Figure: What Mars might have looked like

Recent spectroscopic measurements of molecular hydrogen with the FUSE satellite provide an estimate of the total volume of water once present on Mars. This is the equivalent of a global Martian ocean some ~1200 meters deep. The image above is an artist's concept of what Mars might have looked like when all its low-lying areas were filled with water.

Credit: Text copyright © 1998-2004 Robert W. O'Connell, University of Virginia.
Original text and figures from http://www.astro.virginia.edu/class/oconnell/astr121/marsImages.html.

See http://www.gsfc.nasa.gov/topstory/20011129marswet.html for explanations about the method used to estimate the total volume of water once present on Mars and to see other "faces" of Mars with oceans.