels entering steady state, the online estimated resistance force's relative error is much higher, which can be explained using wheel's vertical velocity. [ABSTRACT FROM AUTHOR]

Abstract The process of identifying the landing site for NASA's Mars 2020 rover began in 2013 by defining threshold mission science criteria related to seeking signs of ancient habitable conditions, searching for biosignatures of past microbial life, assembling a returnable cache of samples for possible future return to Earth, and collecting data for planning eventual human missions to the surface of Mars. Mission engineering constraints on elevation and latitude were used to identify candidate landing sites that addressed the scientific objectives of the mission. However, for the first time these constraints did not have a major influence on the viability of candidate sites and, with the new entry, descent, and landing capabilities included in the baseline mission, the vast majority of sites were evaluated and down-selected on the basis of science merit. More than 30 candidate sites with likely acceptable surface and atmospheric conditions were considered at a series of open workshops in the years leading up to the launch. During that period, iteration between engineering constraints and the evolving relative science potential of candidate sites led to the identification of three final candidate sites: Jezero crater (18.4386°N, 77.5031°E), northeast (NE) Syrtis (17.8899°N,77.1599°E) and Columbia Hills (14.5478°S, 175.6255°E). The final landing site will be selected by NASA's Associate Administrator for the Science Mission Directorate. This paper serves as a record of landing site selection activities related primarily to science, an inventory of the number and variety of sites proposed, and a summary of the science potential of the highest-ranking sites. Highlights • Describes the science process for selecting the Mars 2020 rover landing site. • Down selection based on science merit rather than engineering constraints. • Over 30 candidate sites were narrowed to 3 finalists over three workshops. • Final candidate sites include Columbia Hills, Jezero crater, and NE Syrtis. [ABSTRACT FROM AUTHOR]

Abstract Previous and current Mars rover missions have noted a nearly ubiquitous presence of duricrusts on the planet surface. Duricrusts are thin, brittle layers of cemented regolith that cover the underlying terrain. In some cases, the duricrust hides safe or relatively safe underneath the top soil. However, as was observed by both Mars exploration rovers, Spirit and Opportunity, such crusts can also hide loose, untrafficable terrain, leading to Spirit becoming permanently incapacitated in 2009. Whilst several reports of the Martian surface have indicated the presence of duricrusts, none have been able to provide details on the physical properties of the material, which may indicate the level of safe traversability of duricrust terrains. This paper presents the findings of testing terrestrially-created duricrusts with simulated Martian soil properties, in order to determine the properties of such duricrusts and to discover what level of hazard that they may represent (e.g. can vehicles traverse the duricrust surface without penetration to lower sub-surface soils?). Combinations of elements that have been observed in the Martian soil were used as the basis for forming the laboratory-created duricrusts. Variations in duricrust thickness, water content, and the iron oxide compound were investigated. As was observed throughout the testing process, duricrusts behave in a rather brittle fashion and are easily destroyed by low surface pressures. This indicates that duricrusts are not safe for traversing and they present a definite hazard for travelling on the Martian landscape when utilising only visual terrain classification, as the surface appearance is not necessarily representative of what may be lying beneath. Highlights • Fabrication of artificial Mars duricrusts based on Mars geology. • Empirical testing and evaluation of artificial duricrust mechanical properties. • Testing of safe rover trafficability using standard geotechnical site survey methods. • Useful for full sensor testing (e.g. Ground Penetrating Radar, soil sampling systems) or as a physical analogue only (e.g. rover sinkage experiments). [ABSTRACT FROM AUTHOR]

The key problem of dynamic single epoch GPS positioning is the rapid decomposition of ambiguity. In some special dynamic positioning, the coordinates of the GPS receiver placed on the rover station often have the constraint condition, if this useful information is taken into account, it will help to determine the ambiguity accurately. For this reason, the straight motion trajectory of GPS receiver is used as the constraint condition for single epoch ambiguity resolution, in this algorithm, the wide lane ambiguities are calculated by using the MW combination, and the corresponding alternative combinations of wide lane ambiguity are established, which are determined according to the minimum residual sum of squares criterion firstly, it is used to lay the foundation for the subsequent L 1 and L 2 frequency ambiguity solution. And then the straight trajectory constraint condition and the phase observation equation are used to solve the integer ambiguity N 1 . When the constraint information of the trajectory is unknown, the space linear equation is established as the constraint condition according to the coordinate solution by wide lane relative positioning to solve the unknown problem. By designing the corresponding experiments, the results of this algorithm are proved to be feasible by using different experimental schemes, such as without constraint condition, the constraint condition with known prior information, introducing dynamic constraint condition and so on, to solve the ambiguity, and to compare and analyze the effect of linear constraint condition on single epoch ambiguity resolution. [ABSTRACT FROM AUTHOR]

Since the American Mars Exploration Rover Opportunity landed on Mars in 2004, it has travelled more than 40 km, and heading-determination technology based on its sun sensor has played an important role in safe driving of the rover. A high-precision heading-determination method will always play a significant role in the rover’s autonomous navigation system, and the precision of the measured heading strongly affects the navigation results. In order to improve the heading precision to the 1-arcminute level, this paper puts forward a novel calibration algorithm for solving the comparable distortion of large-field sun sensor by introducing an antisymmetric matrix. The sun sensor and inclinometer alignment model are then described in detail to maintain a high-precision horizon datum, and a strict sun image centroid-extraction algorithm combining subpixel edge detection with circle or ellipse fitting is presented. A prototype comprising a sun sensor, electronic inclinometer, and chip-scale atomic clock is developed for testing the algorithms, models, and methods presented in this paper. Three field tests were conducted in different months during 2017. The results show that the precision of the heading determination reaches 0.28–0.97′ (1σ) and the centroid error of the sun image and the sun elevation are major factors that affect the heading precision. [ABSTRACT FROM AUTHOR]

The article reports on a Mars rock sample cache system assembled by U.S. National Aeronautics and Space Administration's (NASA) Perseverance rover to collect rock samples on the planet for the proposed Mars Sample Return (MSR) mission to study these organic-rich rocks on Earth. Topics include the objective of the rover team to learn whether the organic rocks were made by living things, details of the Plan A of the MSR mission and the significance of establishing sample cache as a backup plan.

Identifying cracks and damages in structures using measured vibrational characteristics has received considerable attention in the past few decades. The possibility of using frequency changes due to the application of a mass appended to the structure has also been considered. In this paper an analytical proof to show that the natural frequencies of a cracked beam with a roving body possessing mass and rotary inertia will generally change abruptly as the body passes over a crack, provided that the crack permits differential flexural rotations, is presented. A novel explicit closed form solution of the governing equation of an Euler-Bernoulli beam with a roving body possessing mass and rotary inertia, in the presence of multiple cracks is also proposed. The presented exact solution is used to conduct a parametric analysis of cracked beams. Numerical results for natural frequencies are provided and a procedure to exploit the occurrence of frequency shifts to detect and locate each crack, without having to perform any additional calculation, is described. [ABSTRACT FROM AUTHOR]

The lunar surface is a complicated and unknown terrain, and hence, astronauts must be trained to travel on that surface by using a prototype vehicle on the Earth's terrain. However, the gravity of the Earth is six times that of the Moon; thus, the acceleration of a prototype vehicle on the Earth will differ from that of a manned lunar rover on the Moon, when the same acceleration handling input is provided. To obtain the same acceleration in the prototype vehicle on the Earth as that obtained on the Moon, an imitation handling ratio describing the relationship between the acceleration handling input and the wheel rolling speed is proposed in order to replicate the lunar gravitational conditions on the Earth. First, a whole-vehicle acceleration model was established based on the mechanical model of a deformable wheel with a mesh surface. Thereby an acceleration imitation algorithm was derived. A prototype vehicle for use on the Earth is proposed for the purpose of imitating the manned lunar rover under four different vehicle conditions. Fitted functions were used in order to obtain the imitation handling ratio. Finally, experiments were conducted to verify the imitation method; the results revealed that the prototype vehicle on the Earth could effectively approximate the same accelerations experienced by a manned lunar rover, when equivalent acceleration handling inputs were provided. [ABSTRACT FROM AUTHOR]

Parameter uncertainties which may lead to divergence of traditional Kalman filters during Mars entry are investigated in this paper. To achieve high precision navigation, a Derivative-free Nonlinear version of an Extended Recursive Three-Step Filter (DNERTSF) is introduced, which suits nonlinear systems with arbitrary parameter uncertainties. A DNERTSF can estimate the state and the parameters simultaneously, and Jacobian and Hessian calculations are not necessary for this filter. Considering the uncertainties in atmosphere density, ballistic coefficient and lift-to-drag ratio, a numerical simulation of Mars entry navigation is carried out. Compared with the standard Unscented Kalman Filter (UKF), DNERTSF can effectively reduce the adverse effects of parameter uncertainties and achieve a high navigation accuracy performance, keeping position and velocity estimation errors at a very low level. In all, the DNERTSF in this paper shows good advantages for Mars entry navigation, providing a possible application for a future Mars pinpoint landing. [ABSTRACT FROM AUTHOR]

This article introduces an optimization framework for the integrated design of a planetary surface rover and its exploration route that is applicable to the initial phase of a planetary exploration campaign composed of multiple surface missions. The scientific capability and the mobility of a rover are modelled as functions of the science weight fraction, a key parameter characterizing the rover. The proposed problem is formulated as a mixedinteger nonlinear program that maximizes the sum of profits obtained through a planetary surface exploration mission by simultaneously determining the science weight fraction of the rover, the sites to visit and their visiting sequences under resource consumption constraints imposed on each route and collectively on a mission. A solution procedure for the proposed problem composed of two loops (the outer loop and the inner loop) is developed. The results of test cases demonstrating the effectiveness of the proposed framework are presented. [ABSTRACT FROM AUTHOR]

In this study, a method to broadcast real-time kinematics (RTK) corrections over a communication satellite is proposed. RTK corrections generated by the reference station are uplinked to the communication satellite within a multiplexed DVB-S carrier. Corrections are received by a satellite dish and the DVB-S satellite receiver. Better than 18 cm of accuracy is achieved for rover distances of up to 500 km in Turkey. The proposed method can be used as an alternative satellite-based augmentation system for Turkey and other countries. [ABSTRACT FROM AUTHOR]

Four kinds of bionic non-smooth surfaces were designed to improve the durability of wheels designed for Mars rovers. A durability test bed was developed, and the wheels were tested over different terrain conditions. Their performance was evaluated based on abrasion mass, energy consumption, and wear morphology. Convex domes exhibited optimal abrasive mass and energy consumption 46% and 16%, respectively, lower than with original wheels under coarse quartz sand conditions. When bedrock was added to the abrasive material, the abrasive mass and energy consumption of the convex dome and scale-like unit forms were reduced by 60% and 67.5%, respectively. These two non-smooth surfaces exhibited increased wear resistance and drag reduction. These results indicate that the durability of wheels can be improved using bionic optimization methods. [ABSTRACT FROM AUTHOR]

This paper outlines an analysis of the traveling performance of a lunar rover. The analysis is in the form of numerical simulations and it uses soil properties, identified in vacuum, and mechanics of wheel-based travel. The wheel-to-ground contact model and soil parameters are determined first so they could be used in the numerical simulation. A soil test device is introduced and the soil parameters are identified from plate-pressing and shear tests. Finally, numerical simulations are conducted using the parameters identified and their results are discussed along with those of the traveling tests conducted in vacuum. The soil tests indicated that the wheel sinkage into the ground can increase in vacuum and that the shear stress acting beneath the wheel in vacuum is almost the same as that in the atmosphere. Because of these trends, the simulations and traveling tests showed that the traveling performance of the wheel can decrease in vacuum. Although it has been widely considered that the vacuum environments enhance the traveling performance of the wheel, this study confirmed that it is not always the case. [ABSTRACT FROM AUTHOR]

In this article, we discuss four fundamental scientific problems of lunar research: (1) lunar chronology, (2) the internal structure of the Moon, (3) the lunar polar regions, and (4) lunar volcanism. After formulating the scientific problems and their components, we proceed to outlining a list of technical solutions and priority lunar regions for research. Solving the listed problems requires investigations on the lunar surface using lunar rovers, which can deliver a set of analytical equipment to places where geological conditions are known from a detailed analysis of orbital information. The most critical research methods, which can answer some of the key questions, are analysis of local geological conditions from panoramic photographs, determination of the chemical, isotopic, and mineral composition of the soil, and deep seismic sounding. A preliminary list is given of lunar regions with high scientific priority. [ABSTRACT FROM AUTHOR]

The Shuiyindong gold deposit is a deeply concealed strata-bound Carlin-type deposit in southwestern Guizhou Province, China. The deposit lies on the eastern limb of the Huijiabao anticline with ores mainly along the anticline axis and hosted in bioclastic limestone, containing calcite veins, of the Permian Longtan Formation units. In this study, we measured carbon and oxygen isotopic ratios and rare earth element (REE) concentrations of the host rocks and calcite veins along a profile across the Shuiyindong deposit. Orebodies in the upper unit of the Longtan Formation have higher δ 18 O values (20.6–22.4‰) and lower δ 13 C values (−3.7 to −0.5‰) than the country rocks (δ 18 O: 18.8–21.4‰; δ 13 C: −0.7 to 0.8‰). However, there are no obvious trends of δ 18 O and δ 13 C values from the country rocks to the orebodies in the middle unit of the Longtan Formation. The spatial distribution of the calcite veins displays distinct halos of δ 13 C and δ 18 O values and REE concentrations. Calcite veins along the anticlinal axis and major reverse fault are enriched in Middle REE (Sm, Eu, Gd, and Tb) and 18 O and depleted in 13 C. Surficial veining calcite-filled fractures/faults that connect to deep concealed strata-bound gold mineralization systems can be vectors toward deep ores in southwestern Guizhou Province, China. [ABSTRACT FROM AUTHOR]

This paper introduces an unsupervised method for the classification of discrete rovers’ slip events based on proprioceptive signals. In particular, the method is able to automatically discover and track various degrees of slip (i.e. low slip, moderate slip, high slip). The proposed method is based on aggregating the data over time, since high level concepts, such as high and low slip, are concepts that are dependent on longer time perspectives. Different features and subsets of the data have been identified leading to a proper clustering, interpreting those clusters as initial models of the prospective concepts. Bayesian tracking has been used in order to continuously improve the parameters of these models, based on the new data. Two real datasets are used to validate the proposed approach in comparison to other known unsupervised and supervised machine learning methods. The first dataset is collected by a single-wheel testbed available at MIT. The second dataset was collected by means of a planetary exploration rover in real off-road conditions. Experiments prove that the proposed method is more accurate (up to 86% of accuracy vs. 80% for K-means) in discovering various levels of slip while being fully unsupervised (no need for hand-labeled data for training). [ABSTRACT FROM AUTHOR]

A previous three-dimensional discrete element method (DEM) model of Mars Exploration Rovers (MERs) wheel mobility demonstrated agreement with test data for wheel drawbar pull and sinkage for wheel slips from 0.0 to 0.7. Here, results from the previous model are compared with wheel mobility data for non-MER wheels that cover the range of wheel slip from 0.0 to 1.0. Wheel slips near 1.0 are of interest for assessing rover mobility hazards. DEM MER wheel model predictions show close agreement with weight-normalized wheel drawbar pull data from 0.0 to 0.99 wheel slip and show a similar trend for wheel sinkage. The nonlinear increase in MER wheel drawbar pull and sinkage for wheel slips greater that 0.7 is caused by development of a tailings pile behind the wheel as it digs into the regolith. Classical terramechanics wheel mobility equations used in the ARTEMIS MER mobility model are inaccurate above wheel slips of 0.6 as they do not account for the regolith tailings pile behind the wheel. To improve ARTEMIS accuracy at wheel slips greater that 0.6 a lookup table of drawbar pull, wheel torque, and sinkage derived from DEM mobility simulations can be substituted for terramechanics equation calculations. [ABSTRACT FROM AUTHOR]

Autonomous rock image classification can enhance the capability of robots for geological detection and enlarge the scientific returns, both in investigation on Earth and planetary surface exploration on Mars. Since rock textural images are usually inhomogeneous and manually hand-crafting features is not always reliable, we propose an unsupervised feature learning method to autonomously learn the feature representation for rock images. In our tests, rock image classification using the learned features shows that the learned features can outperform manually selected features. Self-taught learning is also proposed to learn the feature representation from a large database of unlabelled rock images of mixed class. The learned features can then be used repeatedly for classification of any subclass. This takes advantage of the large dataset of unlabelled rock images and learns a general feature representation for many kinds of rocks. We show experimental results supporting the feasibility of self-taught learning on rock images. [ABSTRACT FROM AUTHOR]

For lunar surface exploration, a deployment system is necessary to allow a rover to leave the lander. The system should be as lightweight as possible and stored retracted when launched. In this paper, two types of retractable deployment systems for lunar landing missions, telescopic- and fold-type ramps, are discussed. In the telescopic-type system, a ramp is stored with the sections overlapping and slides out during deployment. In the fold-type system, it is stored folded and unfolds for the deployment. For the development of these ramps, a design concept study and structural analysis were conducted first. Subsequently, ramp deployment and rover release tests were performed using the developed ramp prototypes. Through these tests, the validity of their design concepts and functions have been confirmed. In the rover release test, it was observed that the developed lightweight ramp was sufficiently strong for a 50-kg rover to descend. This result suggests that this ramp system is suitable for the deployment of a 300-kg-class rover on the Moon, where the gravity is about one-sixth that on Earth. The lightweight and sturdy ramp developed in this study will contribute to both safe rover deployment and increase of lander/rover payload. [ABSTRACT FROM AUTHOR]

A high density of REMS wind measurements were collected in three science investigations during MSL's Bagnold Dunes Campaign, which took place over ∼80 sols around southern winter solstice (Ls∼90°) and constituted the first in situ analysis of the environmental conditions, morphology, structure, and composition of an active dune field on Mars. The Wind Characterization Investigation was designed to fully characterize the near-surface wind field just outside the dunes and confirmed the primarily upslope/downslope flow expected from theory and modeling of the circulation on the slopes of Aeolis Mons in this season. The basic pattern of winds is ‘upslope’ (from the northwest, heading up Aeolis Mons) during the daytime (∼09:00–17:00 or 18:00) and ‘downslope’ (from the southeast, heading down Aeolis Mons) at night (∼20:00 to some time before 08:00). Between these times the wind rotates largely clockwise, giving generally westerly winds mid-morning and easterly winds in the early evening. The timings of these direction changes are relatively consistent from sol to sol; however, the wind direction and speed at any given time shows considerable intersol variability. This pattern and timing is similar to predictions from the MarsWRF numerical model, run at a resolution of ∼490 m in this region, although the model predicts the upslope winds to have a stronger component from the E than the W, misses a wind speed peak at ∼09:00, and under-predicts the strength of daytime wind speeds by ∼2–4 m/s. The Namib Dune Lee Investigation reveals ‘blocking’ of northerly winds by the dune, leaving primarily a westerly component to the daytime winds, and also shows a broadening of the 1 Hz wind speed distribution likely associated with lee turbulence. The Namib Dune Side Investigation measured primarily daytime winds at the side of the same dune, in support of aeolian change detection experiments designed to put limits on the saltation threshold, and also appears to show the influence of the dune body on the local flow, though less clearly than in the lee. Using a vertical grid with lower resolution near the surface reduces the relative strength of nighttime winds predicted by MarsWRF and produces a peak in wind speed at ∼09:00, improving the match to the observed diurnal variation of wind speed, albeit with an offset in magnitude. The annual wind field predicted using this grid also provides a far better match to observations of aeolian dune morphology and motion in the Bagnold Dunes. However, the lower overall wind speeds than observed and disagreement with the observed wind direction at ∼09:00 suggest that the problem has not been solved and that alternative boundary layer mixing schemes should be explored which may result in more mixing of momentum down to the near-surface from higher layers. These results demonstrate a strong need for in situ wind data to constrain the setup and assumptions used in numerical models, so that they may be used with more confidence to predict the circulation at other times and locations on Mars. [ABSTRACT FROM AUTHOR]

The Ma_MISS (Mars Multispectral Imager for Subsurface Studies) experiment is the visible and near infrared (VNIR) miniaturized spectrometer hosted by the drill system of the ExoMars 2020 rover. Ma_MISS will perform IR spectral reflectance investigations in the 0.4-2.2 μm range to characterize the mineralogy of excavated borehole walls at different depths (between 0 and 2 m). The spectral sampling is about 20 nm, whereas the spatial resolution over the target is 120 μm. Making use of the drill's movement, the instrument slit can scan a ring and build up hyperspectral images of a borehole. The main goal of the Ma_MISS instrument is to study the martian subsurface environment. Access to the martian subsurface is crucial to our ability to constrain the nature, timing, and duration of alteration and sedimentation processes on Mars, as well as habitability conditions. Subsurface deposits likely host and preserve H2O ice and hydrated materials that will contribute to our understanding of the H2O geochemical environment (both in the liquid and in the solid state) at the ExoMars 2020 landing site. The Ma_MISS spectral range and sampling capabilities have been carefully selected to allow the study of minerals and ices in situ before the collection of samples. Ma_MISS will be implemented to accomplish the following scientific objectives: (1) determine the composition of subsurface materials, (2) map the distribution of subsurface H2O and volatiles, (3) characterize important optical and physical properties of materials ( e.g., grain size), and (4) produce a stratigraphic column that will inform with regard to subsurface geological processes. The Ma_MISS findings will help to refine essential criteria that will aid in our selection of the most interesting subsurface formations from which to collect samples. Key Words: Mars-Subsurface-Spectroscopy-Mineralogy. Astrobiology 17, 612-620. [ABSTRACT FROM AUTHOR]

MicrOmega is a visible near-infrared hyperspectral microscope that is designed to characterize the texture and composition of martian samples presented to the instrument within the ExoMars rover's analytical laboratory drawer. The spectral range (0.5-3.65 μm) and the spectral sampling (20 cm−1 from 0.95 to 3.65 μm) of MicrOmega have been chosen to allow the identification of most constituent minerals, ices/frosts, and organics with astrobiological relevance within each 20 × 20 μm2 pixel over a 5 × 5 mm2 field of view. Such an unprecedented characterization will enable (1) identification of most major and minor phases, including the potential organics; (2) ascription of their mineralogical context, as a critical set of clues with which to decipher their formation process; and (3) location of specific grains or regions of interest in the samples, which will be further analyzed by Raman Laser Spectrometer and/or Mars Organic Molecule Analyzer. Key Words: Spectroscopy-Microscopy-Composition-Organics-Mineralogy. Astrobiology 17, 621-626. [ABSTRACT FROM AUTHOR]

ISEM (Infrared Spectrometer for ExoMars) is a pencil-beam infrared spectrometer that will measure reflected solar radiation in the near infrared range for context assessment of the surface mineralogy in the vicinity of the ExoMars rover. The instrument will be accommodated on the mast of the rover and will be operated together with the panoramic camera (PanCam), high-resolution camera (HRC). ISEM will study the mineralogical and petrographic composition of the martian surface in the vicinity of the rover, and in combination with the other remote sensing instruments, it will aid in the selection of potential targets for close-up investigations and drilling sites. Of particular scientific interest are water-bearing minerals, such as phyllosilicates, sulfates, carbonates, and minerals indicative of astrobiological potential, such as borates, nitrates, and ammonium-bearing minerals. The instrument has an ∼1° field of view and covers the spectral range between 1.15 and 3.30 μm with a spectral resolution varying from 3.3 nm at 1.15 μm to 28 nm at 3.30 μm. The ISEM optical head is mounted on the mast, and its electronics box is located inside the rover's body. The spectrometer uses an acousto-optic tunable filter and a Peltier-cooled InAs detector. The mass of ISEM is 1.74 kg, including the electronics and harness. The science objectives of the experiment, the instrument design, and operational scenarios are described. Key Words: ExoMars-ISEM-Mars-Surface-Mineralogy-Spectroscopy-AOTF-Infrared. Astrobiology 17, 542-564. [ABSTRACT FROM AUTHOR]