One thing researchers already knew about Mars, even before the rover Curiosity began to investigate the planet’s surface, was that Mars had an abundance of rocks.  As on most planetary surfaces, the rocks on Mars were formed as lava from the its core made its way to the surface, cooled and hardened.  But then the rover stumbled across a particular rock that set the researchers scrambling, according to a story on csmonitor.com.

While looking around on the formation known as Caribou, the rover was taking samples and using the ChemCam, a tool that uses a laser to vaporize a sample of a rock, and perform a chemical analysis.  One this occasion, the findings showed the rock sample contained a high concentration of manganese.

Trace amounts of manganese can be found in the planet’s crust, primarily made of basalt, which is formed when the lava cools, but concentrations of the element at this level were certainly not expected to be found.  In fact, the research team first thought there was an error in the analysis.  After taking additional samples, the team verified the findings.

The scientists say the only way levels of manganese this concentrated could have formed on Mars was if the basalt rock had been dissolved in oxygen-rich water.  Most experts agree that Mars had flowing water millions of years ago, but no one ever thought the planet had significant amounts of oxygen.

Researchers are left to speculate how the oxygen wound up on Mars, but Dr. Nina Lanza, a researcher at Los Alamos National Laboratory who was involved in the analysis, says one theory involves ionizing radiation.  Lanza suggests the radiation from the sun may have split the water molecules once on the planet into hydrogen and oxygen, and the extremely light hydrogen atoms just floated away from the surface, leaving the oxygen to be absorbed into the rocks.  The process of oxidation may also account for the reddish color of rocks on Mars.

Lanza told the Christian Science Monitor that it appears Mars evolved differently than previously thought, and added researchers needed to start looking for other different minerals to tell the story of the history of Mars.