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P. Schenk (LPI)
Recent implementation of a new, fast, stable 2-D photoclinometry process has greatly expanded the topographic database for Europa, complimenting that already acquired from stereo observations. Most of these new observations are regional in character, covering areas 200 km across at pixel resolutions of 200 m. These data confirm that Europa is quite lumpy. Highs range up 1 km above local topography and include ovoid plateaus, some of which are scarp (i.e., fault) bounded. Lows include both ovoid pits and arcuate troughs, some exceeding 700 m relative depth. Many of these highs and lows are not correlated with terrain type or with albedo, although at least one 350 m deep depression (0 N, 225 W) appears to be partially covered by an anomalous dark deposit that may originate from a nearby 800-m high plateau. These topographic features appear to have formed relatively late in crustal history and may reflect a thickening of the crust. Thus many lows may not qualify as potential priority landing sites. Additional observations extend down to 20 m resolution targets. These allow us to characterize the local scale topography in order to guide potential lander designs. At 50 m scales, mean slopes are ~10 degrees (S.D. ~6.5 degrees). Sites at 20 m resolution will be examined next. As is suggested by image inspection, few if any areas larger than a few kilometers across have mean slopes of less than 5 degrees, although the areal coverage of the planet is still quite meager. Proper imaging strategy for a Europa Orbiter will greatly increase our sampling of Europan topography, including the search for a suitable landing site.
The author(s) of this abstract have provided an email address for comments about the abstract: schenk@lpi.usra.edu