Phobos (IMAGE) NASA/Goddard Space Flight Center Caption Image of Phobos, the larger of Mars' two moons. Credit NASA/JPL-Caltech/University of Arizona Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.