The second floats around the edge the raised mound (a mountain some five kilometres high) in the centre of Gale Crater - note the tremendously varied terrain. Gale crater is one of the possible landing sites for the Mars Science Laboratory, a large, robust rover scheduled for launch in 2011. One of its main mission goals is to determine if microbial life ever existed on the surface of Mars; Gale Crater is a prime target for this search because its mound contains clay-bearing layers at its base, with layers of oxygen- and sulphur-rich minerals above, and flowing water seems to have carved channels across the floor of the crater and into its wall.
(By the way, neither of these animations comes with a soundtrack. What would you choose?)