Contents

21 September 2007
Vol 317, Issue 5845

About The Cover

Cover image expansion

COVER False-color image of gully channels in a crater in the southern highlands of Mars, taken by the High-Resolution Imaging Science Experiment (HiRISE) camera on the Mars Reconnaissance Orbiter. The gullies emanating from the rocky cliffs near the crater's rim (upper left) show meandering and braided patterns typical of water-carved channels. North is approximately up and illumination is from the left; image width is about 1 kilometer. See the special section beginning on page 1705. Image: NASA/JPL/University of Arizona