Persona: Ormö, Jens
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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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Ormö
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Jens
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Publicación Acceso Abierto Winding down the Chicxulub impact: The transition between impact and normal marine sedimentation near ground zero(Elsevier BV, 2020-10-17) Whalen, M. T.; Gulick, S. P. S.; Lowery, C. M.; Bralower, T. J.; Morgan, Joanna; Grice, K.; Schaefer, B.; Smit, J.; Ormö, Jens; Wittmann, A.; kring, D. A.; Lyons, S.; Goderis, S.; National Science Foundation (NSF); Australian Research Council (ARC); Belgian Science Policy Office (BELSPO); Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Goderis, S. [0000-0002-6666-7153]; Riller, U. [0000-0002-3803-6792]; Smit, J. [0000-0002-6070-4865]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737The Chicxulub impact led to the formation of a ~ 200-km wide by ~1-km deep crater on México's Yucatán Peninsula. Over a period of hours after the impact the ocean re-entered and covered the impact basin beneath several hundred meters of water. A suite of impactites were deposited across the crater during crater formation, and by the resurge, tsunami and seiche events that followed. International Ocean Discovery Program/International Continental Scientific Drilling Program Expedition 364 drilled into the peak ring of the Chicxulub crater, and recovered ~130 m of impact deposits and a 75-cm thick, fine-grained, carbonate-rich “Transitional Unit”, above which normal marine sedimentation resumed. Here, we describe the results of analyses of the uppermost impact breccia (suevite) and the Transitional Unit, which suggests a gradual waning of energy recorded by this local K-Pg boundary sequence. The dominant depositional motif in the upper suevite and the Transitional Unit is of rapid sedimentation characterized by graded bedding, local cross bedding, and evidence of oscillatory currents. The lower Transitional Unit records the change from deposition of dominantly sand-sized to mainly silt to clay sized material with impact debris that decreases in both grain size and abundance upward. The middle part of the Transitional Unit is interrupted by a 20 cm thick soft sediment slump overlain by graded and oscillatory current cross-laminated beds. The uppermost Transitional Unit is also soft sediment deformed, contains trace fossils, and an increasing abundance of planktic foraminifer and calcareous nannoplankton survivors. The Transitional Unit, as with similar deposits in other marine target impact craters, records the final phases of impact-related sedimentation prior to resumption of normal marine conditions. Petrographic and stable isotopic analyses of carbon from organic matter provide insight into post-impact processes. δ13Corg values are between terrestrial and marine end members with fluctuations of 1–3‰. Timing of deposition of the Transitional Unit is complicated to ascertain. The repetitive normally graded laminae, both below and above the soft sediment deformed interval, record rapid deposition from currents driven by tsunami and seiches, processes that likely operated for weeks to potentially years post-impact due to subsequent continental margin collapse events. Highly siderophile element-enrichment at the top of the unit is likely from fine-grained ejecta that circulated in the atmosphere for several years prior to settling. The Transitional Unit is thus an exquisite record of the final phases of impact-related sedimentation related to one of the most consequential events in Earth history.Publicación Acceso Abierto The Proximal Ejecta Around the Marine-Target Lockne Impact Structure, Sweden(American Geophysical Union, 2023-07) Sturkell, Erik; Ormö, Jens; Austin Hegardt, Eric; Stockmann, Gabrielle; Meland, Erik; Wikström, TorbjörnVery few impact craters on Earth have preserved proximal ejecta (ejecta blanket), which when present help us to better understand the cratering processes when asteroid hits Earth. The 458 Ma old Lockne impact structure consists of a 7.5-km wide nested crater in the crystalline basement surrounded by an approximately 3-km wide brim developed in the upper sedimentary target. The asteroid struck a marine environment with 500 m sea water, 50-m lithified limestone, and 30 m of Cambrian clay covering a peneplainized crystalline basement. The transient crater that developed in rock and water obtained a “soup-plate” shape and reached about 7 km from the impact crater center, the farthest on the down-range side. The brim of the soup-plate was partially stripped of Ordovician limestone and water before the emplacement of inner impact crater ejecta. Most of the ejecta rest upon the Cambrian clay (today shale). The asteroid struck obliquely from the east, which is reflected in the ejecta distribution. The proximal ejecta field is divided into two crescent-shaped areas to the northwest and southwest of the nested crater and covers 26 km2. Resistivity profiles, mapping, and core drilling show that the thickness of the ejecta masses range between 30 and 50 m with a total volume of about 1 km3. They were not re-worked by the resurge. They represent roughly 26 vol% of the calculated excavated volume of crystalline rocks. Thus, it can be concluded that the Lockne impact crater has a well-preserved ejecta blanket.Publicación Acceso Abierto Assessing event magnitude and target water depth for marine-target impacts: Ocean resurge deposits in the Chicxulub M0077A drill core compared(Elsevier BV, 2021-06-15) Ormö, Jens; Gulick, S. P. S.; Whalen, M. T.; King, D. T.; Sturkell, E.; Morgan, Joanna; Polish National Science Centre; Gordon and Betty Moore Foundation (GBMF)The rim wall of water formed from even a modestly-sized marine impact may be kilometers in height. Although modeling has shown that this wave swiftly breaks and relatively rapidly loses energy during outwards travel from the impact site, the portion of the rim wall that collapses inwards may generate a resurge flow with tremendous transport energy. Here we compare the deposits generated by this ocean resurge inside one of the largest marine-target craters on Earth, the 200-km wide Chicxulub crater, Yucatán Peninsula, México, with resurge deposits (breccias) in eight drill cores from five other marine-target craters in Sweden and the United States. Examination of the wide range of cored locations within the craters, and target water depths (H) relative to modeled projectile diameters (d) reveal a high correlation between location, average clast frequency (), and from which any of the four variables can be obtained. The relationship shown here may provide an important tool for diagnosing marine impact cratering processes where there is limited understanding of crater size and/or paleobathymetry.Publicación Acceso Abierto Successful kinetic impact into an asteroid for planetary defence(Springer, 2023-03-01) Terik Dalay, Ronald; Ernst, Carolyn; Barnouin, Oliver; Chabot, Nancy; Rivkin, Andrew; Cheng, Andrew; Adams, Elena; Agrusa, Harrison; Abdel, Elisabeth; Alford, Amy; Asphaug, Erik; Atchison, Justin; Badger, Andrew; Baki, Paul; Ballouz, Ronald; Bekker, Dmitriy; Bellerose, Julie; Bhaskaran, Shyam; Buratti, Bonnie; Cambioni, Saverio; Chen, Michelle; Chesley, Steven; Chiu, George; Collins, Gareth; Cox, Matthew; DeCoster, Mallory; Ericksen, Peter; Espiritu, Raymond; Faber, Alan; Farnham, Tony; Ferrari, Fabio; Fletcher, Zachary; Gaskell, Robert; Graninger, Dawn; Haque, Musad; Harrington Duff, Alicia; Hefter, Sarah; Herreros, Isabel; Hirabayashi, Masatoshi; Huang, Philip; Hsieh, Syau Yun; Jacobson, Seth; Jenkins, Stephen; Jensenius, Mark; John, Jeremy; Jutzi, Martin; Kohout, Tomas; Krueger, Timothy; Laipert, Frank; López, Norberto; Luther, Robert; Lucchetti, Alice; Mages, Declan; Marchi, Simone; Martín, Anna; McQuaide, Marie; Michel, Patrick; Moskovitz, Nicholas; Murphy, Ian; Murdoch, Naomi; Naidu, Shantanu; Nair, Hari; Nolan, Michael; Ormö, Jens; Pajola, Maurizio; Palmer, Eric; Peachey, James; Pravec, Petr; Raducan, Sabina; Ramesh, K. T.; Ramirez, Joshua; Reynolds, Edward; Richman, Joshua; Robin, Colas; Rodríguez, Luis; Roufberg, Lew; Rush, Brian; Sawyer, Carolyn; Scheeres, Daniel; Scheirich, Petr; Schwartz, Stephen; Shannon, Matthew; Shapiro, Brett; Shearer, Caitlin; Smith, Eva; Steele, Joshua; Steckloff, Jordan; Stickle, Angela; Sunshine, Jessica; Superfin, Emil; Tarzi, Zahi; Thomas, Cristina; Thomas, Justin; Trigo Rodríguez, Josep M.; Tropf, Teresa; Vaughan, Andrew; Velez, Dianna; Waller, Dany; Wilson, Daniel; Wortman, Kristin; Zhang, Yun; Swiss National Science Foundation (SNSF); European Commission (EC); National Aeronautics and Space Administration (NASA); Centre National d’Etudes Spatiales (CNES); Agencia Estatal de Investigación (AEI); Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Although no known asteroid poses a threat to Earth for at least the next century, the catalogue of near-Earth asteroids is incomplete for objects whose impacts would produce regional devastation. Several approaches have been proposed to potentially prevent an asteroid impact with Earth by deflecting or disrupting an asteroid. A test of kinetic impact technology was identified as the highest-priority space mission related to asteroid mitigation. NASA’s Double Asteroid Redirection Test (DART) mission is a full-scale test of kinetic impact technology. The mission’s target asteroid was Dimorphos, the secondary member of the S-type binary near-Earth asteroid (65803) Didymos. This binary asteroid system was chosen to enable ground-based telescopes to quantify the asteroid deflection caused by the impact of the DART spacecraft. Although past missions have utilized impactors to investigate the properties of small bodies, those earlier missions were not intended to deflect their targets and did not achieve measurable deflections. Here we report the DART spacecraft’s autonomous kinetic impact into Dimorphos and reconstruct the impact event, including the timeline leading to impact, the location and nature of the DART impact site, and the size and shape of Dimorphos. The successful impact of the DART spacecraft with Dimorphos and the resulting change in the orbit of Dimorphos demonstrates that kinetic impactor technology is a viable technique to potentially defend Earth if necessary.Publicación Acceso Abierto Boulder exhumation and segregation by impacts on rubble-pile asteroids(Elsevier, 2022-07-21) Ormö, Jens; Raducan, Sabina D.; Jutzi, Martin; Herreros, Isabel; Luther, Robert; Collins, Gareth S.; Wünnemann, Kai; Mora Rueda, Marcos; Hamann, C.; European Commission; Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Small asteroids are often considered to be rubble-pile objects, and such asteroids may be the most likely type of Near Earth Objects (NEOs) to pose a threat to Earth. However, impact cratering on such bodies is complex and not yet understood. We perform three low-velocity (≈ 400 m/s) impact experiments in granular targets with and without projectile-size boulders. We conducted SPH simulations that closely reproduced the impact experiments. Our results suggest that cratering on heterogeneous targets displaces and ejects boulders, rather than fragmenting them, unless directly hit. We also see indications that as long as the energy required to disrupt the boulder is small compared to the kinetic energy of the impact, the disruption of boulders directly hit by the projectile may have minimal effect on the crater size. The presence of boulders within the target causes ejecta curtains with higher ejection angles compared to homogeneous targets. At the same time, there is a segregation of the fine ejecta from the boulders, resulting in boulders landing at larger distances than the surrounding fine grained material. However, boulders located in the target near the maximum extent of the expanding excavation cavity are merely exhumed and distributed radially around the crater rim, forming ring patterns similar to the ones observed on asteroids Itokawa, Ryugu and Bennu. Altogether, on rubble-pile asteroids this process will redistribute boulders and finer-grained material heterogeneously, both areally around the crater and vertically in the regolith. In the context of a kinetic impactor on a rubble-pile asteroid and the DART mission, our results indicate that the presence of boulders will reduce the momentum transfer compared to a homogeneous, fine-grained target.Publicación Restringido Effect of Target Layering in Gravity-Dominated Cratering in Nature, Experiments, and Numerical Simulations(AGU Publishing, 2024-04-26) Ormö, Jens; Raducan, S. D.; Housen, K. R.; Wünnemann, K.; Collins, Gareth; Rossi, Angelo Pio; Melero-Asensio, Irene; Consejo Superior de Investigaciones Científicas (CSIC); Agencia Estatal de Investigación (AEI); European Research Council (ERC); Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Impacts into layered targets may generate “concentric craters” where a wider outer crater in the top layer surrounds a smaller, nested crater in the basement, which itself may be complex or simple. The influence of target on cratering depends on the ratio of target strength to lithostatic stress, which, in turn, is affected by gravity, target density, and crater diameter. When this ratio is large, the crater size is primarily determined by target strength, whereas gravitational forces dominate when the ratio is small. In two-layer targets, strength may dominate in one or both layers, whereby the outer crater develops in the weaker top layer and the nested crater in the stronger substrate. However, large natural craters that should be gravity-dominated in both cover strata and substrate may be concentric, the reasons for which are not yet fully understood. We performed qualitative impact experiments at 10–502 G and 1.8 km/s with the Boeing Corp. Hypervelocity centrifuge gun, and at 1 G and 0.4 km/s with the CAB CSIC-INTA gas gun into layered sand targets of different compositions and grain densities but similar granulometry to analyze gravity-dominated cratering. The results are compared with iSALE-2D numerical simulations and natural craters on Earth and Mars. We show that target layering also affects the excavation process and concentric crater formation in gravity-dominated impacts. The most important factors are the density and internal friction of each target layer, respectively. We propose that this is also valid for natural craters of sizes that should make their formation gravity-dominated.
