Stokes Crater, in the Martian northern hemisphere, reveals mineral evidence of ancient surface water. Photo Credit/NASA, ESA, JPL, Caltech
The evidence comes from NASA’s Mars Reconnaissance Orbiter and the European Space Agency’s Mars Express.
MRO has been circling the Red Planet since March 2006, Mars Express since December 2003.
The conclusions, which suggest ancient Mars hosted an abundance of surface water, are based on evidence gathered by both spacecraft of aged clay minerals in the northern as well as the southern hemisphere of the planet.
The findings, from an orbital analysis of the mineral composition of rocks on the surface of the planet estimated at four billion years old, are published in this week’s editions of the Journal Science.
The minerals are associated with the formation of clay, an elastic soil that forms on Earth when water is abundant.
Past studies observed the formation of the clay minerals in the southern highlands of the Red Planet. The new findings report similar observations in the northern lowlands of Mars.
Scientists believe the lowlands were created in an early era of the 4.5 billion year old solar system, when Mars was side swiped by another large planetary object that ripped away a sizeable part of the planet. More recent volcanic activity has covered up much of the crater that was left by the dramatic impact, making it difficult to detect the clay minerals, scientists believe.
“We can now say that the planet was altered on a global scale by liquid water about four billion years ago,” said John Carter of the University of Paris, who served as the lead author for the Science report.
NASA's Mars Reconnaissance Orbiter scans the Red Planet. Image credit/NASA, JPL, Caltech
Using a spectrometer on MRO, scientists checked 91 craters in the northern lowlands. At least nine of the depressions revealed the formation of clays, and clay-like minerals called phyllosilicates, or other water altered silicates known on Earth to form in wet environments either on the surface or underground.
Earlier observations with a less precise spectrometer on Mars Express hinted at the same results in a small number of craters in the Martian northern hemisphere.
Today, Mars is cold and dry. The atmosphere is so thin that water known to be frozen under ground evaporates quickly when exposed to the air.
The latest findings support geological evidence that the Martian environment was once suitable for an abundance of liquid water on the surface and perhaps conditions that were suitable for biological activity.