Scientists have found more evidence of long-term underground water flows on Mars that may have provided a suitable environment for microbial life.
"If there are any sort of fossils, these would be good places to look," the University of Arizona's Chris Okubo said in a telephone interview.
While previous NASA probes have found evidence of past and even present-day water on Mars, scientists previously had few clues if the water existed long enough for life to evolve.
The new findings show light-colored features cutting across dark bands in an area known as Candor Chasma. Okubo and his colleagues believe they are looking at places where rock has been chemically altered by water flowing across the fractures.
"Fluids apparently resided within rock long enough to allow geochemical processes to occur," Okubo said. "That's typically very slow."