Examinando por Autor "Rafkin, Scot C. R."

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Acceso Abierto
A stringent upper limit of 20 pptv for methane on Mars and constraints on its dispersion outside Gale crater
(EDP Sciences, 2021-07-20) Montmessin, F.; Korablev, O. I.; Trokhimovskiy, A.; Lefèvre, F.; Fedorova, A. A.; Baggio, L.; Irbah, A.; Lacombe, G.; Olsen, K. S.; Braude, A. S.; Belyaev, D. A.; Alday, J.; Forget, F.; Daerden, F.; Pla García, J.; Rafkin, Scot C. R.; Wilson, T. F.; Patrakeev, A.; Shakun, A.; Bertaux, J. L.; Agence Nationale de la Recherche (ANR); Natural Sciences and Engineering Research Council of Canada (NSERC); UK Space Agency; Science and Technology Facilities Council (STFC); Montmessin, F. [0000-0002-4187-1457]; Korablev, O. I. [0000-0003-1115-0656]; Trokhimovskiy, A. [0000-0003-4041-4972]; Lefèvre, F. [0000-0001-5294-5426]; Fedorova, A. A. [0000-0002-4176-2955]; Baggio, L. [0000-0002-9263-4937]; Irbah, A. [0000-0003-3265-3148]; Olsen, K. S. [0000-0002-2173-9889]; Braude, A. M. [0000-0003-2437-2151]; Belyaev, D. A. [0000-0003-1123-5983]; Alday, J. [0000-0003-1459-3444]; Forget, F. [0000-0002-3262-4366]; Pla García, J. [0000-0002-8047-3937]; Rafkin, S. [0000-0001-7464-1319]
Context. Reports on the detection of methane in the Martian atmosphere have motivated numerous studies aiming to confirm or explain its presence on a planet where it might imply a biogenic or more likely a geophysical origin. Aims. Our intent is to complement and improve on the previously reported detection attempts by the Atmospheric Chemistry Suite (ACS) on board the ExoMars Trace Gas Orbiter (TGO). This latter study reported the results of a campaign that was a few months in length, and was significantly hindered by a dusty period that impaired detection performances. Methods. We unveil 640 solar occultation measurements gathering 1.44 Martian years worth of data produced by the ACS. Results. No methane was detected. Probing the clear northern summer season allowed us to reach 1σ upper limits of around 10 pptv (20 pptv at 2σ), with an annual mean of the smallest upper limits of 20 pptv. Upper limits are controlled by the amount of dust in the atmosphere, which impairs detection performance around the equator and during the southern spring and summer seasons. Observations performed near Gale crater yielded 1σ upper limits of up to four times less than the background values measured by the Curiosity rover during the corresponding seasons. Conclusions. Reconciliation of the absence of methane in the TGO spectra with the positive detections by Curiosity is even more difficult in light of this annual survey performed by ACS. Stronger constraints are placed on the physical and chemical mechanism capable of explaining why the mean of the best overall upper limits of ACS is ten times below the smallest methane abundances measured by Curiosity.
Restringido
Background levels of methane in Mars’ atmosphere show strong seasonal variations
(Science, 2018-06-08) Webster, Christopher R.; Mahaffy, Paul R.; Atreya, Sushil K.; Moores, John E.; Flesch, Gregory J.; Malespin, Charles A.; McKay, Christopher P.; Martínez, Germán M.; Smith, Christina L.; Martín Torres, Javier; Gómez Elvira, J.; Zorzano, María-Paz; Wong, Michael H.; Trainer, Melissa G.; Steele, Andrew; Archer, Doug; Sutter, Brad; Coll, Patrice J.; Freissinet, Caroline; Meslin, Pierre-Yves; Gough, Raina V.; House, Christopher H.; Pavlov, Alexander; Eigenbrode, Jennifer L.; Glavin, Daniel P.; Pearson, John C.; Keymeulen, Didier; Christensen, Lance E.; Schwenzer, Susanne P.; Navarro González, R.; Pla García, J.; Rafkin, Scot C. R.; Vicente Retortillo, Álvaro; Kahanpää, H.; Viúdez Moreiras, Daniel; Smith, Michael D.; Harri, Ari-Matti; Genzer, María; Hassler, Donald M.; Lemmon, M. T.; Crisp, Joy; Sander, Stanley P.; Zurek, Richard W.; Vasavada, Ashwin R.; National Aeronautics and Space Administration (NASA)
Variable levels of methane in the martian atmosphere have eluded explanation partly because the measurements are not repeatable in time or location. We report in situ measurements at Gale crater made over a 5-year period by the Tunable Laser Spectrometer on the Curiosity rover. The background levels of methane have a mean value 0.41 ± 0.16 parts per billion by volume (ppbv) (95% confidence interval) and exhibit a strong, repeatable seasonal variation (0.24 to 0.65 ppbv). This variation is greater than that predicted from either ultraviolet degradation of impact-delivered organics on the surface or from the annual surface pressure cycle. The large seasonal variation in the background and occurrences of higher temporary spikes (~7 ppbv) are consistent with small localized sources of methane released from martian surface or subsurface reservoirs.
Acceso Abierto
Day-night differences in Mars methane suggest nighttime containment at Gale crater
(EDP Sciences, 2021-06-29) Webster, Christopher R.; Mahaffy, Paul R.; Pla García, J.; Rafkin, Scot C. R.; Moores, J. E.; Atreya, S. K.; Flesch, Gregory J.; Malespin, C. A.; Teinturier, S. M.; Kalucha, H.; Smith, C. L.; Viúdez Moreiras, Daniel; Vasavada, Ashwin R.; Agencia Estatal de Investigación (AEI)
We report new measurements of atmospheric methane by the Curiosity rover’s Tunable Laser Spectrometer that is part of the Sample Analysis at Mars suite (TLS-SAM), finding nondetections during two daytime measurements of average value 0.05 ± 0.22 ppbv (95% confidence interval CI). These are in marked contrast with nighttime background levels of 0.52 ± 0.10 (95% CI) from four measurements taken during the same season of northern summer. This large day-night difference suggests that methane accumulates while contained near the surface at night, but drops below TLS-SAM detection limits during the day, consistent with the daytime nondetection by instruments on board the ExoMars Trace Gas Orbiter. With no evidence for methane production by the rover itself, we propose that the source is one of planetary micro-seepage. Dynamical modeling indicates that such methane release is contained within the collapsed planetary boundary layer (PBL) at night due to a combination of nocturnal inversion and convergent downslope flow winds that confine the methane inside the crater close to the point where it is released. The methane abundance is then diluted during the day through increased vertical mixing associated with a higher altitude PBL and divergent upslope flow that advects methane out of the crater region. We also report detection of a large spike of methane in June 2019 with a mean in situ value over a two-hour ingest of 20.5 ± 4 ppbv (95% CI). If near-surface production is occurring widely across Mars, it must be accompanied by a fast methane destruction or sequestration mechanism, or both.
Acceso Abierto
Meteorological Predictions for Mars 2020 Perseverance Rover Landing Site at Jezero Crater
(Springer Link, 2020-12-14) Pla García, J.; Rafkin, Scot C. R.; Martínez, G. M.; Vicente Retortillo, Álvaro; Newman, C. E.; Rodríguez Manfredi, J. A.; Gómez, Felipe; Molina, A.; Viúdez Moreiras, Daniel; Harri, Ari-Matti; Agencia Estatal de Investigación (AEI); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The Mars Regional Atmospheric Modeling System (MRAMS) and a nested simulation of the Mars Weather Research and Forecasting model (MarsWRF) are used to predict the local meteorological conditions at the Mars 2020 Perseverance rover landing site inside Jezero crater (Mars). These predictions are complemented with the COmplutense and MIchigan MArs Radiative Transfer model (COMIMART) and with the local Single Column Model (SCM) to further refine predictions of radiative forcing and the water cycle respectively. The primary objective is to facilitate interpretation of the meteorological measurements to be obtained by the Mars Environmental Dynamics Analyzer (MEDA) aboard the rover, but also to provide predictions of the meteorological phenomena and seasonal changes that might impact operations, from both a risk perspective and from the perspective of being better prepared to make certain measurements. A full diurnal cycle at four different seasons (L-s 0 degrees, 90 degrees, 180 degrees, and 270 degrees) is investigated. Air and ground temperatures, pressure, wind speed and direction, surface radiative fluxes and moisture data are modeled. The good agreement between observations and modeling in prior works [Pla-Garcia et al. in Icarus 280:103-113, 2016; Newman et al. in Icarus 291:203-231, 2017; Vicente-Retortillo et al. in Sci. Rep. 8(1):1-8, 2018; Savijarvi et al. in Icarus, 2020] provides confidence in utilizing these models results to predict the meteorological environment at Mars 2020 Perseverance rover landing site inside Jezero crater. The data returned by MEDA will determine the extent to which this confidence was justified.
Acceso Abierto
The diverse meteorology of Jezero crater over the first 250 sols of Perseverance on Mars
(Nature Publishing Group, 2023-01-09) Rodríguez Manfredi, J. A.; De la Torre Juárez, M.; Sánchez Lavega, Agustín; Hueso, R.; Martínez, Germán M.; Lemmon, M. T.; Newman, C. E.; Munguira, A.; Hieta, M.; Tamppari, L. K.; Polkko, J.; Toledo, D.; Sebastian, D.; Smith, Michael D.; Jaakonaho, I.; Genzer, María; Vicente Retortillo, Álvaro; Viúdez Moreiras, Daniel; Ramos, Miguel; Saiz López, A.; Lepinette Malvitte, A.; Wolff, Michael; Sullivan, R. J.; Gómez Elvira, J.; Apéstigue, Víctor; Conrad, P.; Del Río Gaztelurrutia, T.; Murdoch, N.; Arruego, Ignacio; Banfield, D.; Boland, J.; Brown, Adrian Jon; Ceballos Cáceres, J.; Domínguez Pumar, M.; Espejo, S.; Fairén, A.; Ferrándiz Guibelalde, Ricardo; Fischer, E.; García Villadangos, M.; Giménez Torregrosa, S.; Gómez Gómez, F.; Guzewich, Scott; Harri, Ari-Matti; Jiménez Martín, Juan José; Jiménez, V.; Makinen, Terhi; Marín Jiménez, M.; Martín Rubio, C.; Martín Soler, J.; Molina, A.; Mora Sotomayor, L.; Navarro López, Sara; Peinado, V.; Pérez Grande, I.; Pla García, J.; Postigo, M.; Prieto-Ballesteros, Olga; Rafkin, Scot C. R.; Richardson, M. I.; Romeral, J.; Romero Guzmán, Catalina; Savijärvi, H.; Schofield, J. T.; Torres, J.; Urquí, R.; Zurita, S.; NASA Jet Propulsion Laboratory (JPL); National Aeronautics and Space Administration (NASA); Instituto Nacional de Técnica Aeroespacial (INTA); European Commission (EC); Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); California Institute of Technology (CIT); Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
NASA’s Perseverance rover’s Mars Environmental Dynamics Analyzer is collecting data at Jezero crater, characterizing the physical processes in the lowest layer of the Martian atmosphere. Here we present measurements from the instrument’s first 250 sols of operation, revealing a spatially and temporally variable meteorology at Jezero. We find that temperature measurements at four heights capture the response of the atmospheric surface layer to multiple phenomena. We observe the transition from a stable night-time thermal inversion to a daytime, highly turbulent convective regime, with large vertical thermal gradients. Measurement of multiple daily optical depths suggests aerosol concentrations are higher in the morning than in the afternoon. Measured wind patterns are driven mainly by local topography, with a small contribution from regional winds. Daily and seasonal variability of relative humidity shows a complex hydrologic cycle. These observations suggest that changes in some local surface properties, such as surface albedo and thermal inertia, play an influential role. On a larger scale, surface pressure measurements show typical signatures of gravity waves and baroclinic eddies in a part of the seasonal cycle previously characterized as low wave activity. These observations, both com
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 Mars Environmental Dynamics Analyzer, MEDA. A Suite of Environmental Sensors for the Mars 2020 Mission
(Springer Link, 2021-04-13) Rodríguez Manfredi, J. A.; De la Torre Juárez, M.; Alonso, A.; Apéstigue, Víctor; Arruego, Ignacio; Atienza, T.; Banfield, D.; Boland, J.; Carrera, M. A.; Castañer, L.; Ceballos Cáceres, J.; Chen Chen, H.; Cobos, A.; Conrad, Pamela G.; Cordoba, E.; Del Río Gaztelurrutia, T.; Vicente Retortillo, Álvaro; Domínguez Pumar, M.; Espejo, S.; Fairén, Alberto G.; Fernández Palma, A.; Ferrándiz, Ricardo; Ferri, F.; Fischer, E.; García Manchado, A.; García Villadangos, M.; Genzer, María; Giménez, Á.; Gómez Elvira, J.; Gómez, Felipe; Guzewich, Scott; Harri, Ari-Matti; Hernández, C. D.; Hieta, M.; Hueso, R.; Jaakonaho, I.; Jiménez Martín, Juan José; Jiménez, V.; Larman, A.; Leiter, R.; Lepinette Malvitte, A.; Lemmon, M. T.; López, G.; Madsen, Soren N.; Mäkinen, T.; Marín Jiménez, M.; Martín Soler, J.; Martínez, Germán M.; Molina, A.; Mora Sotomayor, L.; Moreno Álvarez, J. F.; Navarro López, Sara; Newman, C. E.; Ortega, Cristina; Parrondo, María Concepción; Peinado, V.; Peña, A.; Pérez Grande, I.; Pérez Hoyos, S.; Pla García, J.; Polkko, J.; Postigo, M.; Prieto-Ballesteros, Olga; Rafkin, Scot C. R.; Ramos, Miguel; Richardson, M. I.; Romeral, J.; Romero Guzmán, Catalina; Runyon, Kirby; Saiz López, A.; Sánchez Lavega, Agustín; Sard, I.; Schofield, J. T.; Sebastián, E.; Smith, Michael D.; Sullivan, Robert; Tamppari, L. K.; Thompson, A. D.; Toledo, D.; Torrero, F.; Torres, J.; Urquí, R.; Velasco, T.; Viúdez Moreiras, Daniel; Zurita, S.; Agencia Estatal de Investigación (AEI); European Research Council (ERC); Gobierno Vasco; Rodríguez Manfredi, J. A. [0000-0003-0461-9815]; Saiz López, A. [0000-0002-0060-1581]; Chen, H. [0000-0001-9662-0308]; Pérez Hoyos, S. [0000-0002-2587-4682]
NASA’s Mars 2020 (M2020) rover mission includes a suite of sensors to monitor current environmental conditions near the surface of Mars and to constrain bulk aerosol properties from changes in atmospheric radiation at the surface. The Mars Environmental Dynamics Analyzer (MEDA) consists of a set of meteorological sensors including wind sensor, a barometer, a relative humidity sensor, a set of 5 thermocouples to measure atmospheric temperature at ∼1.5 m and ∼0.5 m above the surface, a set of thermopiles to characterize the thermal IR brightness temperatures of the surface and the lower atmosphere. MEDA adds a radiation and dust sensor to monitor the optical atmospheric properties that can be used to infer bulk aerosol physical properties such as particle size distribution, non-sphericity, and concentration. The MEDA package and its scientific purpose are described in this document as well as how it responded to the calibration tests and how it helps prepare for the human exploration of Mars. A comparison is also presented to previous environmental monitoring payloads landed on Mars on the Viking, Pathfinder, Phoenix, MSL, and InSight spacecraft.