| Texto completo | |
| Autor(es): |
Crosta, A. P.
[1, 2]
;
Silber, E. A.
[3, 4]
;
Lopes, R. M. C.
[1]
;
Johnson, B. C.
[5, 6]
;
Bjonnes, E.
[7]
;
Malaska, M. J.
[1]
;
Vance, S. D.
[1]
;
Sotin, C.
[1, 8]
;
Solomonidou, A.
[9, 10, 11]
;
Soderblom, J. M.
[12]
Número total de Autores: 10
|
| Afiliação do(s) autor(es): Mostrar menos - | [1] CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 - USA
[2] Univ Estadual Campinas, Inst Geosci, POB 6152, BR-13083970 Campinas, SP - Brazil
[3] Western Univ, Dept Earth Sci, London, ON N6A 5B7 - Canada
[4] Western Univ, Inst Earth & Space Explorat, London, ON N6A 3K7 - Canada
[5] Purdue Univ, Dept Phys & Astron, W Lafayette, IN 47907 - USA
[6] Purdue Univ, Dept Earth Atmospher & Planetary Sci, W Lafayette, IN 47907 - USA
[7] Brown Univ, Dept Earth Environm & Planetary Sci, Providence, RI 02912 - USA
[8] Univ Nantes, Fac Sci & Tech, Nantes - France
[9] CALTECH, Pasadena, CA 91125 - USA
[10] UPMC Univ Paris 06, LESIA Observ Paris, CNRS, Univ Paris Diderot, Meudon - France
[11] Czech Univ Life Sci Prague, Fac Environm Sci, Prague - Czech Republic
[12] MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA - USA
Número total de Afiliações: 12
|
| Tipo de documento: | Artigo Científico |
| Fonte: | ICARUS; v. 370, DEC 2021. |
| Citações Web of Science: | 0 |
| Resumo | |
Titan is unique in the solar system: it is an ocean world, an icy world, an organic world, and has a dense atmosphere. It is a geologically active world as well, with ongoing exogenic processes, such as rainfall, sediment transportation and deposition, erosion, and possible endogenic processes, such as tectonism and cryovolcanism. This combination of an organic and an ocean world makes Titan a prime target for astrobiological research, as biosignatures may be present in its surface, in impact melt deposits and in cryovolcanic flows, as well as in deep ice and water ocean underneath the outer ice shell. Impact craters are important sites in this context, as they may have allowed an exchange of materials between Titan's layers, in particular between the surface, composed of organic sediments over icy bedrock, and the subsurface ocean. It is also possible that impacts may have favored the advance of prebiotic chemical reactions themselves, by providing thermal energy that would allow these reactions to proceed. To investigate possible exchange pathways between the subsurface water ocean and the organic-rich surface, we modeled the formation of the largest crater on Titan, Menrva, with a diameter of ca. 425 km. The premise is that, given a large enough impact event, the resulting crater could breach into Titan's ice shell and reach the subsurface ocean, creating pathways connecting the surface and the ocean. Materials from the deep subsurface ocean, including salts and potential biosignatures of putative subsurface biota, could be transported to the surface. Likewise, atmospherically derived organic surface materials could be directly inserted into the ocean, where they could undergo aqueous hydrolysis to form potential astrobiological building blocks, such as amino acids. To study the formation of a Menrva-like impact crater, we staged numerical simulations using the iSALE2D shock physics code. We varied assumed ice shell thickness from 50 to 125 km and assumed thermal structure over a range consistent with geophysical data. We analyze the implications and potential contributions of impact cratering as a process that can facilitate the exchange of surface organics with liquid water. Our findings indicate that melt and partial melt of ice took place in the central zone, reaching ca. 65 km depth and ca. 60 km away from the center of the structure. Furthermore, a volume of ca. 10(2) km(3) of ocean water could be traced to depths as shallow as 10 km. These results highlight the potential for a significant exchange of materials from the surface (organics and ice) and the subsurface (water ocean), particularly in the crater's central area. Our studies suggest that large hypervelocity impacts are a viable and likely key mechanism to create pathways between the underground water ocean and Titan's organic-rich surface layer and atmosphere. (AU) | |
| Processo FAPESP: | 17/27081-1 - Modelagem de processos de impacto na superfície gelada de Titã |
| Beneficiário: | Alvaro Penteado Crósta |
| Modalidade de apoio: | Bolsas no Exterior - Pesquisa |