Of all Solar System planets, Mars has the climate most like that of Earth, both sensitive to small changes in orbital parameters. So the discovery of recent gullies, buried ice and possible snowpack on Mars has stimulated interest among both terrestrial and planetary scientists. New data from the Odyssey and Mars Global Surveyor missions provide more evidence of an icy past. Deposits formed during an ice age 2.1 million to 400,000 years ago point to ice cover at latitudes equivalent to the southern United States and Saudi Arabia on Earth. The cover image shows how Mars would have looked at the height of the ice age. Simulated surface deposit has been superposed on MOLA topography and albedo map.