Water on Mars any point in the year but would be ideal for solid carbon dioxide. The carbon dioxide melting in the warmer summer would yield liquid carbon dioxide which would then form the gullies. Even if gullies are carved by flowing water at the surface, the exact source of the water and the mechanisms behind its motion are not understood. The dry gullies are deep grooves etched into the slopes that are there year-round. There are many other features on Mars, and some of them change seasonally. In August 2011, NASA announced the discovery by undergraduate student Lujendra Ojha of current seasonal
Chronology of discoveries of water on Mars implying that the bright clumps were composed of water ice which sublimated following exposure. Even though dry ice also sublimates under the conditions present, it would do so at a rate much faster than observed. On July 31, 2008, NASA announced that "Phoenix" confirmed the presence of water ice on Mars. During the initial heating cycle of a new sample, the Thermal and Evolved-Gas Analyzer's (TEGA) mass spectrometer detected water vapor when the sample temperature reached 0 °C. Liquid water cannot exist on the surface of Mars with its present low atmospheric pressure, except at the lowest elevations for short