One of Curiosity's famous selfies. This one was captured at the site from which it reached down to drill into a rock target called 'Buckskin' and discovered an unexpected mineral. Image credit: NASA/JPL-Caltech/MSSS
NASA has discovered an unexpected mineral on Mars that could change our understanding of how the planet evolved.
The Curiosity rover found the mineral while exploring sedimentary rocks in Gale Crater, which it has been doing since landing on the Red Planet in August 2012.
The mineral is called tridymite, and its discovery is a bit of a surprise because it is generally associated with silicic volcanism, a process that is known on Earth but was not thought to be present on Mars.
On Earth, tridymite is formed in extremely hot volcanoes like Mount St. Helens through a combination of high temperatures and high silica content.
The discovery means NASA scientists will now have to reconsider the Red Planet’s volcanic history.
It could even emerge that Mars once had explosive volcanoes, which would explain the presence of the tridymite.
Curiosity found the tridymite while collecting powder drilled from rock at an area in Gale Crater called ‘Buckskin’.
It is thought that the mineral found its way into the stone as sediment from the erosion of silicic volcanic rocks.
"I always tell fellow planetary scientists to expect the unexpected on Mars," says coauthor Doug Ming, chief scientist at the Astromaterials Research and Exploration Science (ARES) Division at NASA's Johnson Space Center.
"The discovery of tridymite was completely unexpected.
This discovery now begs the question of whether Mars experienced a much more violent and explosive volcanic history during the early evolution of the planet than previously thought."