When it's not taking selfies or lamenting its mobility situation, Curiosity is finding the wonderful and amazing on that dustball we call Mars. The rover's latest achievement? Collecting mineral samples that have helped NASA deduce that Mars has had very "diverse environments" over its history.
In terms of revelations, it's not the most explosive. No aliens, secret NSA bases or stranded Matt Damons just yet. But slowly, with the aid of our remote robotic friend, our understanding of the Mars environment and how it came to be is getting clearer.
Since arriving on the red planet back in 2012, the rover has been drilling, analysing and collecting data on the ground it covers. This include its landing area, dubbed "Mount Sharp", as well as "Pahrump Hills" and "Confidence Hills", among others.
The blue dots in the image below mark locations where Curiosity "drilled [and collected] samples of powdered rock":
NASA has put together a paper on its research, but a press release from the Jet Propulsion Laboratory does an excellent job of summarising the organisation's findings:
The minerals found in the four samples drilled near the base of Mount Sharp suggest several different environments were present in ancient Gale Crater. There is evidence for waters with different pH and variably oxidizing conditions. The minerals also show that there were multiple source regions for the rocks in "Pahrump Hills" and "Marias Pass."
It goes on to mention the Mount Sharp samples point to a "primitive magma source ... rich in iron and magnesium, similar to basalts in Hawaii", while those take higher contained "silica-rich minerals ... [and] minerals similar to quartz".
Curiosity even found a mineral called "tridymite", which was somewhat perplexing:
Tridymite is found on Earth, for example, in rocks that formed from partial melting of Earth's crust or in the continental crust — a strange finding because Mars never had plate tectonics.
And that's not all. Clay minerals appeared at Confidence Hills and Mojave 2, along with jarosite, which "indicates that there were acidic fluids at some point in time in this region".
In addition, the presence of hematite and magnetite has provided scientists information about water on Mars:
Hematite contains oxidized iron, whereas magnetite contains both oxidized and reduced forms of iron. The type of iron-oxide mineral present may tell scientists about the oxidation potential of the ancient waters.
When considered together, NASA has a more solid picture of a Mars that was "once really wet, but now is dry and cold", according to mission scientist Elizabeth Rampe. It might be a while before we have a definitive history of Mars' ancient waterways, but coming up to its fifth anniversary on the planet, Curiosity continues to do good work.