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At least 145 records · Page 8

Lunar Thermal Wadis and Exploration Rovers: Outpost Productivity and Participatory Exploration

The presentation introduces the concept of a thermal wadi, an engineered source of thermal energy that can be created using native material on the moon or elsewhere to store solar energy for use by various lunar surface assets to survive the extremely cold environment of the lunar night. A principal benefit of this approach to energy storage is the low mass requirement for transportation from Earth derived from the use of the lunar soil, or regolith, as the energy storage medium. The presentation includes a summary of the results of a feasibility study involving the numerical modeling of the performance of a thermal wadi including a manufactured thermal mass, a solar energy reflector, a nighttime thermal energy reflector and a lunar surface rover. The feasibility study shows that sufficient thermal energy can be stored using unconcentrated solar flux to keep a lunar surface rover sufficiently warm throughout a 354 hour lunar night at the lunar equator, and that similar approaches can be used to sustain surface assets during shorter dark periods that occur at the lunar poles. The presentation includes descriptions of a compact lunar rover concept that could be used to manufacture a thermal wadi and could alternatively be used to conduct a variety of high-value tasks on the lunar surface. Such rovers can be produced more easily because the capability for surviving the lunar night is offloaded to the thermal wadi infrastructure. The presentation also includes several concepts for operational scenarios that could be implemented on the moon using the thermal wadi and compact rover concepts in which multiple affordable rovers, operated by multiple terrestrial organizations, can conduct resource prospecting and human exploration site preparation tasks.

Sacksteder, Kurt↗

Positive-Buoyancy Rover for Under Ice Mobility

A buoyant rover has been developed to traverse the underside of ice-covered lakes and seas. The rover operates at the ice/water interface and permits direct observation and measurement of processes affecting freeze- over and thaw events in lake and marine environments. Operating along the 2- D ice-water interface simplifies many aspects of underwater exploration, especially when compared to submersibles, which have difficulty in station-keeping and precision mobility. The buoyant rover consists of an all aluminum body with two aluminum sawtooth wheels. The two independent body segments are sandwiched between four actuators that permit isolation of wheel movement from movement of the central tether spool. For normal operations, the wheels move while the tether spool feeds out line and the cameras on each segment maintain a user-controlled fixed position. Typically one camera targets the ice/water interface and one camera looks down to the lake floor to identify seep sources. Each wheel can be operated independently for precision turning and adjustments. The rover is controlled by a touch- tablet interface and wireless goggles enable real-time viewing of video streamed from the rover cameras. The buoyant rover was successfully deployed and tested during an October 2012 field campaign to investigate methane trapped in ice in lakes along the North Slope of Alaska.

Leichty, John M.↗

Development of the Resource Prospector Planetary Rover

The Resource Prospector (RP) is an In-­‐Situ Resource Utilization (ISRU) lunar rover mission under study by NASA. RP is planned to launch in 2020 to prospect for subsurface volatiles and to extract oxygen from lunar regolith. The mission will address several of NASA's "Strategic Knowledge Gaps" for lunar exploration. The mission will also address the Global Exploration Roadmap's strategic goal of using local resources for human exploration. The distribution of lunar subsurface volatiles drives the mission requirement for mobility. The spatial distribution is hypothesized to be governed by impact cratering with the top 0.5 m being patchy at scales of 100 m. The mixing time scale increases with depth (less frequent larger impacts). Consequently, increased mobility reduces the depth requirement for sampling. The target RP traverse will extend 1 km radially from the landing site to sample craters of varying sizes. Sampling craters with different ages will reveal possible volatile emplacement history. In 1 Ga, approximately 60-­70 craters of 10 m diameter form per km2. Thus, the rover will need to sample at least ten of these craters, which may require a total traverse path length of 2-­‐3 km. During 2014-­2015, we developed an initial prototype rover for RP. The current design is a solar powered, four-­wheeled vehicle, with hub motor drive, offset four wheel steering, and active suspension. Active suspension provides capabilities including changing vehicle ride height, traversing comparatively large obstacles, and controlling load on the wheels. All-­wheel steering enables the vehicle to point arbitrarily while roving, e.g., to keep the solar array pointed at the sun while in motion. The offset steering combined with active suspension improves driving in soft soil. The rover's on-­board software utilizes NASA's Core Flight Software, which is a reusable flight software environment. During 2015, we completed the initial rover software build, which provides low-­level hardware interfaces, basic mobility control, waypoint driving, odometry, basic error checking, and camera services. Development of the prototype rover has enabled maturation of many of the subsystems to TRL 5. During the next year, we will conduct integrated testing of concepts of operation, navigation, and remote driving tools. In addition, we will perform environmental tests including radiation (avionics), thermal and thermal/vacuum (mechanisms), and gravity offload (mobility).

robotics↗

Autonomous rover traverse and precise arm placement on remotely designated targets

Exploring planetary surfaces typically involves traversing challenging and unknown terrain and acquiring insitu measurements at designated locations using arm-mounted instruments. We present field results for a new implementation of an autonomous capability that enables a rover to traverse and precisely place an arm-mounted instrument on remote targets. Using point-and-click mouse commands, a scientist designates targets in the initial imagery acquired from the rover’s mast cameras. The rover then autonomously traverses the rocky terrain for a distance of 10 – 15 m, tracks the target(s) of interest during the traverse, positions itself for approaching the target, and then precisely places an arm-mounted instrument within 2-3 cm from the originally designated target. The rover proceeds to acquire science measurements with the instrument. This work advances what has been previously developed and integrated on the Mars Exploration Rovers by using algorithms that are capable of traversing more rock-dense terrains, enabling tight thread-the-needle maneuvers. We integrated these algorithms on the newly refurbished Athena Mars research rover and fielded them in the JPL Mars Yard. We conducted 43 runs with targets at distances ranging from 5 m to 15 m and achieved a success rate of 93% for placement of the instrument within 2-3 cm.

Volpe, Richard↗

Thermal design of the sample handling assembly in the sampling and caching subsystem on the Mars 2020 rover

The Mars 2020 Rover is scheduled to land on Mars on February 18, 2021. One of the primary mission objectives for the Mars 2020 Rover is to collect a set of Martian regolith samples for potential future return to Earth. Regolith and rock samples will be collected and placed into sample tubes using a coring drill, located at the end of a large Robotic Arm, on the outside of the rover. Filled sample tubes will be transferred from the outside of the Rover into the Adaptive Caching Assembly (ACA), located inside the Rover chassis, via the Bit Carousel. Once the filled sample tube is brought into the ACA, the Sample Handling Assembly (SHA) will transfer it to all of the internal processing stations of the ACA for volume assessment, sealing and finally drop-off on the Martian surface. The ACA is a volume within the rover chassis that is not temperature-controlled. Actuators inside the SHA and its End Effector (EE) must be warmed to above -55°C and -25°C, respectively, prior to use. This paper discusses the thermal design of the SHA that uses heaters and temperature sensors to warm up and maintain the temperature-sensitive arm components within temperature limits during operation. Thermal performance predictions for Mars surface operations are also presented.

Lee, Chern-Jiin↗

Navigation on the Line: Traversability Analysis and Path Planning for Extreme-Terrain Rappelling Rovers

Many areas of scientific interest in planetaryexploration, such as lunar pits, icy-moon crevasses, and Martiancraters, are inaccessible to current wheeled rovers. Rappellingrovers can safely traverse these steep surfaces, but requiretechniques to navigate their complex terrain. This dynamicnavigation is inherently time-critical and communication constraints(e.g. delays and small communication windows) willrequire planetary systems to have some autonomy.Autonomous navigation for Martian rovers is well studiedon moderately sloped and locally planar surfaces, but thesemethods do not readily transfer to tethered systems in nonplanar3D environments. Rappelling rovers in these situationshave additional challenges, including terrain-tether interactionand its effects on rover stability, path planning and control.This paper presents novel traversability analysis and pathplanning algorithms for rappelling rovers operating on steepterrains that account for terrain-tether interaction and theunique stability and reachability constraints of a rapellingsystem. The system is evaluated with a series of simulations andan analogue mission. In simulation, the planner was shown toreliably find safe paths down a 55 degree slope when a stabletether-terrain configuration exists and never recommended anunsafe path when one did not. In a planetary analogue mission,elements of the system were used to autonomously navigateAxel, a JPL rappelling rover, down a 30 degree slope with95% autonomy by distance travelled over 46 meters.

Nesnas, Issa↗

Multi-Mission Terrain Classifier for Safe Rover Navigation and Automated Science

We previously presented Soil Property and Object Classification (SPOC), a machine learning-based terrain classifier for Mars rovers, for automatically segmenting rover images by its surface type such as sand and bedrock. This paper presents a number of practical improvements to pave the way for potential future onboard deployment. First, we achieved 97.0% overall pixel accuracy, evaluated against the classification generated by human experts on images from Mars Science Laboratory (MSL) missions. The substantial increase in accuracy was primarily enabled by the sheer volume of data used for training; we created a new large-scale dataset of Martian terrain labels, namely AI4Mars, which contains more than 400k labels contributed by citizen scientists for 50k images taken by the Mars Exploration Rovers (MER) and Mars Science Laboratory (MSL) rover. Second, we demonstrated that SPOC can quickly adapt to a new mission landed on a previously unseen site. Specifically, we pretrained a model with MER and MSL data from the AI4Mars dataset and then adapted to the Mars 2020 Rover (M2020) by feeding a small volume of data between Sol 0 and 157; the adapted model was tested on Sol 200-203 and resulted in 84.2% overall pixel accuracy and 93.4% reliability (recall) for detecting sand, the most concerning class for rover’s traversability. Third, we found that pretraining can substantially mitigate the decline of accuracy over time. We showed that the performance of a SPOC model pretrained with the ImageNet dataset and then trained by MSL images only up to Sol 390 remains comparable to a model trained by images up to Sol 1689 on the test data after Sol 1689. Fourth, we reimplemented SPOC with a light-weight convolutional neural network (CNN), MobileNetV2, which typically runs within tens of milliseconds (ms) on mobile processors such as Qualcomm’s Snapdragon. Finally, we released the AI4Mars dataset to the public to encourage open innovation.

Ono, Masahiro↗

Perseverance Rover’s Robotic Arm and Turret Mounted Instruments’ Surface Commissioning

The Robotic Arm (RA) on the Perseverance rover is an integral component of the Sampling and Caching System necessary for completing the science goals of the Mars 2020 mission. While the Perseverance rover was based on the Curiosity rover which landed in 2012, the Robotic Arm was redesigned to carry a much larger turret with a new suite of payloads. Shortly after Perseverance landed in Jezero Crater, a series of checkouts was completed with the RA during the first 100 sols of the mission in order to ensure proper functionality of the RA and the instruments mounted on the turret. This period of time in the mission was called Surface Operations Transition (SOX). The objective of SOX was to systematically execute checkout activities for all the basic functionality so that the RA and instruments, as well as other rover components, could be released for scientific exploration.RA activities during SOX can be divided into a few different categories: Mechanism Checkouts, Rover Visual Inspections, Performance Characterization, and Instrument Functional Checkouts. Many of these checkouts built off of each other such that each subsequent activity would verify incrementally complex functionality. Many of the defined activities were executed several times throughout the development of the rover and served as a check that the RA’s performance is consistent with testing on Earth. Other activities were developed uniquely for SOX to respond to challenges discovered during development. They were designed to be verifiable without the help of ground support equipment or previous executions on the flight hardware to compare against.This paper discusses the formulation and conception of the various RA SOX checkout activities, verification and testing required to certify them for flight, execution of the activities on Mars, issues encountered, and finally results and findings as the mission transitioned to nominal science operations. We will be presenting the results and analysis using downlinked imaging and data from the flight vehicle to show how we verified the performance of the Robotic Arm and the turret mounted instruments in order to transition to science operations with a clean bill of health.

Edgett, Kenneth↗

The SuperCam remote sensing instrument suite for the Mars 2020 rover mission: A preview

We present that the SuperCam remote sensing instrument suite under development for the National Aeronautics and Space Administration’s (NASA) Mars 2020 rover performs laser-induced breakdown spectroscopy (LIBS), remote Raman spectroscopy, visible and infrared (VISIR) reflectance spectroscopy, acoustic sensing, and high-resolution color imaging. The instrument builds on the successful architecture of the ChemCam instrument, which provides LIBS and panchromatic images on the Curiosity rover, adding remote Raman spectroscopy by frequency doubling the laser and using a gated intensified detector to obtain Raman signals at distances to 12 m. To the visible reflectance spectroscopy used by ChemCam, an acousto-optic tunable filter (AOTF)-based IR spectrometer is added to cover the 1.3–2.6 µm range that contains important mineral signatures. A complementary metal-oxide semiconductor (CMOS) detector provides color (Bayer filter) images at a pixel resolution of 19 µrad and an optical resolution of 30 µrad. Sounds are recorded via a Knowles Electret microphone, which is the same one that was included but not used on two earlier missions. The acoustic signals of the LIBS plasmas will provide information on the hardness of the targets, while other sounds (wind, rover sounds) will also be recorded. The laser, telescope, IR spectrometer, and camera reside on the rover’s mast and are provided by the Centre national d’etudes spatiales (CNES), while the LIBS, Raman, and VIS spectrometers and data processing unit are built by Los Alamos National Laboratory (LANL) and reside in the rover body. A calibration target assembly provided by the University of Valladolid, Spain, resides on the back of the rover. Lastly, the overall mass of the instrument suite is 10.7 kg.

47 OTHER INSTRUMENTATION↗

The SuperCam Instrument Suite on the NASA Mars 2020 Rover: Body Unit and Combined System Tests

The SuperCam instrument suite provides the Mars 2020 rover, Perseverance, with a number of versatile remote-sensing techniques that can be used at long distance as well as within the robotic-arm workspace. These include laser-induced breakdown spectroscopy (LIBS), remote time-resolved Raman and luminescence spectroscopies, and visible and infrared (VISIR; separately referred to as VIS and IR) reflectance spectroscopy. A remote micro-imager (RMI) provides high-resolution color context imaging, and a microphone can be used as a stand-alone tool for environmental studies or to determine physical properties of rocks and soils from shock waves of laser-produced plasmas. SuperCam is built in three parts: The mast unit (MU), consisting of the laser, telescope, RMI, IR spectrometer, and associated electronics, is described in a companion paper. The on-board calibration targets are described in another companion paper. Here we describe SuperCam’s body unit (BU) and testing of the integrated instrument. The BU, mounted inside the rover body, receives light from the MU via a 5.8 m optical fiber. The light is split into three wavelength bands by a demultiplexer, and is routed via fiber bundles to three optical spectrometers, two of which (UV and violet; 245–340 and 385–465 nm) are crossed Czerny-Turner reflection spectrometers, nearly identical to their counterparts on ChemCam. The third is a high-efficiency transmission spectrometer containing an optical intensifier capable of gating exposures to 100 ns or longer, with variable delay times relative to the laser pulse. This spectrometer covers 535–853 nm ( $105\text{--}7070~\text{cm}^{-1}$ Raman shift relative to the 532 nm green laser beam) with $12~\text{cm}^{-1}$ full-width at half-maximum peak resolution in the Raman fingerprint region. The BU electronics boards interface with the rover and control the instrument, returning data to the rover. Thermal systems maintain a warm temperature during cruise to Mars to avoid contamination on the optics, and cool the detectors during operations on Mars.Results obtained with the integrated instrument demonstrate its capabilities for LIBS, for which a library of 332 standards was developed. Examples of Raman and VISIR spectroscopy are shown, demonstrating clear mineral identification with both techniques. Luminescence spectra demonstrate the utility of having both spectral and temporal dimensions. Finally, RMI and microphone tests on the rover demonstrate the capabilities of these subsystems as well.

47 OTHER INSTRUMENTATION↗

Targeting and Localization for Mars Rover Operations

In this work we discuss how the quality of localization knowledge impacts the remote operation of rovers on the surface of Mars. We look at the techniques of localization estimation used in the Mars Pathfinder and Mars Exploration Rover missions. We examine the motivation behind the modes of targeting for different types of activities, such as navigation, remote science, and in situ science. We discuss the virtues and shortcomings of existing approaches and new improvements in the latest operations tools used to support the Mars Exploration Rover missions and rover technology development tasks at the Jet Propulsion Laboratory. We conclude with future directions we plan to explore in improving the localization knowledge available for operations and more effective targeting of rovers and their instrument payloads.

remote rover operations↗

Supporting Increased Autonomy for a Mars Rover

This paper presents an architecture and a set of technology for performing autonomous science and commanding for a planetary rover. The MER rovers have outperformed all expectations by lasting over 1100 sols (or Martian days), which is an order of magnitude longer than their original mission goal. The longevity of these vehicles will have significant effects on future mission goals, such as objectives for the Mars Science Laboratory rover mission (scheduled to fly in 2009) and the Astrobiology Field Lab rover mission (scheduled to potentially fly in 2016). Common objectives for future rover missions to Mars include the handling of opportunistic science, long-range or multi-sol driving, and onboard fault diagnosis and recovery. To handle these goals, a number of new technologies have been developed and integrated as part of the CLARAty architecture. CLARAty is a unified and reusable robotic architecture that was designed to simplify the integration, testing and maturation of robotic technologies for future missions. This paper focuses on technology comprising the CLARAty Decision Layer, which was designed to support and validate high-level autonomy technologies, such as automated planning and scheduling and onboard data analysis.

autonomous science↗

Using Very Small Rovers to Explore the Surface of Primitive Bodies

This slide presentation reviews the use of very small roving vehicles to assist in exploration of various primitive bodies in the Solar System. It reviews the lessons learned from the mobility of the rovers on Mars, and the importance of the what we learned from these rovers. It also examines the core payload for the what would be a new class of rovers, that include a camera, and spectrometer. It also briefly reviews the MUSES-C (i.e., Hyabusa) mission for which a nano-rover had been planned. A prototype of the rover is shown, along with some of the characteristics.

Muses-C↗

Arusha Rover Deployable Medical Workstation

The NSBE Arusha rover concept offers a means of human transport and habitation during long-term exploration missions on the moon. This conceptual rover calls for the availability of medical supplies and equipment for crew members in order to aid in mission success. This paper addresses the need for a dedicated medical work station aboard the Arusha rover. The project team investigated multiple options for implementing a feasible deployable station to address both the medical and workstation layout needs of the rover and crew. Based on layout specifications and medical workstation requirements, the team has proposed a deployable workstation concept that can be accommodated within the volumetric constraints of the Arusha rover spacecraft

Rover↗

The Effects of Clock Drift on the Mars Exploration Rovers

All clocks drift by some amount, and the mission clock on the Mars Exploration Rovers (MER) is no exception. The mission clock on both MER rovers drifted significantly since the rovers were launched, and it is still drifting on the Opportunity rover. The drift rate is temperature dependent. Clock drift causes problems for onboard behaviors and spacecraft operations, such as attitude estimation, driving, operation of the robotic arm, pointing for imaging, power analysis, and telecom analysis. The MER operations team has techniques to deal with some of these problems. There are a few techniques for reducing and eliminating the clock drift, but each has drawbacks. This paper presents an explanation of what is meant by clock drift on the rovers, its relationship to temperature, how we measure it, what problems it causes, how we deal with those problems, and techniques for reducing the drift.

rovers↗

In-Field Whole-Plant Maize Architecture Characterized by Subcanopy Rovers and Latent Space Phenotyping

Core Ideas * Subcanopy rovers enabled 3D characterization of thousands of hybrid maize plots. * Machine learning produces heritable latent traits that describe plant architecture. * Rover-based phenotyping is far more efficient than manual phenotyping. * Latent phenotypes from rovers are ready for application to plant biology and breeding. Collecting useful, interpretable, and biologically relevant phenotypes in a resource-efficient manner is a bottleneck to plant breeding, genetic mapping, and genomic prediction. Autonomous and affordable subcanopy rovers are an efficient and scalable way to generate sensor-based datasets of in-field crop plants. Rovers equipped with lidar can produce three-dimensional reconstructions of entire hybrid maize (Zea mays L.) fields. In this study, we collected 2103 lidar scans of hybrid maize field plots and extracted phenotypic data from them by latent space phenotyping. We performed latent space phenotyping by two methods, principal component analysis and a convolutional autoencoder, to extract meaningful, quantitative latent space phenotypes (LSPs) describing whole-plant architecture and biomass distribution. The LSPs had heritabilities of up to 0.44, similar to some manually measured traits, indicating that they can be selected on or genetically mapped. Manually measured traits can be successfully predicted by using LSPs as explanatory variables in partial least squares regression, indicating that the LSPs contain biologically relevant information about plant architecture. These techniques can be used to assess crop architecture at a reduced cost and in an automated fashion for breeding, research, or extension purposes, as well as to create or inform crop growth models.

59 BASIC BIOLOGICAL SCIENCES↗

Viking '79 Rover study. Volume 1: Summary report

The results of a study to define a roving vehicle suitable for inclusion in a 1979 Viking mission to Mars are presented. The study focused exclusively on the 1979 mission incorporating a rover that would be stowed on and deployed from a modified Viking lander. The overall objective of the study was to define a baseline rover, the lander/rover interfaces, a mission operations concept, and a rover development program compatible with the 1979 launch opportunity. During the study, numerous options at the rover system and subsystem levels were examined and a baseline configuration was selected. Launch vehicle, orbiter, and lander performance capabilities were examined to ensure that the baseline rover could be transported to Mars using minimum-modified Viking '75 hardware and designs.

Source record↗

A Mars orbital laser altimeter for rover trafficability: Instrument concept and science potential

Limited information on the types of geologic hazards (boulders, troughs, craters etc.) that will affect rover trafficability on Mars are available for the two Viking Lander sites, and there are no prospects for increasing this knowledge base in the near future. None of the instrument payloads on the upcoming Mars Observer or Soviet PHOBOS missions can directly measure surface obstacles on the scales of concern for rover safety (a few meters). Candidate instruments for the Soviet Mars 92 orbiter/balloon/rover mission such as balloon-borne stereo imaging, rover panoramic imaging, and orbital synthetic aperature imaging (SAR) are under discussion, but data from this mission may not be available for target areas of interest for the U.S. Mars Rover Sample Return (MRSR) mission. In an effort to determine how to directly measure the topography of surface obstacles that could affect rover trafficability on Mars, we are studying how to design a laser altimeter with extremely high spatial and vertical resolution that would be suitable for a future Mars Orbiter spacecraft (MRSR precursor or MRSR orbiter). This report discusses some of the design issues associated with such an instrument, gives examples of laser altimeter data collected for Mars analog terrains on Earth, and outlines the scientific potential of data that could be obtained with the system.

Garvin, J. B.↗