Gemstone. Opal is a stone whose kaleidoscopic appearance is formed by the interaction between silica (such as quartz, which it resembles) and water. The water filters between the rocks and is linked at a molecular level with them, generating new whitish structures with flashes of multiple colors.
On Earth, opals can be found in various places, especially in Australia and Ethiopia, but now, thanks to data collected by the Curiosity rover and work by a team of researchers at Arizona State University , we know that it is possible to find them also in different places on Mars.
The discovery was made thanks to the DAN ( Dynamic Albedo of Neutrons ) neutron spectrometer, a device on board Curiosity that, despite having already been depreciated, continues to provide relevant data to scientists. In this case it was the device that helped associate some "halos observed in Martian rocks to this precious stone.
Following the trail. Now, after analyzing the spectrometer data, a team of researchers from NASA and Arizona State University have concluded that these “halos” were the result of a more widespread presence of opal than previously believed. The results of the research have been published in an article in the magazine Journal of Geophysical Research: Planets .
Experts have long suspected the existence of these materials on Mars for more than a decade. Already in 2008 The Mars Reconnaissance Orbiter observed some whitish areas, which were associated with these geological formations.
An aquatic past. The finding is new confirmation that Mars was a planet full of water in the past, but it has also made experts think that this water could have lasted longer than previously believed on the red planet. Only not on the surface but underground.
This would also imply that life could have also existed on Mars until a more recent period than was suspected, also underground, protected from excess solar radiation and extreme surface temperatures and fed by various water reservoirs.
“Given the extensive network of fractures discovered in Gale Crater, it is reasonable to expect that these potentially habitable underground conditions would extend to many other regions of the crater (…) as well, and perhaps in other regions of Mars,” he explained in a note from press Travis Gabriel, one of the co-authors of the research. “These environments would have formed long after the ancient Gale crater lakes dried up.”
Perseverance and beyond. The presence of opals is a good sign for exploration of the red planet. The reason is that opal water is, in principle, usable. Since the bonds between water molecules and silica stones are not as tight as in the case of minerals themselves, the molecules of the essential liquid are extractable from the rock.
Although Mars has important water deposits in the form of ice, these deposits are restricted to the polar areas. If opals are as widespread on Mars as now suspected, it will be possible to expand the radius of explorable regions on future manned missions.
We will still have to wait. For more than two years, Curiosity has been living on the Martian surface with its successor, Perseverance. This investigates the Jezero crater, which could also have opal deposits. It is precisely Perseverance rover which is collecting samples from the Martian surface to try to send them to Earth, although this will be at the beginning of the next decade.