P C Pinet

Y H Daydou

S D Chevrel

OLIVINE COMPOSITION AND REFLECTANCE SPECTROSCOPY RELATIONSHIP REVISITED FROM ADVANCED MGM DECONVOLUTION BASED ON SYNTHETIC SAMPLES

Introduction:

We revisit the behavior of the three primary olivine absorptions near 1 m (referred to as M1-1, M2, M1-2) and their interelationships by means of an advanced version of MGM analysis. We build on the previous works carried out [e.g.,1, 2] to document at best the compositional variation of olivine from diagnostic absorption features across the visible and near-infrared wavelengths due to electronic transitions of Fe2+ in the crystal structure.

MGM implementation:

The principle of the Modified Gaussian Model is to deconvolve overlapping absorptions of mafic mineral spectra into their fundamental absorption components. Its specific interest is to directly account for electronic transition processes[e.g., 3]. The MGM approach is in essence able to achieve a direct detection and quantification of minerals. It is achieved by considering a sum of modified Gaussian functions characterized by their band centers, widths, and intensities. In the following, at the difference of a number of previous studies, the continuum is handled with a second-order polynomial initially adjusted on the local maxima along the reflectance spectrum (curvature, slope, and shift are free to move during the modeling) [4,5,6]. This is achieved by means of three anchor points searched within three spectral windows respectively spanning the intervals: 550-850, 1200-2000, 2300-2600nm. The robustness of modeling is also significantly increased with a set of starting conditions able to address situations ranging from laboratory to orbital data [4,5,6].

For the olivine MGM modeling, a set of 5 dedicated Gaussians (band center, band width, intensity and associated uncertainties) is used. The first Gaussian, centered around 450 nm, is used to model the strong large absorption at shorter wavelength (i.e. charge transfer in ultraviolet). The '650nm' Gaussian, though generally shallow, appears to handle absorptions possibly caused by transitions of minor elements such as Cr, Ni or other charge transfers.

Olivine synthetic samples and spectral processing :

MGM inverse modeling provides with band center, band width and band depth estimates. Band centers are used to determine trend line equations for each individual absorption band M1-1, M2, M1-2, with an assessment on the regression performance (rms spectral distance between band center estimate from MGM and the one from the trend line). The olivine composition (Molar Forsterite Fo#) is then predicted based on minimizing the deviations in band centers from the established trends for the three absorptions simultaneously, using the integrated rms spectral distance to trend quantity (sdt).

Two suites of synthetic olivine samples, with small grain size (<45micron), are available and span the full range of stoichiometric olivine composition along the forsterite-fayalite solid solution series. The first suite is referred to as 'SUNY' (for State University of New York) and comprises 15 samples. The second suite includes 10 samples, prepared at Bristol University and referred to as 'BRISTOL' olivines.

A logical step is to implement our MGM deconvolution on each synthetic suite. The results of the MGM modeling outputs are displayed below for both suites. While for the band widths and strengths (Fig. 1.b), no obvious differences are noticed between the two suites, two trends are clearly found for the band centers (Fig. 1a), with a band center scattering significantly more pronounced for the Bristol suite (see below). For both suites, the scattering associated with the 850nm band center prevails over the 1050 and 1250 band centers ones (see Fig. 1a). Some samples markedly depart, in both suites, from the overall trends and call for caution. We also note that some Bristol samples tend to agree with the Suny trend. Quadratic distances (rms) to trend '850', '1050', '1250' and integrated spectral distance to trend sdt are given hereafter in nm. One obtains 24.4,8.3,7.4, 15.5 nm for the Bristol suite, and 11.5, 5.4, 7.5, 8.5 nm for the Suny suite, respectively. This confirms the larger scattering of the '850nm' band associated with the M1-1 absorption.

Based on these results, and on previous experimental analyses [7], it appears that the Suny suite should be taken as the master list, and possibly completed by Bristol samples to reinforce the robustness of the trend line variations as a function of composition. However, as shown above, in both suites some samples depart from the overall trend. Accordingly, a series of tests is performed on various subsets selected from both Suny and Bristol suites. For each subset of samples, a systematic testing of the coherency is performed to assess the performance of the regression, on the basis of the quantity sdt (more precisely, rsdt: real spectral quadratic distance to trend, associated with Fo#; psdt: predicted spectral quadratic distance to trend, associated with Fô#) and on the standard deviation (rms) associated with the Fo# estimates. The suite composed of 12 samples (9 Suny, 3 Bristol) (see table1), which entirely spans the olivine composition domain from Fo#0 to Fo#90, is found to have the best consistency, in terms of rsdt, psdt and Fo# estimates (rsdt: 6.01nm, psdt: 4.94nm, rms "Fo#-Fô#":0.046). The regression so defined ( Fig. 2) is significantly more robust than either the Bristol (rsdt:15.5nm,psdt:10.9nm, or Suny (rsdt:8.5nm, psdt:5.8nm, rms "Fo#-Fô#":0.087) one considered separately. This way we assess and mitigate, through the statistical consistency of the considered subset, the impact of the 'poor' quality of any given sample/spectrum [2,7] in the regression set to define the trend lines equations. The modeling can be improved for a few spectra by the addition of a couple of bands (2000, 2500nm) to handle minor contaminations. The same regression gives then very consistent results (Fig. 3) for 19 Suny-Bristol spectra (rsdt:6.12nm, psdt:5.49nm, rms "Fo#-Fô#":0.036), the 6 ones discarded being subject to impurities, concerns in the sample preparation or the spectral measurements [2,7]. 2009) Am. Miner.,94,[883][884][885][886][887][888][889][890][891][892][893][894][895][896][897][898] Han, H-J. et al, (2020) Res. Astr. Astroph.,20,129.

Fig. 1

 1 Fig.1.a Band centers from MGM deconvolution for both suites (Symbol x is for "bristol" samples; symbol + is for "suny"ones). Respective regression trend lines are displayed in green (Suny) and red (Bristol).

Fig. 1

 1 Fig. 1.b. Band widths and normalized strengths. (Symbol x is for "bristol" samples; symbol + is for "suny"ones)

Fig. 2 .

 2 Fig. 2. Regression built from 12 samples suite (see table1).

Fig. 3 .

 3 Fig. 3. Results with 19 samples Suny-bristol suite. Conclusions: The trend lines equations derived from the current MGM modeling are more robust than previous solutions [1, 2, 8]. The band center positions of the three primary olivine absorptions (M1-1, M2, M1-2) are used simultaneously to produce a constrained prediction across an extended range Fo#[0-90] of olivine composition with synthetic or natural samples. References: [1] Sunshine J. M. and C. M. Pieters (1998) JGR, 103, 13,675-13,688. [2] Isaacson P.J. et al (2014) Am. Miner., 99, 467-478. [3] Sunshine J.M. et al. (1990) JGR, 95, B5, 6955-6966. [4] Clenet, H. et al. (2011) Icarus, 213, 404-422. [5]Clenet, H. et al.(2013) JGR, 118, doi:10.1002/Jgre.20112. [6] Pinet P.C. et al. (2019) LPSC L, Abstract #1806. [7] Dyar M.D. et al. (2009) Am.Miner., 94,[883][884][885][886][887][888][889][890][891][892][893][894][895][896][897][898] Han, H-J. et al, (2020) Res.Astr. Astroph., 20, 129.

Table 1

 1 Results for the considered 12 Suny-Bristol samples suite.


P C Pinet

Y H Daydou

S D Chevrel

OLIVINE COMPOSITION AND REFLECTANCE SPECTROSCOPY RELATIONSHIP REVISITED

Introduction:

We revisit the behavior of the three primary olivine absorptions near 1 m (referred to as M1-1, M2, M1-2) and their interelationships by means of an advanced version of MGM analysis [1,2]. We build on previous works carried out [e.g., 3,4] to document at best the compositional variation of olivine from diagnostic absorption features across the visible and near-infrared wavelengths due to electronic transitions of Fe2+ in the crystal structure.

Olivine synthetic samples and spectral processing : MGM inverse modeling provides with band center, band width and band depth estimates. Band centers are used to determine trend line equations for each individual absorption band M1-1, M2, M1-2, with an assessment on the regression performance (rms spectral distance between band center estimate from MGM and the one from the trend line). The olivine composition (Molar Forsterite Fo#) is then predicted based on minimizing the deviations in band centers from the established trends for the three absorptions simultaneously, using the integrated rms spectral distance to trend quantity (sdt).

Two suites of synthetic olivine samples, with small grain size (<45micron), are available and span the full range of stoichiometric olivine composition along the forsterite-fayalite solid solution series. The first suite is referred to as 'SUNY' (for State University of New York) and comprises 15 samples. The second suite includes 10 samples, prepared at Bristol University and referred to as 'BRISTOL' olivines.

A logical step is to implement our MGM deconvolution on each synthetic suite. While for the band widths and strengths, no obvious differences are noticed between the two suites, two trends are clearly found for the band centers, with a band center scattering significantly more pronounced for the Bristol suite. For both suites, the scattering associated with the 850nm band center prevails over the 1050 and 1250 band centers ones. Some samples markedly depart, in both suites, from the overall trends and call for caution. We also note that some Bristol samples tend to agree with the Suny trend.

Based on these results, and on previous experimental analyses [5], it appears that the Suny suite should be taken as the master list, and possibly completed by Bristol samples to reinforce the robustness of the trend line variations as a function of composition. However, as shown above, in both suites some samples depart from the overall trend.

Accordingly, a series of tests is performed on various subsets selected from both Suny and Bristol suites. For each subset of samples, a systematic testing of the coherency is performed to assess the performance of the regression, on the basis of the quantity sdt (more precisely, rsdt: real spectral quadratic distance to trend, associated with Fo#; psdt: predicted spectral quadratic distance to trend, associated with Fô#) and on the standard deviation (rms) associated with the Fo# estimates.

A suite composed of 12 samples (9 Suny, 3 Bristol), which entirely spans the olivine composition domain from Fo#0 to Fo#90, is found to have the best consistency, in terms of rsdt, psdt and Fo# estimates (rsdt: 6.01nm, psdt: 4.94nm, rms "Fo#-Fô#":0.046). The regression so defined is significantly more robust than either the Bristol (rsdt:15.5nm, psdt:10.9nm, rms "Fo#-Fô#":0.110) or Suny (rsdt:8.5nm, psdt:5.8nm, rms "Fo#-Fô#":0.087) one considered separately.

This way we assess and mitigate, through the statistical consistency of the considered subset, the impact of the 'poor' quality of any given sample/spectrum [4,5] in the regression set to define the trend lines equations. With the addition for a few spectra of a couple of bands (2000, 2500nm) in the MGM modeling to handle minor contaminations, the same regression gives then very consistent results for 19 Suny-Bristol spectra (rsdt:6.12nm, psdt:5.49nm, rms "Fo#-Fô#":0.036).

Conclusions:

The trend lines equations derived from the current MGM modeling are more robust than previous solutions [3,4,6]. The band center positions of the three primary olivine absorptions (M1-1, M2, M1-2) are used simultaneously to produce a constrained prediction across an extended range Fo#[0-90] of olivine composition with synthetic or natural samples.


H Hiesinger
email: hiesinger@uni-muenster.de

C H Van Der Bogert

A Wedler

R Jaumann

U Mall

J W Head

M Anand

B Jolliff

P Pinet

L Xiao

M Ivanov

B Gundlach

N Schmitz

M Schweitzer

C Bergemann-Mecucci

A Jaime

The Rima Bode Region -Candidate for a Future Lunar Landing Site

Introduction: Much of our knowledge about the history and evolution of the Moon stems from orbital and laboratory analyses of volcanic materials [e.g., 1,2]. Pyroclastics are our best source of information about lunar mantle composition and mineralogy, P/T conditions, and volatiles in the interior [e.g., 3,4]. The volatiles in pyroclastic glasses are also relevant for in situ resource utilization (ISRU) [e.g., 5]. Together with mare basalts that originate from comparatively shallower mantle sources, they provide complementary insights into the three-dimensional structure of the lunar interior. Other magmatic deposits bear clues to the crystallization of the magma ocean (e.g., Mg-suite rocks), relating to the formation and global distribution of KREEP [e.g., 6]. Ages of volcanic deposits, determined via crater sizefrequency distributions (CSFD) and/or radiometric and exposure ages, allow reconstruction of the thermal evolution of the Moon [e.g., 7,8]. Other important questions address the ascent and eruption of magmas and the dichotomy of volcanic deposits between the nearside and farside [e.g., 9]. Evidence for evolved magmas, i.e., domes and silicic pyroclastic deposits is also present on the Moon, providing added key information on the geochemical, mineralogical, and thermal evolution of the Moon [e.g., 10]

Framework: Our mission concept is based on a lander and a rover, which will have similar technical capabilities as other current landers/rovers in terms of surface clearing, slopes, traverse length, etc. For operational simplicity, we restricted our landing site search to areas with continuous visibility of the Earth for direct communication. We favor spatially extensive and geologically diverse landing sites to fully exploit the capabilities of a rover. We envision a 100-200 kg-class rover that can carry a comprehensive suite of instruments and travel several tens of kilometers to return samples to the lander for further in situ studies or sample-return to Earth. The lander could perform ISRU technology demonstrations as well as geophysical measurements (heat flow, seismic, magnetization) and geochemical analyses of samples (e.g., in situ radiometric age determination with a laser ablation resonance ionization mass spectrometer [11]). The rover could carry sampling tools and a suite of instruments (e.g., LIBS, Raman, IR-spectrometer, multispectral stereo camera) to characterize and pre-select interesting samples. A ground-penetrating radar that operates continuously while the rover moves would yield information on the sub-surface regolith structure [12].

Surviving lunar night would enable more in-depth investigations, a larger spatial coverage by the rover, and the opportunity to perform long-term measurements, for example of heat flow or seismic activity. Thus, we envision that both lander and rover are able to survive the lunar night.

Objectives: With our mission concept, we aim to comprehensively study lunar volcanism with respect to timing, spatial distribution, composition, mineralogy, eruption style, volumes, and ISRU potential. Mission goals include deployment of a geophysics package and testing of ISRU technologies. Table 1 summarizes some aspects of our mission concept and also includes a list of potential instruments to achieve goals and objectives.

Landing Site: We present a candidate landing site south of crater Bode C (Fig. 1), which is low risk in terms of rock abundance and slopes. Compared to previous mission proposals to this general area [e.g., 13], we propose a landing site further to the south (11.6°N / 4.7°W) in order to study pyroclastics, mare basalts, and the local regolith, in addition to Eratosthenes and Copernicus ray materials as well as highland material. Along several traverses, the rover could access: 1) pyroclastic deposits (within 13 km distance of the landing site), 2) a fresh crater and a panoramic view of a large crater wall (10 km), 3) high-TiO2 or glass-rich pyroclastic deposits and olivine-rich materials (11 km), 4) a volcanic dome and material from Rima Bode (25 km), 5) highland material (26 km), 6) Copernicus ray material (10 km), 7) low-TiO2 mare basalts (16 km), 8.) a wrinkle ridge (23 km), and 9) exposed underlying plagioclase-rich material and potential layering in a crater wall (19 km).

We estimate that during 1 year of operations, we can travel tens of kilometers and collect tens of kilograms of rock samples either for return to Earth or for in situ analyses on the lander. After landing, we would immediately sample the site vicinity and store a contingency sample in the return canister or feed the analytical instruments on the lander before the rover embarks on its traverses. Although some in situ analyses will be performed, we prefer that the larger part of the samples will be returned to Earth. We consider 1 year of

1485.pdf 52nd Lunar and Planetary Science Conference 2021 (LPI Contrib. No. 2548)

operationality as minimum because our geophysical package (e.g., heat flow, seismometer, magnetometer) will benefit tremendously from longer-period observations. Conclusions: On the basis of our preliminary landing site assessment, we find the region south of crater Bode C to be safe and scientifically of high interest in order to better understand volcanic activity on the Moon. With the capabilities of modern lander/rover (e.g., EL3, VIPER, LUNA, Chang'e), major scientific advancement could be achieved and various techniques of ISRU could be tested in preparation of a human lunar outpost at the Moon. Knowledge gained in both fields, science and exploration, would feed forward into human exploration beyond the Earth/Moon system.


Gale Crater S Le Mouélic

O Gasnault

W Rapin

A B Bryk

W E Dietrich

G Dromart

R C Wiens

G Caravaca

N Mangold

H Newsom

E Dehouck

P Pinet

K E Herkenhoff

Lpg

HOUSEDON HILL -A CHEMCAM RMI MEGA MOSAIC TO INVESTIGATE DISTANT FEATURES IN

Introduction:

The ChemCam Remote Micro-Imager (RMI) onboard Curiosity was originally designed to document the tiny areas analyzed by the instrument's laser-induced breakdown spectroscopy (LIBS) technique on rocks within a few meters around the rover [1,2]. The RMI produces 1024x1024 pixel black and white images directly from ChemCam's telescope focal plane. Early in the mission, it was recognized that, thanks to its powerful optics, RMI could also play a role as a long-distance reconnaissance tool, complementing other cameras on the remote sensing mast, and taking advantage of its very long focal length [3].

The Housedon_Hill long distance imaging experiment: Between sols 2878 and 2921, Curiosity stayed parked at the Mary Anning/Groken site to perform various rock sampling analyses. This opportunity was used to observe distant outcrops of interest and progressively build a very large RMI mosaic, named "Housedon_Hill" after the initial outcrop targeted on sol 2878. In the end, a total of 216 overlapping images were acquired, covering an area ranging from the bottom layers of Mount Sharp to the edge of Vera Rubin Ridge (~50° in azimuth). This product is the largest RMI mosaic acquired in the entire mission. Fig. 1 (top) shows the viewshed of the RMI mega-mosaic, indicated from the rover's imaging location on a CTX orbital mosaic.

Results: Fig. 2 shows the 216 RMI images stitched into a single panorama of 46947 by 7260 pixels, which covers various geologic landforms. A dune field with sand ripples appears at 2 km in the vicinity of Vera Rubin ridge on the leftmost part (Fig. 3). By stretching the contrast of the image in the middle of the panorama above the foreground (which is up to 19 km away), one can recognize in the distance features corresponding to large blocky rocks that rolled partway down from Gale's crater wall (Fig. 1 bottom and Fig. 4). When compared to orbital imagery, these blocks appear to be 59 km from the rovera distance record for a Chem-Cam/RMI observation. This indicates that despite the dust in the atmosphere, which varies significantly during seasons, the sky at this time was clear enough to perform such distant imaging. The images were taken between Ls ~275 and ~302, so during the dust storm season, but in between the two peaks of atmospheric opacity usually observed at Gale (see Fig. 4A in [4]).

Fig. 4: Exposure of layered rocks in the foreground. The hill at the top center is ~20 km away. The light-toned upper background is Gale crater's wall, seen through the hazy atmosphere (see stretched version in Fig. 1).

On the middle and rightmost part of the panorama, a wide variety of layered units, some with crossbedding, illustrates the complex depositional history of the sedimentary rocks comprising Mount Sharp. Fig. 5a shows an example of crossbeddings outcropping ~7 km from the rover. Fig. 5b shows meter-scale laminations revealed on a mesa seen 16 km from the rover. 6 shows a part of the "Marker Bed", with its characteristic irregular thickness and blocky morphology. The "Marker Bed" is a single landform that can be traced across a long distance, allowing long-range correlations across remote areas of the Mount Sharp. This feature extends almost all along its base over tens of kilometers. This darker rocky bed of strata potentially represents a key transition within the ancient depositional environment of the sediments as it marks the upper boundary of the crossbedded interval visible on outcrops such as the one illustrated in Fig. 7.

Fig. 1 :

 1 Fig. 1: Context image of the most distant feature seen in the RMI mosaic. The top image is a global CTX mosaic (source https://mars.nasa.gov/maps/location/?mission=Curiosity). The MSL rover's traverse is indicated in white, and the viewshed of the RMI mega-mosaic is indicated from the rover's imaging location. The white box indicates the location of the zoomed-in panels displayed in the middle. Distant rocks fallen partway down from Gale's crater wall are seen as dark specks in both the CTX and the contrast-stretched inset of the RMI mosaic (bottom) taken from 59 km away.

Fig 3 :

 3 Fig 3: Dune field next to Vera Rubin ridge, 2 km away from the rover. The interval between ripple crests is ~1 m.

Fig 5 :

 5 Fig 5: Example of layering. (a) cross bedding: Layers in the front dip from right to left while the layers in the background dip the other way. (b) This mesa at 16 km shows evidence of fine-meter-scale bedding (arrows).

Fig.

  Fig.6shows a part of the "Marker Bed", with its characteristic irregular thickness and blocky morphology. The "Marker Bed" is a single landform that can be traced across a long distance, allowing long-range correlations across remote areas of the Mount Sharp. This feature extends almost all along its base over tens of kilometers.

Fig. 6 :

 6 Fig. 6: The erosion-resistant lip identified as a "Marker Bed" transition (~9 km away).

Fig. 7 :

 7 Fig. 7: Eroded butte within the lower crossbedded section or transition interval. Conclusion and future work: Imaging areas several kilometers from the rover with RMI provides pictures that are very complementary to orbital observations and gives a more human-like, ground-based perspective. It is particularly useful for steep and subvertical faces that orbital data cannot show well. It also shows higher detail at greater distances than we would otherwise have ever been able to identify with other cameras. RMI imaging provides insights into the morphologic and stratal components of Mount Sharp such as the yardang [5] or the sulfate-bearing unit [6]. Bibliography: [1] Maurice et al., Space Sci. Rev.,170, 95-166, 2012. [2] Wiens et al., Sapce Sci. Rev. 170, 167-227, 2012. [3] Le Mouélic et al., Icarus 249, 93-107, 2015. [4] Moore et al., Icarus 329, 197-206, 2019. [5] Dromart et al., EPSL, 554, 2021. [6] Rapin et al., Geology, in revision.


SSERVI FRENCH NODE 2020 Annual Report

Patrick PINET*

Overall context:

IRAP has become a SSERVI partner, with the official signing on May, 24 th , 2016 of its affiliation to SSERVI, in the presence of Gregory Schmidt (SSERVI Deputy Director, Director of International Partnerships) and Doris Daou (Associate Director), and representatives of the US consulate in Toulouse, as the result of the submission of the proposal 'SSMMAC-France' (Space Studies of the Moon, Mercury, Asteroids and Comets in France) by the Principal Investigator Patrick Pinet (IRAP, Toulouse).

Events, Meetings and Committees:

Though not directly connected to the SSERVi main objectives, IRAP is also heavily committed to Solar Orbiter and Mars-2020/ Perseverance missions, respectively launched successfully on February, 10 th , 2020 and July, 30 th , 2020.

IRAP attended Microsymposium 60 th and LPSC 50 th meetings held in Houston (March, 20 th -24 th , 2019) and met with the SSERVI partners and staff at the EC meeting held on March, 19 th . IRAP also regularly interacted with SSERVI officers and staff in order to prepare and organize the ELS 7 and 8th meetings which occurred respectively, in Manchester (May 2019) and initially Padua (Italy), turned into a virtual online meeting (May 2020) due to the pandemic.

N. André has been appointed member of an ad hoc Science Team by the Human spaceflight and Exploration Science Advisory Committee (HESAC) of ESA in order to prepare a strategy for science at the Moon. P. Pinet is, at the request of ESA, a member of the international Science Definition Team for the Human-Enhanced Robotic Architecture Capability for Lunar Exploration and Science (HERACLES) project. In preparation of the scientific payload of the Deep Space Gateway, I. Dandouras is chairing at ESA a topical team formed to support the definition of payload studies in the field of space plasma physics.

Outreach activities :

On the occasion of the 50 th anniversary of the first man on the Moon (1969Moon ( -2019)), a book(+) on the Apollo Expeditions has been published by S. Chevrel, with a number of related public conferences on the subject.

(+) Chevrel, S., Missions Apollo / Expéditions scientifiques sur la Lune, 471 p., ed. EMPREINTE, Mai 2019.

*with the contributions from N. André, I. Dandouras, J. Lasue, P.Y. Meslin

A few science and projects highlights:

Lunar Orbital Imaging Spectroscopy and Geology:

Laboratory data are used to improve the capability of the MGM (Modified Gaussian Model) to realistically model complex mafic mineralogies and to accurately characterize olivine composition (Pinet et al, 2019[START_REF] Pinet | Olivine Detection and Composition Determination at Copernicus and Eratosthenes Craters[END_REF], with implications for inferring the lunar crust subsurface mineralogy from orbital and/ or in situ visible near-infrared spectroscopy [START_REF] Pinet | The Moon's mantle unveiled[END_REF].

The exploration strategy aims at linking spectral composition (M3: Moon Mineralogy Mapper imaging spectrometer) and morphological features at high resolution (LRO) [START_REF] Chevrel | Large Impact Craters: Linking Spectral Composition (M3) and Morphological Features at High Resolution (LRO)[END_REF] to better constrain the lunar crust lithology and cratering process. It has been tested on a few impact craters (e.g.,Copernicus and Eratosthenes) with the objective of documenting the local/regional petrology through the characterization of exposed outcrops (e.g., central peaks, inner wall, rims or on the floor) from plagioclase and mafic crystal field absorptions [START_REF] Pinet | Olivine Detection and Composition Determination at Copernicus and Eratosthenes Craters[END_REF].

Recently this has also been applied to Zhinyu crater (3.8km in diameter), one of the largest craters within a few tens of kilometers from the Chang'e-4 landing site located in Von Karman crater (186 km in diameter), lying in the northwest of South Pole-Aitken (SPA) basin on the lunar farside and flooded by mare basalts during the Imbrian period. Zhinyu crater is the product of a fresh impact that excavated subsurface, basaltic materials onto the surface. The compositional characteristics of the continuous ejecta around the crater vary radially with distance, suggesting possible mineral heterogeneity at depth. The derived mineral abundances vary radially and discontinuously from the crater rim outwards, forming compositionally distinct annuli. The variations in the mineral olivine and clinopyroxene abundances support the idea that there could be at least three distinct basalt layers within the Von Kármán crater (Gou et al., Icarus, in press).

Lunar Environmment / solar wind / interaction with the terrestrial magnetosphere:

The Moon is a unique location to study the deep space plasma environment, due to the absence of a substantial intrinsic magnetic field and the direct exposure to the solar wind, galactic cosmic rays (GCRs) and solar energetic particles (SEPs). However, 5-6 days each orbit, the Moon crosses the tail of the terrestrial magnetosphere facilitating the in-situ study of the terrestrial magnetotail plasma environment as well as atmospheric escape from the ionosphere (Figure 1). When back outside of the magnetosphere, a variety of these and other phenomena, e.g. those driving solar-terrestrial relationships, can be investigated through remote sensing using a variety of imaging techniques. Most importantly, the lunar environment offers a unique opportunity to study the interaction of the solar wind and the magnetosphere with the lunar surface and the lunar surface-bounded exosphere (Dandouras et al., EGU, 2019;De Keyser et al., European Space Weather Week, 2019;Dandouras, ISSI, 2020).

The Lunar Orbiter Platform -Gateway (or Deep Space Gateway) is an international crewed platform that will be assembled and operated in the vicinity of the Moon in the early 2020s and will offer new opportunities for fundamental and applied scientific research (e.g. Dandouras et al., Space Sci. Rev., 2020). In preparation of the scientific payload of the Lunar Orbiter Platform -Gateway, we formed a team that undertook for ESA a conceptual design study for a Space Plasma Physics Payload Package onboard the Gateway (SP4GATEWAY). The main goal of this study (Dandouras et al., EGU, 2020) has been to provide first a science rationale for hosting space plasma physics instrumentation on the Gateway, and then to proceed to a conceptual payload design addressing these objectives and compatible with the technical requirements (Figure 2). The Gateway modules that are best-suited for placing there the in-situ measurement plasma instruments have been identified following a simulation we performed of the interaction between the Gateway and its plasma environment. The fields-of-view (FOVs) of the remote sensing instruments, as projected on the sky and on the celestial objects, were analysed by simulating their evolution along the Gateway orbit.

ROSETTA:

Rosetta mission ended in late 2016 and IRAP has been involved in the work related to the data analysis and interpretation, with in particular, a significant participation in the dust working group of the mission dedicated to giving a multi-scale multi-instrument review of the properties of dust particles in the coma of 67P/Churyumov-Gerasimenko [START_REF] Levasseur-Regourd | Interpretation through experimental simulations of phase functions revealed by Rosetta in 67P/Churyumov-Gerasimenko dust coma[END_REF][START_REF] Güttler | Synthesis of the morphological description of cometary dust at comet 67P/Churyumov-Gerasimenko[END_REF][START_REF] Lasue | Flattened loose particles from numerical simulations compared to particles collected by Rosetta[END_REF][START_REF] Hoang | Investigating the Rosetta/RTOF observations of comet 67P/Churyumov-Gerasimenko using a comet nucleus model: influence of dust mantle and trapped CO[END_REF]. Finally, J. Lasue participated in the review panel for the public release of the Rosetta end of mission data to the PSA and PDS.

IRAP teams continue their work on exploring the relationship between small bodies (asteroids, comets), the interplanetary dust and exozodiacal dust clouds. These studies are essential to better understand planetary systems formation, especially the optical and thermal properties of the dust particles during their accretionary stage. The focus is put on comparing light scattering properties of dust particles (see Figure 4 below) studied in the Solar System, and observed in exoplanetary disks to better model their properties [START_REF] Lasue | The REgolith Moon ExplOrer (ROMEO) Camera Science Case and Implementation[END_REF]Levasseur-Regourd et al. 2020).

Future lunar and small bodies missions and instruments:

IRAP is currently involved in several missions proposals, with various ongoing collaborations with ESA, NASA, JAXA, CSA and the Chinese Academy of Sciences (CAS)/ Chinese Space Agency (CNSA).

Since 2012, LIBS (Laser-induced Breakdown Spectroscopy) has been successfully used under low atmospheric pressure for exploring the geology of Mars at Gale Crater with the Mars Science Laboratory rover's ChemCam instrument. Laboratory studies performed at IRAP have also demonstrated that LIBS can give accurate and precise results under vacuum conditions. The potential of LIBS for rapid and accurate in situ elemental analysis of lunar materials and characterization of potential resources for future lunar and planetary exploration is currently under study [START_REF] Wiens | Laser-induced breakdown spectroscopy in planetary science[END_REF]. IRAP is collaborating on a NASA PRISM proposal named EUREKA (Exploring Ubiquitous Regolith to Elucidate Kemical Analyses). This rover mission will seek to address outstanding science and in-situ resource utilization (ISRU) questions at Schrödinger Basin on the Moon using LIBS techniques.

IRAP is also participating to the NASA PRISM proposal named CIPS (Carruthers Integrated Payload Suite) led by SwRI and intended to decipher the mysteries of Reiner Gamma Swirl and to understand more of the relationships between magnetic fields, space weathering, maturity, hydration and physical structure of the regolith in the lunar surface environment.

IRAP is also involved in the development of new space cameras based on the CMOS technology. These cameras equip the Perseverance Rover and the SuperCam instrument onboard. These detectors are very versatile and could find their use in many configurations (e.g., Lasue et al., LPSC 2020).

DORN (Detection of Outgassing RadoN) Instrument

Since the early stages of the lunar exploration, radon-222 and its progeny (218Po, 214Po, 210Pb and 210Po) have been identified as key tracers of the present-day lunar seismic and venting activity. Long-term monitoring of the radon cycle on the surface of the Moon would thus provide valuable ground truth for orbital measurements and would help address several key issues related to the transport of lunar volatiles and dust, including the study of the transport of gases through the lunar regolith and of volatiles and dust in the lunar exosphere, the monitoring of the venting activity of the Moon and identification of active outgassing spots. An in situ instrument called DORN (for "Detection of Outgassing RadoN") has been selected to be part of the Chang'e-6 payload and is under construction at IRAP (e.g., [START_REF] Meslin | Radon and Polonium as Tracers of Lunar Outgassing, Volatiles, and Dust: Going Back to the Moon?[END_REF]. It is aimed at measuring both radon and polonium atoms around the lander, and the subsurface flux of radon at the Chang'e-6 landing site. The mission is scheduled to take place in 2023.

Small bodies

IRAP-OMP is involved in the MMX project of the JAXA space agency by actively collaborating in the MMX Infrared Spectrometer (MIRS) French instrument. The MMX mission (Figure 5) will be launched in 2024 to explore the satellite system of Mars, Phobos and Deimos, and more specifically to collect Phobos samples and bring them back to Earth by 2030. MMX will therefore be able to decipher the still debated origin of the Moons of Mars. In particular, MIRS will explore the surface of Phobos, Deimos and Mars in the wavelength range 0.9 to 3.6 μm which includes typical absorption bands for ice (3.0 -3.2 μm) and document the geological context of the collected samples. IRAP is starting laboratory studies to explore how weathering by flash heating may affect the surface spectral behavior of Phobos. ESA has selected its first fast-class mission in June 2019. Comet Interceptor will be the first space mission to be carried out with:

(i) the exploration of a comet newly entered into the inner solar system ("dynamically new comet") or, even if the probability is lower, an object from another solar system.

(ii) multi-point exploration of the environment of a comet The Comet Interceptor mission will indeed include three probes: a mother satellite two daughter satellites which will be launched towards the point of Lagrange L2 with ARIEL in 2028 and will remain in parking lot at the point of Lagrange L2 until the identification, by means of ground observations, of the arrival of a comet newly entered in the system internal solar with a trajectory that can be intercepted by Comet Interceptor.

The European contributions will be on board the parent satellite and one of the daughter satellites, the second daughter satellite being Japanese. IRAP contribution is part of the Dust, Field and Plasma Consortium dedicated to in situ multipoint measurements of ionized and dusty phases as well as of the electromagnetic field in the cometary environment and its interaction with the Sun and the solar wind. IRAP will supply one miniaturized electron analyzer, the Low-Energy Electron Spectrometer (LEES, Figure 6 below) on the mother spacecraft to the consortium with the aim of identifying and measuring the main sources of cometary gas ionization. In 2020 Phase A/B1 of the project has started and a full prototype of the instrument is being built, tested and validated at IRAP, and should be delivered by the end of 2021.

Figure 1 .

 1 Figure 1. Moon's orbit with respect to the Earth's magnetosphere. Earth's and Moon's sizes not to scale.

Figure 2 .

 2 Figure 2. Example of a space plasma physics payload configuration onboard the Gateway studied.

Figure 3 .

 3 Figure 3. Bepi Colombo on its way to Mercury.

Figure 4 .

 4 Figure 4. Comparison between brightness phase dependence for two debris disks and cometary dust. (Levasseur-Regourd et al. 2020).

Figure 5 .

 5 Figure 5. MMX mission of the Japan Space Agency JAXA (credit JAXA).

Figure 6 .

 6 Figure 6. Sketch of the Low-Energy Electron Spectrometer (LEES)