Sulfur Cycling and Mass Balance at Meridiani, Mars

Abstract

AbstractThe Opportunity rover was sent to Meridiani Planum, Mars, to investigate aqueous processes as inferred from orbiter observations of hematite. While the rover found the source of the hematite signal, it also identified abundant bedrock enriched in SO3 on average by >20 wt% throughout its >40‐km traverse. Geological mapping and orbiter data show that the layered sulfate deposits occur over ~4 × 105 km2, an area larger than Germany. Multiple scenarios for formation of the sediment and sulfur sources in the Meridiani sulfate‐rich bedrock have been proposed, including groundwater upwelling in a playa environment, volcanic ash, ice deposits, and fluvial input. Mass balance calculations show that none of the existing scenarios as currently portrayed can account for the total sediment volume and sulfur mass in the Meridiani region. Thus, after 14 Earth years of rover observations, there are still fundamental questions that remain regarding formation mechanisms of the sulfate‐rich bedrock.