Planetary Geology
Transcripción
Planetary Geology
1 2 Planetary Geology Coordinator: Olga Prieto Members of the research line: José Javier Álvaro Blasco , Ricardo Amils Pibernat, Tania Barragan Gonzalez, David Fernández Remolar, Maite Fernández Sampedro , Miriam García Villadangos , Damhait Gleeson , Felipe Gómez Gómez , Laura Jiménez Bonales , Fernando Izquierdo Ruiz, Emmanuel Aléxis Lalla, María Paz Martín Redondo, Jesús Martínez Frías , Paloma Martínez Sarmiento, Jesús Medina García, Irene Melero Asensio , Antonio Molina Jurado, Victoria Muñoz Iglesias , Delphine Nna Mvondo, Jens Olof Ormö, Fernando Rull Pérez, Mónica Sánchez Román, Antonio Sansano Caramazana, José Aurelio Sanz Arranz, Fernando Tornos Arroyo, Jesús Ignacio Velasco Acebes, Gloria Venegas del Valle Resumen: Planetary Geology is the study of solid surface planetary objects in the Universe, including Earth. Specifically, this scientific discipline investigates the composition, structure and processes and agents by which planets, satellites, comets, asteroids and meteorites evolve since its formation. These issues are crucial in determining the habitability of planetary environments, and basically outline the main objectives of this research area at CAB: 1) participation in planetary exploration missions, 2) determination of the influence of the geology on extreme paleo-, and current terrestrial environments analogous to those developed on other planets, 3) the characterization of planetary material regarding habitability, and 4) understanding the geological processes that affects the evolution of the planets and natural satellites. The close relationship with other fields of astrobiology, which arises naturally during the approach to these problems, is well reflected in the activities that were carried out during 2012. Participation In Planetary Missions The experience of the researchers working in Planetary Geology and Astrobiology is required for the development of instruments and planning planetary mission to different solar system bodies. 2012 was very fruitful for CAB regarding participation in planetary missions, to be noted two milestones with significant participation of researchers of the area of Planetary Geology: In May 2012, the European Space Agency (ESA) elected the mission JUICE (Jupiter Icy Moon Explorer) as the first large-budget mission to be executed within the Cosmic Vision program. This mission, in which members of CAB have worked for more than five years, will arrive to the Jupiter system in 2030. The main themes of this mission are the study of the emergence of habitable worlds around gas giant planets, with particular interest to the satellite Ganymede, and the examination of the Jupiter system as an archetype of such planets in the Universe. Another important event occurred in August 2012 when the Curiosity rover of MSL (Mars Science Laboratory) mission managed by NASA (National Aeronautics and Space Administration) reached the surface of Mars and began its explorations. Since then, the science team of the REMS instrument (Rover Environmental Monitoring Station) led by CAB and with participation of members of this research line began the operations and data interpretation. REMS reports daily on atmospheric pressure, humidity and ultraviolet radiation on the Martian surface, data of great importance for the understanding of the current environment and how it affects the rocks on Mars' surface. The development of a Raman spectrometer for the ExoMars mission, led by members of this research line, continues in technological and scientific success. Significant progress is made in the spectrometer development with components in temperature, radiation, and thermal and mechanical design. There has been extensive work in the excitation laser to optimize its performance and stability as well as on the optical head, whose responsibility within the international consortium fell on the German team so far, but now also includes Spanish involvement. Numerous tests have also been executed at INTA’s to establish the radiometric model of the spectrometer, estimate the calibration functions at different temperatures, and verify scientific requirements. The results of these trials have been excellent. Also, there have been substantial advances in software, algorithms and the spectral processing mode. Among the activities to support the science of the instrument are those related to the simulator equipment, which includes the development of a Martian environmental chamber for studies of polycrystalline samples with flattened distribution following the procedure of the ExoMars’ rover, and on relevant geological samples. This chamber is considered of great value to ESA for future testing in coordination with the rover's analytical laboratory. The most important tests are those where the Raman is combined with other instruments such as MOMA and Micromega, and in particular using unknown samples where Raman has shown great ability to detect both minerals and organic materials, and also in the analysis of perchlorates in polycrystalline samples. In addition, members of the research line have also participated in scientific meetings related to the development of exploration strategies and techniques to detect life on samples to be retrieved by a future sample return mission to Mars. Likewise, members of 4 3 2 Figura 1. Simulation of planetary processes and environments in the unique facilities at CAB. A) The Experimental Projectile Impact Chamber (EPIC) in the Laboratory for Experimental Impact Cratering, and B) High Pressure Equipment for the analysis of planetary geochemistry. . the research line are also participating with their geological expertize in the development of the Mercury Imaging X-ray Spectrometer (MIXS) mineralogical mapper instrument developed for the Bepi Colombo mission to Mercury to be launched in 2015. This geological reference work focuses on the effects of impact cratering, the dominant surface process of Mercury and most other solid objects in the solar system, and is carried out through experiments in the unique Laboratory for Experimental Impact Cratering at CAB (Fig. 1A) as well as through remote sensing and field studies of natural impact craters. Characterization Of The Geology Of Current Extreme Environments And Paleo-Environments During the year 2012 various extreme environments of great interest to astrobiology visited. Geological field work provided samples for mineralogical, geochemical and biogeochemical analysis. These analyses were performed both in the laboratory facilities of CAB as well as other collaborating institutes, including the University of Western Ontario (Canada), the Natural History Museum in London (United Kingdom) and the University of Salamanca (Spain). Most of the explored environments are in part analogs to some environments observed at planetary objects in our solar system, like Mars or Europa. Concerning the exploration of inaccessible places, their study has been possible thanks to the support of local researchers and institutions, such as the GNS-Science (Institute of Geological and Nuclear Sciences, New Zealand), the University of Chile or the Spanish Polar Committee and the Army, which manage the Antarctic bases. One example of active extreme environments explored in 2012 is the hydrothermal systems on the seafloor in New Zealand, and those located in cold climate areas such as Deception Island (Antarctica). Investigations have also been carried out on the genesis of singular magmas of magnetite-apatite and associated hydrothermal systems in the Andes (Chile). Environments of fossil hydrothermal systems are being studied for some time in El Jaroso, Cabo de Gata and the Iberian Pyrite Belt (Spain). In this regard, the further development of the EU-funded project Iberian Pyrite Belt Subsurface Life (IPBSL) has included the drilling of the basement at the Rio Tinto to study the community of microorganisms that induce the extreme conditions of the river. In 2012, the drilling of the longest borehole was completed, which reached the depth of 613 meters. During this campaign, the drilling and sampling of the terraces of the Rio Tinto river system has also proceeded for evaluating the degree of preservation of biological information in extreme conditions dominating over 7 million of years. In addition to that, sampling inside some caves has been performed to determine the processes of crystallization of minerals (carbonates and sulfates) that appear there, such as some from Almeria (Spain) and northern Italy. In some cases, the interest of a geological site is that its rocks record periods of Earth history in which decisive events occurred for the environment or the life of the planet. This occurs in several studied Neo-ProterozoicCambrian outcrops including primitive microbial communities (e.g. Montagne Noire in France, Atlas in Morocco, Ossa Morena in Portugal and Spain, or in the Baltic of Russia) (Fig. 2). During 2012 some interesting results from the analysis of samples from previous campaigns have been obtained, such as details regarding the sedimentation and microbial associations with hydrothermal mineralization within Proterozoic rocks (Burkina Faso) and the salt basins from the Neoproterozoic-Cambrian (Mauritania), evidences by TOF-SIMS analysis of 6 5 3 Figure 2. A) Image of a columnar stromatolite in a carbonatic rock that marks the Marinoense glaciation (basal Ediacaran) in Kayes (Mali) taken with a petrographic microscope with parallel light. It shows alternating layers of microbial mats and barite cement (BaSO4), developed on a low temperature hydrothermal emanation, where sulfur is provided by the sea and barium hydrothermal fluid). B) Brecciated rock from a slope flanking a microbial reef complex of the Lower Cambrian unit of Ossa-Morena (Estremoz quarries, Portugal) organic aggregates comparable to bacterial cell structures in rocks of the Achaean age obtained during the 2011 Barbeton campaign (South Africa), detection of biological bearing molecules such as DNA, proteins or protein complexes that have great potential for preservation in hypersaline deposits of Atacama (Chile) that are analogs of chlorides deposits observed in Sirenum Terra on Mars, or details of the microbial communities associated with the permafrost of Deception Island (Antarctica). In addition, contributions to realize some 1/50 000 maps edited by the Ministry of Energy and Mining, Morocco have been realized, such as The Atrous, Irara, Merzouga, M'fis and Taouz (Tafilalt, eastern AntiAtlas). Characterization Of Planetary Material Related To Habitability The essential elements for life are contained in the materials of the geosphere, atmosphere and hydrosphere of the planetary objects. In the area of Planetary Geology planetary minerals, fluids and their interactions are investigated from different perspectives. One method involves the experimental analysis on both natural samples (e.g. meteorites) and synthetic samples. Another procedure for obtaining information about the composition of a planetary object is the analysis of sensor data from space missions such as spectrometers of different wavelengths or mass spectrometers. An advantage that CAB’s researchers have is the availability of facilities for experimental simulations of planetary environments, e.g. the high pressure equipment that allows studies of solid and liquid materials in the conditions of deep planetary environments such as the oceans of the icy satellites and niches within the crust of rocky planets. During 2012, there have been some equipment modifications to optimize both, the control of the temperature and for obtaining the spectroscopic signal within the chambers (Fig. 1B), and various experiments for characterization of materials at high pressure were carried out, e.g. the crystallization of hydrated minerals associations at the prevailing pressures in the crust and ocean from Europa satellite. This was used to assess the evolution of the cryomagmas involved in mobilizing liquid water within this icy satellite. High pressure experiments are part of the collaboration with the Spanish network of scientists working at high pressure in the context of a Consolider-Ingenio project (MALTA). Also, the development of spectral databases of minerals for applications of the Raman instrument of ExoMars mission has continued during this period. Analyzes have been made of the material changes due to Martian conditions and the structural transformation phenomena (especially the hydration-dehydration process) that can happen when the samples obtained under the Martian surface enter the rover for analysis. 7 8 4 Characterization Of Geological Processes The evolution of planetary objects is determined by the geological processes that affect their internal and external dynamics. Some of these processes are of particular interest because they have effects on the environments in which life can develop or thrive, i.e. the formation of habitats through access to energy source (hydrothermalism) and space (fracturing). The cratering phenomenon is extended to all the planets of the solar system and has great relevance to Astrobiology because it greatly disturbs the surface properties of the impacted object. The cratering process is sensitive to these surface properties and an analysis of the craters formed by this exogenous process can be used to reconstruct paleo-environments that could have supported, or even still support, life, for instance past aquatic environments or ground water/ice reservoirs. In the Laboratory for Experimental Impact Cratering at CAB, meteorite impact processes are studied through experiments with projectiles in Experimental Projectile Impact Chamber (EPIC), with numerical simulations, field studies at natural craters, and through the analysis of planetary analogous data. In 2012, the installation of the hardware facilities has finished, and tests have been performed to verify the scaling relations between the obtained experimental impact craters and large natural craters. The impact process is analyzed with a new high resolution camera. Experiments at oblique impact angles over stratified targets have been conducted, which is essential for the understanding of the layered upper crust of Mars, impacts in oceanic environments, as well as calculations on deflection techniques of lifethreatening near earth objects. Furthermore, some reference structures for impacts into layered marine targets that were already under study such as the Lockne/Malingen doublet impact structure (Sweden), and the Wetumpka crater (USA) have been analyzed to even greater detail, and a new structure was discovered in the high Swedish arctic (the Vakkejokk breccia) that show promising features for the understanding of ejecta formation in a wet-target environment.