Examinando por Autor "Silvestro, S."

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Periodic Bedrock Ridges at the ExoMars 2022 Landing Site: Evidence for a Changing Wind Regime
(Advancing Earth and Space Science AGU, 2021-01-12) Silvestro, S.; Pacifici, A.; Salese, F.; Vaz, D. A.; Neesemann, A.; Tirsch, D.; Popa, C. I.; Pajola, M.; Franzese, G.; Mongelluzzo, G.; Ruggeri, A. C.; Cozzolino, F.; Porto, C.; Esposito, F.; National Aeronautics and Space Administration (NASA); European Research Council (ERC); Agenzia Spaziale Italiana (ASI); Pajola, M. [0000-0002-3144-1277]; Ruggeri, A. C. [0000-0002-1556-2474]; Tirsch, D. [0000-0001-5905-5426]; Salese, F. [0000-0003-0491-0274]; Silvestro, S. [0000-0002-3196-6620]; Mongelluzzo, G. [0000-0003-1182-8252]; Franzese, G. [0000-0001-5911-3163]
Wind-formed features are abundant in Oxia Planum (Mars), the landing site of the 2022 ExoMars mission, which shows geological evidence for a past wet environment. Studies of aeolian bedforms at the landing site were focused on assessing the risk for rover trafficability, however their potential in recording climatic fluctuations has not been explored. Here we show that the landing site experienced multiple climatic changes in the Amazonian, which are recorded by an intriguing set of ridges that we interpret as Periodic Bedrock Ridges (PBRs). Clues for a PBR origin result from ridge regularity, defect terminations, and the presence of preserved megaripples detaching from the PBRs. PBR orientation differs from superimposed transverse aeolian ridges pointing toward a major change in wind regime. Our results provide constrains on PBR formation mechanisms and offer indications on paleo winds that will be crucial for understanding the landing site geology.
Restringido
Techniques to verify the sampling system and flow characteristics of the sensor MicroMED for the ExoMars 2022 Mission
(Elsevier, 2021-08-21) Cozzolino, F.; Franzese, G.; Mongelluzzo, G.; Molfese, C.; Esposito, F.; Cosimo Ruggeri, A.; Porto, C.; Silvestro, S.; Popa, C. I.; Mennella, V.; Scaccabarozzi, D.; Saggin, B.; Ortega Rico, A. M.; Arruego, I.; Santiuste, Nuria; Brienza, D.; Cortecchia, F.; de Mingo Martín, José Ramón; Instituto Nacional de Técnica Aeroespacial (INTA); Agenzia Spaziale Italiana (ASI); Istituto Nazionale di Astrofisica (INAF)
Suspended dust has a prominent role in Martian climatology. Several significant dust related phenomena can be observed at various scales, starting from global dust storms to local dust devils, which have important effects such as the increase of troposphere temperature, the modification of the wind regime and the localized motion of sand at the surface. These phenomena depend on dust grain characteristics such as the size distribution or the chemical and bulk composition. Currently, we do not have direct measurement of the dust properties; the only available information in this regard are derived from spectrometric measurements, optical depth, and albedo coming from instruments aboard satellites and in-situ. Herein, we describe the tests performed on the optical particle counter named MicroMED, designed and built to perform the first ever direct in-situ measurement of suspended dust grains in the Martian atmosphere close to the surface. MicroMED is a dust particle size analyzer which was selected to join the Dust Complex payload aboard the ESA/Roscosmos ExoMars 2022 mission. It has the capability to suck in dust that is suspended in atmosphere and to measure the sizes of single grain. The sensor sucks in the dust grains using a sampling system, guides the grains through ducts and concentrates them in an area illuminated by laser. Detecting the intensity of the light scattered by the grains during the crossing through the illuminated area, it is possible to determinate the size of grain. Here we present the innovative techniques in order to verify the performances in terms of dust suction efficiency of the MicroMED Flight Model, using a prototype called MM1.
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.; Bellucci, G.; Berthelier, J. J.; Calcutt, S.; Forget, F.; Genzer, M.; Gilbert, Pierre; Haukka, H.; Jiménez, Juan J.; 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, S.; Rannou, P.; Rennó, N. O.; Schmidt, W.; 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."