NASA’s Curiosity rover is currently climbing a mountain. The rover is in the business of climbing lots of things, but, according to the data it’s transmitting back to scientists, this particular mountain is full of groundwater, making the rock strata chemically active and diverse — a good sign as we search for microbial life. Curiosity also located boron, the first time the element has ever been found on Mars. NASA’s Jet Propulsion Laboratory announced the promising news in a press release Tuesday.

The rover is drilling into Mount Sharp, a site scientists chose hoping it would provide us with exactly this kind of geologic record. The central mound’s sediment is layered, providing a chronological account of early environmental conditions on Mars.

“There is so much variability in the composition at different elevations, we’ve hit a jackpot,” California Institute of Technology professor John Grotzinger told JPL. “A sedimentary basin such as this is a chemical reactor … Elements get rearranged. New minerals form and old ones dissolve. Electrons get redistributed. On Earth, these reactions support life.”

As Curiosity progresses higher up the mountain, it’s also finding various clay minerals and hematite not present at lower altitudes. As for the boron, on Earth we generally find in drier regions where the water has evaporated, so scientists are still floating ideas as to why we just found it deposited by Mars’s groundwater. The two prevailing theories at the moment are that either a lake evaporated under a layer of boron, which later re-dissolved and trickled down through the cracks to the more ancient layers Curiosity is sampling, or that the process by which groundwater transports boron was chemically altered, an idea supported by the fact that we also found hematite.

“Variations in these minerals and elements indicate a dynamic system,” Grotzinger said. “They interact with groundwater as well as surface water. The water influences the chemistry of the clays, but the composition of the water also changes. We are seeing chemical complexity indicating a long, interactive history with the water. The more complicated the chemistry is, the better it is for habitability. The boron, hematite, and clay minerals underline the mobility of elements and electrons, and that is good for life.”

The Curiosity rover touched down on Mars in 2012 and has been searching for signs of life ever since. While we’ve seen plenty of promising evidence from various forms of water and minerals that life could exist there, there’s still no proof that it does, which is why discoveries like this one are so crucial. The better we understand how microbial life might survive on Mars, the better-prepared we are to survive on it ourselves.

Photos via NASA/JPL-Caltech