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-02344283] The potential science and engineering value of samples delivered to Earth by Mars sample return
Date: 6 11 月 2019 - 09:24
Desc: Return of samples from the surface of Mars has been a goal of the international Mars science community for many years. Affirmation by NASA and ESA of the importance of Mars exploration led the agencies to establish the international MSR Objectives and Samples Team (iMOST). The purpose of the team is to re-evaluate and update the sample-related science and engineering objectives of a Mars Sample Return (MSR) campaign. The iMOST team has also undertaken to define the measurements and the types of samples that can best address the objectives. Seven objectives have been defined for MSR, traceable through two decades of previously published international priorities. The first two objectives are further divided into sub-objectives. Within the main part of the report, the importance to science and/or engineering of each objective is described, critical measurements that would address the objectives are specified, and the kinds of samples that would be most likely to carry key information are identified. These seven objectives provide a framework for demonstrating how the first set of returned Martian samples would impact future Martian science and exploration. They also have implications for how analogous investigations might be conducted for samples returned by future missions from other solar system bodies, especially those that may harbor biologically relevant or sensitive material, such as Ocean Worlds (Europa, Enceladus, Titan) and others.
[hal-00669087] Interpretation of COSAC mass spectrometer data acquired during Rosetta's Lutetia fly-by 10 July 2010
Date: 11 2 月 2012 - 10:16
Desc: On 10 July 2010 the Rosetta spacecraft flew-by asteroid Lutetia. At that time all the mass spectrometers in the payload of the Philae Lander capable of gas analysis were in operation. Among these, the COSAC (Cometary Sampling and Composition) experiment is a gas-chromatograph mass spectrometer which was switched on twice during the fly-by, once three hours prior to Closest Approach for 126 sec and one hour afterwards for 126 sec. The instrument performed well and two mass spectra were obtained from which the composition of the gas phase was evaluated. These spectra show no evidence of the presence of an exosphere at Lutetia. The most likely interpretation of the records is that traces of residual gas from Philae and from COSAC itself were recorded, with a slight change in composition between the two measurements. A mean upper pressure limit inside COSAC derived from the two measurements is of the order of 5×10<sup>−9</sup> mbar. This is the highest limit quoted by the various onboard instruments but is explicable in the context that COSAC was designed to operate in environments characterized by relatively higher pressure.
[hal-00867867] Evaluating the robustness of the enantioselective stationary phases on the Rosetta mission against space vacuum vaporization
Date: 30 9 月 2013 - 16:50
Desc: The European Space Agency's Rosetta mission was launched in March 2004 in order to reach comet 67P/Churyumov-Gerasimenko by August 2014. The Cometary Sampling and Composition experiment (COSAC) onboard the Rosetta mission's lander "Philae" has been designed for the cometary in situ detection and quantification of organic molecules using gas chromatography coupled to mass spectrometry (GC-MS). The GC unit of COSAC is equipped with eight capillary columns that will each provide a specific stationary phase for molecular separation. Three of these stationary phases can be used to chromatographically resolve enantiomers, as they are composed of liquid polymers of polydimethylsiloxane (PDMS) to which chiral valine or cyclodextrin units are attached. Throughout the ten years of Rosetta's journey through space to reach comet 67P, these liquid stationary phases have been exposed to space vacuum, as the capillary columns within the COSAC unit were not sealed or filled with carrier gas. Long term exposures to space vacuum can cause damage to such liquid stationary phases as key monomers, volatiles, and chiral selectors can be vaporized and lost in transit. We have therefore exposed identical spare units of COSAC's chiral stationary phases over eight years to vacuum conditions mimicking those experienced in space and we have now investigated their resolution capabilities towards different enantiomers both before and after exposure to space vacuum environments. We have observed that enantiomeric resolution capabilities of these chiral liquid enantioselective stationary phases has not been affected by exposure to space vacuum conditions. Thus we conclude that the three chiral stationary phases of the COSAC experiment onboard the Rosetta mission lander "Philae" can be considered to have maintained their resolution capacities throughout their journey prior to cometary landing in November 2014.
[hal-03835531] Gas chromatography for in situ analysis of a cometary nucleus: IV. Study of capillary column robustness for space application
Date: 31 10 月 2022 - 18:42
Desc: As part of the development of the European Space Agency Rosetta space mission to investigate a cometary nucleus, the selection of columns dedicated to the gas chromatographic subsystem of the Cometary Sampling and Composition (COSAC) experiment was achieved. Once the space probe launched, these columns will be exposed to the harsh environmental constraints of space missions: vibrations, radiation (by photons or energetic particles), space vacuum, and large temperature range. In order to test the resistance of the flight columns and their stationary phases, the columns were exposed to these rough conditions reproduced in the laboratory. The comparison of the analytical performances of the columns, evaluated prior and after the environmental tests, demonstrated that all the columns withstand space constraints, and that their analytical properties were preserved. Therefore, all the selected capillary columns, even having porous layer or chiral stationary phases, were qualified for space exploration.
[hal-01452008] Decay of COSAC and Ptolemy mass spectra at comet 67P/Churyumov-Gerasimenko
Date: 22 11 月 2019 - 16:03
Desc: The Rosetta lander Philae successfully landed on the nucleus of comet 67P/Churyumov-Gerasimenko on 12 November 2014. Philae is equipped with two gas analyzers: The Cometary Sampling and Composition experiment (COSAC) and the gas chro- matograph and mass spectrometer Ptolemy. COSAC is designed for in situ analysis of organic molecules on 67P while Ptolemy is optimised to measure ratios of stable isotopes. On 12 to 14 November 2014 both instruments measured the organic composition of the comet nucleus material through seven measurements in sniffing mode during Philae’s hopping and at its final landing site Abydos. We compare the temporal evolution of intensities of several ion species identified by both mass spectrometers. For COSAC this is the first analysis of the temporal behaviour of the measured ion species. All ion species showed the highest intensities in the first spectra measured by both instruments about 20 to 30 minutes after Philae’s first touchdown at Agilkia, and a decay during the six consecutive measurements at Abydos. Both instruments measured a nearly identical decay of the water peak (m/z 18), and also CO (m/z 28) behaved similarly. In the COSAC measurements the peak at m/z 44 decays much slower than all the other ion species, including the water peak. In particular, the m/z 44 peak decays much slower in the COSAC measurements than in the Ptolemy data. This supports our earlier interpretation that COSAC for the first time analyzed a regolith sample from a cometary nucleus in situ, while Ptolemy measured cometary gas from the ambient coma. The m/z 44 peak measured by COSAC was likely dominated by organic species, whereas the peak measured by Ptolemy was interpreted to be mostly due to CO<sub>2</sub>. Ion species heavier than m/z 30 tend to decay somewhat slower in the COSAC measurements than in the Ptolemy data, which may be related to differences in the exhaust designs between both instruments.
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