Persona: Martínez, Germán M.
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Centro de Astrobiologia
El Centro de Astrobiología (CAB) es un centro mixto de investigación en astrobiología, dependiente tanto del Instituto Nacional de Técnica Aeroespacial (INTA) como del Consejo Superior de Investigaciones Científicas (CSIC).
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Martínez
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Germán M.
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Publicación 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.Publicación Acceso Abierto Convective Vortices and Dust Devils Detected and Characterized by Mars 2020(AGU Advancing Earth and Space Science, 2023-02-10) Hueso, R.; Newman, C. E.; Del Río Gaztelurrutia, T.; Munguira, A.; Sánchez Lavega, Agustín; Toledo, D.; Apéstigue, Víctor; Arruego, Ignacio; Vicente Retortillo, Álvaro; Martínez, Germán M.; Lemmon, M. T.; Lorenz, Ralph; Richardson, M. I.; Viúdez Moreiras, Daniel; De la Torre Juárez, M.; Rodríguez Manfredi, J. A.; Tamppari, L. K.; Murdoch, N.; Navarro López, Sara; Gómez Elvira, J.; Baker, M.; Pla García, J.; Harri, Ari-Matti; Hieta, M.; Genzer, María; Polkko, J.; Jaakonaho, I.; Makinen, Terhi; Stott, Alexander; Mimoun, D.; Chide, B.; Sebastián Martínez, Eduardo; Banfield, D.; Lepinette Malvitte, A.; Gobierno Vasco; Ministerio de Ciencia e Innovación (MICINN); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Los Alamos National Laboratory (LANL); Arizona State University (ASU); Universities Space Research Association (USRA); NASA Jet Propulsion Laboratory (JPL); Comunidad de Madrid; Academy of Finland (AKA); Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737We characterize vortex and dust devils (DDs) at Jezero from pressure and winds obtained with the Mars Environmental Dynamics Analyzer (MEDA) instrument on Mars 2020 over 415 Martian days (sols) (Ls = 6°–213°). Vortices are abundant (4.9 per sol with pressure drops >0.5 Pa correcting from gaps in coverage) and they peak at noon. At least one in every five vortices carries dust, and 75% of all vortices with Δp > 2.0 Pa are dusty. Seasonal variability was small but DDs were abundant during a dust storm (Ls = 152°–156°). Vortices are more frequent and intense over terrains with lower thermal inertia favoring high daytime surface-to-air temperature gradients. We fit measurements of winds and pressure during DD encounters to models of vortices. We obtain vortex diameters that range from 5 to 135 m with a mean of 20 m, and from the frequency of close encounters we estimate a DD activity of 2.0–3.0 DDs km−2 sol−1. A comparison of MEDA observations with a Large Eddy Simulation of Jezero at Ls = 45° produces a similar result. Three 100-m size DDs passed within 30 m of the rover from what we estimate that the activity of DDs with diameters >100 m is 0.1 DDs km−2sol−1, implying that dust lifting is dominated by the largest vortices in Jezero. At least one vortex had a central pressure drop of 9.0 Pa and internal winds of 25 ms−1. The MEDA wind sensors were partially damaged during two DD encounters whose characteristics we elaborate in detail.Publicación Restringido Radiometric and angular calibration tests for the MEDA-TIRS radiometer onboard NASA’s Mars 2020 mission(Elsevier BV, 2020-11-02) Sebastián, E.; Martínez, Germán M.; Ramos, Miguel; Haenschke, F.; Ferrándiz, Ricardo; Fernández Sampedro, M.; Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Fernández Sampedro, M. [0000-0003-1932-7591]; Rodríguez Manfredi, J. A. [0000-0003-0461-9815]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737This article describes a comprehensive testing method for the radiometric and angular calibration of the Thermal InfraRed Sensor (TIRS) onboard NASA’s Mars 2020 mission. First, details of the TIRS opto-mechanical design, construction aspects of the IR detectors, and an update of the mathematical model used for the calculation of sensor internal IR fluxes are provided. Then, a set of sequential calibration tests to identify the radiometer model parameters are defined. The test setups are described, highlighting their limitations and restrictions based on differences between simulated and actual Martian environmental conditions. Finally, the uncertainty sources and potential systematic errors associated with the calibration tests are quantified and compared with the radiometer scientific requirements established by the Mars 2020 science team.Publicación Acceso Abierto Diurnal and Seasonal Variations of Aerosol Optical Depth Observed by MEDA/TIRS at Jezero Crater, Mars(Advancing Earth and Space Science (AGU), 2023-01-09) Smith, Michael D.; Martínez, Germán M.; Sebastián, E.; Lemmon, M. T.; Wolff, Michael; Apéstigue, Víctor; Arruego, Ignacio; Toledo, D.; Viúdez Moreiras, Daniel; Rodríguez Manfredi, J. A.; De la Torre Juárez, M.; National Aeronautics and Space Administration (NASA); Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737The two upward-looking Thermal InfraRed Sensor (TIRS) channels from the Mars Environmental Dynamics Analyzer (MEDA) instrument suite on board the Perseverance rover enable the retrieval of total aerosol optical depth (dust plus water ice cloud) above the rover for all observations when TIRS is taken. Because TIRS observes at thermal infrared wavelengths, the retrievals are possible during both the day and night and thus, they provide an excellent way to monitor both the diurnal and seasonal variations of aerosols above Jezero Crater. A retrieval algorithm has been developed for this purpose and here, we describe that algorithm along with our results for the first 400 sols of the Perseverance mission covering nearly the entire aphelion season as well as a regional dust storm and the beginning of the perihelion season. We find systematic diurnal variations in aerosol optical depth that can be associated with dust and water ice clouds as well as a clear change from a cloud-filled aphelion season to a perihelion season where dust is the dominant aerosol. A comparison of retrieved optical depths between TIRS and the SkyCam camera that is also part of MEDA indicates evidence of possible diurnal variations in cloud height or particle size.Publicación Acceso Abierto Seasonal Variations in Atmospheric Composition as Measured in Gale Crater, Mars(American Geophysical Union: Advancing Earth and Space Science, 2019-11-12) Trainer, M. G.; Wong, Michael H.; McConnochie, Tim H.; Franz, H. B.; Atreya, S. K.; Conrad, Pamela G.; Lefèvre, F.; Mahaffy, Paul R.; Malespin, C. A.; Manning, H. L. K.; Martín Torres, Javier; Martínez, Germán M.; McKay, Christopher P.; Navarro González, R.; Vicente Retortillo, Álvaro; Webster, Christopher R.; Zorzano, María-Paz; Universidad Nacional Autónoma de México (UNAM); Zorzano, M. P. [0000-0002-4492-9650]; Navarro González, R. [0000-0002-6078-7621]; Martín Torres, J. [0000-0001-6479-2236]; Vicente Retortillo, A. [0000-0002-4553-7624]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737The Sample Analysis at Mars (SAM) instrument onboard the Mars Science Laboratory Curiosity rover measures the chemical composition of major atmospheric species (CO2, N2, 40Ar, O2, and CO) through a dedicated atmospheric inlet. We report here measurements of volume mixing ratios in Gale Crater using the SAM quadrupole mass spectrometer, obtained over a period of nearly 5 years (3 Mars years) from landing. The observation period spans the northern summer of MY 31 and solar longitude (LS) of 175° through spring of MY 34, LS = 12°. This work expands upon prior reports of the mixing ratios measured by SAM QMS in the first 105 sols of the mission. The SAM QMS atmospheric measurements were taken periodically, with a cumulative coverage of four or five experiments per season on Mars. Major observations include the seasonal cycle of CO2, N2, and Ar, which lags approximately 20–40° of LS behind the pressure cycle driven by CO2 condensation and sublimation from the winter poles. This seasonal cycle indicates that transport occurs on faster timescales than mixing. The mixing ratio of O2 shows significant seasonal and interannual variability, suggesting an unknown atmospheric or surface process at work. The O2 measurements are compared to several parameters, including dust optical depth and trace CH4 measurements by Curiosity. We derive annual mean volume mixing ratios for the atmosphere in Gale Crater: CO2 = 0.951 (±0.003), N2 = 0.0259 (±0.0006), 40Ar = 0.0194 (±0.0004), O2 = 1.61 (±0.09) x 10‐3, and CO = 5.8 (±0.8) x 10‐4.Publicación 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.Publicación Acceso Abierto The sound of a Martian dust devil(Nature, 2022-12-13) Murdoch, N.; Stott, A. E.; Gillier, M.; Hueso, R.; Lemmon, M. T.; Martínez, Germán M.; Apéstigue, Víctor; Toledo, D.; Lorenz, R. D.; Chide, B.; Munguira, A.; Sánchez Lavega, Agustín; Vicente Retortillo, Álvaro; Newman, C. E.; Maurice, S.; De la Torre Juárez, M.; Bertrand, T.; Banfield, D.; Navarro López, Sara; Marín, M.; Torres, J.; Gómez Elvira, J.; Jacob, Xavier; Cadu, A.; Sournac, A.; Rodríguez Manfredi, J. A.; Mimoun, D.; National Aeronautics and Space Administration (NASA); Centre National D'Etudes Spatiales (CNES); NASA Jet Propulsion Laboratory (JPL); Comunidad de Madrid; Gobierno Vasco; Agencia Estatal de Investigación (AEI); Los Alamos National Laboratory; Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Dust devils (convective vortices loaded with dust) are common at the surface of Mars, particularly at Jezero crater, the landing site of the Perseverance rover. They are indicators of atmospheric turbulence and are an important lifting mechanism for the Martian dust cycle. Improving our understanding of dust lifting and atmospheric transport is key for accurate simulation of the dust cycle and for the prediction of dust storms, in addition to being important for future space exploration as grain impacts are implicated in the degradation of hardware on the surface of Mars. Here we describe the sound of a Martian dust devil as recorded by the SuperCam instrument on the Perseverance rover. The dust devil encounter was also simultaneously imaged by the Perseverance rover’s Navigation Camera and observed by several sensors in the Mars Environmental Dynamics Analyzer instrument. Combining these unique multi-sensorial data with modelling, we show that the dust devil was around 25 m large, at least 118 m tall, and passed directly over the rover travelling at approximately 5 m s−1. Acoustic signals of grain impacts recorded during the vortex encounter provide quantitative information about the number density of particles in the vortex. The sound of a Martian dust devil was inaccessible until SuperCam microphone recordings. This chance dust devil encounter demonstrates the potential of acoustic data for resolving the rapid wind structure of the Martian atmosphere and for directly quantifying wind-blown grain fluxes on Mars.Publicación 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-2017-0765The 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.Publicación Acceso Abierto In Situ UV Measurements by MSL/REMS: Dust Deposition and Angular Response Corrections(Springer Link, 2020-07-21) Vicente Retortillo, Álvaro; Martínez, Germán M.; Rennó, N. O.; Lemmon, M. T.; De la Torre Juárez, M.; Gómez Elvira, J.; NASA Jet Propulsion Laboratory (JPL); Retortillo, A. V. [0000-0002-4553-7624]; Gómez Elvira, J. [0000-0002-9068-9846]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Measurements by the REMS/UV sensor onboard the MSL Curiosity rover constitute the first in situ dataset of UV radiation flux at the surface of Mars. Due to its position on the Curiosity deck, the UV sensor has been directly exposed to dust deposition. Inaccuracies in the original angular response calibration functions have led to discrepancies between measured and physically-expected UV fluxes when the solar zenith angle (theta) relative to the rover frame is between 20 degrees and 55 degrees. Here we present a methodology to correct UV fluxes when theta < 55 degrees for both effects, and show results of the corrected data set for the first 2003 sols (similar to 3 Martian Years, MY) of the MSL mission, from L-s similar to 151 degrees in MY 31 to L-s similar to 149 degrees in MY 34. Close to noon, when. values are typically < 30 degrees, relative differences between corrected and original UV fluxes are similar to 35 - 40% on average. Outside hours close to noon, when theta is typically > 30 degrees, relative differences are greater than 100%. Measurements acquired when 20 degrees < theta < 55 degrees represent similar to 45% of the whole dataset with theta < 90 degrees. UV fluxes generated in this study are available in the NASA Planetary Data System (https://atmos.nmsu.edu/PDS/data/mslrem_1001/DATA_UV_CORRECTED/), and are important to study the effect of UV radiation on the variability of atmospheric constituents, to recreate accurate UV doses for biological laboratory experiments, to perform combined analyses of satellite and ground-based measurements, and to allow comparisons of the UV radiation environment at different locations with the upcoming ExoMars 2020 and Mars 2020 missions.Publicación Restringido Model Update and Surface Operation Performance of the MEDA-TIRS Radiometer Onboard NASA’s Mars 2020 Perseverance Rover(Springer Nature, 2025-07-14) Sebastián Martínez, Eduardo; Martínez, Germán M.; Smith, Michael; Peinado, V.; Mora Sotomayor, L.; Vicente Retortillo, Álvaro; Rodríguez Manfredi, J. A.; Ministerio de Economía y Competitividad (MINECO); Ministerio de Ciencia e Innovación (MICINN); Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA); Instituto Nacional de Técnica Aeroespacial (España); Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737We describe new updates in the data retrieval process of the Mars Environmental Dynamics Analyzer Thermal-InfraRed Sensor (MEDA-TIRS) onboard NASA’s Mars 2020 Perseverance rover and analyze its performance under these new updates for the first 700 sols of this mission. The primary goal of these updates is to reduce the uncertainty in each of the quantities measured by TIRS, thereby improving its performance in measuring atmospheric and ground temperature, reflected shortwave solar radiation, and the upwelling and downwelling longwave irradiances across the entire spectrum. Our updates include results from new modeling efforts and tests conducted during the cruise and operational phase on Mars to characterize the electronic conditioning system and to calculate new noise and offset values. Based on the annual degradation rates of the TIRS channel detectors due to dust deposition, we compare projected values of resolution and accuracy to pre-flight requirements. These projections are useful for estimating the radiometer’s lifetime and for using its data in the context of the future Mars Sample Return and other future mission.
