As of December 2009, there are more than 1,500,000 orbital images of Mars available on the Planetary Data System’s Imaging Node (from Mars Odyssey, Mars Express, Mars Global Surveyor, and Mars Reconnaissance Orbiter). The volume of image data is steadily increasing, as is the number of repeat images that allow for the possibility of detecting surface changes such as dark slope streaks, new impact craters and gullies, ground ice excavated by fresh impact craters, etc. The number of overlapping image pairs is growing quickly enough that there is a need for automated methods for detecting and characterizing those changes. In addition to greatly accelerating the analysis process, automated methods offer the opportunity to discover entirely new types of transient features, not just ones we can already search for.