Rover data from more than 20 years ago has revealed clues to the existence of liquid water on ancient Mars. The traces of hematite in de Souza's study were excavated from 32 Gusev soil sites that were undisturbed. Revisiting Past DataAccording to de Souza, each rover measurement wasn't enough to come to a definitive conclusion about water on Mars. If it works out as expected, hundreds of measurements will be analyzed and combined to form a "big picture" assessment of water on Mars in that region, as well. For More InformationNew ECU Discovery Adds to Evidence Mars Once Had WaterA Consolidated Mössbauer Spectrum for Undisturbed Soils from Gusev Crater, Mars