This sequence shows distinct changes in the parachute. In the first four images, there are only subtle changes, perhaps explained by differences in viewing and illumination geometry. Sometime between Sept. 8, 2012, (the fourth image) and Nov. 30, 2012, (the fifth image) there was a major change in which the parachute extension to the southeast (lower right) was moved inward, so the parachute covers a smaller area. In the same time interval some of the dark ejecta around the back shell brightened, perhaps from deposition of airborne dust. Another change happened between Dec. 16, 2012, (the sixth image) and Jan. 13, 2013, (the final image) when the parachute shifted a bit to the southeast. This type of motion may kick off dust and keep parachutes on the surface bright, to help explain why the parachute from Viking 1, which landed on Mars in 1976, remains detectable (as seen at http://photojournal.jpl.nasa.gov/catalog/PIA01881 ).