Mapa Detalhado de Ganimedes

Crédito: USGS Astrogeology Science Center/Wheaton/NASA/JPL-Caltech

Crédito: USGS Astrogeology Science Center/Wheaton/NASA/JPL-Caltech

Ganimedes é uma lua de Júpiter (a 7ª a contar do planeta). É a maior lua do sistema solar.
Temos agora o primeiro mapa geológico global desta lua.

O mapa combina as melhores imagens obtidas pelas sondas Voyager 1 e 2, em 1979, e pela sonda Galileo, entre 1995 e 2003.
Este mapa global foi publicado pelo U.S. Geological Survey como um mapa global.

Robert Pappalardo, do JPL, NASA, referiu: “Este mapa ilustra a incrível variedade de feições geológicas em Ganimedes e ajuda a dar ordem ao aparente caos da sua complexa superfície. O mapa global ajuda os cientistas planetários a compreender a evolução deste mundo gelado e irá auxiliar as observações de futuras sondas”.

Sabe-se que Ganimedes é um complexo mundo gelado, cuja superfície apresenta um contraste entre dois tipos de terrenos: terreno escuro, bastante antigo e coberto de crateras; e terreno brilhante, mais jovem, com longas cadeias e dobras.

Os cientistas pensam que existiram 3 períodos geológicos em Ganimedes: período de intensos impactos, período tectónico, e período com um forte declínio da atividade geológica.

Leiam o artigo na NASA, aqui.
Podem ler todas as informações sobre o mapa na U.S. Geological Survey, aqui, aqui e aqui.

ganimedes

4 comentários

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    • Dinis Ribeiro on 14/12/2014 at 11:47
    • Responder

    Eu gosto mais da lua Gamimedes, por diversas razões…. entre as quais incluo uma dose menos intensa de radiação letal.

    Hiding from Jupiter’s Radiation
    http://www.astrobio.net/news-exclusive/hiding-from-jupiters-radiation/

    The project—led by Louise Prockter of John Hopkins University as part of NASA’s Exobiology and Evolutionary Biology program—will identify dead zones where radiation would likely fry any interesting chemical compounds, as well as possible safe havens that might harbor material expelled from the ocean below

    Radiation menace

    Assuming the ocean contains biologically-useful compounds and that some of these find their way to the surface, they may not survive very long there.

    “It is unlikely that any big molecules will be found in exposed regions,” says Chris Paranicas, also from Johns Hopkins University.

    Radiation in the form of high-energy electrons and ions continuously bombard the top layers of Europa’s icy crust. This deadly dose is due to the fact that Europa—along with the three other Galilean moons (Io, Ganymede and Callisto)—orbits within Jupiter’s radiation belts.

    These belts are much like Earth’s Van Allen belts but bigger, since Jupiter’s magnetic field is ten times stronger than Earth’s. Electrons and ions from the solar wind become trapped in the magnetic field and spiral down onto Jupiter’s poles to create impressive auroras.

    The radiation in Jupiter’s belts is a million times more intense than in Earth’s belts. <———–

    For this reason, spacecraft—such as the Galileo orbiter—have typically tried to spend as little time as possible inside the belts. Although the radiation is generally well-understood, no one has yet figured out precisely what the effect is on Jupiter’s moons.

    For such mixing to happen, the same geological process that brings oceanic material up to the surface must also be shuttling surface material down to the ocean.

    Safe havens

    If this complicated procedure was taking place on Europa, it would be hard to verify since the radiation would destroy all evidence for it on the surface of the moon.

    However, all is not lost.

    The radiation belts are rotating around Jupiter faster than Europa does. This results in the radiation predominantly striking the trailing hemisphere of the moon—which is always the same portion of the moon since Europa is locked in a synchronous orbit around Jupiter. Moreover, there is a constant stream of micrometeorites landing on the leading hemisphere. These tiny rocks form a regolith layer up to 3 meters thick that could protect oceanic material from incoming radiation.

    “Optimizing the search for interesting [molecular] species requires looking for young areas that aren’t heavily irradiated,” Carlson says. “The leading hemisphere is still heavily bombarded and won’t provide pristine samples by itself, but some regions may provide effective topographic shielding.”

    One of the goals of the project is to pinpoint these protected regions.

    Patterson thinks the boundary between trailing and leading hemispheres may be a good target.

    Here, enough radiation may hit to see some of the positive effects, while enough regolith may be present to shield out most of the negative effects.

    http://en.wikipedia.org/wiki/Louise_Prockter

    • jpaulo cesar sodre on 13/12/2014 at 20:51
    • Responder

    Ganimedes, Calisto e Europa. Qual desses três tem mais chances de abrigar vida. De que é composto o espaço “vazio” não ocupado pelos planetas, satélites, cometas, estrelas e etc.

    1. Europa, como pode ler nos artigos sob a categoria astrobiologia.

      De tudo menos “vazio”, como pode ler nos artigos da categoria cosmologia 😉

      abraços

    • Hélio Martins on 24/03/2014 at 21:18
    • Responder

    Obrigado por divulgarem e publicarem o mapa.

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