During Martian solar days 57–100, the Mars Science Laboratory Curiosity rover acquired and processed a solid (sediment) sample and analyzed its mineralogy and geochemistry with the Chemistry and Mineralogy and Sample Analysis at Mars instruments. An aeolian deposit—herein referred to as the Rocknest sand shadow—was inferred to represent a global average soil composition and selected for study to facilitate integration of analytical results with observations from earlier missions. During first‐time activities, the Mars Hand Lens Imager (MAHLI) was used to support both science and engineering activities related to sample assessment, collection, and delivery. Here we report on MAHLI activities that directly supported sample analysis and provide MAHLI observations regarding the grain‐scale characteristics of the Rocknest sand shadow. MAHLI imaging confirms that the Rocknest sand shadow is one of a family of bimodal aeolian accumulations on Mars—similar to the coarse‐grained ripples interrogated by the Mars Exploration Rovers Spirit and Opportunity—in which a surface veneer of coarse‐grained sediment stabilizes predominantly fine‐grained sediment of the deposit interior. The similarity in grain size distribution of these geographically disparate deposits support the widespread occurrence of bimodal aeolian transport on Mars. We suggest that preservation of bimodal aeolian deposits may be characteristic of regions of active deflation, where winnowing of the fine‐sediment fraction results in a relatively low sediment load and a preferential increase in the coarse‐grained fraction of the sediment load. The compositional similarity of Martian aeolian deposits supports the potential for global redistribution of fine‐grained components, combined with potential local contributions.

The Mars Phoenix Lander was equipped with a 2.4 m Robotic Arm (RA) with an Icy Soil Acquisition Device capable of excavating trenches in soil deposits, grooming hard icy soil surfaces with a scraper blade, and acquiring icy soil samples using a rasp tool. A camera capable of imaging the scoop interior and a thermal and electrical conductivity probe were also included on the RA. A dozen trench complexes were excavated at the northern plains landing site and 31 samples (including water‐ice‐bearing soils) were acquired for delivery to instruments on the Lander during the 152 sol mission. Deliveries included sprinkling material from several centimeters height to break up cloddy soils on impact with instrument portals. Excavations were done on the side of the Humpty Dumpty and the top of the Wonderland polygons, and in nearby troughs. Resistive forces encountered during backhoe operations show that soils above the 3–5 cm deep icy soil interfaces are stronger with increasing depth. Further, soils are similar in appearance and properties to the weakly cohesive crusty and cloddy soils imaged and excavated by the Viking Lander 2, which also landed on the northern plains. Adsorbed H2O is inferred to be responsible for the variable nature and cohesive strength of the soils. Backhoe blade chatter marks on excavated icy soil surfaces, combined with rasp motor currents, are consistent with laboratory experiments using grain‐supported icy soil deposits, as is the relatively rapid decrease in icy soil strength over time as the ice sublimated on Mars.

Abstract-We present an interpolation-based planning and replanning algorithm that is able to produce direct, lowcost paths through three-dimensional environments. Our algorithm builds upon recent advances in 2D grid-based path planning and extends these techniques to 3D grids. It is often the case for robots navigating in full three-dimensional environments that moving in some directions is significantly more difficult than others (e.g. moving upwards is more expensive for most aerial vehicles). Thus, we also provide a facility to incorporate such characteristics into the planning process. Along with the derivation of the 3D interpolation function used by our planner, we present a number of results demonstrating its advantages and real-time capabilities.

Abstract-In January 2004, NASA's twin Mars Exploration Rovers (MERs), Spirit and Opportunity, began searching the surface of Mars for evidence of past water activity. In order to localize and approach scientifically interesting targets, the rovers employ an on-board navigation system. Given the latency in sending commands from Earth to the Martian rovers (and in receiving return data), a high level of navigational autonomy is desirable. Autonomous navigation with hazard avoidance (AutoNav) is currently performed using a local path planner called GESTALT (Grid-based Estimation of Surface Traversability Applied to Local Terrain). GESTALT uses stereo cameras to evaluate terrain safety and avoid obstacles. GESTALT works well to guide the rovers around narrow and isolated hazards, however, it is susceptible to failure when clusters of closely spaced, non-traversable rocks form extended obstacles. In May 2005, a new technology task was initiated at the Jet Propulsion Laboratory to address this limitation. A version of the Carnegie Mellon University Field D* global path planner has been integrated into MER flight software, enabling simultaneous local and global planning during AutoNav. A revised version of AutoNav was uploaded to the rovers during the summer of 2006. This paper describes how global planning was integrated into the MER flight software, and presents results of testing the improved AutoNav system using the MER Surface System TestBed rover.

The Phoenix Lander investigated the polygonal terrain and associated soil and icy soil deposits of a high northern latitude site on Mars. The soil physical properties component involved the analysis of force data determined from motor currents from the Robotic Arm (RA)'s trenching activity. Using this information and images of the landing site, soil cohesion and angle of internal friction were determined. Dump pile slopes were used to determine the angle of internal friction of the soil: 38° ± 5°. Additionally, an excavation model that treated walls and edges of the scoop as retaining walls was used to calculate mean soil cohesions for several trenches in the Phoenix landing site workspace. These cohesions were found to be consistent with the stability of steep trench slopes. Cohesions varied from 0.2 ± 0.4kPa to 1.2 ± 1.8 kPa, with the exception of a subsurface platy horizon unique to a shallow trough for which cohesion will have to be determined using other methods. Soil on polygon mounds had the greatest cohesion (1.2 ± 1.8 kPa). This was most likely due to the presence of adsorbed water or pore ice above the shallow icy soil surface. Further evidence for enhanced cohesion above the ice table includes lateral increase in excavation force, by over 30 N, as the RA approached ice.