Examinando por Autor "Rannou, P."

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Acceso Abierto
Decline in Water Ice Abundance in the Martian Mesosphere during Aphelion
(Europlanet, 2024-07-03) Toledo, D.; Rannou, P.; Apéstigue, Víctor; Rodríguez Veloso, Raúl; Arruego, I.; Martínez, Germán M.; Tamppari, L. K.; Munguira, A.; Lorenz, Ralph; Stcherbinine, Aurélien; Montmessin, F.; Sánchez Lavega, Agustín; Patel, P.; Viúdez Moreiras, Daniel; Hueso, R.; Bertrand, T.; Pla García, J.; Yela González, Margarita; De la Torre Juárez, M.; Rodríguez Manfredi, J. A.
Clouds play a crucial role in the past and current climate of Mars. Cloud particles impact the planet's energy balance and atmospheric dynamics, as well as influence the vertical distribution of dust particles through dust scavenging. This process of dust scavenging by clouds has significant consequences for the planet's water cycle. For example, regions in the atmosphere with insufficient quantities of dust particles, or condensation nuclei, can inhibit the formation of H2O clouds, leading to the presence of water vapor in excess of saturation [1]. Recent observations made by the MEDA Radiation and Dust Sensor (RDS) [2,3] have shown a marked decline in mesospheric cloud activity (above 35-40 km) when Mars is near its aphelion (within the Aphelion Cloud Belt-ACB season), notably occurring during solar longitudes (Ls) between Ls 70° and 80° [4] (see Figure 1). In order to investigate the possible factors leading to this decrease in water ice abundance, we used a one-dimensional cloud microphysical model [5,6], which includes the processes of nucleation, condensation, coagulation, evaporation, precipitation, and coalescence, and where the vertical mixing is parameterized using an eddy diffusion profile (Keddy). Combining cloud microphysics modeling with ground-based (Mars 2020 and InSight) and orbital observations (TGO and MRO) of clouds, water vapor, and temperature, we will discuss in this presentation the main factors controlling the water abundance in the Martian mesosphere during the ACB season.
Acceso Abierto
Drying of the Martian mesosphere during aphelion induced by lower temperatures
(Springer Nature, 2024-11-20) Toledo, D.; Rannou, P.; Apéstigue, Víctor; Rodríguez Veloso, Raúl; Rodríguez Manfredi, J. A.; Arruego, Ignacio; Martínez, Germán M.; Tamppari, L. K.; Munguira, A.; Lorenz, Ralph; Stcherbinine, Aurélien; Montmessin, F.; Sánchez Lavega, Agustín; Patel, P.; Smith, Michael D.; Lemmon, M. T.; Vicente Retortillo, Álvaro; Newman, C. E.; Viúdez Moreiras, Daniel; Hueso, R.; Bertrand, T.; Pla García, J.; Yela González, Margarita; De la Torre Juárez, M.; Ministerio de Ciencia e Innovación (MICINN); Jet Propulsion Laboratory (JPL); National Aeronautics and Space Administration (NASA); Gobierno Vasco; Agencia Estatal de Investigación (AEI); Unidad de Excelencia Científica María de Maeztu Instituto de Astrofísica de Cantabria, MDM-2017-0765
The formation of water ice clouds or hazes on Mars imposes substantial limitations on the vertical transport of water into the middle-upper atmosphere, impacting the planet’s hydrogen loss. Recent observations made by the Mars Environmental Dynamics Analyzer instrument onboard Mars 2020 Perseverance rover have shown a marked decline in water ice abundance within the mesosphere (above 35-40 km) when Mars is near its aphelion (near the northern summer solstice), notably occurring during solar longitudes (Ls) between Ls 70∘ and 80∘. Orbital observations around the same latitudes indicate that temperatures between ~ 30-40 km reach a minimum during the same period. Using cloud microphysics simulations, we demonstrate that this decrease in temperature effectively increases the amount of water cold-trapped at those altitudes, confining water ice condensation to lower altitudes. Similarly, the reinforcement of the cold trap induced by the lower temperatures results in significant reductions in the water vapor mixing ratio above 35–40 km, explaining the confinement of water vapor observed around aphelion from orbiters.
Restringido
Measurement of dust optical depth using the solar irradiance sensor (SIS) onboard the ExoMars 2016 EDM
(Elsevier, 2017-01-20) Toledo, D.; Arruego, Ignacio; Apéstigue, Víctor; Jiménez Martín, Juan José; Gómez Martín, L.; Yela González, Margarita; Rannou, P.; Pommereau, J. P.; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Economía y Competitividad (MINECO)
"The solar irradiance sensor (SIS) was included in the DREAMS package onboard the ExoMars 2016 Entry Descent and Landing Demonstrator Module, and has been selected in the METED meteorological station onboard the ExoMars 2020 Lander. This instrument is designed to measure at different time intervals the scattered flux or the sum of direct flux and scattered flux in UVA (315-400 nm) and NIR (700-1100 nm) bands. For SIS'16, these measurements are performed by a total of 3 sensors per band placed at the faces of a truncated tetrahedron with face inclination angles of 60. The principal goal of SIS'16 design is to perform measurements of the dust opacity in UVA and NIR wavelengths ranges, crucial parameters in the understanding of the Martian dust cycle. The retrieval procedure is based on the use of radiative transfer simulations to reproduce SIS observations acquired during daytime as a function of dust opacity. Based on different sensitivity analysis, the retrieval procedure also requires to include as free parameters (1) the, dust effective radius; (2) the dust effective variance; and (3) the imaginary part of the refractive index of dust particles in UVA band. We found that the imaginary part of the refractive index of dust particles does not have a big impact on NIR signal, and hence we can kept constant this parameter in the retrieval of dust opacity at this channel. In addition to dust opacity measurements, this instrument is also capable to detect and characterize clouds by looking at the time variation of the color index (CI), defined as the ratio between the observations in NIR and UVA channels, during daytime or twilight. By simulating CI signals with a radiative transfer model, the cloud opacity and cloud altitude (only during twilight) can be retrieved. Here the different retrieval procedures that are used to analyze SIS measurements, as well as the results obtained in different sensitivity analysis, are presented and discussed."
Acceso Abierto
Microphysical modeling of methane ice clouds in the atmospheres of the Ice Giants
(Europlanet, 2024-07-03) Toledo, D.; Rannou, P.; Irwin, Patrick Gerard Joseph; De Batz de Trenquelléon, Bruno; Apéstigue, Víctor; Roman, Michael; Arruego, Ignacio; Yela González, Margarita
Voyager 2 radio occultation measurements of Uranus and Neptune revealed a layer approximately 2-4 km thick near 1.2 and 1.6 bars, respectively, wherein the atmospheric refractivity exhibited a slope variation (1, 2). These findings were interpreted as indicating a region where methane gas was undergoing condensation, forming an ice cloud centered around this pressure level. While the formation of this putative cloud would explain the observed decrease in methane abundance with height above 1.2 and 1.6 bars, or the banded structure of Uranus through latitudinal variations in the opacity of this cloud, several recent works and observations do not provide direct evidence in favor of this cloud (3): (i) radiative transfer models show an enhancement in the scattering opacity at pressures near 4-6 bars, more consistent with the presence of H2S ice (4, 5); (ii) observations from ground-based telescopes (or observations from telescopes in orbit around the Earth) of methane clouds indicate cloud tops near 0.4 bars in both planets (6), approximately a scale height above the base of the putative methane cloud.
Restringido
The DREAMS experiment flown on the ExoMars 2016 mission for the study of Martian environment during the dust storm season
(Elsevier, 2018-02-01) Bettanini, C.; Esposito, F.; Debei, S.; Molfese, C.; Colombatti, G.; Aboudan, A.; Brucato, J. R.; Cortecchia, F.; Di Achille, G.; Guizzo, G. P.; Friso, Enrico; Ferri, F.; Marty, Laurent; Mennella, V.; Molinaro, R.; Schipani, P.; Silvestro, S.; Mugnuolo, R.; Pirrotta, S.; Marchetti, Edoardo; Ari-Matti, H.; Montmessin, F.; Wilson, Colin; Arruego, I.; Abbaki. S.; Apéstigue, V.; Bellucci, G.; Berthelier, J. J.; Calcutt, S.; Forget, F.; Genzer, María; Gilbert, Pierre; Haukka, H.; Jiménez Martín, Juan José; Jiménez, Salvador; Josset, J. L.; Karatekin, Özgür; Landis, G.; Lorenz, Ralph; Martínez Oter, J.; Möhlmann, D.; Moirin, D.; Palomba, E.; Patel, M.; Pommereau, J. P.; Popa, C. I.; Rafkin, Scot C. R.; Rannou, P.; Rennó, N. O.; Schmidt, Walter; Simoes, F.; Spiga, A.; Valero, F.; Vázquez, L.; Apéstigue, Víctor; Agenzia Spaziale Italiana (ASI); Istituto Nazionale di Astrofisica (INAF)
"The DREAMS (Dust characterization, Risk assessment and Environment Analyser on the Martian Surface) instrument on Schiaparelli lander of ExoMars 2016 mission was an autonomous meteorological station designed to completely characterize the Martian atmosphere on surface, acquiring data not only on temperature, pressure, humidity, wind speed and its direction, but also on solar irradiance, dust opacity and atmospheric electrification; this comprehensive set of parameters would assist the quantification of risks and hazards for future manned exploration missions mainly related to the presence of airborne dust. Schiaparelli landing on Mars was in fact scheduled during the foreseen dust storm season (October 2016 in Meridiani Planum) allowing DREAMS to directly measure the characteristics of such extremely harsh environment. DREAMS instrument’s architecture was based on a modular design developing custom boards for analog and digital channel conditioning, power distribution, on board data handling and communication with the lander. The boards, connected through a common backbone, were hosted in a central electronic unit assembly and connected to the external sensors with dedicated harness. Designed with very limited mass and an optimized energy consumption, DREAMS was successfully tested to operate autonomously, relying on its own power supply, for at least two Martian days (sols) after landing on the planet. A total of three flight models were fully qualified before launch through an extensive test campaign comprising electrical and functional testing, EMC verification and mechanical and thermal vacuum cycling; furthermore following the requirements for planetary protection, contamination control activities and assay sampling were conducted before model delivery for final integration on spacecraft. During the six months cruise to Mars following the successful launch of ExoMars on 14th March 2016, periodic check outs were conducted to verify instrument health check and update mission timelines for operation. Elaboration of housekeeping data showed that the behaviour of the whole instrument was nominal during the whole cruise. Unfortunately DREAMS was not able to operate on the surface of Mars, due to the known guidance anomaly during the descent that caused Schiaparelli to crash at landing. The adverse sequence of events at 4 km altitude anyway triggered the transition of the lander in surface operative mode, commanding switch on the DREAMS instrument, which was therefore able to correctly power on and send back housekeeping data. This proved the nominal performance of all DREAMS hardware before touchdown demonstrating the highest TRL of the unit for future missions. The spare models of DREAMS are currently in use at university premises for the development of autonomous units to be used in cubesat mission and in probes for stratospheric balloons launches in collaboration with Italian Space Agency."
Acceso Abierto
The UMR: Uranus Multi-Experiment Radiometer for Haze and Clouds Characterization
(Europlanet, 2024-07-03) Apéstigue, Víctor; Toledo, D.; Arruego, Ignacio; Irwin, P.; Rannou, P.; Gonzalo Melchor, Alejandro; Martínez Oter, J.; Ceballos Cáceres, J.; Azcue, J.; Jiménez Martín, Juan José; De Mingo, J. R.; Serrano, F.; Nuñez, J.; Andrés, S.; Torres Redondo, J.; Martín Ortega, A.; Yela González, Margarita; Sorribas, M.; Sebastián, E.; Vázquez García de la Vega, D.; Espejo, S.; Ragel, A.
The present understanding of Uranus and Neptune has been derived primarily from terrestrial observations and observations conducted using space telescopes. Furthermore, a brief flyby conducted by the Voyager 2 spacecraft nearly three decades ago has contributed to our knowledge of these celestial bodies. Recently, the Decadal Survey [1] has identified a mission to Uranus as a high-priority objective for NASA's space exploration program and its ongoing missions to Mars and Europa. The main mission study [2] establishes the scientific priorities for an orbiter, including analyzing the planet's bulk composition and internal structure, magnetic field, atmosphere circulation, rings, and satellite system. On the other hand, the mission includes a descent probe, whose primary mission is obtaining data on the atmospheric noble gas abundances, noble gas isotope ratios, and thermal structure using a mass spectrometer and a meteorological package. Investigation of the vertically distributed aerosols (hazes and clouds) and their microphysical and scattering properties is required to comprehend the thermal structure and dynamics of Uranus' atmosphere. These aerosols play a crucial role in the absorption and reflection of solar radiation, which directly influences the planet’s energy balance. In this work, we present a lightweight radiometer instrument [3] to be included in the descent probe for studying the aerosols in the first km of the Uranus’ atmosphere. The UMR, the Uranus Multi-experiment Radiometer, takes its heritage from previous missions for Mars exploration [4-6], where its technology, including mixed-signal ASICs radiation hardened by design [7-8], has demonstrated its endurance for extreme environments of operation, using limited resources in terms of power consumption, mass and volume footprints, and data budget. These characteristics make this instrument a valuable probe’s payload for studying Uranus’ atmosphere with a high scientific return. In this contribution, we will present the actual design of the instrument and the future perspective before a possible announcement of opportunity.
Acceso Abierto
The Uranus Multi-Experiment Radiometer for Haze and Clouds Characterization
(Springer Link, 2024-01-09) Apéstigue, Víctor; Toledo, D.; Irwin, P. G. J.; Rannou, P.; Gonzalo Melchor, Alejandro; Martínez Oter, J.; Ceballos Cáceres, J.; Azcue, J.; Jiménez Martín, Juan José; Sebastián, E.; Yela González, Margarita; Sorribas, M.; de Mingo Martín, José Ramón; Martín-Ortega, Alberto; Belenguer Dávila, T.; Álvarez, Maite; Vázquez García de la Vega, D.; Espejo, S.; Arruego, Ignacio
The aerosols (clouds and hazes) on Uranus are one of the main elements for understanding the thermal structure and dynamics of its atmosphere. Aerosol particles absorb and scatter the solar radiation, directly affecting the energy balance that drives the atmospheric dynamics of the planet. In this sense, aerosol information such as the vertical distribution or optical properties is essential for characterizing the interactions between sunlight and aerosol particles at each altitude in the atmosphere and for understanding the energy balance of the planet’s atmosphere. Moreover, the distribution of aerosols in the atmosphere provides key information on the global circulation of the planet (e.g., regions of upwelling or subsidence). To address this challenge, we propose the Uranus Multi-experiment Radiometer (UMR), a lightweight instrument designed to characterize the aerosols in Uranus’ atmosphere as part of the upcoming Uranus Flagship mission’s descending probe payload. The scientific goals of UMR are: (1) to study the variation of the solar radiation in the ultra-violet (UV) with altitude and characterize the energy deposition in the atmosphere; (2) to study the vertical distribution of the hazes and clouds and characterize their scattering and optical properties; (3) to investigate the heating rates of the atmosphere by directly measuring the upward and downward fluxes; and (4) to study the cloud vertical distribution and composition at pressures where sunlight is practically negligible (p > 4-5 bars). The instrument includes a set of photodetectors, field-of-view masks, a light infrared lamp, and interference filters. It draws on the heritage of previous instruments developed at the Instituto Nacional de Técnica Aeroespacial (INTA) that participated in the exploration of Mars, where similar technology has demonstrated its endurance in extreme environments while utilizing limited resources regarding power consumption, mass and volume footprints, and data budget. The radiometer’s design and characteristics make it a valuable complementary payload for studying Uranus’ atmosphere with a high scientific return.