Suppose I want to climb the tallest mountain on each of the four Galilean satellites. Is it known what they are?
Io has one of the most spectacularly tall mountains in the solar system, Boösaule Montes, at about 18 km from base to peak.
But googling turns up almost nothing specific on Europa, Ganymede, and Callisto. I'm having a hard time figuring out whether this is just because they don't have as much surface relief, so they aren't as much fun to discuss, or if there is actually no data on their topography. How do we know, for example, how tall Boösaule Montes is? Since we've never inserted anything into orbit around these bodies, I assume there is no radar data. Is our knowledge from estimates based on the lengths of shadows?
My guesses were that since Callisto and Ganymede are heavily pocked with craters, their highest mountains would be the ramparts of crater rims. Maybe on Callisto it would be one of the concentric rims of the Valhalla system. Europa is thought to be extremely smooth, which might make it difficult to determine much about its topography.