Close-up images of a region of Mars scientists had previously only seen from orbit have revealed “dramatic evidence” of where water once flowed on the Red Planet.
The new images taken by NASA’s Curiosity Mars rover raises fresh questions about how the Martian surface was changing billions of years ago.
Mars once had rivers, lakes, and possibly an ocean, NASA said. Scientists aren’t sure why the water eventually dried up, leading the planet to transform into the chilly desert it is today.
Curiosity’s images show evidence of ancient groundwater crisscrossing low ridges, arranged in what geologists call a boxwork pattern, the space agency said.
“By the time Curiosity’s current location formed, the long-lived lakes were gone in Gale Crater, the rover’s landing area, but water was still percolating under the surface,” NASA said in a news release. “The rover found dramatic evidence of that groundwater when it encountered crisscrossing low ridges.”
“The bedrock below these ridges likely formed when groundwater trickling through the rock left behind minerals that accumulated in those cracks and fissures, hardening and becoming cementlike,” the release continued. “Eons of sandblasting by Martian wind wore away the rock but not the minerals, revealing networks of resistant ridges within.”
The rover has been exploring the planet’s Mount Sharp since 2014, where the boxwork patterns have been found.
Curiosity essentially “time travels” as it ascends from the oldest to youngest layers, searching for signs of water and environments that could have supported ancient microbial life, NASA explained.
“A big mystery is why the ridges were hardened into these big patterns and why only here,” Curiosity’s project scientist, Ashwin Vasavada, said. “As we drive on, we’ll be studying the ridges and mineral cements to make sure our idea of how they formed is on target.”
In another clue, scientists observed that the ridges have small fractures filled with the salty mineral calcium sulfate, left behind by groundwater.
Curiosity’s deputy project scientist, Abigail Fraeman, said it was a “really surprising” discovery.
“These calcium sulfate veins used to be everywhere, but they more or less disappeared as we climbed higher up Mount Sharp,” Fraeman said. “The team is excited to figure out why they’ve returned now.”
