Examinando por Autor "Spiga, A."

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Acceso Abierto
A Comodulation Analysis of Atmospheric Energy Injection Into the Ground Motion at InSight, Mars
(Advancing Earth and Space Science AGU, 2021-02-08) Charalambous, C.; Stott, A. E.; Pike, W. T.; McClean, J. B.; Warren, T.; Spiga, A.; Banfield, D.; García, R. F.; Clinton, J.; Stähler, S. C.; Navarro, Sara; Lognonné, P.; Scholz, J. R.; Kawamura, T.; Van Driel, M.; Böse, M.; Ceylan, S.; Khan, A.; Horleston, A.; Orhand Mainsant, G.; Sotomayor, L. M.; Murdoch, N.; Giardini, D.; Banerdt, W. B.; Murdoch, N. [0000-0002-9701-4075]; Lognonne, P. [0000-0002-1014-920X]; Charalambous, C. [0000-0002-9139-3895]; Stott, A. E. [0000-0001-6121-705X]; Spiga, A. [0000-0002-6776-6268]; Stähler, S. [0000-0002-0783-2489]; Scholz, J. R. [0000-0003-1404-2335]; Ceylan, S. [0000-0002-6552-6850]; Khan, A. [0000-0003-4462-3173]; Van Driel, M. [0000-0002-8938-4615]; Horleston, A. [0000-0002-6748-6522]; Giardini, D. [0000-0002-5573-7638]; Banerdt, W. B. [0000-0003-3125-1542]
Seismic observations involve signals that can be easily masked by noise injection. For the NASA Mars lander InSight, the atmosphere is a significant noise contributor, impeding the identification of seismic events for two-thirds of a Martian day. While the noise is below that seen at even the quietest sites on Earth, the amplitude of seismic signals on Mars is also considerably lower, requiring an understanding and quantification of environmental injection at unprecedented levels. Mars’ ground and atmosphere are a continuously coupled seismic system, and although atmospheric functions are of distinct origins, the superposition of these noise contributions is poorly understood, making separation a challenging task. We present a novel method for partitioning the observed signal into seismic and environmental contributions. Atmospheric pressure and wind fluctuations are shown to exhibit temporal cross-frequency coupling across multiple bands, injecting noise that is neither random nor coherent. We investigate this through comodulation, quantifying the synchrony of the seismic motion, wind and pressure signals. By working in the time-frequency domain, we discriminate between the different origins of underlying processes and determine the site's environmental sensitivity. Our method aims to create a virtual vault at InSight's landing site on Mars, shielding the seismometers with effective postprocessing in lieu of a physical vault. This allows us to describe the environmental and seismic signals over a sequence of sols, to quantify the wind and pressure injection and estimate the seismic content of possible marsquakes with a signal-to-noise ratio that can be quantified in terms of environmental independence. Finally, we exploit the relationship between the comodulated signals to identify their sources.
Restringido
Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data
(Nature Research Journals, 2020-02-24) Lognonné, P.; Banerdt, W. B.; Pike, W. T.; Giardini, D.; Christensesn, U.; García, R. F.; Kawamura, T.; Kedar, S.; Knapmeyer Endrun, B.; Margerin, L.; Nimmo, F.; Panning, M.; Tauzin, B.; Scholz, J. R.; Antonangeli, D.; Barkaoui, S.; Beucler, E.; Bissig, F.; Brinkman, N.; Calvet, M.; Ceylan, S.; Charalambous, C.; Davis, P.; Van Driel, M.; Drilleau, M.; Fayon, L.; Joshi, R.; Kenda, B.; Khan, A.; Knapmeyer, M.; Lekic, V.; McClean, J.; Mimoun, D.; Murdoch, N.; Pan, L.; Perrin, C.; Pinot, B.; Pou, L.; Menina, S.; Rodríguez, Sébastien; Schmelzbach, C.; Schmerr, N.; Sollberg, D.; Spiga, A.; Stähler, S.; Stott, A.; Stutzmann, E.; Tharimena, S.; Widmer Schnidrig, R.; Andersson, F.; Ansan, V.; Beghein, C.; Knollenberg, M.; Krasner, S.; krause, C.; Lorenz, R.; Michaut, C.; Myhill, R.; Nissen Meyer, T.; Ten Pierick, J.; Plesa, A. C.; Quantin Nataf, C.; Robertsson, J.; Rochas, L.; Schimmel, M.; Smrekar, S.; Spohn, T.; Teanby, N.; Tromp, J.; Vallade, J.; Verdier, N.; Vrettos, C.; Weber, R.; Banfield, D.; Barrett, E.; Bierwith, M.; Calcutt, S.; Compaire, N.; Johnson, C. L.; Mance, D.; Euchner, F.; Kerjean, L.; Mainsant, G.; Mocquet, A.; Rodríguez Manfredi, J. A.; Pont, G.; Laudet, P.; Nebut, T.; Raucort, S.; Robert, O.; Russell, C. T.; Sylvestre Baron, A.; Tillier, S.; Warren, T.; Wieczorek, Mark A.; Yana, C.; Zweifel, P.; Centre National D'Etudes Spatiales (CNES); Agence Nationale de la Recherche (ANR); Lognonné, P.[0000-0002-1014-920X]; Spiga, A. [0000-0002-6776-6268]; Murdoch, N. [0000-0002-9701-4075]; Fayon, L. [0000-0002-4276-8160]; Knapmeyer, M. [0000-0003-0319-2514]; Tromp, J. [0000-0002-2742-8299]; Perrin, C. [0000-0002-7200-5682]; Schimmel, M. [0000-0003-2601-4462]; Panning, M. P. [0000-0002-2041-3190]; Rodríguez Manfredi, J. [0000-0003-0461-9815]; Pan, L. [0000-0002-8151-2125]; García, R. F. [0000-0003-1460-6663]; Rodríguez, S. [0000-0003-1219-0641]; Sollberger, D. [0000-0001-6408-6681]; Ceylan, S. [0000-0002-6552-6850]; Irving, J. [0000-0002-0866-8246]; Warren, T. [0000-0003-3877-0046]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Mars’s seismic activity and noise have been monitored since January 2019 by the seismometer of the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) lander. At night, Mars is extremely quiet; seismic noise is about 500 times lower than Earth’s microseismic noise at periods between 4 s and 30 s. The recorded seismic noise increases during the day due to ground deformations induced by convective atmospheric vortices and ground-transferred wind-generated lander noise. Here we constrain properties of the crust beneath InSight, using signals from atmospheric vortices and from the hammering of InSight’s Heat Flow and Physical Properties (HP3) instrument, as well as the three largest Marsquakes detected as of September 2019. From receiver function analysis, we infer that the uppermost 8–11 km of the crust is highly altered and/or fractured. We measure the crustal diffusivity and intrinsic attenuation using multiscattering analysis and find that seismic attenuation is about three times larger than on the Moon, which suggests that the crust contains small amounts of volatiles.
Acceso Abierto
Lander and rover histories of dust accumulation on and removal from solar arrays on Mars
(Elsevier, 2021-11-01) Lorenz, R. D.; Martínez, G. M.; Spiga, A.; Vicente Retortillo, Á.; Newman, C. E.; Murdoch, N.; Forget, F.; Millour, E.; Pierron, T.; National Aeronautics and Space Administration (NASA); Agence Nationale de la Recherche (ANR); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The degradation in electrical output of solar arrays on Mars landers and rovers is reviewed. A loss of 0.2% per Sol is typical, although observed rates of decrease in ‘dust factor’ vary between 0.05% and 2% per Sol. 0.2%/Sol has been observed throughout the first 800 Sols of the ongoing InSight mission, as well as the shorter Mars Pathfinder and Phoenix missions. This rate was also evident for much of the Spirit and Opportunity missions, but the degradation there was episodically reversed by cleaning events due to dust devils and gusts. The enduring success of those rover missions may have given an impression of the long-term viability of solar power on the Martian surface that is not globally-applicable: the occurrence of cleaning events with an operationally-useful frequency seems contingent upon local meteorological circumstances. The conditions for significant cleaning events have apparently not been realized at the InSight landing site, where, notably, dust devils have not been detected in imaging. Optical obscuration by dust deposition and removal has also been observed by ultraviolet sensors on Curiosity, with a similar (but slightly higher) degradation rate. The observations are compared with global circulation model (GCM) results: these predict a geographically somewhat uniform dust deposition rate, while there is some indication that the locations where cleaning events were more frequent may be associated with weaker background winds and a deeper planetary boundary layer. The conventional Dust Devil Activity metric in GCMs does not effectively predict the different dust histories.
Acceso Abierto
Multi-model Meteorological and Aeolian Predictions for Mars 2020 and the Jezero Crater Region
(Springer Link, 2021-02-08) Newman, C. E.; Torres Juárez, M.; Pla García, J.; Wilson, R. J.; Lewis, S. R.; Neary, L.; Kahre, M. A.; Forget, F.; Spiga, A.; Richardson, M. L. A.; Daerden, F.; Bertrand, T.; Viúdez Moreiras, Daniel; Sullivan, Robert; Sánchez Lavega, A.; Chide, B.; Rodríguez Manfredi, J. A.; National Aeronautics and Space Administration (NASA); European Space Agency (ESA); Centre National D'Etudes Spatiales (CNES); Sánchez Lavega, Á. [0000-0001-7234-7634]; Lewis, S. [0000-0001-7237-6494]
Nine simulations are used to predict the meteorology and aeolian activity of the Mars 2020 landing site region. Predicted seasonal variations of pressure and surface and atmospheric temperature generally agree. Minimum and maximum pressure is predicted at Ls∼145∘ and 250∘, respectively. Maximum and minimum surface and atmospheric temperature are predicted at Ls∼180∘ and 270∘, respectively; i.e., are warmest at northern fall equinox not summer solstice. Daily pressure cycles vary more between simulations, possibly due to differences in atmospheric dust distributions. Jezero crater sits inside and close to the NW rim of the huge Isidis basin, whose daytime upslope (∼east-southeasterly) and nighttime downslope (∼northwesterly) winds are predicted to dominate except around summer solstice, when the global circulation produces more southerly wind directions. Wind predictions vary hugely, with annual maximum speeds varying from 11 to 19 ms−1 and daily mean wind speeds peaking in the first half of summer for most simulations but in the second half of the year for two. Most simulations predict net annual sand transport toward the WNW, which is generally consistent with aeolian observations, and peak sand fluxes in the first half of summer, with the weakest fluxes around winter solstice due to opposition between the global circulation and daytime upslope winds. However, one simulation predicts transport toward the NW, while another predicts fluxes peaking later and transport toward the WSW. Vortex activity is predicted to peak in summer and dip around winter solstice, and to be greater than at InSight and much greater than in Gale crater.
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."