Amalthea was thought to be the innermost satellite of Jupiter until Voyager 2 discovered tiny Adrastea (1979J1). The Voyager 1 camera revealed Amalthea as an irregular dark reddish object with dimensions of 270 × 160 kilometers. These three images have resolutions of (b) 25 kilometers; (c) 13 kilometers; (d) 8 kilometers. [260-503]
(b)
(c)
(d)
Although Callisto was heavily covered with craters up to 200 kilometers in diameter, Dr. Soderblom commented on the absence of larger impact basins. Perhaps there was one in the huge bullseye feature; however, it was not a “standard” looking basin like those on the Moon. Callisto was “extremely smooth and free of any relief. The structure [the bullseye], if impact caused, shows no relief; the limb does not show any relief; maybe it’s possible that Callisto cannot support relief.” By the next day, the geologists on the Imaging Team were becoming more convinced that the Callisto “bullseye” was the frozen remnant of an enormous impact into Callisto’s surface. Since Callisto is composed in large part of water and has an icy crust, the team speculated that any raised features created by the impact would eventually “slide” back into the surface, “and the ripple marks from the shock wave caused by the impact were frozen” into the surface.
