The Perseverance rover has outdone itself this week, collecting not one but two samples of Martian rock for analysis. Now, NASA scientists have revealed what these samples can tell us about the history of Mars and the presence of water on the planet.
Scientists know that Mars is currently dry but there was once liquid water on its surface. However, they don’t agree about how long this water was there for, and understanding that is key to knowing whether the planet was ever habitable. These new samples provide evidence that water was indeed present for a significant period.
“It looks like our first rocks reveal a potentially habitable sustained environment,” said Ken Farley of Caltech, project scientist for the mission. “It’s a big deal that the water was there a long time.”
The history of water is indicated by the presence of salts within the rocks which could have been left behind when liquid water evaporated into the atmosphere. An exciting possibility is that there may even be tiny bubbles of water left within these salt minerals, which would allow researchers to peer back into Martian history.
To know more, they’ll need to get the samples back to Earth as part of the Mars Sample Return mission.
“These samples have high value for future laboratory analysis back on Earth,” said Mitch Schulte of NASA Headquarters, the mission’s program scientist. “One day, we may be able to work out the sequence and timing of the environmental conditions that this rock’s minerals represent. This will help answer the big-picture science question of the history and stability of liquid water on Mars.”
Another reason the samples are of interest is that they are basaltic, and could have formed from flowing lava millions of years ago. Volcanic rocks are especially valuable to geologists because the point at which they hardened from lava to rock can be accurately dated, making them useful in understanding the geological history of a region.
“Each sample can serve as part of a larger chronological puzzle,” NASA writes, “put them in the right order, and scientists have a timeline of the most important events in the crater’s history.”
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