Proyecto de Investigación: IMPACTOS COSMICOS EN CUERPOS PLANETARIOS: EFECTOS DEL PROYECTIL Y OBJETIVO EN LA MORFOLOGIA DEL CRATER COMO INSTRUMENTOS PARA EVALUAR PALEO-AMBIENTES Y RIESGOS CATASTROFICOS
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PID2021-125883NB-C22
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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, Torbjörn
Very 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.
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-2017-0737
Impacts 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.
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-2017-0737
Although 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.
