Mars Exploration Rover
The name "Meridiani Planum" ("Meridian Plain") is used to refer specifically to the landing site of Mars Exploration Rover "Opportunity", in the western portion of Sinus Meridiani. This site was chosen by the Mars Exploration Rover team both for its characteristic as a flat and mostly rock-free plain (and hence a safe landing site), and also as a site which showed the spectral signature of the mineral hematite, which is often a sign of deposition in an aqueous environment.