Mars crystals recently discovered by the NASA Curiosity rover bear a resemblance to gypsum crystals formed in drying lakes on Earth.
Although the Mars crystals appear as if they’ve formed by the same mechanism as gypsum crystals on our own planet, NASA scientists are currently considering multiple possibilities for why exactly we’re seeing these newly discovered crystals.
One aspect of note regarding the rover’s discovery of these Mars crystals is when exactly these features formed when compared to the layers of sediment around them. Another pressing question is whether the original material that crystallized remains inside them or was later dissolved away and replaced with something else. These Mars crystals may point to evidence of a drying lake or to groundwater that flowed through the sediment, lending credence to the idea that there was once water flowing over the surface of Mars.
In addition to taking a look at these Mars crystals, the team behind the Curiosity rover is also looking at other clues around the same area in order to discover more about the planet’s history. Other findings of note include stick-shaped figures roughly the size of rice, mineral veins with multicolored zones, color variations in the planet’s bedrock, and several other unexpected findings on the planet’s surface.
“There’s just a treasure trove of interesting targets concentrated in this one area,” said Curiosity Project Scientist Ashwin Vasavada of NASA’s Jet Propulsion Laboratory, Pasadena, California in a press release. “Each is a clue, and the more clues, the better. It’s going to be fun figuring out what it all means.”
The Mars crystals were found on the Vera Rubin Ridge, which is relatively unique as an “erosion-resistant band on the north slope of lower Mount Sharp inside Gale Crater.” This area was the planned destination even before the 2012 landing, and the Curiosity rover has begun climbing the ridge around 5 months ago – just now reaching the uphill southern edge.
The area where the Mars crystals were discovered was examined because the bedrock is noticeably pale and gray, in stark contrast to the red bedrock that forms most of the Verin Rubin Ridge.
“These tiny ‘V’ shapes really caught our attention, but they were not at all the reason we went to that rock,” said Curiosity science-team member Abigail Fraeman of the Jet Propulsion Laboratory. “We were looking at the color change from one area to another. We were lucky to see the crystals. They’re so tiny, you don’t see them until you’re right on them.”
“These shapes are characteristic of gypsum crystals…These can form when salts become concentrated in water, such as in an evaporating lake,” said Sanjeev Gupta, a Curiosity science-team member at Imperial College, London.
“So far on this mission, most of the evidence we’ve seen about ancient lakes in Gale Crater has been for relatively fresh, non-salty water…If we start seeing lakes becoming saltier with time, that would help us understand how the environment changed in Gale Crater, and it’s consistent with an overall pattern that water on Mars became more scarce over time,” said Vasavada.
It remains to be seen what practical implication the discovery of these Mars crystals will bring about, but it’s an exciting find that gives us another hint towards the history of the Red Planet.