After a 34-kilometre trek, NASA’s indefatigable rover Opportunity has discovered veins of hydrothermally deposited minerals at the edge of Endeavour crater, where it will over-winter in its eighth year.
The bright, stick-like veins, apparently comprised of the mineral gypsum, indicate that hot, mineral-rich water was once pulsing through fractures in the volcanic rock. The mineral precipitates out in an environment much less acidic than the ones responsible for the water-altered sulfate minerals that Opportunity has previously discovered — which means that the site would have been more habitable than others explored by the rovers.
Principal investigator Steve Squyres, of Cornell University in Ithaca, New York, says that the discovery is the most “bullet proof” yet for ancient water. “There’s no ambiguity about this.” Squyres presented the results today at a meeting of the American Geophysical Union in San Francisco, California. Gypsum has been detected before from orbit, and even dunes comprised of gypsum dust have been identified, but Squyres says it is more exciting to discover it where it formed, in situ.
Yet space agencies should not necessarily be targeting Endeavour crater with life-detection missions, says project scientist Bruce Banerdt, of the Jet Propulsion Laboratory in Pasadena, California. Although microbes on Earth can exist in hydrothermal cracks, he says that the veins were probably originally deposited when the region was buried under kilometres of sediment — a situation much less favorable for life.
Image credit: NASA/JPL-Caltech/Cornell/ASU