Scientists on Earth have investigated the microscopic pictures of Martian soil returned by NASA's Opportunity rover, and found features that are unlike anything seen on Mars before, including spherical particles that could have been formed by the erosion of water. Opportunity also used its instruments to create a mineral map of the area, and discovered large quantities of hematite right at the surface, especially near the rim of the crater which the rover landed in. Engineers will have the rover drive forward about 3 metres - halfway to the outcrop of rock - and dig a trench with its wheel to see material down a few centimetres.