IntroductionThe flight Raman instrument for the ExoMars 2022 mission, the Raman Laser Spectrometer (RLS) [1], was delivered and integrated in the Rosalind Franklin rover. In parallel, the RLS flight spare (FS) model is being used at INTA facilities to thoroughly characterize and understand the instrument performance, as well as to optimize the scientific return of the flight instrument through a proper parameterization. In addition, the RLS ExoMars simulator developed by the University of Valladolid (UVA), is used for thorough analysis of samples, emulating the operation mode of the RLS instrument (including the automated adaptation to the sample spot), as well as the sample preparation and distribution system (SPDS) of the rover, in those aspects related to sample management.In this work we present experiments and analysis performed with the different ground models, aimed at the optimization and characterization of the RLS performance, by addressing the following three issues: 1- optimizing the acquisition by studying the SNR of spectra with different configurations of the spectra acquisition algorithms implemented onboard the RLS instrument [2] (especially the number of accumulations), while also considering the influence of the instrument stability (laser power, CCD temperature, etc.). 2- optimizing the spectral quality of the acquired data by evaluating several on-ground spectral data-processing strategies. 3- evaluate and analyze the performance of the different models (FM, FS and Simulator) to understand the expected inter-correlation of the results obtained with them.Experiments and previous workSeveral samples with different emission efficiencies (diamond, calcite, serpentine, hematite and vermiculite), have been analyzed with the RLS FS and the RLS ExoMars Simulator, acquiring a relatively high number of acquisitions. The data has been processed to establish the spectral quality (measured as the SNR) as a function of the number of accumulations.The RLS ExoMars simulator, on the other hand, has also been reworked to integrate the RAD1 spectrometer (RAman Demonstrator 1, a laboratory model with characteristics and design similar to RLS). This will bring the RLS ExoMars Simulator closer to the expected performance of the instrument that will fly to Mars.Optimal naThe RLS instrument features an automated integration time (ti) calculation algorithm, which allows optimizing this time for every spot in the sample. However, due to several reasons, the number of accumulations (na) has to be established from ground as a system parameter, so it will be the same for all the samples and spots obtained during one operational cycle (sol). It has been reported [2] that, for constant total acquisition times (ti*na) in instruments such as RLS, the signal to noise ratio (SNR) of a spectrum increases more by maximizing ti, than by maximizing na. This is in agreement with the implementation performed on the onboard software of RLS. Thus, the present study is centered in the characterization of the optimal number of accumulations (which is configurable from ground) for the RLS operation.The results in this work have been used to infer the SNR evolution of the spectra as a function of the number of accumulations, which is critical to establish the on-ground parameter for na for an optimal acquisition. The results are obtained by comparing several SNR calculation methods, and have helped determining a good compromise in the selection of the na at a value of 30.This analysis has shown noise levels behaving very close to the theoretical behavior, with the noise intensity following the expected inverse exponential decay with na. However, it has also provided insight as to how the spectra peak intensity is highly affected by the laser power or CCD temperature stability. In this sense it has been concluded that it will be necessary to perform some tests at arrival on Mars, in temperature conditions representative of the environment during Martian operations.Data processing for optimal spectral qualityThe analysis of the acquired data has also shown how the spectral quality of the spectra can be influenced by the data processing: CCD binning method, dark subtraction, baseline correction approach… but also how different intensity correction methods can help improve the quality of the spectra. For example, the correction with BZn [3] has been used to perform correction of the spectra (using different correction methods), showing how the data analysis strategy incorporated into the science processing pipelines of RLS during operation will need to include this correction. Other data processing strategies to be considered are the use of optimized binning methods (adjusted for each spectrum), or the dark correction of spectra, which also improves the spectral quality.Correlation between instrument modelsTo have ground models which can be correlated with the instrument on Mars is critical for analysis during operations, but also to prepare and validate the science that will be obtained from the instrument once on Mars. The RLS FS instrument is identical to the flight instrument in every sense, which makes it very representative of the RLS FM, except in the operational conditions, as it is not possible to simulate the Martian conditions in a daily operational basis (and, for example, the CCD working temperature is kept at values higher than what will be expected on Mars).On the other hand, the correlation of ground emulators such as the RLS ExoMars Simulator is of paramount importance to obtain results that are realistically correlated with the actual RLS instrument. The integration of the RAD1 spectrometer in the RLS ExoMars Simulator is a great step forward to achieve representative results that can ultimately be used to take decisions as to how to parameterize the flight instrument for Martian operation.AcknowledgementsMINECO grants ESP2014-56138-C3-1-R, ESP2014-56138-C3-2-R, ESP2107-87690-C3-1-R, ESP2107-87690-C3-3-R.References[1] Rull, F. et al. Astrobiology 17, 627–654 (2017).[2] Lopez-Reyes, G. et al. J. Raman Spectrosc. 48, (2017).[3] A. Sanz-Arranz et al. J. Raman Spectrosc. 48, (2017).

NASA/Mars 2020 [1] and ESA/ExoMars [2] missions are scheduled to be launched in 2020 and 2022 respectively. For the first time in history, the analytical payload of both exploration rovers will be equipped with Raman systems that will work in combination with complementary spectroscopic techniques such as LIBS and NIR. Prior to science operations, detailed laboratory investigations are necessary to constrain the potential scientific outcome of Raman spectrometers, as well as to facilitate the comprehension of the advantages provided by combined Raman/LIBS (e.g. the SuperCam analytical suite [3] onboard the Perseverance rover) and Raman/NIR (as is the case of ExoMars RLS [4] and MicrOmega coordinated studies) analysis. In this framework, beside coordinating the development of Mars 2020/SuperCam Calibration Target (SCCT) and ExoMars/Raman Laser Spectrometer (RLS), the ERICA research group is developing novel tools that are meant to facilitate both science operation teams in the analysis and interpretation of the spectroscopic data soon gathered from Mars. As such, the three main tools under development are presented below: * 1) Planetary Terrestrial Analogue Library (PTAL) Funded by the European Research Council through the H2020-Compet-2015 programme (grant 687302), the Planetary terrestrial analogue library (PTAL) project will provide science operation teams (and, in a broader extent, the whole scientific community) with free access to an extended multi spectral database of terrestrial analogues materials that have been selected basing on their congruence to well-known Martian geological and environmental contexts [5]. Through the collaboration of the Universities of Valladolid (UVa, Spain), Oslo (UiO, Norway) and Paris-Sud (UPSud, France) the PTAL database will offer Raman, LIBS, NIR and XRD data collected from 1) natural geological samples collected from terrestrial analogues sites and 2) artificial samples replicating Martian protoliths composition and altered in the laboratory under controlled physical-chemical conditions. Beside the use of conventional laboratory instruments, the mineralogical and geochemical composition of PTAL samples is characterized by means of spacecraft derived instrumentation, as is the case of the RLS ExoMars Simulator, MicrOmega and ChemCam spare models. Furthermore, the PTAL platform will provide the opportunity to request physical access to Martian analogue materials thus enabling future users to combine PTAL spectroscopic data with further laboratory analysis. * 2) Analytical DAtabase of Martian Minerals (ADAMM) Complementary to PTAL, the ADAMM database will include diffractometric (XRD) and spectroscopic (Raman, NIR, LIBS) data from a wide collection of pure mineral phases that have been detected on Mars by orbital and on-ground analytical systems, as well as from the laboratory study of Martian meteorites. Financed by the Ministry of Economy and Competitiveness (MINECO, grant ESP2017-87690-C3-1-R) the ADAMM database also includes additional phases that, according to the modern knowledge about the geological evolution of Mars, are most likely to be present at the (sub)surface of the red planet. As such, over 300 specimens are being analyzed using both commercial and spacecraft derived instrumentations. Besides the previously mentioned RLS ExoMars Simulator, mineral samples will be also analyzed by means of SimulCam, a remote Raman/LIBS system recently developed by the ERICA research group to reliably simulate SuperCam analytical outcomes. After comparing ADAMM database with the mineralogy detected from orbit at Jezero Crater and Oxia Planum (the landing site for Mars 2020 and ExoMars missions, respectively) a more detailed analysis of selected samples will be carried out. Thus, complementary analysis will be performed in the framework of the SIGUE-Mars consortium by using additional instruments (including the RLS spare model), and under Martian conditions (temperature and atmospheric pressure). In this way, a reliable estimation of the potential scientific outcome of the forthcoming rover missions to Mars will be provided. * 3) IDAT/SpectPro The Instrument Data Analysis Tool (IDAT)/SpectPro software was developed by the University of Valladolid to receive, decodify, calibrate and verify the telemetries generated by the RLS instrument on Mars [6]. IDAT/SpectPro is able to open and process data in PDS4 format, as required by the ExoMars mission. In this way, as soon as the data from the processors is available, IDAT/SpectPro will automatically process it to obtain science and engineering (housekeeping) calibrated data and even generate autolooks. IDAT/SpectPro also provides access to an extended set of analytical tools for spectral analysis such as labelling, trimming, shifting, normalization, baseline correction, and features a general-purpose spectrum calculator to perform lineal combinations, product, division and derivative of spectra. An automated identification algorithm to classify Raman spectra is also under development. This algorithm is based on the comparison of peak positions and intensities, which has provided good results, even for the detection of all samples present in simple mixtures. The mentioned analytical tools will be made available to PTAL and ADAMM users through a dedicated version of IDAT/SPectPro software, which will have a direct interface to access the two databases. Acknowledgements: This work is financed through the European Research Council in the H2020- COMPET-2015 programme (grant 687302) and the Ministry of Economy and Competitiveness (MINECO, grant ESP2017-87690-C3-1-R). The authors gratefully acknowledge the support of the SIGUE-Mars consortium (MINECO, grant RDE2018-102600-T). References: [1] Williford, K. H. et al. From Habitability to Life on Mars (Elsevier Inc., 2018). [2] Vago, J. L. et al. Astrobiology 17, 471–510 (2017). [3] Wiens, R. C., Maurice, S. & Perez, F. R. Spectrosc. (Santa Monica) 32, 50–55 (2017). [4] Rull, F. et al. Astrobiology 17, 627–654 (2017). [5] Veneranda, M. et al. J. Raman Spectrosc. 50, 1–19 (2019). [6] Lopez-Reyes G. et al. European Planetary Science Congress 2018 12 1–2 (2018).

IntroductionThe Raman Laser Spectrometer (RLS) [1] is part of the analytical instrumental suite (Pasteur Payload) located inside the Analytical Laboratory Drawer (ALD) of the Rosalind Franklin rover for the ExoMars 2022 mission to Mars. RLS is based on the inelastic scattering of the matter when illuminated by a monochromatic light. This emitting radiation contains physicochemical information of the observed material through the vibrations of its atomic components. It this way RLS will contribute to the ExoMars scientific mission objectives identifying minerals and organic compounds at the mineral grain scale. And with this information supporting the key astrobiological questions the mission will address analyzing samples on the Martian surface and subsurface.The instrument consists in four main units which are depicted in Figure 1 and its development and delivered models are described in references [1–5].In this work interest is mainly devoted to the analysis of the scientific performances of the flight model (FM) currently integrated in the Rosalind Franklin rover, comparing it with the performances of the flight spare (FS) located at INTA in Madrid. This comparison is part of the general plan to characterize both instruments to better understand the FM behavior in support to the future operation in Mars. This plan also includes the correlation of the FS scientific outcome and the RLS ExoMars Simulator, a laboratory setup located in Valladolid University [6] emulating the RLS acquisition algorithms [7], as well as the sample preparation and distribution system (SPDS) positioning of the samples. Figure 1. RLS instrument units. a) The SPU is the Spectrometer Unit, with a theoretical spectral resolution of 6-8 cm-1 [5]. b) The internal Optical Head (iOH) features an autofocus system, with 50 microns collection and excitation fibers [2,8]. c) The ICEU is the control electronics unit, also integrating the redundant 532 nm excitation laser [9]. d) The Calibration Targets will allow the calibration of the instrument, as well as the spatial correlation of the field-of-views of the different instruments of the Rosalind Franklin Analytical Laboratory Drawer [3].ExperimentalThe instrument performances were evaluated after an appropriate calibration procedure that included observation of Ne and Ar-Hg emission lines to obtain the correlation function between pixels and correct wavelengths and the Raman observation of standard samples and the PET calibration target to obtain the right wavenumber positions.After that a campaign with selected samples of very different Raman molar efficiency was undertaken. In the FM case this campaign comprised the pre-delivery experiments with a limited set of samples, given the extremely tight delivery schedule for the flight instrument to ESA. Once after integration, only the Calibration Target material (PET) can be used for health or any other checks, as no samples will be introduced into the sealed ultra-clean zone of the analytical laboratory drawer (ALD) of the rover until arrival to Mars. However, the development of the RLS FS (identical in every sense to the FM), has provided a unique opportunity to perform thorough scientific analysis that will be used to properly characterize and parameterize the flight instrument. These experiments will be correlated with heavy duty analysis performed by the RLS ExoMars Simulator, which is designed to work in a laboratory environment, thus allowing the analysis of samples without the operational constraints of the RLS FS. Several samples relevant to Mars have been analyzed at the present. These samples are collected from the ADAMM database, a collection of materials representative of different Martian locations and specifically the landing sites of ExoMars 2022 (Oxia Planum) and Mars 2020 (Jezero Crater) missions, which is presented in this conference. In addition, synthetic mixtures of materials used to perform calibration curves for the quantification of mineral abundances from RLS data (publication in press), or other representative materials to optimize the acquisition parameters of the instrument are analyzed (a dedicated presentation is presented in this conference).Results and discussion In this conference we will present and discuss the evolution of Raman spectra of the CT acquired with the RLS FM instrument, to verify the evolution of the instrument throughout all the steps from the pre-delivery stage, including the spectra obtained in relevant environments during the Assembly, Integration and Test (AIT) phases of the ALD and rover integration process. And also, the results regarding the correlation of the FS instrument and the RLS ExoMars Simulator data to the RLS FM instrument. These results will be key for defining the instrument capabilities and expected scientific performance of the instrument once on Mars. AcknowledgementsMINECO grants ESP2014-56138-C3-1-R, ESP2014-56138-C3-2-R, ESP2107-87690-C3-1-R, ESP2107-87690-C3-3-R.References[1] F. Rull et al., et al. Astrobiology. 17 (2017) 627–654. https://doi.org/10.1089/ast.2016.1567.[2] A. Santiago et al. Proc. SPIE - Int. Soc. Opt. Eng., 2018. https://doi.org/10.1117/12.2313462.[3] G. Lopez‐Reyes et al. J. Raman Spectrosc. (2020) jrs.5832. https://doi.org/10.1002/jrs.5832.[4] A.G. Moral et al. J. Raman Spectrosc. (2019) jrs.5711. https://doi.org/10.1002/jrs.5711.[5] J.F. Cabrero et al. In: Proc. SPIE 11180 (2019) 115. https://doi.org/10.1117/12.2536035. [6] G. Lopez-Reyes et al. Eur. J. Mineral. 25 (2013) 721–733. https://doi.org/10.1127/0935-1221/2013/0025-2317.[7] G. Lopez-Reyes, F. Rull Pérez, J. Raman Spectrosc. 48 (2017) 1654–1664. https://doi.org/10.1002/jrs.5185.[8] G. Ramos et al. In: Proc. SPIE - Int. Soc. Opt. Eng., (2017). https://doi.org/10.1117/12.2277003.[9] P. Ribes-Pleguezuelo et al. Proc SPIE - Opt. Eng. 55(11), 116107 (2016), https://doi: 10.1117/1.OE.55.11.116107

The PTAL Project: Mars2020/Perseverance 1 and ExoMars/Rosalind Franklin 2 rovers will look for traces of present or past life on Mars. To do so, the spectroscopic systems included in their analytical payloads will investigate the geochemistry and mineralogy of Martian rocks and soils to detect geological samples that could potentially host biomarkers. In order to optimize the scientific exploitation of planetary spectroscopic analysis, the PTAL project will provide the scientific community with a novel library of terrestrial analogue materials that have been selected based on their similarity to well-known Martian geological contexts. Funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement Nº 687302, the PTAL online platform will be released to public in October 2021. As further detailed by Werner et al. during this conference, the core of the database are the spectroscopic data collected by means of multiple Raman (University of Valladolid, UVa, Spain), NIR (University of Paris-Sud, UP-Sud, France) and LIBS (French National Centre for Scientific Research, IRAP, France) systems. Spectroscopic results are additionally supported by X-ray diffractograms and thin section observations (University of Oslo, Uio, Norway) to provide an exhaustive geochemical and mineralogical characterization of the samples. The whole set of data, collected by means of both commercial systems and prototypes/flight spares (FS) of analytical instruments validated for Mars exploration (RLS-Sim, MicrOmega-FS, ChemCam-FS), will be available to the public thanks to a dedicated online platform, which main characteristics are detailed below.The online PTAL platform:The PTAL database will be accessible to public through the following URL: http://erica.uva.es/PTAL/. After login (credentials will be provided by the PTAL consortium upon request), future users will have access to the whole set of diffractometric and spectroscopic data collected from a total of 102 analogue materials. On one side, clicking on the sample name, the metadata associated to the selected terrestrial analogues are provided (e.g., Sample Name and Lithology, Sampling Campaign and coordinates) together with high quality pictures of the terrestrial analogue sample. On the other side, by clicking on “analytical summary”, the PTAL platform displays the list of NIR, LIBS, Raman and XRD analyses associated to the selected terrestrial analogue, together with a table summarizing and comparing the main results gathered from each technique (Figure 1).Figure 1: Screenshots collected from the PTAL online database: a) list of samples, b) summary result of a selected analogue, and c) online visualization of a selected Raman spectrum.At this stage, all NIR, XRD, Raman and LIBS data have been successfully uploaded to the PTAL database 3–5. In detail, the PTAL database provides access to 102 diffractograms (1 per sample), 102 LIBS spectra, 102 NIR spectra collected by means of the commercial spectrometer, and 102 NIR data cubes obtained through the MicrOmega system (of them composed of 62500 spectra collected at steps of 20µm in a field of view of 5x5mm). Regarding Raman results, only the spectra providing the highest mineralogical information were uploaded to the PTAL database. As such, the number of Raman spectra was reduced from over 4500 to 577 (an average of 5-6 spectra per sample). 245 of them were collected by means of the RLS-Sim, while the remaining 332 were obtained with a commercial spectrometer. All data can be either visualized online or downloaded for further data comparison and processing. In this framework, it must be underlined the PTAL platform also gives access to a dedicated software for data treatment. Named SpectPro, the details of this downloadable software are detailed below.The SpectPro software:Developed in the framework of the ExoMars mission 6, the PTAL version of the SpectPro software could be downloaded from the PTAL webpage (download section) for both windows and MacOs operating systems. Through the SpectPro software, PTAL users will be able to run individual and multi-spectra operations such as labelling, trimming, shifting, normalization, baseline correction (see Figure 2).Figure 2: Screenshot of PTAL/SpectPro, in which the main functionalities and characteristics of the software are highlighted.Among the main functionalities, the software also features a general-purpose spectrum calculator to perform lineal combinations, product and derivative of spectra, among others. The software team has been working to facilitate a direct access from SpectPro to the PTAL database, using the same credentials for access to the PTAL web interface. This connection will boost the capability of the scientist working in a planetary mission (but not only) to perform a fast and comprehensive characterization and identification of the mineral phases present in a sample by comparing the data obtained from the sample with the extensive spectral information included in the PTAL database. This will be possible by profiting from the navigation pane included in SpectPro. In addition, using the peak detection capabilities of SpectPro, it will be possible to perform sample identification based on the acquired spectra.Acknowledgments: This work is financed through the European Research Council in the H2020- COMPET-2015 programme (grant 687302).References: 1 Farley, K. A. et al. Space Sci. Rev. 216, 142 (2020); 2 Vago, J. L. et al. Astrobiology 17, 471–510 (2017); 3 Lantz, C. et al. Planet. Space Sci. 189, 104989 (2020); 4 Loizeau, D. et al. Planet. Space Sci. 193, 105087 (2020); 5 Veneranda, M. et al. J. Raman Spectrosc. 1–19 (2019) doi:10.1002/jrs.5652; 6 Lopez-Reyes G. et al. European Planetary Science Congress 2018 vol. 12 1–2 (2018).

The 2020s could be called, with little doubt, the "Mars decade". No other period in space exploration history has experienced such interest in placing orbiters, rovers and landers on the Red Planet. In 2021 alone, the Emirates' first Mars Mission (the Hope orbiter), the Chinese Tianwen-1 mission (orbiter, lander and rover), and NASA's Mars 2020 Perseverance rover reached Mars. The ExoMars mission Rosalind Franklin rover is scheduled for launch in 2022. Beyond that, several other missions are proposed or under development. Among these, MMX to Phobos and the very important Mars Sample Return can be cited. One of the key mission objectives of the Mars 2020 and ExoMars 2022 missions is the detection of traces of potential past or present life. This detection relies to a great extent on the analytical results provided by complementary spectroscopic techniques. The development of these novel instruments has been carried out in step with the analytical study of terrestrial analogue sites and materials, which serve to test the scientific capabilities of spectroscopic prototypes while providing crucial information to better understand the geological processes that could have occurred on Mars. Being directly involved in the development of three of the first Raman spectrometers to be validated for space exploration missions (Mars 2020/SuperCam, ExoMars/RLS and RAX/MMX), the present review summarizes some of the most relevant spectroscopy-based analyses of terrestrial analogues carried out over the past two decades. Therefore, the present work describes the analytical results gathered from the study of some of the most distinctive terrestrial analogues of Martian geological contexts, as well as the lessons learned mainly from ExoMars mission simulations conducted at representative analogue sites. Learning from the experience gained in the described studies, a general overview of the scientific outcome expected from the spectroscopic system developed for current and forthcoming planetary missions is provided.

The Mars2020/Perseverance and ExoMars/Rosalind Franklin rovers are both slated to return the first Raman spectra ever collected from another planetary surface, Mars. In order to optimize the rovers scientific outcome, the scientific community needs to be provided with tailored tools for data treatment and interpretation. Responding to this need, the purpose of the Analytical Database of Martian Minerals (ADaMM) project is to build an extended multianalytical database of mineral phases that have been detected on Mars or are expected to be found at the landing sites where the two rovers will operate. Besides the use of conventional spectrometers, the main objective of the ADaMM database is to provide access to data collected by means of laboratory prototypes simulating the analytical performances of the spectroscopic systems onboard the Mars 2020 and ExoMars rovers. Planned to be released to the public in 2022, ADaMM will also provide access to data treatment and visualization tools developed in the framework of the mentioned space exploration missions. As such, the present work seeks to provide an overview of the ADaMM online platform, spectral tools, and mineral collection. In addition to that, the manuscript describes the Raman spectrometers used to analyze the mineral collection and presents a representative example of the analytical performance ensured by the Raman prototypes assembled to simulate the Raman Laser Spectrometer (RLS) and SuperCam systems.

The 2020s could be called, with little doubt, the "Mars decade". No other period in space exploration history has experienced such interest in placing orbiters, rovers and landers on the Red Planet. In 2021 alone, the Emirates' first Mars Mission (the Hope orbiter), the Chinese Tianwen-1 mission (orbiter, lander and rover), and NASA's Mars 2020 Perseverance rover reached Mars. The ExoMars mission Rosalind Franklin rover is scheduled for launch in 2022. Beyond that, several other missions are proposed or under development. Among these, MMX to Phobos and the very important Mars Sample Return can be cited. One of the key mission objectives of the Mars 2020 and ExoMars 2022 missions is the detection of traces of potential past or present life. This detection relies to a great extent on the analytical results provided by complementary spectroscopic techniques. The development of these novel instruments has been carried out in step with the analytical study of terrestrial analogue sites and materials, which serve to test the scientific capabilities of spectroscopic prototypes while providing crucial information to better understand the geological processes that could have occurred on Mars. Being directly involved in the development of three of the first Raman spectrometers to be validated for space exploration missions (Mars 2020/SuperCam, ExoMars/RLS and RAX/MMX), the present review summarizes some of the most relevant spectroscopy-based analyses of terrestrial analogues carried out over the past two decades. Therefore, the present work describes the analytical results gathered from the study of some of the most

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Introduction: The SuperCam instrument onboard the NASA/Perseverance rover will offer the unprecedented opportunity to collect both Raman and LIBS spectra from remote targets on Mars [1-4]. By collecting complementary molecular and elemental information from the same spot of analysis, SuperCam spectroscopic datasets will optimize the geochemical and mineralogical characterization of Martian rocks and soils over spectroscopic systems used in previous missions. The combination of Raman and LIBS data has been successfully used in previous works to optimize the discrimination of mineral phases [5,6]. However, it should be noted that many of these studies are based on the treatment of spectra gathered by state-of-the-art analytical instruments, the analytical features of which are not comparable to instruments built for space exploration. To overcome this issue, this study proposes tailored analytical strategies based on the combination of LIBS and Raman data remotely collected by a SuperCamrepresentative standoff Raman-LIBS prototype. Taking into account the mineralogy of the landing site and the main objective of the Mars2020 mission, Raman-LIBS combination strategies were applied to the study of carbonate minerals.

NASA/Mars2020 and ESA/ExoMars missions will look for traces of present or past life on Mars. To do so, both Perseverance and Rosalind Franklin rovers have been equipped with a wide set of spectroscopic systems to investigate the geochemistry and mineralogy of Martian rocks and soils. As spectroscopic techniques are acquiring an increasing importance in the field of Mars exploration, many research groups are trying to estimate and optimize their potential scientific return by carrying out representative analytical studies in the laboratory. In this framework, PTAL is a research project founded by the European Commission through the H2020 program, which is aimed to provide the scientific community with a novel library of terrestrial analogue materials that have been selected based on their similarity to well-known Martian geological contexts. Planned to be released to public on January 2022, the PTAL platform (http://erica.uva.es/PTAL/) will provide future users with access to complementary spectroscopic and diffractometric data gathered from over 100 terrestrial analogues. In detail, the XRD analysis of each analogue was carried out to gather a reliable overview of samples mineralogy. Then, LIBS, IR and Raman spectrometers were used to collect additional elemental and molecular data, these being the key analytical tools onboard NASA/Perseverance and ESA/Rosalind Franklin rovers. Beside the use of commercial spectrometers, the RLS ExoMars Simulator, the MicrOmega-Flight (FS) (Spare Model) and the ChemCam-FS were also employed to collect LIBS, Raman and NIR spectra (respectively) qualitatively comparable to those that will soon gathered on Mars. In addition to analytical data, the PTAL platform will also provide direct access to a dedicated software (SpectPro) for spectral visualization and treatment [1] To conclude, future users can also request physical access to the terrestrial analogues, so that the data contained in the PTAL library can be combined with further analysis in the laboratory. To obtain further information about the PTAL project, please use the QR code provided in Figure 01. Figure 01: PTAL QR code Acknowledgements: This work is financed through the European Research Council in the H2020- COMPET-2015 programme (grant 687302) and the Ministry of Economy and Competitiveness (MINECO, grant PID2019-107442RB-C31). References: [1] Saiz J. et al., (2019) EGU general Assembly, 21, 17904.

Introduction: The aim of the PTAL project is to create a multi-analytical database of Terrestrial analogue samples that have been collected on the basis of their congruence to well-known Martian geological and environmental contexts. As a whole, the multi analytical data will provide a comprehensive view of the geochemical and mineralogical composition of the over 100 analogue materials. The PTAL platform will also give access to data collected from artificial samples that have been altered in the laboratory under controlled physical-chemical conditions (gas pressures, aqueous salinity, temperature etc.) to reproduce putative alteration processes occurred on Mars. The PTAL website will also implement a novel functionality that will allow future users to request physical access to analogues and synthesized materials. In this way, it will offer the opportunity to combine the data contained in the PTAL library with further analysis in the laboratory. Being in the latest stage of its development, the PTAL platform is expected to be released to public at the end of 2021. Further information about the project and related publications can be found at the PTAL official webpage (https://ptal.eu/), which can be directly accessed through the QR code provided in Figure 01.

This work presents the latest chemometric tools developed by the RLS science team to optimize the scientific outcome of the Raman system onboard the ExoMars 2022 rover. Feldspar, pyroxene and olivine samples were first analyzed through the RLS ExoMars Simulator to determine the spectroscopic indicators to be used for a proper discrimination of mineral phases on Mars. Being the main components of Martian basaltic rocks, lepidocrocite, augite and forsterite were then used as mineral proxies to prepare binary mixtures. By emulating the operational constraints of the RLS, Raman datasets gathered from laboratory mixtures were used to build external calibration curves. Providing excellent coefficients of determination (R2 0.9942÷0.9997), binary curves were finally used to semi-quantify ternary mixtures of feldspar, pyroxene and olivine minerals. As Raman results are in good agreement with real concentration values, this work suggests the RLS could be effectively used to perform semi-quantitative mineralogical studies of the basaltic geological units found at Oxia Planum. As such, crucial information about the geological evolution of Martian Crust could be extrapolated. In light of the outstanding scientific impact this analytical method could have for the ExoMars mission, further methodological improvements to be discussed in a dedicated work are finally proposed.

Raman Spectroscopy is an analytical technique that will be deployed on Mars in the following years and could be part of other payloads for planetary exploration missions in the future. Its ability for identification of mineral phases and its interest in Mars has been deeply discussed in bibliography [1]. Perseverance rover, to be launched in 2020, and ExoMars rover, to be launched in 2022, will carry three Raman instruments, different in concept and capabilities. SHERLOC (mounted on Perseverance’s arm) is a UV Raman instrument mainly focused in the direct detection of biomarkers, SuperCam (mounted on Perseverance’s mast) is a standoff, multi-technique, instrument that performs Raman and LIBS at distances of several meters from the rover. Finally, RLS, mounted in Rosalind Franklin Rover, in the Pasteur analytical laboratory, is a continuous wave, 532 nm excitation source Raman instrument. While the first one is focused in detection limits of organics, RLS is intended to investigate mineralogy and possible biomarkers, while SuperCam, due to its standoff and time resolved design, is a different concept to que other two Raman instruments, as it is also capable of fusing data from different techniques. Carbonates are minerals of great interest for astrobiology, and, as suggested by CRISM data, the landing site selected for the NASA/Mars 2020 rover mission (Jezero crater) presents a variety of Fe-Ca-Mg carbonate units [2]. For Oxia Planum, Rosalind Franklin’s landing site, although no carbonates have been detected in that area by orbiter data, Earth analogues suggest that small amounts of carbonates might be found in the clay rich area. On Earth, top bench Raman spectrometers can be effectively used to discriminate carbonates and to determine the Mg/Fe concentration ratio of mineral species from dolomite (CaMg(CO3)2) - ankerite (CaFe(CO3)2) and magnesite (MgCO3) - siderite (FeCO3) solid solutions series [3]. The previously mentioned instruments might present limitations derived from the design constrains of space exploration. Resolution, far from ideal, and low intensity of the signal, are two of the main factors that could affect the possible calculations done with data from the three Raman instruments. SuperCam is a special case, as it is able to obtain data from several techniques from the same spot of the sample, and that might help to overcome those difficulties. In this work a complete set of Ca-Mg-Fe carbonates is analysed by different Raman instruments, including automated contact instruments and combined standoff developments. The initial characterization of the samples is done with XRD, as gold standard. Then, a characterization of all those carbonates based only on Raman data sets was done, aiming to evaluate the impact of resolution in the classification power of Raman-based calculations. A detailed vibrational mode analysis was carried out for interpreting the structural modifications induced by cationic substitution. Here, after a detailed interpretation it was found that Raman active internal modes are less sensitive to the carbonate chemistry than the external modes (i.e. the 155cm-1 and 286cm-1 respectively). Same collection of carbonates is analysed using standoff Raman-LIBS combination. In this case we will evaluate how having the complementary information of the elemental composition improves the results obtained by standoff Raman spectroscopy [4], as LIBS is more sensitive to the possible changes in the cations in the samples. Using these data sets, a combination of univariate and multivariate calculations are done to evaluate their classification capacity. As commented before, LIBS can classify better these minerals thanks to its lower detection limit and a better functionality in standoff configuration. However, the effect from other phases, different from carbonates, might disturb the LIBS calculations, reason why having an assessment of all the phases in play by Raman spectroscopy is of great interest, supporting the idea of the power of technique combination. 1 F. Rull, S. Maurice, I. Hutchinson et al. Astrobiology, Vol. 17 (2017), No. 6-7 2 B.H.N. Horgan, R.B. Anderson, G. Dromart, E.S. Amador, M.S. Rice Icarus, 339 (2020) 113526. 3 P. Kristova, L. Hopkinson, K. Rutt, H. Hunter, G. Cressey, American Mineralogist, 98 (2013) 401-409. 4 J.A. Manrique-Martinez et al. Journal of Raman Spectroscopy (2020) 1-16.

The multi analytical study of terrestrial analogues is a useful strategy to deepen the knowledge about the geological and environmental evolution of Mars and other extraterrestrial bodies. In spite of the increasing importance that LIBS, NIR and Raman techniques are acquiring in the field of space exploration, there is a lack web-based platform providing free access to a wide multi-spectral database of terrestrial analogue materials. The Planetary Terrestrial Analogue Library (PTAL) project aims at responding to this critical need by developing and providing free web accessibility to LIBS, NIR and Raman data from more than 94 terrestrial analogues selected according to their congruence with Martian geological contexts. In this framework, the present manuscript provides the scientific community with a complete overview of the over 4500 Raman spectra collected to feed the PTAL database. Raman data, obtained through the complementary use of laboratory and spacecraft-simulator systems, confirmed the effectiveness of this spectroscopic technique for the detection of major and minor mineralogical phases of the samples, the latter being of critical importance for the recognition of geological processes that could have occurred on Mars and other planets. In light of the forthcoming missions to Mars, the results obtained through the RLS ExoMars Simulator offer a valuable insight on the scientific outcome that could derive from the RLS spectrometer that will soon land on Mars as part of the ExoMars rover payload.

Raman and laser-induced breakdown spectroscopy (LIBS) spectroscopies will play an important role in planetary exploration missions in the following years, not only with Raman instruments like Raman laser spectrometer on board of Rosalid Franklin Rover or scanning habitable environments with Raman and luminescence for organics and chemicals on board Mars2020 Rover but also with combined instruments such as SuperCam. These techniques will be part of the upcoming planetary exploration missions because they can provide complementary information from the analysed sample while potentially sharing hardware components, maximizing the scientific return of the samples while limiting mass. In this framework, this study seeks to test the feasibility of combining several univariate and multivariate analysis techniques with data fusion techniques of different instruments (532 and 785 nm Raman and LIBS) to evaluate the improvements in the quantitative classification of samples in binary mixtures. We prepared two-component mixtures that are potentially relevant in planetary exploration missions, using two different sulfates and a chloride. A more accurate classification of the samples is possible through a univariate analysis that combines the calculated concentration indicators for Raman and LIBS. On the other hand, multivariate analysis was run on Raman, LIBS, and Raman + LIBS low-level fused data sets. The results showed a better improvement when fusing LIBS and Raman when compared with the redundant fusion but not a systematic improvement when compared with individual sets. We demonstrate that a quantification of the mineral abundances in binary mixtures can be obtained from Raman and LIBS data using univariate and multivariate analysis techniques, being the latter remarkably better, moving from performances of classification, in the whole range of concentrations, that could be over the 10% to values under 3.5%. Furthermore, the fusion of data coming from these techniques improves the classification limit with respect to the individual techniques. Thus, besides the (evident) hardware convenience of combining LIBS with 532-nm Raman, there could be analytical advantages as well.