6 results on '"Evdokimova, Daria"'
Search Results
2. Long-Endurance Mars Exploration Flying Vehicle: A Project Brief.
- Author
-
Karpovich, Elena, Kombaev, Timur, Gueraiche, Djahid, Evdokimova, Daria, and Alexandrov, Kirill
- Subjects
MARTIAN exploration ,COMPUTER input design ,MARTIAN atmosphere ,MARTIAN surface ,REQUIREMENTS engineering - Abstract
The paper presents specifications for the Long-Endurance Mars Exploration Flying Vehicle (LEMFEV), which will be used as future design input data. The specifications are based on the analysis of previous Mars missions and scientific data collected by the operating Martian probes. The design specifications include the requirements related to the airplane's delivery to the Martian surface; the requirements related to the Martian conditions (atmosphere and climate); and the requirements related to the scientific payload parameters and the mission flight profile. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
3. Study of minor species in the Venus night mesosphere
- Author
-
Evdokimova, Daria, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Université Paris-Saclay, Space Research Institute of the Russian Academy of Sciences (IKI), Franck Montmessin, Denis Belyaev, and STAR, ABES
- Subjects
[SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology ,Atmosphere ,[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,[SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,Spectroscopie ,[SDU.STU.PL] Sciences of the Universe [physics]/Earth Sciences/Planetology ,[PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph] ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,Spectroscopy ,Composition - Abstract
Chemical processes of the dense CO2-atmosphere of Venus are determined by trace gases such as SO2, O3, H2O, CO, etc. Among these atmospheric components, a group of sulfur and oxygen compounds occupies a central position. The objective of this thesis is a study of sulfur dioxide and ozone at the night side of Venus' upper mesosphere that is related to altitudes from 85 to 110 km. Chemistry and dynamics of this altitude range is very active. The sulfuric chemical cycle in the mesosphere leads to a formation of the thick cloud deck at 47-70 km globally enshrouding the planet. Furthermore, it has not yet been determined exactly which chemical interactions are responsible for stabilizing the equilibrium in the chemical cycles of the atmosphere, and maintaining a high mixing ratio of CO2. The difficulty of evaluating the oxidizing capacity of the atmosphere, due to the lack of direct measurements of the amount of molecular oxygen, is one reason for this. However, indirect O2 estimations can be made based on derivatives of this molecule, and one of them is ozone. This gas is involved in reactions with species, probably mainly chlorinated compounds, leading to the general chemical cycles.The research is based on the data obtained from the first stellar occultation experiment released for Venus. It was performed by the UV channel of the SPICAV spectrometer onboard Venus Express orbiter working in 2006-2014. This is a powerful instrument to measure absorption of CO2, SO2 and O3 at the night side of Venus’ atmosphere above the cloud layer. This study also includes a detailed assessment of the accuracy of the spectral data processing methods used to retrieve vertical atmospheric gas concentration distributions. Mainly it concerns a separation of a stellar light from UV emission signal originated from different spread sources, which is a parasitic light for the stellar occultation data investigation. A significant influence of a calibration assignment of wavelength to a digital pixel number was obtained. The required accuracy was achieved by a determination of stellar lines position for a large set of stars' spectra measuring in each observational session. Thus, it allowed to establish a profile of the SO2 content from 85 km to 100 km mainly devoted to mid-latitudinal range. On average, it shows a stable mixing ratio with altitude. For this gas, a prevailed short-period variability has been confirmed. However, a weak possible increase of SO2 abundance with local time is noticed from the morning to the evening terminator at 90-95 km. After the discovery of the ozone layer on Venus made by Montmessin et al. (2011), the ozone content was confirmed in more than 100 occultation sessions. The current study also shows that the detected ozone values correspond to its maximum values rather than to the thick stable layer. These results are the first detailed vertical distribution of the SO2 and O3 content in the upper mesosphere on the night side, which opens up new possibilities for the theoretical description of processes occurring in the atmosphere of Venus., Les processus chimiques de l'atmosphère dense de CO2 de Vénus sont contrôlés par des gaz à traces tels que SO2, O3, H2O, CO, etc. Parmi ces composants atmosphériques, un groupe de composés soufrés et oxygènés occupe une place centrale.L'objectif de cette thèse concerne l'étude du dioxyde de soufre et de l'ozone présents du côté nuit de la haute mésosphère de Vénus entre 85 et 110 km d’altitude. La chimie et la dynamique sont très actives dans cette région et le cycle chimique du soufre dans cette région conduit à la formation de l’épaisse couche nuageuse entre 47 et 70 km d’altitude tout autour de la planète. En outre, on n'a pas encore déterminé exactement quelles interactions chimiques étaient responsables de l'équilibre sur le long terme du CO2. Une réelle difficulté subsiste en effet quant à notre capacité à évaluer la capacité d'oxydation de l'atmosphère vénusienne, du fait de l'absence de mesures directes de la quantité d'oxygène moléculaire. Cependant, des estimations indirectes de l'O2 peuvent être faites sur la base des dérivés de cette molécule, dont l'un en particulier est l'ozone. On s’attend à ce que l’ozone soit impliqué dans des réactions avec des espèces principalement chlorées très présentes sur Vénus.Mon travail de recherche est basé sur les données obtenues par le canal UV du spectromètre SPICAV à bord de l'orbiteur Venus Express qui a opéré entre 2006 et 2014. SPICAV est un instrument particulièrement bien adapté à la mesure de CO2, SO2 et O3 du côté nuit de l'atmosphère de Vénus au-dessus de la couche nuageuse. Mon étude comprend également une ré-évaluation détaillée de la précision des méthodes de traitement des données spectrales employées jusqu’alors pour déterminer les distributions verticales de la concentrations de gaz dans l'atmosphère. Il s'agit principalement d'une séparation entre la lumière d’une étoile utilisée pour la mesure et celle d’émissions UV provenant de différentes sources, que l’on considère comme parasitant l’interprétation des données obtenues lors des occultations stellaires. Une influence très forte de la calibration en longueur d'onde a pu être mise en évidence, et a abouti à une modification de la technique de calibration se basant sur la comparaison de la position des raies stellaires avec une base de données de référence. Ainsi, cela a permis d'établir des profils de SO2 de 85 km à 100 km principalement localisés dans les latitudes moyennes. Ces profils suggèrent que SO2 est uniformément mélangé dans cette gamme d’altitude et qu’il est soumis à une variabilité forte sur de faibles échelles de temps. Cependant, une faible augmentation a été constatée entre le matin et le soir dans les zones du terminateur vénusien et à une altitude de 90-95 km. Enfin, après la découverte de la couche d'ozone sur Vénus faite par Montmessin et al. (2011), la présence de l’ozone a pu être confirmée dans plus de 100 séances d'occultation. L'étude actuelle montre également que les valeurs d'ozone détecté correspondent à ses valeurs maximales plutôt qu'à l'épaisse couche stable que l’on trouve près du sommet des nuages. Ces résultats représentent la première base de données sur la distribution verticale détaillée de la teneur en SO2 et O3 dans la mésosphère supérieure du côté nuit, ce qui ouvre de nouvelles perspective pour la compréhension théorique des processus se produisant dans l'atmosphère de Vénus.
- Published
- 2021
4. First global extraction of mesospheric Venusian O 3 and SO 2 concentrations from the entire SPICAV-UV/VEX stellar occultations dataset
- Author
-
Evdokimova, Daria, Montmessin, Franck, Belyaev, Denis, Bertaux, Jean-Loup, Space Research Institute of the Russian Academy of Sciences (IKI), Russian Academy of Sciences [Moscow] (RAS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), and Cardon, Catherine
- Subjects
[SDU] Sciences of the Universe [physics] ,[SDU]Sciences of the Universe [physics] - Abstract
International audience; The SPICAV spectrometer was a part of the ESA's Venus Express spacecraft functioning on the Venus orbit in 2006-2014 [1]. Its UV channel worked in a spectral range of 118-320 nm that covered gaseous absorption bands of SO2, O3 and CO2. Observations of stellar occultations in the UV allowed to study nighttime vertical distributions of these gases within altitude range of 80-110 km corresponding to Venus upper mesosphere. Temporal and spatial variations of the gaseous content are able to be analyzed considering the SPICAV dataset accumulated for the entire mission period. In our work we present results of O3 and reprocessed SO2 retrievals based on the whole SPICAV UV dataset. The data processing pipeline was improved since the recent studies [2] that allowed to extend the number of considering observations.
- Published
- 2019
5. Distribution of SO2 content at the night side of Venus' upper mesosphere
- Author
-
Belyaev, Denis A., Evdokimova, Daria, Montmessin, Franck, Marcq, Emmanuel, Fedorova, Anna, Korablev, Oleg, Space Research Institute of the Russian Academy of Sciences (IKI), Russian Academy of Sciences [Moscow] (RAS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), RFFI, CNES, CNRS, ISSI, and Cardon, Catherine
- Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] ,[SDU.ASTR.SR] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] ,[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,[SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] - Abstract
International audience; Venus has a dense CO2 atmosphere with a thick cloud layer (50-70 km) consisting of sulfuric acid (H2 SO4) aerosols. Sulfur oxides (SOx) are directly associated with those aerosols and plays an important role in chemistry of the atmosphere. Any change of its content within or above the clouds has an influence on photochemical processes in the mesosphere (70-100 km). Recent ground-based observations [1-4] and continuous monitoring from the Venus Express orbiter [5-7] have shown high temporal and spatial variability of SO2 abundance mostly on the day side: from 20 to 500 ppbv above the clouds. There is a lack in the detailed analysis at the night-time mesosphere where photo dissociation of sulfur dioxide is replaced by interaction with the global subsolar/antisolar circulation and chemical reactions with atoms of Cl, OH, O etc. In this paper we present vertical distribution of SO2 content at the night side of Venus upper meso-sphere that resulted from stellar occultations made by the SPICAV UV spectroscopy. This mode of occultation occurred for the entire VEx mission, and it gave us possibility to observe yearly variations for period 2006-2014 at altitudes 85-100 km. In parallel, we have reprocessed the terminator dataset from the UV solar occultations at the same altitude range [5] up to 2014. Like this, we have got whole the night-time coverage of SO2 distribution from the sunset to the sunrise twilights of the upper mesosphere. Experiment: SPICAV UV channel operated in the spectral range 118-320 nm with a resolution 1-2 nm at nadir or stellar/solar occultation modes [8]. Here we deal with measurements of SO2 atmospheric absorption in stellar and solar occultation modes. In the case of stellar occultation the instrument observes night-side mesosphere while in solar occultation it probes evening/morning twilights at altitude range 85-100 km. SPICAV can register SO2 absorption bands at 190-220 and 270-300 nm and CO2 bands at 120-210 nm. In the occultation mode an instrument registers the solar (or a stellar) flux out of planetary atmosphere and a flux, having passed through different levels of the atmosphere. The ratio of the second flux to the first one determines the atmospheric transmission at a fixed tangent altitude. This transmission (a relative quantity) is interpreted as due to the extinction from aerosols and gases that can be identified by their spectral signature, and their quantity along the line of sight (LOS) of the instrument (Fig. 1).
- Published
- 2016
6. Retrieval the gaseous composition of Venus night-side mesosphere with SPICAV UV onboard Venus Express.
- Author
-
Evdokimova, Daria, Baggio, Lucio, Belyaev, Denis, Montmessin, Franck, and Bertaux, Jean-Loup
- Subjects
- *
MESOSPHERE - Published
- 2018
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.