On ancient Mars, water carved channels and transported sediments to form fans and deltas within lake basins. Examination of spectral data acquired from orbit show that some of these sediments have minerals that indicate chemical alteration by water. In the Jezero Crater delta, sediments contain clays and carbonates. (This image combines information from two instruments on NASA's Mars Reconnaissance Orbiter, the Compact Reconnaissance Imaging Spectrometer for Mars and the Context Camera.)  Image: NASA/JPL-Caltech/MSSS/JHU-APL