More than two decades after NASA’s Spirit rover explored Mars, its data is offering new evidence that the planet once contained far more liquid water than scientists previously thought. Researcher Paulo de Souza of Edith Cowan University in Australia reached this conclusion by combining years of mineral measurements collected by Spirit at Gusev Crater, tells IEEE Spectrum.
Spirit carried a Mössbauer spectrometer that analyzed minerals in Martian soil, rocks, and dust. Individual measurements did not provide definitive evidence of water. However, when de Souza examined the data collectively, previously hidden patterns emerged. Most significant was the detection of small amounts of crystalline hematite and altered magnetite in soil from 32 undisturbed sites.
Hematite is an iron oxide commonly associated with liquid water, although it can also form in volcanic environments. Magnetite occurs in both igneous and sedimentary rocks and can provide evidence of interactions between water and rock. Their widespread presence suggests that significant areas of ancient Mars may have experienced wetter conditions.
The findings were unexpected because hematite concentrations in individual Spirit measurements were too small to identify confidently. By combining numerous observations, de Souza created what the article describes as the most detailed iron-mineral profile of Martian soil to date.
The analysis also has broader implications. Dust layers containing traces of water-related minerals at Gusev Crater appear across large portions of Mars. These deposits likely accumulated and spread over millions of years through wind erosion, temperature changes, weathering, and massive dust storms.
De Souza now plans to apply the same analytical method to hundreds of measurements collected by NASA’s Opportunity rover at Meridiani Planum. The research demonstrates the continuing scientific value of archived rover data while highlighting the importance of equipping future Mars missions with spectrometers capable of conducting extended soil studies.
