NASA's Curiosity rover has taken a second bite out of its target mountain, this time finding that Mount Sharp can 'taste' a lot more acidic than experts expected.

After perusing around the mountain back in November, Curiosity finally picked out its next most promising drill spot. There, the rover "sunk its teeth" into, so to speak, the rock known as Mojave 2.

The rover tentatively used a new low-percussion-level drilling technique to collect sample powder from the spot - almost like sampling the sauce on your food to determine if you're going to like it.

And what the rover found was that Mojave 2 tasted like nothing it had sampled before.

Back in September, the rover sunk its teeth into a lower outcrop around Mount Sharp called Pahrump Hills, at a spot named "Confidence Hills." That was the drilling robot's first true taste test, but back then NASA's Mars Science Laboratory team saw results that were pretty much expected for the Red Planet's dusty environment - not so for Mojave 2.

"Our initial assessment of the newest sample indicates that it has much more jarosite (an oxidized mineral containing iron and sulfur that forms in acidic environments) than Confidence Hills," David Vaniman, the Deputy Principal Investigator for the Chemistry and Mineralogy (CheMin) instrument on Curiosity, explained in a statement.

Now Vaniman and his colleagues are asking questions about the state of water on Mars during Mount Sharp's formation. Past theories were that the mountain - about the size of Washington's Mount Rainier - had humble beginnings as a sediment dump after several Martian lakes filled and dried over the course of Mars' past.

Mojave 2 was one of several points in the Mojave drilling site, which was selected because it boasts an abundance of slender features, slightly smaller than rice grains, which are visible on the rock surface. Researchers sought to determine whether these were salt-mineral crystals, such as those that could result from evaporation of a drying lake.

Other research has suggested that the Red Planet even went though several drastic periods of freezing and thaw, causing water to shift across its surface en masse. That could have easily contributed to Mount Sharp's formation, although what led to the highly acidic conditions around Mojave remains up for debate.

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