Machine learning methods applied to combined Raman and LIBS spectra: Implications for mineral discrimination in planetary missions

Producción CientíficaThe combined analysis of geological targets by complementary spectroscopic techniques could enhance the characterization of the mineral phases found on Mars. This is indeed the case with the SuperCam instrument onboard the Perseverance rover. In this framework, the present study seeks to evaluate and compare multiple machine learning techniques for the characterization of carbonate minerals based on Raman-LIBS (Laser-Induced Breakdown Spectroscopy) spectroscopic data. To do so, a Ca-Mg prediction curve was created by mixing hydromagnesite and calcite at different concentration ratios. After their characterization by Raman and LIBS spectroscopy, different multivariable machine learning (Gaussian process regression, support vector machines, ensembles of trees, and artificial neural networks) were used to predict the concentration ratio of each sample from their respective datasets. The results obtained by separately analyzing Raman and LIBS data were then compared to those obtained by combining them. By comparing their performance, this work demonstrates that mineral discrimination based on Gaussian and ensemble methods optimized the combine of Raman-LIBS dataset outperformed those ensured by Raman and LIBS data alone. This demonstrated that the fusion of data combination and machine learning is a promising approach to optimize the analysis of spectroscopic data returned from Mars.Agencia Estatal de Investigación, grant (PID2022-142490OB-C32)Ministerio de Economía y Competitividad (MINECO),Grant/Award Number (RDE2018-102600-T

An enduring rapidly moving storm as a guide to Saturn's Equatorial jet's complex structure

This work is licensed under a Creative Commons Attribution 4.0Saturn has an intense and broad eastward equatorial jet with a complex three-dimensional structure mixed with time variability. The equatorial region experiences strong seasonal insolation variations enhanced by ring shadowing, and three of the six known giant planetary-scale storms have developed in it. These factors make Saturn’s equator a natural laboratory to test models of jets in giant planets. Here we report on a bright equatorial atmospheric feature imaged in 2015 that moved steadily at a high speed of 450 ms-1 not measured since 1980–1981 with other equatorial clouds moving within an ample range of velocities. Radiative transfer models show that these motions occur at three altitude levels within the upper haze and clouds. We find that the peak of the jet (latitudes 10ºN to 10º S) suffers intense vertical shears reaching þ2.5 ms-1 km-1, two orders of magnitude higher than meridional shears, and temporal variability above 1 bar altitude level.Peer ReviewedPostprint (published version

A planetary-scale disturbance in a long-living three-vortex coupled system in Saturn's atmosphere

The zonal wind profile of Saturn has a singular structure in the latitude range 50ºN-65ºN planetocentric, with a double peak that reaches maximum zonal velocities close to 100ms-1[1]. A survey of Cassini ISS images shows that a system of three vortices formed in this latitudinal region in 2012 and has remained active until present, confirming that vortices in Saturn can be long lived [2]. In May 2015 a disturbance started to develop at the location of the triple vortex. Since at the time Cassini orbits were not favorable to the observation of the region, we were granted Director Discretionary Time of the Hubble Space Telescope to observe the region before the perturbation faded away. Here we report the dynamics and vertical structure of the three-vortex system and of the disturbance that developed at its location, based on HST and Cassini images. We also present results of numerical models to explain the stability of vortices in the region.Peer ReviewedPostprint (published version

A complex storm system in Saturn's north polar atmosphere in 2018

Saturn’s convective storms usually fall in two categories. One consists of mid-sized storms ~2,000¿km wide, appearing as irregular bright cloud systems that evolve rapidly, on scales of a few days. The other includes the Great White Spots, planetary-scale giant storms ten times larger than the mid-sized ones, which disturb a full latitude band, enduring several months, and have been observed only seven times since 1876. Here we report a new intermediate type, observed in 2018 in the north polar region. Four large storms with east–west lengths ~4,000–8,000¿km (the first one lasting longer than 200 days) formed sequentially in close latitudes, experiencing mutual encounters and leading to zonal disturbances affecting a full latitude band ~8,000¿km wide, during at least eight months. Dynamical simulations indicate that each storm required energies around ten times larger than mid-sized storms but ~100 times smaller than those necessary for a Great White Spot. This event occurred at about the same latitude and season as the Great White Spot in 1960, in close correspondence with the cycle of approximately 60 years hypothesized for equatorial Great White Spots.Peer ReviewedPostprint (author's final draft

A planetary-scale disturbance in a long-living three-vortex coupled system in Saturn's atmosphere

The zonal wind profile of Saturn has a singular structure in the latitude range 50ºN-65ºN planetocentric, with a double peak that reaches maximum zonal velocities close to 100ms-1[1]. A survey of Cassini ISS images shows that a system of three vortices formed in this latitudinal region in 2012 and has remained active until present, confirming that vortices in Saturn can be long lived [2]. In May 2015 a disturbance started to develop at the location of the triple vortex. Since at the time Cassini orbits were not favorable to the observation of the region, we were granted Director Discretionary Time of the Hubble Space Telescope to observe the region before the perturbation faded away. Here we report the dynamics and vertical structure of the three-vortex system and of the disturbance that developed at its location, based on HST and Cassini images. We also present results of numerical models to explain the stability of vortices in the region.Peer Reviewe

Jupiter’s Great Red Spot: strong interactions with incoming anticyclones in 2019

Jupiter’s Great Red Spot (GRS), a giant anticyclone, is the largest and longest-lived of all the vortices observed in planetary atmospheres. During its history, the GRS has shrunk to half its size since 1879, and encountered many smaller anticyclones and other dynamical features that might tend to erode it. In 2018-2020, while having a historically small size, its structure and even its survival appeared to be threatened when a series of anticyclones moving in from the east tore off large fragments of the red area and distorted its shape. In this work we report observations of the dynamics of these interactions and show that as a result the GRS increased its internal rotation velocity, maintaining its vorticity but decreasing its visible area, and suffering a transient change in its otherwise steady 90-day oscillation in longitude. From a radiative transfer analysis and numerical simulations of the dynamics we show that the interactions affected the upper cloud tops of the GRS. We argue that the intense vorticity of the GRS, together with its larger size and depth compared to the interacting vortices, guarantees its long lifetime.This work has been supported by the Spanish project AYA2015-65041-P and PID2019-109467GB-I00 (MINECO/ FEDER, UE) and Grupos Gobierno Vasco IT1366-19. PI acknowledges a PhD scholarship from Gobierno Vasco. EGM is Serra Hunter Fellow at UPC. This work used data acquired from the NASA/ESA HST Space Telescope, asso- ciated with OPAL program (PI: Simon, GO13937), and archived by the Space Telescope Science Institute, which is operated by the Association of Universi- ties for Research in Astronomy, Inc., under NASA contract NAS 5–26,555. All maps are available at http://dx.doi. org/10.17909/T9G593. PlanetCam ob- servations were collected at the Centro Astronómico Hispánico en Andalucía (CAHA), operated jointly by the Insti- tuto de Astrofisica de Andalucia (CSIC) and the Andalusian Universities (Junta de Andalucía). EGM, MS, APG, MAC and ASL thankfully acknowledge the computer resources at Mare Nostrum and the technical support provided by Barcelona Supercomputing Center (AECT-2019-2-0006). This research has made use of the USGS Integrated Software for Imagers and Spectrometers (ISIS). We appreciate the contribution from all observers cited in TableS1 for his fundamental contribution to this study with Jupiter images obtained with high dedication and skill. GSO and TM were supported by NASA with funds distributed to the Jet Propulsion Laboratory, California Institute of Technology.Peer ReviewedPostprint (author's final draft

A complex storm system in Saturn's north polar atmosphere in 2018

Saturn’s convective storms usually fall in two categories. One consists of mid-sized storms ~2,000¿km wide, appearing as irregular bright cloud systems that evolve rapidly, on scales of a few days. The other includes the Great White Spots, planetary-scale giant storms ten times larger than the mid-sized ones, which disturb a full latitude band, enduring several months, and have been observed only seven times since 1876. Here we report a new intermediate type, observed in 2018 in the north polar region. Four large storms with east–west lengths ~4,000–8,000¿km (the first one lasting longer than 200 days) formed sequentially in close latitudes, experiencing mutual encounters and leading to zonal disturbances affecting a full latitude band ~8,000¿km wide, during at least eight months. Dynamical simulations indicate that each storm required energies around ten times larger than mid-sized storms but ~100 times smaller than those necessary for a Great White Spot. This event occurred at about the same latitude and season as the Great White Spot in 1960, in close correspondence with the cycle of approximately 60 years hypothesized for equatorial Great White Spots.Peer Reviewe