Planetary Surface Exploration Research Articles

LIBS for prospecting and Raman spectroscopy for monitoring: two feasibility studies for supporting in-situ resource utilization

Laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy are still rather new techniques for in-situ exploration of extraterrestrial planetary surfaces but have shown their suitability and great potential in several successful robotic missions already. Next to serving primary scientific applications, both methods can also be used in the context of in-situ resource utilization (ISRU) such as scouting for wanted substances and the surveillance of extraction processes. Here, we present two laboratory studies conducted in the context of ISRU with a focus on the chain from prospecting to extracting oxygen from lunar regolith. For LIBS, with optimized data processing and combined with state-of-the-art multivariate data analysis approaches, we show the potential of the technique for identifying samples with increased ilmenite content and for elemental quantification. The measurements were done using lunar regolith simulant and low pressures simulating vacuum on atmosphereless bodies such as the Moon. With Raman spectroscopy, we analyzed lunar regolith simulant samples that underwent electrochemical alteration for oxygen extraction and production of metal alloys demonstrating the potential of Raman spectroscopy for ISRU process monitoring. We also discuss the results in a broader context, evaluating the potential of both methods for other aspects of ISRU support.

A novel digital intermediate frequency module for hyperspectral microwave radiometers based on the parallel fast Fourier transform algorithm.

Microwave radiometers, possessing all-day and all-weather operational capabilities, are extensively utilized in the exploration of planetary atmospheres and surfaces. The potential of the hyperspectral detection technology to enhance the precision and resolution of microwave radiometer detection has made it a crucial research focus. This paper introduces an intermediate frequency (IF) module for hyperspectral microwave radiometers. The IF module is constructed with two 6.4 gigabit samples per second sampling-rate analog-to-digital converter (ADC) chips and a Xilinx Virtex-7 field programmable gate array. By implementing a parallel fast Fourier transform algorithm and a pipeline architecture, the IF module can efficiently process all ADC sampling data in real-time, generating 512 channels of output for each ADC. The test results, including linearity, sensitivity, and flatness, are presented and thoroughly analyzed for the IF module. Furthermore, the module is interfaced with the radio frequency front-end of the microwave radiometer to measure hot and cold calibration sources and assess its sensitivity. When combined with a suitable front-end receiver, the IF module can form a radiometer system suitable for various applications of microwave remote sensing.

Permittivity sensor development for lunar and planetary surface exploration

Permittivity sensors measure the electric permittivity (formerly known as the dielectric constant) of a sample between its electrodes and offer a reliable method to characterize the subsurface of planetary bodies in situ. One potential application is the identification and mapping of water ice at the poles of the Moon. In this paper, the scientific background and heritage of the permittivity sensor concept are discussed, and the implemented electronic architecture is introduced, focusing on the novel patch electrodes. The data processing approach for the measurements is based on Fourier transformation, and numerical simulation setups are used for performance predictions. The calibration of the sensor validates the functionality of the electronics, and the results from both simulations and characterization experiments show that the concept is applicable in the exploration scenario. Considering both engineering and scientific aspects, the results highlight the permittivity sensor’s suitability for lunar and planetary exploration missions, albeit further points for improvement are identified.

Study of passive steering mechanism for small Mars surface exploration rovers

Planetary surface exploration rovers are required to have the ability to travel over uneven ground such as sandy or rocky terrain. In addition, to maintain long-term functionality under severe mass constraints, the rover must be highly reliable with a simple configuration. The reduction in the number of actuators will also contribute to a reduction in the number of electrical components involved and improve reliability. This paper proposes a lightweight and simple traveling and steering mechanism that combines a path-following system based on the difference in rotational speed of the left and right wheels when traveling in a curve and a passive Ackermann mechanism without an actuator, assuming a small exploration rover of a size and mass that can be mounted on a Japanese launch vehicle. We also propose a correction method to improve the path-following performance. We also developed a prototype wheeled rover of the target size and weight, and tested and evaluated the effectiveness of the proposed method in following the target path and overcoming obstacle on simulated soil.

AOR: Adaptive opportunistic routing based on reinforcement learning for planetary surface exploration

Planetary surface exploration mobile ad-hoc networks (PSEMANET) show the characteristics of routing void caused by craters and electromagnetic interference, relatively high dynamics caused by node heterogeneity, and small node capacity caused by load constraints, which is the reason for the increase of communication delay and packet loss. Adaptive opportunistic routing based on reinforcement learning (AOR) is an opportunistic routing protocol that determines the forwarding node based on the current coordinates, queue length, and the number of neighbors. The full forwarding areas are used to avoid routing void, and the dual competition mechanism is designed to avoid the node hidden problem. The Q-value obtained by reinforcement learning is used to design the dynamic delay cost (DDC) so that nodes in the forwarding areas can compete to achieve adaptive path switching to the environment. Compared with representative proactive routing OLSR, reactive routing AODV, geographic routing GPSR and opportunistic routing BLR, AOR and AOR with memory(AOR-M) have high packet delivery ratio (PDR) and low end-to-end delay in planetary surface exploration scenarios implemented by our simulation system. And the AOR-M protocol shows the lowest expected end-to-end delay and highest channel utilization in both high and low speed scenarios. The result shows that the AOR-M provides efficient and robust routing in planetary surface exploration mobile ad-hoc networks with a complex environment, highly dynamic nodes, and performance constraints.

Nonparametric estimation for planetary soil based on numerical simulation of penetration process

Penetration detection is an important method for in-situ scientific exploration of planetary surfaces, and is used to indirectly detect the mechanical properties of planetary subsurface soil. In this study, four ogive-nosed penetrators with different radii were simulated to penetrate planetary soil of varying compactness under different impact velocities using a nonlinear finite element (FE) method based on HyperMesh/LS-DYNA. A nonparametric estimation method was proposed through analysis of the corresponding results. Three main characteristic parameters in the penetration process were adopted in the method: maximum deceleration am, penetration depth z, and trajectory deviation xp. Twenty parameters for identifying planetary soil properties were derived based on these three characteristic parameters. The terrain consisted of simulant soil classified non-parametrically and artificially defined as three states (low, medium, and high compactness) based on different harnesses, and five estimation criteria (slack, ideal, partially strict, relatively strict, and strict) were proposed. Three identification parameters were derived through the analysis of the evaluation indices (identification rate ηi, accurate rate ηa, and conservative rate ηc) under different estimation criteria. am2xp2 was selected as the optimal identification parameter and the superior estimation criterion is the ideal criterion. The verification results of simulation tests show that the accurate success rate and conservative success rate of the final evaluation are 60% and 80%, respectively, indicating that the nonparametric estimation method in this study can be used to estimate the mechanical properties of planetary soil effectively.

Pioneers project: Looking inside planetary interiors

Pioneers project: Looking inside planetary interiors PIONEERS European project develops the next generation of instruments that will reveal planetary interiors, explains Professor Raphael F. Garcia from ISAE-SUPAERO. After decades of exploration of planetary surfaces, our knowledge of planetary interiors and internal structures remains very limited. However, the structure of a planetary body tells us a lot about how it formed and evolved during the last 4.5 billion years. It is critical to understand our solar system to know better the thousands of planets orbiting other stars in our galaxy. Are these planets water-rich? for how long? Can these sustain life? Even at the scale of our solar system these questions are not fully solved because the clues to their answers are hidden deep inside our nearby planets, their moons, and asteroid bodies. Even if all these objects formed from the same materials that formed our Sun, the hazard of accretion generated very different objects evolving differently.

Special spherical mobile robot for planetary surface exploration: A review

Considering the requirements of high scientific return, low cost, less complexity, and more reliability for the robot proposed by the extreme environment exploration task on the planet surface, this article comprehensively reviews the history of the special spherical robot used for extraterrestrial surface exploration and summarizes the environmental characteristics and task difficulties of different planet surface. This article compares the advantages of different types of ground spherical robots and points out the superiority of special spherical robots, such as omni-direction, airtightness, zero-radius turning, under-actuated, swarming, and lightweight. In addition, the research progress of special spherical robots for extraterrestrial exploration, such as wind ball, jumping ball, fly ball, ball with leg, pendulum driven ball, tensegrity structure, are reviewed respectively. Finally, the performance characteristics of all these robots are analyzed, their application scope given.

Bionic Design of Multi-Toe Quadruped Robot for Planetary Surface Exploration

To increase the knowledge and exploit new resources beyond the Earth, planetary surface exploration on the Moon or Mars attracts significant attention around the globe. Due to the fact that these planetary surfaces are widely covered by soil-like materials, various structures of planetary rovers have been proposed to adapt to the terrains. Nonetheless, the traditional rover structures, such as wheeled and leg-wheeled, have shown limitations in moving on granular soils. To improve the mobility, this paper proposes a multi-toe quadruped robot inspired by the desert chameleon animal. The key features are that each bionic foot possesses four toes to stabilize them on granular materials. Moreover, a bionic flexible spine is designed to coordinate with walking and turning gaits and to make the robot approach an animal-like mobility. To assess the robot performances, kinematics analysis and analytical modeling of foot, leg, and spine movements are carried out. The results demonstrate that this robot can effectively walk and turn in accordance with the adopted gaits. Finally, field tests of moving over sands have been conducted. It shows that the robot can stably walk and turn on sands, which indicates that it is adaptable to planetary granular terrains.

A new concept of acousto-optic tunable filter-based near-infrared hyperspectral imager for planetary surface exploration.

In the past two decades, near-infrared (NIR) hyperspectral imaging instruments have revolutionized our conception of planetary surfaces in terms of evolution, geology, mineralogy, and alteration processes. The cornerstone of this remote analysis technique is the synergy between imagery, giving the geomorphological context of the observations, and NIR spectroscopy whose spectral range is sensitive to the main absorption features of most of the minerals present on planetary surfaces. The development of a generation of space instrument based on Acousto-Optic Tunable Filters (AOTFs) increases the capacity of these spectrometers to be set up in a variety of space probes. The ExoCam concept, developed at Institut d'Astrophysique Spatiale and profiting from the lab's previous experience (MicrOmega onboard Phobos-Grunt, Hayabusa 2 and ExoMars), thus, proposes for the first time to do hyperspectral imagery through a wide aperture AOTF (15 × 15 mm2) in the 0.95-3.6 µm spectral range. The characterization of this instrumental concept, led on a representative breadboard built for this purpose, showed that the acousto-optic diffraction preserves the image quality up to the diffraction/resolution limit over the whole field of view. The spectral resolution (from 2 to 25 nm over the spectral range) and accuracy of the instrument are also consistent with the identification of planetary surface minerals. This paper describes the ExoCam concept and objectives, the setup of an optical breadboard representative of a space instrument based on this concept, and the results of performance characterizations realized on the breadboard.

Optimal Planetary Surface Routing Considering Exploration Values and Synergies

This paper proposes a new routing problem that can handle the synergy of exploring multiple sites for planetary surface exploration planning. The new problem aims to maximize the sum of profits (e.g., scientific information) obtainable by visiting a subset of candidate sites with given resource constraints (e.g., time and fuel) while considering the synergy (both positive and negative) from visiting two or more related sites. A mathematical formulation for this new problem referred to as the vehicle routing problem with profits considering synergy is developed. A special formulation for the problem considering the synergy only within a single route, referred to as the vehicle routing problem with profits considering single-route synergy, is also investigated. Column-generation-based procedures to find near-optimal solutions and corresponding optimality gaps for these problems are presented. The effectiveness of the proposed problem formulations and solution procedures are demonstrated through numerical experiments.

Hopping path planning in uncertain environments for planetary explorations

Hopping robots, called hoppers, are expected to move on rough terrains, such as disaster areas or planetary environments. The uncertainties of the hopping locomotion in such environments are high, making path planning algorithms essential to traverse these uncertain environments. Planetary surface exploration requires to generate a path which minimises the risk of failure and maximises the information around the hopper. This paper newly proposes a hopping path planning algorithm for rough terrains locomotion. The proposed algorithm takes into account the motion uncertainties using Markov decision processes (MDPs), and generates paths corresponding to the terrain conditions, or the mission requirements, or both. The simulation results show the effectiveness of the proposed route planning scheme in three cases as the rough terrain, sandy and hard ground environment, and non-smooth borders.

Development of a New Pressure-Sinkage Model for Rover Wheel-Lunar Soil Interaction based on Dimensional Analysis and Bevameter Tests

A rover is a planetary surface exploration device designed to move across the ground on a planet or a planetary-like body. Exploration rovers are increasingly becoming a vital part of the search for scientific evidence and discoveries on a planetary satellite of the Sun, such as the Moon or Mars. Reliable behavior and predictable locomotion of a rover is important. Understanding soil behavior and its interaction with rover wheels—the terramechanics—is of great importance in rover exploration performance. Up to now, many researchers have adopted Bekker’s semiempirical model to predict rover wheelsoil interaction, which is based on the assumption that soil is deformable when a pressure is applied to it. Despite this basic assumption of the model, the pressure-sinkage relation is not fully understood, and it continues to present challenges for rover designers. This article presents a new pressure-sinkage model based on dimensional analysis (DA) and results of bevameter tests. DA was applied to the test results in order to propose a new pressure-sinkage model by reducing physical quantitative parameters. As part of the work, a new bevameter was designed and built so that it could be successfully used to obtain a proper pressure-sinkage relation of Korean Lunar Soil Simulant (KLS-1). The new pressure-sinkage model was constructed by using three different sizes of flat plate diameters of the bevameter. The newly proposed model was compared successfully with other models for validation purposes.

Spatiotemporal characterization of the laser-induced plasma plume in simulated Martian conditions

With ChemCam on NASA's Curiosity rover, SuperCam on NASA's Perseverance rover, and MarSCoDe on the Zhurong rover of the China National Space Administration, there are currently three instruments on Mars that employ laser-induced breakdown spectroscopy (LIBS) to analyze the chemical composition of Martian rocks and soils. With more than 880,000 LIBS measurements on Mars by ChemCam alone, the LIBS technique has been proven to be uniquely qualified for the in-situ robotic exploration of planetary surfaces. Since the laser-induced plasma exhibits a complex spatiotemporal evolution that has a significant impact on the recorded LIBS spectra, fundamental investigations of the plasma propagation and the spatial distributions of the plasma emissions can provide important insight that can help to improve the analysis of Martian LIBS spectra. Here we present first results from our LIBS plasma imaging setup, which allows us to spatially and temporally resolve the spectral emissions from the laser-induced plasma in simulated Martian atmospheric conditions. Investigating a calcium sulfate sample, we find that the commonly applied assumption of a nearly isothermal and homogeneous plasma with a colder outer layer is not sufficient to describe the laser-induced plasma on Mars. Instead, different spectral features show unique spatial distributions that suggest a strong influence of the outgoing shock wave. After plasma formation, the plasma center is found to rapidly become colder and more rarefied than the outer plasma regions. Molecular emissions are found to originate in this cold plasma center.

Intermittent short-arm centrifugation is a partially effective countermeasure against upright balance deterioration following 60-day head-down tilt bed rest.

This study investigated whether artificial gravity (AG), induced by short-radius centrifugation, mitigated deterioration in standing balance and anticipatory postural adjustments (APAs) of trunk muscles following 60-day head-down tilt bed rest. Twenty-four participants were allocated to one of three groups: control group (n = 8); 30-min continuous AG daily (n = 8); and intermittent 6 × 5 min AG daily (n = 8). Before and immediately after bed rest, standing balance was assessed in four conditions: eyes open and closed on both stable and foam surfaces. Measures including sway path, root mean square, and peak sway velocity, sway area, sway frequency power, and sway density curve were extracted from the center of pressure displacement. APAs were assessed during rapid arm movements using intramuscular or surface electromyography electrodes of the rectus abdominis; obliquus externus and internus abdominis; transversus abdominis; erector spinae at L1, L2, L3, and L4 vertebral levels; and deep lumbar multifidus muscles. The relative latency between the EMG onset of the deltoid and each of the trunk muscles was calculated. All three groups had poorer balance performance in most of the parameters (all P < 0.05) and delayed APAs of the trunk muscles following bed rest (all P < 0.05). Sway path and sway velocity were deteriorated, and sway frequency power was less in those who received intermittent AG than in the control group (all P < 0.05), particularly in conditions with reduced proprioceptive feedback. These data highlight the potential of intermittent AG to mitigate deterioration of some aspects of postural control induced by gravitational unloading, but no protective effects on trunk muscle responses were observed.NEW & NOTEWORTHY This study presents novel insights into the effect of artificial gravity (AG) on the deterioration of standing balance and anticipatory postural adjustments (APAs) of trunk muscles induced by 60-day strict head-down bed rest. The results indicated severe balance dysfunction and delayed APAs during rapid arm movement. AG partially mitigated the deterioration in standing balance and may thus be considered as a potential countermeasure for future planetary surface explorations. Optimization of AG protocols might enhance effects.

Model-Based Slippage Estimation to Enhance Planetary Rover Localization with Wheel Odometry

The exploration of planetary surfaces with unmanned wheeled vehicles will require sophisticated software for guidance, navigation and control. Future missions will be designed to study harsh environments that are characterized by rough terrains and extreme conditions. An accurate knowledge of the trajectory of planetary rovers is fundamental to accomplish the scientific goals of these missions. This paper presents a method to improve rover localization through the processing of wheel odometry (WO) and inertial measurement unit (IMU) data only. By accurately defining the dynamic model of both a rover’s wheels and the terrain, we provide a model-based estimate of the wheel slippage to correct the WO measurements. Numerical simulations are carried out to better understand the evolution of the rover’s trajectory across different terrain types and to determine the benefits of the proposed WO correction method.

Planetary Surface Mobility and Exploration: A Review

Planetary Surface Mobility and Exploration: A Review

Unmanned Six-Wheels Bogie Rover with Robotic Arm for Surveillance and Fixing Objects

Wheeled mobile robots’ utilization is increased rapidly and in dangerous situation such as planetary surface exploration. This paper provides a manner to construct a mobile controlled six-wheels Rover with robotic arm and camera which can stream video over internet. This project is controlled by blynk custom designed mobile application. With robotic arm can collect samples from the affected area.

Remote science activities during the AMADEE-18 Mars analog mission: Preparation and execution during a simulated planetary surface mission

In preparation for future human-robotic exploration missions to Mars, the interaction between the in-situ Field Crews and a Remote Science Support (RSS) team on Earth is key. Human robotic exploration missions will experience communication delays, reduced bandwidth, limited availability of astronauts and robotic assets. This, in turn, elucidates the necessity for relatively autonomous frameworks such as robust protocols and comprehensive decision-making workflows. The AMADEE-18 analog mission in Oman simulated selected components of human planetary surface exploration, emphasizing the overall workflow integrating operational constraints with exploration-science related needs. In this work, we outline the operational objectives, processes, and lessons learned corresponding to the interaction between the remote science team and the mission's associated stakeholders. We have taken the lessons learned from past simulated missions and the training procedures established by OeWF (Austrian Space Forum), from which we were able to rigorously evaluate the role of the RSS team in the AMADEE-18 mission. We have analyzed the integration of a WorkFlow and Exploration Cascade within the context of the RSS in-depth, which cumulatively allowed for the successful deployment of Extravehicular activities during the mission. We found that a serial node work distribution of the remote science team was optimal for the success of integral tasks . Moreover, we implemented various modes of communication and found that Slack was the most effective and robust. The AMADEE-18 mission, along with its predecessors, forms part of a continuously developing body of research serving to inform and improve future human planetary exploration.

Toward Better Planetary Surface Exploration by Orbital Imagery Inpainting

Planetary surface images are collected by sophisticated imaging devices onboard the orbiting spacecraft. Although these images enable scientists to discover and visualize the unknown, they often suffer from the `no-data' region because the data could not be acquired by the onboard instrument due to the limitation in operation time of the instrument and satellite orbiter control. This greatly reduces the usability of the captured data for scientific purposes. To alleviate this problem, in this article, we propose a machine learning-based `no-data' region prediction algorithm. Specifically, we leverage a deep convolutional neural network (CNN) based image inpainting algorithm to predict such unphotographed pixels in a context-aware fashion using adversarial learning on planetary images. The benefit of using our proposed method is to augment features in the unphotographed regions leading to better downstream tasks such as interesting landmark classification. We use the Moon and Mars orbital images captured by the JAXA's Kaguya mission and NASA's Mars Reconnaissance Orbiter (MRO) for experimental purposes and demonstrate that our method can fill in the unphotographed regions on the Moon and Mars images with good visual and perceptual quality as measured by improved PSNR and SSIM scores. Additionally, our image inpainting algorithm helps in improved feature learning for CNN-based landmark classification as evidenced by an improved F1-score of 0.88 compared to 0.83 on the original Mars dataset.COMP: Please replace colons appearing after figure numbers and table numbers with period in all figure and table captions.