Carbonates found on Mars, increases chance of past life

William Atkins
Friday, 19 December 2008 22:06

Science - Space

The scientists state in the abstract to this paper, “Geochemical models for Mars predict carbonate formation during aqueous alteration. Carbonate-bearing rocks had not previously been detected on Mars' surface, but Mars Reconnaissance Orbiter mapping reveals a regional rock layer with near-infrared spectral characteristics that are consistent with the presence of magnesium carbonate in the Nili Fossae region.”

“The carbonate is closely associated with both phyllosilicate-bearing and olivine-rich rock units and probably formed during the Noachian or early Hesperian era from the alteration of olivine by either hydrothermal fluids or near-surface water.”

They conclude, “The presence of carbonate as well as accompanying clays suggests that waters were neutral to alkaline at the time of its formation and that acidic weathering, proposed to be characteristic of Hesperian Mars, did not destroy these carbonates and thus did not dominate all aqueous environments.”

Bethany Ehlmann, lead author in the study, states, “The carbonates that CRISM has observed are regional rather than global in nature, and therefore, are too limited to account for enough carbon dioxide to form a thick atmosphere.”

He adds, “Although we have not found the types of carbonate deposits which might have trapped an ancient atmosphere, we have found evidence that not all of Mars experienced an intense, acidic weathering environment 3.5 billion years ago, as has been proposed.”

Ehlmann concludes, “We've found at least one region that was potentially more hospitable to life."

The discovery of carbonate minerals in this location on Mars, provides an important place for future Mars missions to land, either by unmanned robots or humans, in their search for life within the solar system.