NASA’s Curiosity rover has discovered opal on Mars. The deposits may prove to be valuable to future Martian explorers not as jewelry but as a potential source of water.
Opal is formed when water weathers silica-rich rocks, forming a solution that settles into cracks and crevices in the rock. Over time, this solution hardens into a solid lump that can be cloudy and dull or a dazzling display of color. Most supplies come from either Australia or Ethiopia, but now a new source has been discovered – Mars.
Throughout old images gathered by the Curiosity rover, lighter-colored rocks have been seen surrounding fracture “halos” that criss-cross the surface of the Red Planet. Samples of these rocks had previously been collected by the rover’s instruments, and in the new study, researchers from Arizona State University analyzed this archival data using new techniques.
The composition of the rocks seemed to be mostly silica and water – the core ingredients of opal. This was consistent across various veins that Curiosity crossed at different points in its mission, even in very different types of rock.
“Our new analysis of archival data showed striking similarity between all of the fracture halos we've observed much later in the mission,” said Travis Gabriel, co-lead author of the study. “Seeing that these fracture networks were so widespread and likely chock-full of opal was incredible.”
This isn’t the first time opal-like material has been discovered on Mars. As far back as 2008, the Mars Reconnaissance Orbiter detected large, pale patches in several regions of the Red Planet that were attributed to deposits of hydrated silica. Now, it seems that the material is more widespread than previously thought.
The implications of finding opal on Mars go beyond future astronaut adornments. For one, it suggests that water was present on Mars far more recently than is currently believed. Even after the surface dried out and became inhospitable for any microbes that may have lived there, conditions below the surface would have remained potentially habitable for much longer. That’s good news for Curiosity and its successor rover Perseverance, which is currently searching for signs of life in Jezero Crater – a site that’s also rich in opal-like material.
The other implication is that this opal could be a useful source of water for future human visitors. Since the water isn’t tightly bound inside a crystal structure, it can be released from the material if it’s ground down and heated. The team estimated that a 1-meter-long (3.3-ft) halo could contain up to 5.7 liters (1.5 gallons) of water in the top 0.3 m (1 ft) from the surface.
The research was published in the Journal of Geophysical Research: Planets.
Source: Arizona State University
