TES discovered hematite in Meridiani Planum. Finding this iron-oxide mineral led NASA to send the Mars Exploration Rover Opportunity to Meridiani, a remarkable place with a water-rich history.
A “water stain” covers part of Meridiani Planum: a layer rich in the iron-oxide mineral hematite. Discovered by the Thermal Emission Spectrometer (TES) on the Mars Global Surveyor orbiter, the hematite – which requires liquid water to form – led NASA to choose Meridiani as the landing site for the Mars Exploration Rover Opportunity. Colors map percentages of hematite in the surface materials. Opportunity landed within the black oval line and found rocks that had once been drenched in water.