This vertical cross-section of the Meridiani Planum region shows that the hematite-bearing plains are part of an extensive set of deposits on top of the ancient, heavily cratered terrain. The Mars Exploration Rover Opportunity is targeted to land here on January 24, 2004 Pacific Standard Time. The background surface image of Meridiani Planum was acquired by the Mars Orbital Camera on NASA's Mars Global Surveyor. On Earth, grey hematite is an iron oxide mineral that typically forms in the presence of liquid water. The rover Opportunity will study the martian terrain and examine the hematite deposits to determine whether liquid water was present in the past when rocks were being formed.