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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >The search for current geologic activity on Europa
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The search for current geologic activity on Europa

机译：搜索欧罗巴当前的地质活动

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Observational evidence and theoretical arguments suggest that Jupiter's satellite Europa could be geologically active and possess an "ocean" of liquid water beneath its surface at the present time. We have searched for evidence of current geologic activity on Europa in the form of active plumes venting material above the surface and by comparison of Voyager and Galileo images to look for any changes on the surface. So far, we have observed no plumes and have detected no definitive changes. The lack of observed activity allows us to estimate a maximum steady state surface alteration rate of 1 km(2) y(-1) in the regions analyzed, assuming alterations will cover contiguous areas of at least 4 km(2) over a period of 20 years. Assuming this as a constant, globally uniform resurfacing rate leads to a minimum average surface age of 30 million years. We also suggest that the lack of obvious circular albedo patterns on the surface due to plumes, coupled with the presence of bright-rayed craters such as Pwyll and the predicted sputtering erosion rate, implies that no large-scale plume activity has taken place over at least the last few thousand years. We thus conclude that if Europa's surface is currently active, any changes must be relatively small in spatial scale or episodic in nature rather than continuous. To detect potential small-scale surface changes, we need high-resolution comparisons between the Galileo data and future Europa Orbiter images. [References: 63]
机译：观测证据和理论论据表明，木星的欧罗巴卫星可能具有地质活跃性，目前在其表面之下拥有液态海洋“海洋”。我们搜索了欧罗巴上当前地质活动的证据，其形式为通过表面上方的活动羽流排放材料，并通过比较航海家和伽利略图像来寻找表面上的任何变化。到目前为止，我们还没有观察到羽状流，也没有发现任何确定的变化。缺乏观测到的活动使我们能够估计所分析区域中最大稳态表面变化率为1 km（2）y（-1），假设变化将覆盖至少4 km（2）的连续区域。 20年。假设这是一个恒定的，全球统一的表面重铺率，则可以使最低平均表面寿命达到3000万年。我们还建议，由于羽状流，表面上没有明显的圆形反照率模式，再加上诸如Pwyll之类的明亮陨石坑的存在以及预计的溅射腐蚀速率，意味着在该温度下没有大规模的羽状流活动发生。至少最近几千年。因此，我们得出的结论是，如果欧罗巴的表面当前处于活动状态，则任何变化在空间尺度上都必须相对较小或本质上是情景性的，而不是连续的。为了检测潜在的小尺度表面变化，我们需要在Galileo数据和未来的Europa Orbiter图像之间进行高分辨率比较。 [参考：63]

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