collect detailed local evidence of water and signs of life. In early the 2000s, the hematite map of Figure 1b and the confirmation (from the topography mapping done by the Mars Global Surveyor) that this area is a flat plain and relatively easy to land on were the decisive pieces of evidence for choosing the Meridiani Planum as one of the landing sites for NASA's two bigger Mars Exploration Rovers (MERs), named Opportunity and Spirit. The decisiveness for NASA of the hematite map of Figure 1b for choosing the landing site for Opportunity was because NASA was using high hematite levels as proxy evidence for large amounts of liquid water flowing in the region in the past. (Hematite only forms in the presence of liquid water in geological settings). In 2003, this high-hematite region was a high-priority place to start to search for signs of life on Mars. Squyres, S. W., Arvidson, R. E., Baumgartner, E. T., Bell III, J. F., Christensen, P. R., Gorevan, S., et al., 2003, "Athena Mars Rover science investigation," J. Geophys. Res.: Planets, 108(E12), 8062. https://doi.org/10.1029/2003JE002121 New name: Meridiani Planum The hematite map of Figure 1b covered part of a larger area called the Sinus Meridiani by 19th-century Mars map-makers. In 2004, senior scientists for the upcoming MER Opportunity mission introduced the new place name Meridiani Planum for (roughly) the high hematite area in Figure 1b. Discovery of Spherules on the Ground NASA'S rover Opportunity successfully made the "hole-in-one" landing into Eagle Crater at Meridiani Planum on January 24th(PST), 2004. On the first sol (Martian day), the rover immediately discovered thousands and thousands of small (4-6 mm diameter) spherules lying all over the place inside Eagle Crater. Figure 2 shows a thumbnail of the view from Opportunity's Pancam (panoramic camera) on the first sol. (The actual image is very large, 7838 x 2915 pixels). The lead of the Pancam team, Jim Bell, soon wrote about this view: "Scientists are intrigued by the abundance of rock outcrops dispersed throughout the crater, as well as the crater's soil, which appears to be a mixture of coarse gray grains and fine reddish grains." Figure 3 is a detail of Figure 2 showing the grey spherules more clearly (click to enlarge). Tests quickly found that the grey spherules are rich in grey hematite.Rieder, R., et al. 2004. "Chemistry of Rocks and Soils at Meridiani Planum from the Alpha Particle