Close-Up Imager Research Articles

Identifying optimal working conditions for close-up imagining during the ExoMars rover mission

A Close-Up Imager named CLUPI is one of the instruments that will be onboard the Rosalind Franklin rover, a robot that will explore the surface of Mars in the framework of the ESA/Roscosmos ExoMars mission. CLUPI will be principally used for acquiring close-up images of rock textures and sedimentary structures, identifying materials that may record information about the hypothetical existence of past microbial life. Although the technical specifications of CLUPI are well known, it is not possible to readily translate such specifications in terms of feasibility to recognize “textures of interest” at a given distance under specific light conditions on Mars. Accurate predictions are important for making fast and informed decisions during the daily tactical planning of the rover. Here, we describe the results of some mission-preparation activities, during which a commercial camera that allows for producing images analogue to those of CLUPI has been used to photograph rock samples in an indoor facility (i.e., the Marslabor of the University of Basel) that has been built ad hoc for simulating a Martian landscape. By varying the working distance and light conditions it has been possible to perform a preliminary assessment of the minimal-working-distance required for interpreting rock textures and sedimentary structures that are potentially present on Mars, including textures that allow for differentiating sedimentary rocks from igneous rocks, grains that allow for classifying sedimentary rocks based on their granulometry, and stromatolitic laminations representing morphological biosignatures. In general, the results suggest that rock textures tend to be recognizable even from distances that exceed those one would predict based on the resolution of the instrument and the size of the structure or particles that defines the rock texture or sedimentary structure. We also show that the angle between the illumination axis (i.e., the direction of incident light) and the target surface plays a significant role for the recognition of textural and compositional heterogeneities within the acquired images. The produced data represents a first step in identifying ideal CLUPI working-distances and illumination, and in preparing an image database that will be of help for optimizing rover operations and the scientific return of CLUPI during the ExoMars mission.

Multiscale spectral discrimination of poorly crystalline and intermixed alteration phases using aerial and ground-based ExoMars rover emulator data

A key goal of the ExoMars rover Rosalind Franklin is to analyze accessible hydrated mineral deposits using panoramic multiscale and multispectral imagery. We conducted a multiscale spectroscopic study on hydrothermally-altered basalt-hosted soils in the geothermal area of Námafjall in northern Iceland. Basaltic lavas here that have experienced first-order geochemical alteration produce a variety of cm-to-meter scale poorly crystalline alteration patterns. The resulting unconsolidated sediments provide a natural analogue material to investigate intimately mixed soils comprising multiple poorly crystalline hydrated phases. We use emulator instruments which replicate the capabilities of the ExoMars 2022 Panoramic Camera (PanCam), the Infrared Spectrometer for ExoMars (ISEM), and the CLose-UP Imager (CLUPI), alongside Raman, aerial, and X-Ray Fluorescence spectroscopic data to investigate how the detection of these mixed basalt-derived alteration phases varies as a function of spatial and spectral scale. We find soils at our study site to be comprised of unconsolidated sediments including Al-OH minerals, hydrated silica, and a variety of ferric oxides, all of which Rosalind Franklin will likely encounter along its traverse at Oxia Planum. We report on (i) the synergy and limitations between Mars rover instrument emulators as an integral part of mission preparation, (ii) how the mixed nature of these hydrothermally-altered soils affects resulting mineralogical interpretations at multiple scales, and (iii) geochemical inferences that can be made using ExoMars 2022 imaging emulators.

Multiscale and Multispectral Characterization of Mineralogy with the ExoMars 2022 Rover Remote Sensing Payload

AbstractIn 2022, the European Space Agency and Roscosmos will launch the ExoMars rover, with the scientific objective to detect evidence of life within the Martian surface via the deployment of a 2 m drill. The ExoMars Pasteur payload contains several imaging and spectroscopic instruments key to this objective: the Panoramic Camera (PanCam), Infrared Spectrometer for ExoMars (ISEM), and Close‐UP Imager (CLUPI). These instruments are able to collect data at a variety of spatial (sub‐mm to decimeter) and spectral (3.3 to 120 nm) resolutions across the 440 to 3,300 nm wavelength range and collectively will form a picture of the geological and morphological characteristics of the surface terrain surrounding the rover. We deployed emulators of this instrument suite at terrestrial analog sites that formed in a range of aqueous environments to test their ability to detect and characterize science targets. We find that the emulator suite is able to effectively detect, characterize, and refine the compositions of multiple targets at working distances spanning from 2 to 18 m. We report on (a) the detection of hydrothermal alteration minerals including Fe‐smectites and gypsum from basaltic substrates, (b) the detection of late‐stage diagenetic gypsum veins embedded in exposures of sedimentary mudstone, (c) multispectral evidence of compositional differences detected from fossiliferous mudstones, and (d) approaches to cross‐referencing multi‐scale and multi‐resolution data. These findings aid in the development of data products and analysis toolkits in advance of the ExoMars rover mission.

Geological appraisals of core samples using the ExoMars 2020 rover instrumentation

The ExoMars 2020 mission will characterise a Martian locality with potential former habitability – Oxia Planum – and attempt to identify preserved morphological and chemical biosignatures. The payload will include a drill retrieving cores from the subsurface (up to 2 m depth), which will be imaged at high resolution by two instruments: the Panoramic Camera High Resolution Camera (PanCam HRC) and CLose UP Imager (CLUPI). These instruments will provide guiding interpretation and govern the approach used by the analytical instruments, which will conduct their analyses after crushing of the core sample. Blind tests using Mars-analogue lithological samples provide valuable mission training in terms of maximising scientific return. Previous blind tests evaluating the abilities of the ExoMars 2020 payload to conduct geological approaches used solid rock hand samples as test specimens. Here, we prepared test samples of ExoMars mission-equivalent shapes and dimensions (3 × 1 cm cores) to evaluate the extent of geological interpretation possible using only the images of the core that will obtained during the mission. In the worst-case scenario, core samples will be different from outcrop rock and these images and associated organogeochemical analyses on crushed powders by the other rover instruments will be the sole basis for their interpretation. Imaging these samples using mission-equivalent original resolutions to avoid image processing artefacts, we found that the difficulty inherent in making definitive geological conclusions using traditional ‘field petrography’ approaches is increased when only limited amounts of core sample are available for observation. Challenges involved in the interpretation of core samples include representativeness problems inherent to small samples, distinction between layer-specific characteristics at the sub-centimetre to centimetre scale, and mechanical effects, such as drill marks and dust covering. These issues vary depending upon the rock type and change as a function of the mechanical properties (and thus composition) of the sample. Despite these challenges, we find that CLUPI and PanCam HRC images alone allow many accurate and detailed geological observations; however, confidence and detail of interpretation are notably increased when additional geochemical data are provided, in this case, Raman spectra reflecting the contribution of the Raman Laser Spectrometer (RLS) instrument. Our results argue for the importance of detailed core imaging during the experimental phase of the rover mission despite the challenges involved in interpretation, since HRC and CLUPI images offer a degree of synergy. Inter-instrumental collaboration will be essential during the ExoMars 2020 rover mission (and indeed in any rover mission), since no single payload instrument is able to perform a comprehensive assessment of a putative biosignature within its geological context, and since the instrument suite provides highly complementary data at multiple scales that are key to maximising scientific return.

Mars-Relevant Field Experiences in Morocco: The Importance of Spatial Scales and Subsurface Exploration.

During field work at the Ibn Battuta Mars analogue sites, two research questions were analyzed: (1) How do we identify sampling sites using remote and local imaging and (2) what kind of information can be gained from shallow subsurface exploration? While remote images help in targeting field activities in general, the connection between observations at different spatial scales for different rocky desert terrain types is not well established; in this, focused comparison of remote in situ images of well-selected analogues would help a great deal. Dried up lake beds as discerned in remotely acquired data may not show signatures of past water activity, while shallow subsurface exploration could reveal the lacustrine period. Acquisition of several satellite images of the same terrain under different geometries would help to support the planning of such in situ work. The selection of appropriate sampling sites in fluvial settings could be improved by analyzing long, meter-high, open-air outcrops that formed during most recent fluvial episodes. Such settings are abundant on Earth and could be present on Mars but may be just below the resolution of available data. By using 20-30-cm-deep excavations, shallow subsurface exploration could reveal the last period of geological history that would have been unattainable by surface observation alone. Aggregates embedded in the original strata or from heavily pulverized samples could not be identified; only weakly fragmented samples viewed right after acquisition showed aggregates, and thus, the Close-Up Imager (CLUPI) on the ExoMover might provide information on cementation-related aggregation on the observing plate before crushing. The mechanical separation of different size grains (mainly clays and attached minerals) would also support the identification of individual components. To maximize context information during subsurface exploration, rover imaging should be accomplished before crushing; however, currently planned imaging may not be ideal for this.

Subsurface scientific exploration of extraterrestrial environments (MINAR 5): analogue science, technology and education in the Boulby Mine, UK

AbstractThe deep subsurface of other planetary bodies is of special interest for robotic and human exploration. The subsurface provides access to planetary interior processes, thus yielding insights into planetary formation and evolution. On Mars, the subsurface might harbour the most habitable conditions. In the context of human exploration, the subsurface can provide refugia for habitation from extreme surface conditions. We describe the fifth Mine Analogue Research (MINAR 5) programme at 1 km depth in the Boulby Mine, UK in collaboration with Spaceward Bound NASA and the Kalam Centre, India, to test instruments and methods for the robotic and human exploration of deep environments on the Moon and Mars. The geological context in Permian evaporites provides an analogue to evaporitic materials on other planetary bodies such as Mars. A wide range of sample acquisition instruments (NASA drills, Small Planetary Impulse Tool (SPLIT) robotic hammer, universal sampling bags), analytical instruments (Raman spectroscopy, Close-Up Imager, Minion DNA sequencing technology, methane stable isotope analysis, biomolecule and metabolic life detection instruments) and environmental monitoring equipment (passive air particle sampler, particle detectors and environmental monitoring equipment) was deployed in an integrated campaign. Investigations included studying the geochemical signatures of chloride and sulphate evaporitic minerals, testing methods for life detection and planetary protection around human-tended operations, and investigations on the radiation environment of the deep subsurface. The MINAR analogue activity occurs in an active mine, showing how the development of space exploration technology can be used to contribute to addressing immediate Earth-based challenges. During the campaign, in collaboration with European Space Agency (ESA), MINAR was used for astronaut familiarization with future exploration tools and techniques. The campaign was used to develop primary and secondary school and primary to secondary transition curriculum materials on-site during the campaign which was focused on a classroom extra vehicular activity simulation.

Fluvial or aeolian grains? Separation of transport agents on Mars using earth analogue observations

The particle size, shape, surface texture and composition of aeolian and fluvial sedimentary samples were analyzed and compared using optical microscope-based automatized image analysis, in order to suggest indicators that could discriminate these two modes of transport on Mars. The principal goal is to assess if such indicators – established on Earth – could be used on Mars thereby aiding interpretations on the origin of sediments analysed by the ExoMars 2020 rover during its mission. Wind and water transported sand from, respectively, the Sahara Desert and the Maros river bar in Hungary were investigated and treated as mainly aeolian and fluvial end-members. In addition, two Mars-analogue aeolian and fluvial basaltic sediments from Iceland were analysed similarly.Our analyses demonstrated that useful parameters for the distinction of aeolian and fluvial transport included the degree of sorting, the grain diameter/perimeter ratio, the circularity (reflecting the sphericity of the grains) and convexity (showing roughness of the grains) of particles. Mature aeolian sands are always well-sorted with high diameter/perimeter ratios since they are dominated by rounded grains. Differences were observed in both surface textures and the range of mineral compositions, wherein the aeolian samples reflect a more mature state. Separation of the two Icelandic samples with different origins was less straightforward due to both shorter transport distances and the fact that the fluvial sample was made of scoria, although the intermixing of grains with a probable aeolian origin could be also determined. The characteristics of grain size and shape parameters are potential indicators allowing the separation of the two transport modes, and their determination is shown to be feasible based on high resolution Close-UP Imager (CLUPI) observations. Nonetheless, knowledge of the geological context – for instance sedimentary facies, layering, sorting of the sediments and grain shape – is a requirement for proper interpretations. These sedimentary features could be party determined by MaMISS, CLUPI and PanCam observations. Differences between aeolian and fluvial grains are expected to be more pronounced on Mars than on Earth due to the episodic and likely short-term subaqueous transport, as opposed to the long-term activity of wind. However, future interpretations of the ExoMars 2020 rover images of martian sedimentary grains will be hampered by the limited knowledge of fluvial/aeolian transport on Mars. Based on our results, future research should focus on determining the dominant transport mode of any sediment and the degree of grain mixing, which strongly based on the transport mode.

The Close-Up Imager Onboard the ESA ExoMars Rover: Objectives, Description, Operations, and Science Validation Activities.

The Close-Up Imager (CLUPI) onboard the ESA ExoMars Rover is a powerful high-resolution color camera specifically designed for close-up observations. Its accommodation on the movable drill allows multiple positioning. The science objectives of the instrument are geological characterization of rocks in terms of texture, structure, and color and the search for potential morphological biosignatures. We present the CLUPI science objectives, performance, and technical description, followed by a description of the instrument's planned operations strategy during the mission on Mars. CLUPI will contribute to the rover mission by surveying the geological environment, acquiring close-up images of outcrops, observing the drilling area, inspecting the top portion of the drill borehole (and deposited fines), monitoring drilling operations, and imaging samples collected by the drill. A status of the current development and planned science validation activities is also given. Key Words: Mars-Biosignatures-Planetary Instrumentation. Astrobiology 17, 595-611.

Planetary science and exploration in the deep subsurface: results from the MINAR Program, Boulby Mine, UK

AbstractThe subsurface exploration of other planetary bodies can be used to unravel their geological history and assess their habitability. On Mars in particular, present-day habitable conditions may be restricted to the subsurface. Using a deep subsurface mine, we carried out a program of extraterrestrial analog research – MINe Analog Research (MINAR). MINAR aims to carry out the scientific study of the deep subsurface and test instrumentation designed for planetary surface exploration by investigating deep subsurface geology, whilst establishing the potential this technology has to be transferred into the mining industry. An integrated multi-instrument suite was used to investigate samples of representative evaporite minerals from a subsurface Permian evaporite sequence, in particular to assess mineral and elemental variations which provide small-scale regions of enhanced habitability. The instruments used were the Panoramic Camera emulator, Close-Up Imager, Raman spectrometer, Small Planetary Linear Impulse Tool, Ultrasonic drill and handheld X-ray diffraction (XRD). We present science results from the analog research and show that these instruments can be used to investigate in situ the geological context and mineralogical variations of a deep subsurface environment, and thus habitability, from millimetre to metre scales. We also show that these instruments are complementary. For example, the identification of primary evaporite minerals such as NaCl and KCl, which are difficult to detect by portable Raman spectrometers, can be accomplished with XRD. By contrast, Raman is highly effective at locating and detecting mineral inclusions in primary evaporite minerals. MINAR demonstrates the effective use of a deep subsurface environment for planetary instrument development, understanding the habitability of extreme deep subsurface environments on Earth and other planetary bodies, and advancing the use of space technology in economic mining.

Testing the ability of the ExoMars 2018 payload to document geological context and potential habitability on Mars

The future ExoMars rover mission (ESA/Roscosmos), to be launched in 2018, will investigate the habitability of the Martian surface and near subsurface, and search for traces of past life in the form of textural biosignatures and organic molecules. In support of this mission, a selection of relevant Mars analogue materials has been characterised and stored in the International Space Analogue Rockstore (ISAR), hosted in Orléans, France. Two ISAR samples were analysed by prototypes of the ExoMars rover instruments used for petrographic study. The objective was to determine whether a full interpretation of the rocks could be achieved on the basis of the data obtained by the ExoMars visible-IR imager and spectrometer (MicrOmega), the close-up imager (CLUPI), the drill infrared spectrometer (Ma_Miss) and the Raman spectrometer (RLS), first separately then in their entirety. In order to not influence the initial instrumental interpretation, the samples were sent to the different teams without any additional information. This first step was called the “Blind Test” phase. The data obtained by the instruments were then complemented with photography of the relevant outcrops (as would be available during the ExoMars mission) before being presented to two geologists tasked with the interpretation. The context data and photography of the outcrops and of the samples were sufficient for the geologists to identify the rocks. This initial identification was crucial for the subsequent, iterative interpretation of the spectroscopic data. The data from the different spectrometers was, thus, cross-calibrated against the photographic interpretations and against each other. In this way, important mineralogical details, such as evidence of aqueous alteration of the rocks, provided relevant information concerning potential habitable conditions. The final conclusion from this test is that, when processed together, the ExoMars payload instruments produce complementary data allowing reliable interpretation of the geological context and potential for habitable environments. This background information is fundamental for the analysis and interpretation of organics in the processed Martian rocks.

Mobile Payload Element (MPE): Concept study for a sample fetching rover for the ESA Lunar Lander Mission

In late 2010, the DLR Space Administration invited the German industry to submit a proposal for a study about a Mobile Payload Element (MPE), which could be a German national contribution to the ESA Lunar Lander Mission. Several spots in the south polar region of the moon come into consideration as landing site for this mission. All possible spots provide sustained periods of solar illumination, interrupted by darkness periods of several 10h. The MPE is outlined to be a small, autonomous, innovative vehicle in the 10kg class for scouting and sampling the environment in the vicinity of the lunar landing site. The novel capabilities of the MPE will be to acquire samples of lunar regolith from surface, subsurface as well as shadowed locations, define their geological context and bring them back to the lander. This will enable access to samples that are not contaminated by the lander descent propulsion system plumes to increase the chances of detecting any indigenous lunar volatiles contained within the samples.Kayser-Threde, as prime industrial contractor for Phase 0/A, has assembled for this study a team of German partners with relevant industrial and institutional competence in space robotics and lunar science. The primary scientific objective of the MPE is to acquire clearly documented samples and to bring them to the lander for analysis with the onboard Lunar Dust Analysis Package (L-DAP) and Lunar Volatile Resources Analysis Package (L-VRAP). Due to the unstable nature of volatiles, which are of particular scientific interest, the MPE design needs to provide a safe storage and transportation of the samples to the lander.The proposed MPE rover concept has a four-wheeled chassis configuration with active suspension, being a compromise between innovation and mass efficiency. The suspension chosen allows a compact stowage of the MPE on the lander as well as precise alignment of the solar generators and instruments. Since therefore no further complex mechanics are necessary, the active suspension significantly contributes to the lightweight MPE design. The thermal control system enables the MPE to operate in shaded areas for about 2h and hibernate darkness periods of about 14h. Increasing the hibernation capability requires additional battery capacity and thus increases the MPE mass. As operational modes teleoperations from earth and autonomous navigation are foreseen. The MPE payload includes navigation cameras, a close-up imager and a mole as sampling device.The MPE phase 0/A study finished in early 2012. This article describes the resulting MPE rover concept with focus on its scientific benefit for the Lunar Lander Mission.