Laboratoire Interuniversitaire des Systèmes Atmosphériques
Présentation
Le LISA, Laboratoire Interuniversitaire des Systèmes Atmosphériques est une unité de recherche de structure originale dépendant des Universités Paris Est Créteil et Paris Diderot, et du CNRS (UMR CNRS 7583).
Le LISA compte environ 130 personnes, dont 50 enseignants-chercheurs et chercheurs (CNRS & IRD), 36 ITA-IATOS et environ 45 post-doctorants, doctorants et étudiants de Master.
Il dispose d'un important potentiel technique et expérimental réparti sur 3.600m2 de locaux à Créteil et d'une antenne opérationnelle sur le site Paris Rive Gauche, incluant aussi des équipements lourds. Les recherches y sont développées autour d’un thème générale : l’Atmosphère (comme le nom du laboratoire l’indique), Ses principaux thèmes de recherche portent ainsi sur la compréhension du fonctionnement des atmosphères terrestres et planétaires, et des impacts liés à la modification de la composition de l'atmosphère par les activités humaines. Les méthodes utilisées sont fondées sur des observations en atmosphère réelle, sur de la simulation expérimentale en laboratoire et de la modélisation numérique.
Pour mener à bien ces recherches, le LISA regroupe des scientifiques de plusieurs disciplines : physiciens, géochimistes, environnementalistes et une majorité de chimistes. Ce dernier aspect est une de ses caractéristiques importantes par rapport aux autres laboratoires du domaine. Un département technique (doté de 4 pôles : chimie, instrumentation, terrain et informatique) et un département administratif sont en soutien des activités de recherche.
Thèmes de recherche
- Pollution atmosphérique Oxydante et Particulaire
- Devenir du Carbone Organique
- Cycle de l’Aérosol Désertique
- Spectroscopie et Atmosphères
- Exobiologie et Astrochimie
[hal-01238192] Volatile and Organic Compositions of Sedimentary Rocks in Yellowknife Bay, Gale Crater, Mars
Date: 22 4 月 2021 - 15:11
Desc: H<sub>2</sub>O, CO<sub>2</sub>, SO<sub>2</sub>, O<sub>2</sub>, H<sub>2</sub>, H<sub>2</sub>S, HCl, chlorinated hydrocarbons, NO, and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H<sub>2</sub>O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO<sub>2</sub>. Concurrent evolution of O<sub>2</sub> and chlorinated hydrocarbons suggests the presence of oxychlorine phase(s). Sulfides are likely sources for sulfur-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic carbon sources may be preserved in the mudstone; however, the carbon source for the chlorinated hydrocarbons is not definitively of martian origin.
[hal-01815575] Possible Detection of Nitrates on Mars by the Sample Analysis at Mars (SAM) Instrument
Date: 14 6 月 2018 - 12:56
Desc: Introduction: Planetary models suggest that nitrogen was abundant in the early Martian atmosphere as dinitrogen (N 2). However, it has been lost by sputtering and photochemical loss to space [1, 2], impact erosion [3], and chemical oxidation to nitrates [4]. Nitrates , produced early in Mars' history, are later decomposed back into N 2 by the current impact flux [5], making possible a nitrogen cycle on Mars. It is estimated that a layer of about 3 m of pure NaNO 3 should be distributed globally on Mars [5]. Nitrates are a fundamental source for nitrogen to terrestrial microorganisms. Therefore, the detection of soil nitrates is important to assess habitability in the Martian environment. The only previous mission that was designed to search for soil nitrates was the Phoenix mission but was unable to detect evolved N-containing species by TEGA and the MECA WCL [6]. Nitrates have been tentatively identified in the Nakhla meteorite [7]. The purpose of this work is to determine if nitrates were detected in first solid sample (Rocknest) in Gale Crater examined by the SAM instrument. Materials and Methods: Samples collected from Rocknest, located in Gale Crater, which consists of an inactive, sandy wind drift mantled with dust, were analyzed by the SAM instrument. Prior to sample analysis, a blank was run using an empty quartz cup to characterize the background of the SAM instrument. The quartz cup was sealed inside the pyrolysis oven and heated to ~840°C at a rate of 35°C/min under a He carrier gas flow rate of 1.5 cm 3 /min and at an oven pressure of ~30 mbar. A small fraction of the gas released from the cup was measured directly by electron impact quadrupole mass spectrometry (QMS mass range 2-535 Da, resolution 0.1 Da). Then four samples of Rocknest bedform materials < 150 μm diameter size fraction (~20 mg) were examined by SAM. A thermal analyzer (Netzsch STA 449 F1 Jupiter Simultaneous TG/DSC) coupled to a mass spectrometer (Netzsch QMS 403 C Aeolos) was used in the laboratory to heat samples upto 1200°C at a rate of 20°C/min under a He
[hal-01815627] Detection of Nitric Oxide by the Sample Analysis at Mars (SAM) Instrument. Implications for the Presence of Nitrates
Date: 14 6 月 2018 - 13:24
Desc: One of the main goals of the Mars Science Laboratory is to determine whether the planet ever had environmental conditions able to support mi-crobial life. Nitrogen is a fundamental element for life, and is present in structural (e.g., proteins), catalytic (e.g., enzymes and ribozymes), energy transfer (e.g.,ATP) and information storage (RNA and DNA) bio-molecules. Planetary models suggest that molecularnitrogen was abundant in the early Martian atmosphere, but was rapidly lost to space by photochemistry, sput-tering [1, 2], impact erosion [3], and oxidized and de-posited to the surface as nitrate [4]. Nitrates are a fun-damental source for nitrogen to terrestrial microorgan-isms. Therefore, the detection of nitrates in soils and rocks is important to assess the habitability of a Mar-tian environment. SAM is capable of detecting nitrates by their thermal decomposition into nitric oxide, NO [5]. Here we analyze the release of NO from soils and rocks examined by the SAM instrument at Gale crater, and discuss its origin.
[hal-00694758] The Sample Analysis at Mars Investigation and Instrument Suite
Date: 14 1 月 2020 - 20:01
Desc: The Sample Analysis at Mars (SAM) investigation of the Mars Science Laboratory (MSL) addresses the chemical and isotopic composition of the atmosphere and volatiles extracted from solid samples. The SAM investigation is designed to contribute substantially to the mission goal of quantitatively assessing the habitability of Mars as an essential step in the search for past or present life on Mars. SAM is a 40 kg instrument suite located in the interior of MSL's Curiosity rover. The SAM instruments are a quadrupole mass spectrometer, a tunable laser spectrometer, and a 6-column gas chromatograph all coupled through solid and gas processing systems to provide complementary information on the same samples. The SAM suite is able to measure a suite of light isotopes and to analyze volatiles directly from the atmosphere or thermally released from solid samples. In addition to measurements of simple inorganic compounds and noble gases SAM will conduct a sensitive search for organic compounds with either thermal or chemical extraction from sieved samples delivered by the sample processing system on the Curiosity rover's robotic arm.
[insu-01303895] Effect of the presence of chlorates and perchlorates on the pyrolysis of organic compounds: implications for measurements done with the SAM experiment onboard the Curiosity rover
Date: 18 4 月 2016 - 18:24
Desc: The Sample Analysis at Mars (SAM) experiment onboard the Curiosity rover of the Mars Science Laboratory mission is partly devoted to the in situ molecular analysis of gases evolving from solid samples collected on Mars surface/sub-surface. SAM has a gas-chromatograph coupled to a quadrupole mass spectrometer (GC-QMS) devoted to the separation and identification of organic and inorganic material [1]. Before proceeding to the GC-QMS analysis, the solid sample collected by Curiosity is subjected to a thermal treatment thanks to the pyrolysis oven to release the volatiles into the gas processing system. As the Viking landers in 1976 [2], SAM detected chlorohydrocarbons with the pyrolysis GC-QMS experiment [3,4]. The detection of perchlorates salts in soil at the Phoenix Landing site [6] suggests that these chloro- hydrocarbons could come from the reaction of organics with oxychlorines. Oxychlorines indeed decomposed into molecular oxygen and volatile chlorine when heated and react with the organic matter in the samples by oxidation and/or chlorination processes. [3,5,7,8]. During SAM pyrolysis, samples are heated to 850◦C. SAM detected C1 to C3 chloroalkanes, entirely attributed to reaction products occurring during the pyrolysis experiment between oxychlorines and organic carbon from instrument background [3] and chlorobenzene and C2 to C4 dichloroalkanes produced by reaction between Mars endogenous organics with oxychlorines [4]. To help understanding the influence of perchlorate and chlorate salts on organic matter during SAM pyrolysis, we systemically study the reaction products formed during pyrolysis of various organic compounds mixed with various perchlorates and chlorates. We selected organics from simple molecule forms as for instance PAHs and amino acids to complex material (>30 carbon atoms) such as kerogen. The perchlorate and chlorate salts are prepared at 1 wt % concentration in silica and mixed with the organics to study the potential qualitative and/or quantitative effects. The experiments are performed on a laboratory GC-QMS with a Restek Rxi-5 column (30m x 0.25mm x 0.25μm) and an Intersciences pyrolyser. The mixture is pyrolyzed at different temperatures up to 900◦C to cover the SAM temperature range. Different experiments are done to discriminate the pyrolysis products directly coming from the organics, and those produced from the reaction with oxychlorine. These experiments are under progress and should bring key information on the potential to identify Martian organics when pyrolyzing solid samples. Depending on the organic families studied, we may find recurring molecules, which are potentially present in Mars’ surface samples. This work could thus highlight some organic precursors of the chlorinated compounds found on Mars, and support the interpretation of SAM measurements.
Autres contacts
Direction du LISA
Maison des Sciences de l’Environnement 4ème étage
UPEC Campus Centre
61, avenue du Général de Gaulle
94010 CRETEIL CEDEX
contact@lisa.u-pec.fr / 01.45.17.15.60