Leading/trailing albedo asymmetries of Thebe, Amalthea, and Metis

Using Galileo clear-filter images (effective wavelength approximate to0.64 mum), we have created the first albedo maps of the small inner jovian satel lites Thebe, Amalthea, and Metis. These maps clearly show that the leading sides of all three satellites are significantly brighter than their corresp onding trailing sides, confirming and extending a result first reported by P. C. Thomas ct al. (1998, Icarus 135, 360-371). In particular, on all thre e moons the leading side is brighter than the trailing side by 25 to 30%. T he fact that the direction and size of this albedo asymmetry is identical f rom satellite to satellite suggests that one common physical mechanism is g overning the global albedo patterns of all three moons. The most plausible such mechanism is the impact of macroscopic meteoroids that originated outs ide the jovian system. These impacts, which eject the dust that forms Jupit er's ring system (M. E. Ockert-Bell et al., 1999, Icarus 138, 188-213; J. A . Burns et al., 1999, Science 284, 1146-1150), are probably also responsibl e for brightening the leading sides of these Small satellites. (C) 2000 Aca demic Press.