Constraints On Effusive Cryovolcanic Eruptions On Europa Using Topography From Galileo Images

(a) Image 5452r from Galileo SSI and (b) the associate DEM produced with SfS. The blue line indicates the limit of the flow-like feature. Blue arrows show the lobate zones interpreted as filling the valleys between the ridges. The two profiles numbered (c) 1 and (d) 2 are respectively perpendicular and parallel to the surrounding ridges. Schematic representations of sections of the feature along these two profiles are shown in Fig. 4. Black crosses indicate the chosen points used to calculate the reference level of the pre-existing terrain beneath the smooth feature.

Images of Europa's surface taken by the Galileo Solid State Imager (SSI) show smooth features measuring a few kilometers, potentially resulting from eruptions of low-viscosity material.

We estimate the volumes of four of these smooth features by producing digital elevation models (DEM) from Galileo/SSI images. We use the shape-from-shading method with special care to estimate the uncertainties on the produced DEMs and estimate the features' volumes to be between (5.7∗107 m3 and (2.7∗108 m3. We discuss the implications for putative sub-surface liquid reservoir dimensions in case of eruptions induced from freezing reservoirs.

We improved upon our previous cryovolcanic eruption model by considering a cycle of cryomagma freezing and effusion and by estimating the vaporized cryolava fraction once it spreads onto Europa's surface. Our results show that the cryomagma reservoirs would have to be quite large to generate these smooth features (1 to 100 km3 if the flow features result from a single eruption, and 0.4 to 60 km3 for a full eruption cycle). The two future missions JUICE (ESA) and Europa Clipper (NASA) should reach Europa in the late 2020s. They shall give more information on those putative cryovolcanic regions that are interesting targets to understand the surface/interior exchanges.

Elodie Lesage, Frédéric Schmidt, François Andrieu, Hélène Massol
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2009.14103 [astro-ph.EP] (or arXiv:2009.14103v1 [astro-ph.EP] for this version)
Submission history
From: Elodie Lesage
[v1] Tue, 29 Sep 2020 15:37:34 UTC (32,300 KB)
Astrobiology, Astrochemistry,

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