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 dynamic atmospheric and aeolian environment of Jezero crater, Mars(Science Publishin Group, 2022-05-25) Newman, C. E.; Hueso, R.; Lemmon, M. T.; Munguira, A.; Vicente Retortillo, Álvaro; Apéstigue, Víctor; Martínez, Germán M.; Toledo, D.; Sullivan, Robert; Herkenhoff, K. E.; De la Torre Juárez, M.; Richardson, M. I.; Stott, A.; Murdoch, N.; Sánchez Lavega, Agustín; Wolff, Michael; Arruego, Ignacio; Sebastián, E.; Navarro López, Sara; Gómez Elvira, J.; Tamppari, L. K.; Smith, Michael D.; Lepinette Malvitte, A.; Viúdez Moreiras, Daniel; Harri, Ari-Matti; Genzer, María; Hieta, M.; Lorenz, R. D.; Conrad, Pamela G.; Gómez, Felipe; McConnochie, Timothy; Mimoun, D.; Tate, C.; Bertrand, T.; Belli, J. F.; Maki, Justin N.; Rodríguez Manfredi, J. A.; Wiens, Roger; Chide, B.; Maurice, Sylvestre; Zorzano, María-Paz; Mora Sotomayor, L.; Baker, M. M.; Banfield, D.; Pla García, J.; Beyssac, O.; Brown, Adrian Jon; Clark, B.; Montmessin, F.; Fischer, E.; Patel, P.; Del Río Gaztelurrutia, T.; Fouchet, T.; Francis, Raymond; Guzewich, Scott; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Ciencia e Innovación (MICINN); Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Gobierno Vasco; National Aeronautics and Space Administration (NASA); Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Despite the importance of sand and dust to Mars geomorphology, weather, and exploration, the processes that move sand and that raise dust to maintain Mars’ ubiquitous dust haze and to produce dust storms have not been well quantified in situ, with missions lacking either the necessary sensors or a sufficiently active aeolian environment. Perseverance rover’s novel environmental sensors and Jezero crater’s dusty environment remedy this. In Perseverance’s first 216 sols, four convective vortices raised dust locally, while, on average, four passed the rover daily, over 25% of which were significantly dusty (“dust devils”). More rarely, dust lifting by nonvortex wind gusts was produced by daytime convection cells advected over the crater by strong regional daytime upslope winds, which also control aeolian surface features. One such event covered 10 times more area than the largest dust devil, suggesting that dust devils and wind gusts could raise equal amounts of dust under nonstorm conditions.Publicación 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, Germán 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-2017-0737The 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.Publicación Acceso Abierto Dust, Sand, and Winds Within an Active Martian Storm in Jezero Crater(AGU Advancing Earth and Space Science, 2022-11-16) Lemmon, M. T.; Smith, Michael D.; Viúdez Moreiras, Daniel; De la Torre Juárez, M.; Vicente Retortillo, Álvaro; Munguira, A.; Sánchez Lavega, Agustín; Hueso, R.; Martínez, Germán M.; Chide, B.; Sullivan, Robert; Toledo, D.; Tamppari, L. K.; Bertrand, T.; Bell, James; Newman, C. E.; Baker, M.; Banfield, D.; Rodríguez Manfredi, J. A.; Maki, Justin N.; Apéstigue, Víctor; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Ciencia e Innovación (MICINN); Ministerio de Economía y Competitividad (MINECO); NASA Jet Propulsion Laboratory (JPL); Arizona State University (ASU); European Research Council (ERC); Agencia Estatal de Investigación (AEI); Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Rovers and landers on Mars have experienced local, regional, and planetary-scale dust storms. However, in situ documentation of active lifting within storms has remained elusive. Over 5–11 January 2022 (LS 153°–156°), a dust storm passed over the Perseverance rover site. Peak visible optical depth was ∼2, and visibility across the crater was briefly reduced. Pressure amplitudes and temperatures responded to the storm. Winds up to 20 m s−1 rotated around the site before the wind sensor was damaged. The rover imaged 21 dust-lifting events—gusts and dust devils—in one 25-min period, and at least three events mobilized sediment near the rover. Rover tracks and drill cuttings were extensively modified, and debris was moved onto the rover deck. Migration of small ripples was seen, but there was no large-scale change in undisturbed areas. This work presents an overview of observations and initial results from the study of the storm.Publicación Acceso Abierto Radiation and Dust Sensor for Mars Environmental Dynamic Analyzer Onboard M2020 Rover(Multidisciplinary Digital Publishing Institute (MDPI), 2022-04-10) Apéstigue, Víctor; Gonzalo Melchor, Alejandro; Jiménez Martín, Juan José; Boland, J.; Lemmon, M. T.; de Mingo Martín, José Ramón; García-Menéndez, Elisa; Rivas, J.; Azcue, J.; Bastide, L. ; Andrés Santiuste, N.; Martínez Oter, J.; González Guerrero, M.; Martín-Ortega, Alberto; Toledo, D.; Álvarez Ríos, F. J.; Serrano, F.; Martín Vodopivec, B.; Manzano, Javier; López Heredero, Raquel; Carrasco, I.; Aparicio, S.; Carretero, Á.; MacDonald, D. R.; Moore, L. B.; Alcacera Gil, María Ángeles; Fernández Viguri, J. A.; Martín, I.; Yela González, Margarita; Álvarez, Maite; Manzano, Paula; Martín, J. A.; del Hoyo Gordillo, Juan Carlos; Reina Aranda, Manuel; Urquí, R.; Rodríguez Manfredi, J. A.; De la Torre Juárez, M.; Hernández, Christina; Córdoba, Elizabeth; Leiter, R.; Thompson, Art; Madsen, Soren N.; Smith, Michael D.; Viúdez Moreiras, Daniel; Saiz López, A.; Sánchez Lavega, Agustín; Gómez Martín, L.; Martínez, Germán M.; Gómez Elvira, J.; Arruego, Ignacio; Instituto Nacional de Técnica Aeroespacial (INTA); Comunidad de Madrid; Gobierno Vasco; Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA)The Radiation and Dust Sensor is one of six sensors of the Mars Environmental Dynamics Analyzer onboard the Perseverance rover from the Mars 2020 NASA mission. Its primary goal is to characterize the airbone dust in the Mars atmosphere, inferring its concentration, shape and optical properties. Thanks to its geometry, the sensor will be capable of studying dust-lifting processes with a high temporal resolution and high spatial coverage. Thanks to its multiwavelength design, it will characterize the solar spectrum from Mars’ surface. The present work describes the sensor design from the scientific and technical requirements, the qualification processes to demonstrate its endurance on Mars’ surface, the calibration activities to demonstrate its performance, and its validation campaign in a representative Mars analog. As a result of this process, we obtained a very compact sensor, fully digital, with a mass below 1 kg and exceptional power consumption and data budget features.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, Timothy; 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 Acceso Abierto Surface Energy Budget, Albedo, and Thermal Inertia at Jezero Crater, Mars, as Observed From the Mars 2020 MEDA Instrument(AGU Advancing Earth and Space Science, 2023-02) Martínez, Germán M.; Sebastián, E.; Vicente Retortillo, Álvaro; Smith, Michael D.; Johnson, J. R.; Fischer, E.; Savijärvi, H.; Toledo, D.; Hueso, R.; Mora Sotomayor, L.; Gillespie, H.; Munguira, A.; Sánchez Lavega, Agustín; Lemmon, M. T.; Gómez, Felipe; Polkko, J.; Mandon, Lucía; Apéstigue, Víctor; Arruego, Ignacio; Ramos, Miguel; Conrad, Pamela G.; Newman, C. E.; De la Torre Juárez, M.; Jordan, Francisco; Tamppari, L. K.; McConnochie, Timothy; Harri, Ari-Matti; Genzer, María; Hieta, M.; Zorzano, María-Paz; Siegler, M.; Prieto-Ballesteros, Olga; Molina, A.; Rodríguez Manfredi, J. A.; Comunidad de Madrid; Universities Space Research Association (USRA); Agencia Estatal de Investigación (AEI); Gobierno Vasco; Instituto Nacional de Técnica Aeroespacial (INTA); Centre National D'Etudes Spatiales (CNES); National Aeronautics and Space Administration (NASA); Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737The Mars Environmental Dynamics Analyzer (MEDA) on board Perseverance includes first-of-its-kind sensors measuring the incident and reflected solar flux, the downwelling atmospheric IR flux, and the upwelling IR flux emitted by the surface. We use these measurements for the first 350 sols of the Mars 2020 mission (Ls ∼ 6°–174° in Martian Year 36) to determine the surface radiative budget on Mars and to calculate the broadband albedo (0.3–3 μm) as a function of the illumination and viewing geometry. Together with MEDA measurements of ground temperature, we calculate the thermal inertia for homogeneous terrains without the need for numerical thermal models. We found that (a) the observed downwelling atmospheric IR flux is significantly lower than the model predictions. This is likely caused by the strong diurnal variation in aerosol opacity measured by MEDA, which is not accounted for by numerical models. (b) The albedo presents a marked non-Lambertian behavior, with lowest values near noon and highest values corresponding to low phase angles (i.e., Sun behind the observer). (c) Thermal inertia values ranged between 180 (sand dune) and 605 (bedrock-dominated material) SI units. (d) Averages of albedo and thermal inertia (spatial resolution of ∼3–4 m2) along Perseverance's traverse are in very good agreement with collocated retrievals of thermal inertia from Thermal Emission Imaging System (spatial resolution of 100 m per pixel) and of bolometric albedo in the 0.25–2.9 μm range from (spatial resolution of ∼300 km2). The results presented here are important to validate model predictions and provide ground-truth to orbital measurements.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, Sylvestre; 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 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.
