论文标题
地aldus的间歇泉的糊状来源
A mushy source for the geysers of Enceladus
论文作者
论文摘要
由于卡西尼航天器测量的$ \ rm h_2o $ plume弹出物以及潮汐加热维持的推断地下海洋，土埃拉德斯是天体生物学的主要目标。通过从海洋到地面的直接连接来采购羽毛，需要通过整个冰壳裂缝（$ \ sim $ 10 km）。在这里，我们探索了一种替代机制，在这种机制中，较浅的老虎条纹骨折内的剪切加热会在冰壳中产生部分熔化，并且间质对流可以使流体被弹出为间歇泉。我们使用理想化的二维多相反应转运模型来模拟由咸冰壳中局部剪切加热速率的上限估算产生的糊状区域的热力学。从我们的模拟中，我们可以预测骨折周围内闪闪发光的糊状区域的温度，孔隙率，盐分含量，融化速率和液体体积。我们发现，内部熔化的速率可以与观察到的$ \ rm H_2O $喷发率相匹配，并且在糊状区域内有足够的盐水量，可以维持间歇泉，以$ \ sim350 $ kyr，而无需额外熔化。然而，由于部分融化，液态盐水的组成与海洋的组成不同。间歇泉形成的这种剪切加热机制适用于土卫和其他冰冷的月亮，对我们对冰冷卫星的地球物理过程和天体生物学潜力的理解具有影响。
Enceladus is a primary target for astrobiology due to the $\rm H_2O$ plume ejecta measured by the Cassini spacecraft and the inferred subsurface ocean sustained by tidal heating. Sourcing the plumes via a direct connection from the ocean to the surface requires a fracture through the entire ice shell ($\sim$10 km). Here we explore an alternative mechanism in which shear heating within shallower tiger stripe fractures produces partial melting in the ice shell and interstitial convection allows fluid to be ejected as geysers. We use an idealized two-dimensional multiphase reactive transport model to simulate the thermomechanics of a mushy region generated by an upper bound estimate for the localized shear heating rate in a salty ice shell. From our simulations, we predict the temperature, porosity, salt content, melting rate, and liquid volume of an intrashell mushy zone surrounding a fracture. We find that the rate of internal melting can match the observed $\rm H_2O$ eruption rate and that there is sufficient brine volume within the mushy zone to sustain the geysers for $\sim350$ kyr without additional melting. The composition of the liquid brine is, however, distinct from that of the ocean, due to partial melting. This shear heating mechanism for geyser formation applies to Enceladus and other icy moons and has implications for our understanding of the geophysical processes and astrobiological potential of icy satellites.
