NASA's Perseverance rover has currently collected two rock samples with indications that they have been in contact with water for an extended period of time, confirming the existence of ancient life on the Red Planet.
“It looks like our first stones are opening up a potentially livable, sustainable environment,” said Ken Farley, a mission scientist, in a statement Friday. "It's a big deal that the water has been there for a long time."
The six-wheeled robot collected its first sample, dubbed Montdenier on September 6, and the second, Montagnac, from the same stone on September 8.
Both samples, slightly wider than a pencil in diameter and about six centimeters long, are now stored in sealed tubes inside the rover.
The first attempt to collect samples in early August failed after the rock was too fragile to withstand drilling by the rover.
The rover was working in an area known as Jezero Crater, north of the equator, where the lake was located 3.5 billion years ago, when conditions on Mars were much warmer and wetter than today.
The rock from which the first samples were obtained turned out to be basaltic in composition and, probably, a product of lava flows.
Volcanic rocks contain crystalline minerals that are useful in radiometric dating.
This, in turn, could help scientists gain insight into the geological history of the area, such as when the crater formed, when the lake appeared and disappeared, and how the climate has changed over time.
“An interesting feature of these rocks is also that they show signs of stable interaction with groundwater,” NASA geologist Katie Stack Morgan told a press conference.
Scientists already knew that there was a lake in the crater, but could not rule out the possibility that it was a "flash in a pan" when flood waters filled the crater in just 50 years.
They are now more confident that groundwater has been present here for much longer.
“If these rocks have been exposed to water for an extended period of time, these rocks may have habitable niches that could support ancient microbial life,” added Stack Morgan.
Salt minerals in rock cores may have trapped tiny bubbles of ancient Martian water.
“Salts are excellent minerals for preserving signs of ancient life here on Earth, and we expect the same may be true of rocks on Mars,” added Morgan Stack.
NASA hopes to return samples to Earth for in-depth laboratory analysis as part of a joint mission with the European Space Agency sometime in the 2030s.