This image shows a possible landing site for the 2020 Mission: Jezero Crater, as seen by NASA Mars Reconnaissance Orbiter.
It's not only when trying to find a scientifically interesting place to land that the high-resolution images from HiRISE come in handy: it's also to identify potential hazards within a landing ellipse.
This is one of the trickier aspects of selecting landing sites on Mars: a place to do good science but also where the risks of landing are low. Jezero Crater is an ancient crater where clay minerals have been detected, and with a delta deposit indicating that water was once flowing into a lake. Since clays form the in presence of water, this crater would be a very good candidate for a lander to explore and build on what we've learned from the Mars Science Laboratory. Could some form of ancient life have existed here and for how long?
http://photojournal.jpl.nasa.gov/catalog/PIA19303