Mise au point d'un systeme d'expression de proteines heterologues chez Streptococcus faecium

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Comparison of orbital and Supercam in situ investigation of the floor Units of Jezero crater

International audienceOn February 18, 2021, NASA’s Mars 2020 Perseverance rover landed successfully on the floor of Jezero crater. Two geological and compositional units had previously been identified from orbital data analysis within the floor of Jezero crater [1,2]: a dark pyroxene-bearing floor unit and an olivine-bearing unit exposed in erosional windows [3]. During the 420 first sols of the mission, the rover has completed an in situ exploration campaign of these two units.The SuperCam instrument contains a suite of techniques including passive spectroscopy in the 0.40-0.85 (VIS) and 1.3-2.6 microns (IR) wavelength ranges, Raman spectroscopy, Laser Induced Breakdown Spectroscopy (LIBS) and a camera providing high resolution context images [4,5]. Since the landing, SuperCam has acquired more than 3 thousands of observations.From orbit the two geological units in the floor of Jezero have distinctive morphology and spectral signature. The crater floor unit called Cf-fr (Crater floor fractured rough) has a pyroxene signature [2] with no clear evidence of alteration.  The unit is laying on the top of the olivine rich unit. The interpretations varied from lacustrine deposits to volcanic deposits. The underlying unit seems to be part of the regional olivine-rich deposits with parts altered into carbonates and clays [1,6]. Interestingly, this regional olivine rich unit has a unique spectral signature on Mars, an effect of either grain size or composition [7]. Many hypotheses have been suggested: Isidis impact related ejectas layer [8], pyroclastic deposits [i.e. 6] or clastics deposits [9].   In situ, we discovered that the Cf-fr, composed of different sub-units is not layered, composed of grainy rocks, dominated by plagioclase and Fe-rich pyroxenes [10] with a restricted but pervasive multistage [10]. From in situ data, Maaz is interpreted lava flows [11, 12] emplaced before the last lacustrine activity associated with the main western delta fan. Below the cf-fr, Seitah occurs as layered Mg-olivine rich rocks generally flat but slightly plunging below Maaz on the edges. The rocks are dominated by mm grains of pristine Olivine and some pyroxenes [10, 13, 14] .  The various spectroscopic methods detected alteration phases such as Mg- phyllosilicate and Mg Carbonates. [15, 16]. The rock texture and petrology of Seitah were interpreted as an olivine cumulate with limited alteration.Lessons learned from this in situ campaign will be presented such as how accurate are the orbital spectral analyses, the morphological analysis and how to transfer the results of Jezero to the other places on Mars investigate by orbital data only

Mafic chemistry and mineralogy (including olivine) of the coarse-grained regolith analyzed by SuperCam at Jezero crater, Mars

International audienceOn February 18, 2021 NASAs Perseverance rover landed in Jezero Crater where the floor consists of various rock lithologies and abundant regolith. Using the rovers imagery and the LIBS and VISIR spectroscopies from SuperCam, we focus on the chemistry and mineralogy of coarse-grained regolith. Such regolith has been observed all along the rover traverse since the landing: it is widespread either on flat surfaces/rocks or in aeolian ripples. This coarse regolith is composed of rounded granules rather homogeneous in size (~1-2 mm), shape (nearly isotropic) and color. Some VISIR spectra are highly consistent with the presence of olivine in the regolith. No hydration band is detected, and no H is detected by LIBS, suggesting that this olivine is rather pristine. SuperCam LIBS has a laser spot size of 300 mm and is operated by performing rasters of up to 10 sampling points, each accumulating up to 50 laser shots. Combining high-resolution RMI images with microphone recordings during the laser shots, we can assess whether the LIBS laser sampled dust/fine sand or granules during the shot series, and if the laser significantly ablates a granule. Careful analysis of the LIBS spectra and derived chemical compositions, including comparison with data from calibration targets and shot to shot variability, reveal the presence at the LIBS spot size of (i) olivine only, (ii) olivine and andesine mixtures, and (iii) other assemblages including the former and/or other minerals such as pyroxenes. Most olivine grains are Fo# 60-75, but locally some grains may be lower Fo#; they all exhibit low content of Cr and Mn, Ni is below detection limit. Interestingly, this coarse regolith displays a different chemistry and mineralogy compared to the surrounding rocks raising questions about its provenance. The rover is currently making its way toward the adjacent Seitah unit which is a possible source as it may contain olivine based on orbital data. There are also some differences in composition between these granules and the finer fractions of the regolith. All these data will be compared to orbital data and observations by Curiosity on similar coarse-grained regolith at Gale crater. They will also be discussed in light of knowledge from Martian meteorites to place constraints on the formation of olivine and magmatic processes on Mars

Mafic chemistry and mineralogy (including olivine) of the coarse-grained regolith analyzed by SuperCam at Jezero crater, Mars

International audienceOn February 18, 2021 NASAs Perseverance rover landed in Jezero Crater where the floor consists of various rock lithologies and abundant regolith. Using the rovers imagery and the LIBS and VISIR spectroscopies from SuperCam, we focus on the chemistry and mineralogy of coarse-grained regolith. Such regolith has been observed all along the rover traverse since the landing: it is widespread either on flat surfaces/rocks or in aeolian ripples. This coarse regolith is composed of rounded granules rather homogeneous in size (~1-2 mm), shape (nearly isotropic) and color. Some VISIR spectra are highly consistent with the presence of olivine in the regolith. No hydration band is detected, and no H is detected by LIBS, suggesting that this olivine is rather pristine. SuperCam LIBS has a laser spot size of 300 mm and is operated by performing rasters of up to 10 sampling points, each accumulating up to 50 laser shots. Combining high-resolution RMI images with microphone recordings during the laser shots, we can assess whether the LIBS laser sampled dust/fine sand or granules during the shot series, and if the laser significantly ablates a granule. Careful analysis of the LIBS spectra and derived chemical compositions, including comparison with data from calibration targets and shot to shot variability, reveal the presence at the LIBS spot size of (i) olivine only, (ii) olivine and andesine mixtures, and (iii) other assemblages including the former and/or other minerals such as pyroxenes. Most olivine grains are Fo# 60-75, but locally some grains may be lower Fo#; they all exhibit low content of Cr and Mn, Ni is below detection limit. Interestingly, this coarse regolith displays a different chemistry and mineralogy compared to the surrounding rocks raising questions about its provenance. The rover is currently making its way toward the adjacent Seitah unit which is a possible source as it may contain olivine based on orbital data. There are also some differences in composition between these granules and the finer fractions of the regolith. All these data will be compared to orbital data and observations by Curiosity on similar coarse-grained regolith at Gale crater. They will also be discussed in light of knowledge from Martian meteorites to place constraints on the formation of olivine and magmatic processes on Mars

Mafic chemistry and mineralogy (including olivine) of the coarse-grained regolith analyzed by SuperCam at Jezero crater, Mars

International audienceOn February 18, 2021 NASAs Perseverance rover landed in Jezero Crater where the floor consists of various rock lithologies and abundant regolith. Using the rovers imagery and the LIBS and VISIR spectroscopies from SuperCam, we focus on the chemistry and mineralogy of coarse-grained regolith. Such regolith has been observed all along the rover traverse since the landing: it is widespread either on flat surfaces/rocks or in aeolian ripples. This coarse regolith is composed of rounded granules rather homogeneous in size (~1-2 mm), shape (nearly isotropic) and color. Some VISIR spectra are highly consistent with the presence of olivine in the regolith. No hydration band is detected, and no H is detected by LIBS, suggesting that this olivine is rather pristine. SuperCam LIBS has a laser spot size of 300 mm and is operated by performing rasters of up to 10 sampling points, each accumulating up to 50 laser shots. Combining high-resolution RMI images with microphone recordings during the laser shots, we can assess whether the LIBS laser sampled dust/fine sand or granules during the shot series, and if the laser significantly ablates a granule. Careful analysis of the LIBS spectra and derived chemical compositions, including comparison with data from calibration targets and shot to shot variability, reveal the presence at the LIBS spot size of (i) olivine only, (ii) olivine and andesine mixtures, and (iii) other assemblages including the former and/or other minerals such as pyroxenes. Most olivine grains are Fo# 60-75, but locally some grains may be lower Fo#; they all exhibit low content of Cr and Mn, Ni is below detection limit. Interestingly, this coarse regolith displays a different chemistry and mineralogy compared to the surrounding rocks raising questions about its provenance. The rover is currently making its way toward the adjacent Seitah unit which is a possible source as it may contain olivine based on orbital data. There are also some differences in composition between these granules and the finer fractions of the regolith. All these data will be compared to orbital data and observations by Curiosity on similar coarse-grained regolith at Gale crater. They will also be discussed in light of knowledge from Martian meteorites to place constraints on the formation of olivine and magmatic processes on Mars

Analysis of potential surface coatings in Jezero crater by SuperCam on the Perseverance rover

International audienceThe NASA Perseverance Mars rover has been exploring Jezero crater since February 2021. During that time, several rocks with potential coatings were observed. Rock coatings can record the interactions of rock surfaces with atmosphere, regolith, and water, and are important targets for understanding environmental conditions. The SuperCam instrument uses multiple analytical techniques including Laser-Induced Breakdown Spectroscopy (LIBS), a microphone for obtaining acoustic data from the LIBS shockwave, remote micro-imagery (RMI), visible-near infrared (VISIR), Raman, and luminescence spectroscopy. On sols 75-83, SuperCam analyzed a flat paver rock called Nataani that appeared to have a dusty surface with shiny, dark-toned material underneath and ~cm-sized spots of splotchy coating. An initial 10-point LIBS raster with 30 laser pulses per point indicated a potential systematic change in composition with depth, a known signature of coatings and thin layers. To investigate this further, the team conducted two depth profile LIBS rasters consisting of 5-point LIBS rasters with 150 laser pulses per location to sample deeper into the rock. Two additional locations were analyzed with co-located LIBS, Raman, and VISIR. Acoustics data were also collected during the LIBS depth profile analyses. LIBS chemistry data indicate the surface may be relatively enriched in Mg, Mn, Cr, and possibly H, whereas the interior was relatively enriched in Si, Al, and Sr. Notably, the acoustic data did not show a systematic change in amplitude with depth; this suggests that the surface and interior materials had similar material properties, i.e. hardness, optical, and thermal properties. Raman spectra suggested the presence of amorphous silica but due to SuperCams long optical fiber, which also produces a weak signature of amorphous silica, this feature could not be clearly attributed to Nataani. VISIR spectra exhibit a feature attributable to H2O at 1.9 microns, similar to other targets in Jezero. Due to their larger spot sizes relative to LIBS, the fields of view for both Raman and VISIR may contain some signal from dust and/or uncoated rock. Efforts to better understand these signatures, including collection of additional LIBS and acoustics data on similar martian rocks and terrestrial analogs, are ongoing

Analysis of potential surface coatings in Jezero crater by SuperCam on the Perseverance rover

International audienceThe NASA Perseverance Mars rover has been exploring Jezero crater since February 2021. During that time, several rocks with potential coatings were observed. Rock coatings can record the interactions of rock surfaces with atmosphere, regolith, and water, and are important targets for understanding environmental conditions. The SuperCam instrument uses multiple analytical techniques including Laser-Induced Breakdown Spectroscopy (LIBS), a microphone for obtaining acoustic data from the LIBS shockwave, remote micro-imagery (RMI), visible-near infrared (VISIR), Raman, and luminescence spectroscopy. On sols 75-83, SuperCam analyzed a flat paver rock called Nataani that appeared to have a dusty surface with shiny, dark-toned material underneath and ~cm-sized spots of splotchy coating. An initial 10-point LIBS raster with 30 laser pulses per point indicated a potential systematic change in composition with depth, a known signature of coatings and thin layers. To investigate this further, the team conducted two depth profile LIBS rasters consisting of 5-point LIBS rasters with 150 laser pulses per location to sample deeper into the rock. Two additional locations were analyzed with co-located LIBS, Raman, and VISIR. Acoustics data were also collected during the LIBS depth profile analyses. LIBS chemistry data indicate the surface may be relatively enriched in Mg, Mn, Cr, and possibly H, whereas the interior was relatively enriched in Si, Al, and Sr. Notably, the acoustic data did not show a systematic change in amplitude with depth; this suggests that the surface and interior materials had similar material properties, i.e. hardness, optical, and thermal properties. Raman spectra suggested the presence of amorphous silica but due to SuperCams long optical fiber, which also produces a weak signature of amorphous silica, this feature could not be clearly attributed to Nataani. VISIR spectra exhibit a feature attributable to H2O at 1.9 microns, similar to other targets in Jezero. Due to their larger spot sizes relative to LIBS, the fields of view for both Raman and VISIR may contain some signal from dust and/or uncoated rock. Efforts to better understand these signatures, including collection of additional LIBS and acoustics data on similar martian rocks and terrestrial analogs, are ongoing