Ancient Mars Video (VIDEO) NASA/Goddard Space Flight Center This video is under embargo. Please login to access this video. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Caption Hydrogen atoms escape from the Mars upper atmosphere, while water containing heavy hydrogen (deuterium) remains trapped on the planet. The escape of hydrogen helped to turn Mars from a wet planet 4.5 billion years ago into a dry world today. Credit NASA 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.