Ripple by ripple, trough by trough... - Sol 550 (1)

Original caption:"Opportunity continues to make progress South toward Erebus crater. The Rover Planners are doing an excellent job keeping Opportunity safely within the confines of the ripple troughs and determining where the Rover can cross from one ripple trough into another. The Rover Team tries to keep Opportunity inside the ripple troughs and plans to follow the troughs South until Opportunity can safely move into a 'better' trough".