Phobos (image) Brown University Caption The Martian moon Phobos has accumulated dust and debris from the surface of Mars, knocked into its orbital path by projectiles colliding with the planet. A sample-return mission to Phobos would thus return material both from Phobos and from Mars. Credit NASA Usage Restrictions None 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.