[link|http://www.jpl.nasa.gov/images/mer/2005-05-24/sol_460.F_haz_L-ani.mov|http://www.jpl.nasa....0.F_haz_L-ani.mov]
You can see that it seems to be making more progress at the end of this movie. Then again, the frame frequency may have also changed. The strategy is to go back using the path it came in on. The jerky shadows are caused by daily sun cycles. This is several day's worth of frames.