TY - JOUR
T1 - Evidence for a subsurface ocean on Europa
AU - Carr, Michael H.
AU - Belton, Michael J.S.
AU - Chapman, Clark R.
AU - Davies, Merton E.
AU - Geissler, Paul
AU - Greenberg, Richard
AU - McEwen, Alfred S.
AU - Tufts, Bruce R.
AU - Greeley, Ronald
AU - Sullivan, Robert
AU - Head, James W.
AU - Pappalardo, Robert T.
AU - Klaasen, Kenneth P.
AU - Johnson, Torrence V.
AU - Kaufman, James
AU - Senske, David
AU - Moore, Jeffrey
AU - Neukum, Gerhard
AU - Schubert, Gerald
AU - Burns, Joseph A.
AU - Thomas, Peter
AU - Veverka, Joseph
PY - 1998/1/22
Y1 - 1998/1/22
N2 - Ground-based spectroscopy of Jupiter's moon Europa, combined with gravity data, suggests that the satellite has an icy crust roughly 150 km thick and a rocky interior. In addition, images obtained by the Voyager spacecraft revealed that Europa's surface is crossed by numerous intersecting ridges and dark bands (called lineae) and is sparsely cratered, indicating that the terrain is probably significantly younger than that of Ganymede and Callisto. It has been suggested that Europa's thin outer ice shell might be separated from the moon's silicate interior by a liquid water layer, delayed or prevented from freezing by tidal heating; in this model, the lineae could be explained by repetitive tidal deformation of the outer ice shell. However, observational confirmation of a subsurface ocean was largely frustrated by the low resolution (>2 km per pixel) of the Voyager images. Here we present high-resolution (54 m per pixel) Galileo spacecraft images of Europa, in which we find evidence for mobile 'icebergs'. The detailed morphology of the terrain strongly supports the presence of liquid water at shallow depths below the surface, either today or at some time in the past. Moreover, lower- resolution observations of much larger regions suggest that the phenomena reported here are widespread.
AB - Ground-based spectroscopy of Jupiter's moon Europa, combined with gravity data, suggests that the satellite has an icy crust roughly 150 km thick and a rocky interior. In addition, images obtained by the Voyager spacecraft revealed that Europa's surface is crossed by numerous intersecting ridges and dark bands (called lineae) and is sparsely cratered, indicating that the terrain is probably significantly younger than that of Ganymede and Callisto. It has been suggested that Europa's thin outer ice shell might be separated from the moon's silicate interior by a liquid water layer, delayed or prevented from freezing by tidal heating; in this model, the lineae could be explained by repetitive tidal deformation of the outer ice shell. However, observational confirmation of a subsurface ocean was largely frustrated by the low resolution (>2 km per pixel) of the Voyager images. Here we present high-resolution (54 m per pixel) Galileo spacecraft images of Europa, in which we find evidence for mobile 'icebergs'. The detailed morphology of the terrain strongly supports the presence of liquid water at shallow depths below the surface, either today or at some time in the past. Moreover, lower- resolution observations of much larger regions suggest that the phenomena reported here are widespread.
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U2 - 10.1038/34857
DO - 10.1038/34857
M3 - Article
C2 - 9450749
AN - SCOPUS:18144435537
SN - 0028-0836
VL - 391
SP - 363
EP - 365
JO - Nature
JF - Nature
IS - 6665
ER -