Has there ever been life on Mars?
We’re not sure, and current investigations focus around what happened to the water on Mars, which has long since disappeared from the planet’s surface. In 2007, the Opportunity rover detected the presence of meridianiite at its landing site in Meridiani Planum. Meridianiite (also known as MS11) is MgSO4∙11H2O, a hydrated sulfate mineral that is only stable at temperatures below 2°C. Satellite observations tell us that there are outcrops of hydrated sulfate minerals, several kilometres thick, in the walls of Valles Marineris, and meridianiite is thought to be widespread on Mars. Could hydrated minerals such as these be locking away all the water that once flowed on Mars?