The U.S. Geological Survey has released the most thorough map of the Martian surface to date.
The new map of Mars, which was released Monday, relies on data collected by three NASA spacecraft — Mars Global Surveyor, Mars Odyssey and Mars Reconnaissance Orbiter — plus the European Space Agency's Mars Express probe. The map covers the entire surface of the planet, piecing together various data to reveal some new insights, researchers said.
For example, the map reveals that the surface of Mars is older than previously thought. Three times as much surface area formed during the Early Noachian Epoch — the first major geologic time period, which ranges from about 4.1 to 3.7 billion years ago — than had been previously mapped.
Characteristics of the Early Noachian include a high rate of meteorite impacts, widespread erosion and the likely presence of water on the Martian surface, researchers said. (Planets in the solar system are thought to have formed approximately 4.5 billion years ago.)
The new map also confirms previous work suggesting that the Red Planet has continued to be geologically active up to today. It provides additional evidence that climate changes on Mars have at times allowed for surface water and near-surface groundwater and ice to form temporarily.
You can download the new map for free at the USGS site here: http://pubs.usgs.gov/sim/3292/