An international team of scientists analyzing data from NASA’s Mars Rover Opportunity has announced that the rover found what appeared to be veins of gypsum when examining the edge of the crater “Endeavour” in 2011. The presence of gypsum indicates that conditions conducive to life have existed on Mars at least temporarily.
Color view of a mineral vein from the panoramic camera on NASA's Mars Exploration Rover Opportunity. The vein is about 1.5 cm wide and about 45 cm long. Opportunity examined it in November 2011 and found it to be rich in calcium and sulfur, possibly the calcium-sulfate mineral gypsum (NASA / JPL-Caltech / Cornell / ASU)
Opportunity has been trundling along the Martian soil for eight years now, and has covered more than 33 km. One of its goals has been the Endeavour, a crater formed more than 3.7 billion years ago, which is 22 km across. The crater displays geological layers, which are older than the sulfur-rich sandstone surrounding Opportunity’s landing site.
To identify the gypsum vein in the Endeavour and the nature of the surrounding rock, the researchers used data from the rover’s alpha-particle X-ray spectrometer (APXS), a device that analyses the chemical element composition by exposing martian materials to energetic alpha particles and X-rays from curium-244, and then measuring the energy spectra of backscattered alpha and X-radiation.
Gypsum (chemical formula CaSO4∙2H2O) only forms in water below 60°C. At a higher temperature, other minerals, such as anhydrite, CaSO4, would also be present. The team suggests that water circulated through cracks in the rock after the crater was made. Had it been high in sulfur, it would probably have led to the formation of the sulfur-rich sandstone found around the landing site.
“The gypsum was precipitated from low-temperature aqueous fluids flowing upward from the ancient materials of the rim, leading temporarily to potentially habitable conditions and providing some of the waters involved in formation of the ubiquitous sulfate-rich sandstones of the Meridiani region,” the team led by Cornell University researchers explained in the study published in the journal Science.
The results of this study show that conditions conducive to life once existed on the edge of the Endeavour crater.
