BLUE dust has been found within Mars by NASA’s Curiosity rover 4WD droid, which has been exploring the planet for 40 months.
As it carried out sampling on “buckskin” rocks in the Mount Sharp area of the planet, the drill found a rare mineral and disturbed the blue dust.
Much of Mars, beneath the immediate red surface, which is thought to be a rust deposited by volcanoes, has been found to be a pale blue.
During the sampling, the rover uncovered something that has never ever been detected on Mars before and is rare on Earth – tridymite.
The mineral could be a clue for NASA scientists in determining Mars suspected volcanic past, that would have made it a lot like Earth when it was also covered in lakes and seas billions of years ago.
The usual origin of tridymite on Earth involves high temperatures in igneous or metamorphic rocks, but the finely layered sedimentary rocks examined by Curiosity have been interpreted as lakebed deposits.
Tridymite is found in volcanic deposits with high silica content.
Rocks on Mars’ surface generally have less silica, like basalts in Hawaii, though some silica-rich rocks have been found by Mars rovers and orbiters.
A NASA spokesman said: “Magma, the molten source material of volcanoes, can evolve on Earth to become silicic. Tridymite found at Buckskin may be evidence for magmatic evolution on Mars.”
The rover has also found much higher concentrations of silica at some sites it has investigated in the past seven months than anywhere else it has visited since landing on Mars.
Silica makes up nine-tenths of the composition of some of the rocks.
Magma, the molten source material of volcanoes, can evolve on Earth to become silicic. Tridymite found at Buckskin may be evidence for magmatic evolution on Mars.
It is a rock-forming chemical combining the elements silicon and oxygen, commonly seen on Earth as quartz, but also in many other minerals.
Albert Yen, a Curiosity science team member at NASA’s Jet Propulsion Laboratory, Pasadena, California, said: “These high-silica compositions are a puzzle. You can boost the concentration of silica either by leaching away other ingredients while leaving the silica behind, or by bringing in silica from somewhere else.
“Either of those processes involve water. If we can determine which happened, we’ll learn more about other conditions in those ancient wet environments.”
Water that is acidic would tend to carry other ingredients away and leave silica behind. Alkaline or neutral water could bring in dissolved silica that would be deposited from the solution.
Apart from presenting a puzzle about the history of the region where Curiosity is working, the recent findings on Mount Sharp have intriguing threads linked to what an earlier NASA rover, Spirit, found halfway around Mars.
There, signs of sulfuric acidity were observed, but Curiosity’s science team is still considering both scenarios – and others – to explain the findings on Mount Sharp.
Curiosity has been studying geological layers of Mount Sharp, going uphill, since 2014, after two years of productive work on the plains surrounding the mountain.
The mission delivered evidence in its first year that lakes in the area billions of years ago offered favourable conditions for life, if microbes ever lived on Mars.
As Curiosity reaches successively younger layers up Mount Sharp’s slopes, the mission is investigating how ancient environmental conditions evolved from lakes, rivers and deltas to the harsh aridity of today’s Mars.
Seven months ago, Curiosity approached “Marias Pass,” where two geological layers are exposed in contact with each other.
The rover’s laser-firing instrument for examining compositions from a distance, Chemistry and Camera (ChemCam), detected bountiful silica in some targets the rover passed on its way to the contact zone.
The rover’s Dynamic Albedo of Neutrons instrument simultaneously detected that the rock composition was unique in this area.
Jens Frydenvang of Los Alamos National Laboratory in New Mexico and the University of Copenhagen, Denmark, said: “The high silica was a surprise – so interesting that we backtracked to investigate it with more of Curiosity’s instruments.”
The identification of tridymite prompted the team to look at possible explanations.
Liz Rampe, of Aerodyne Industries at NASA’s Johnson Space Center, Houston, said: “We could solve this by determining whether trydymite in the sediment comes from a volcanic source or has another origin.
“A lot of us are in our labs trying to see if there’s a way to make tridymite without such a high temperature.”
Curiosity project scientist Ashwin Vasavada said: “What we’re seeing on Mount Sharp is dramatically different from what we saw in the first two years of the mission.
“There’s so much variability within relatively short distances.
“The silica is one indicator of how the chemistry changed.
“It’s such a multifaceted and curious discovery, we’re going to take a while figuring it out.”