We don't have a good Ceres map yet - Dawn will get there in 2015. Telescope observations have shown light and dark spots, which might be craters. "Piazzi" is the only one named so far. http://spaceref.com/news/viewpr.html?pid=21032 http://www.newscientist.com/articleimages/dn10266/1-infrared-map-of-gian... Overall, Ceres' surface looks pretty boring: no big differences in albedo, probably because it is fairly evolved. An upper layer of regolith made of cronstedtite, dolomite and siderite, hiding ice deeper inside. From Li, Jian-Yang; McFadden, Lucy A.; Parker, Joel Wm. (2006). "Photometric analysis of 1 Ceres and surface mapping from HST observations". Icarus 182 (1): 143–160. http://www.sciencedirect.com/science/article/pii/S0019103506000054

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The albedo features show local heterogeneity on Ceres, although variations from the average are very small. The features are quite consistent but with different relative strengths at three wavelengths (Fig. 5, Table 4). The most obvious, #2, the big bright area, is centered at 130° longitude and 15° latitude, about 60° across, with an elongated shape. Other small features appear to be circular, including the one at 0° longitude (#1, defining the longitude system), and the series of features (#3–5) along a diagonal line to the right of the biggest bright area. A dark area (#7) to the left of the biggest bright area is open toward the south pole. Another dark area (#8) close to the equator and to the right of #2 has a bright rim around it, and is consistently dark at all three wavelengths. Its latitude is consistent with the “Piazzi” feature reported previously (Parker et al., 2002), but a certain identification cannot be made due to insufficient longitude constraints of the earlier observations. Table 4. Summary of features on Ceres' surface. Their albedo at 535 nm for #1 to #6 are brighter than surrounding background and for #7–11 darker than surrounding area Index,Longitude (°),Latitude (°),Size (°),V-band SSA (×0.073),335–535 nm color (mag) 1,1,12,4,1.04,0.40 2,130,13,33,1.04,0.47 3,164,−32,5,1.04,0.41 4,208,−1,10,1.00,0.42 5,231,25,6,1.01,0.41 6,303,−23,13,1.02,0.46 7,43,−23,13,0.96,0.47 8,188,20,16,0.96,0.44 9,241,−25,12,0.96,0.44 10,245,35,10,0.97,0.43 11,280,−29,7,0.96,0.43

[img]http://ars.els-cdn.com/content/image/1-s2.0-S0019103506000054-gr005.jpg[...

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Fig. 5. The composite albedo deviation maps of Ceres through F555W (upper panel), F330W (middle panel), and F220W (lower panel) filters. The color bar represents the percentage deviation from their corresponding average values at three wavelengths ... Circles with numbers in the upper panel mark the features we identified. From #1 to #6 are bright features, and from #7 to #11 are dark features.

One degree corresponds to 8.5 km on the surface. So, in EP I think we can make the educated guess that Aventine/Wujec is on the equator, and if Piazzi is the location (might be a weak spot in the ice) even located at 180 longitude. Other habitats might be anywhere.

Quincey Forder wrote:

neighbourhood wise, it's said that Ceres is part of the Gefion familly. How close are they, in terms of travel time? And how visible are they?

There are about 800 members, http://en.wikipedia.org/wiki/Gefion_family and they orbit around 2.75 AU from the sun. That means that if they are evenly spread out around the orbit the closest would typically be 0.02 AU away - close, but still 2,991,960 kilometres. That is about 10 times Earth-Moon. So I would assume a few days with a normal shuttle: convenient, but not super-close. Visibility would be pretty low since they are both dark and just a few kilometres across. Of course, there is artistic licence...