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English: This map shows concentration estimates of equivalent-weight water found in the regions around the equator of Mars. The map is based upon gamma ray data collected for the element hydrogen. Regions of high hydrogen concentration are shown in red while regions of low hydrogen concentration are shown in blue. The highest equatorial concentrations of hydrogen are found around and to the east of Apollineris (left and right center of map) and centered around Arabia Terra (center of map). This hydrogen may be in the form of hydrated minerals or buried ice deposits, but the former is more likely. The white sections at the top and bottom of the map represent regions of the planet with high hydrogen concentration due to large amounts of buried water ice; see July 2004 updates for maps of these regions. The locations of the five successful lander missions are marked: Viking 1 (VL1), Viking 2 (VL2), Pathfinder (PF), Spirit at Gusev (G), and Opportunity at Meridiani (M).