A recent discovery made by NASA's Curiosity rover suggests that living organisms may have thrived on the surface of Mars, NBC News reported.
Based on the photos taken by the rover, the Red Planet has ancient rock formations that resemble those created by microbes on Earth.
The discovery was made in 2012 when the rover passed through a dry lake bed on Mars' Gale Crater. According to NASA scientists who studied Curiosity's photos, the rock formations closely resembled Earth's microbially-induced sedimentary structures (MISS).
On our planet, these structures are created by microbes residing in the shallow parts of bodies of water. Over time, these layered sedimentary structures become fossilized.
A closer analysis on Gillespie Lake in Mars' Gale Crater revealed that it existed about 3.7 billion years ago.
Due to the similarities between the MISS on Earth and Mars, Nora Noffke, a geobiologist at Virginia's Old Dominion University and one of the scientists who studied Curiosity's discovery, believes the rock structures suggest that life existed on Mars.
However, she noted that further investigations need to be conducted in order to confirm this notion.
"All I can say is, here's my hypothesis and here's all the evidence that I have," she told the Astrobiology Magazine. "Although I do think that this evidence is a lot."
Noffke came up with her hypothesis after closely comparing Earth's MISS to that of Mars. She detailed her findings in a report published by the scientific journal of Astrobiology.
"In one image, I saw something that looked very familiar," she told the magazine. "So I took a closer look, meaning I spent several weeks investigating certain images centimeter by centimeter, drawing sketches, and comparing them to data from terrestrial structures."
"And I've worked on these for 20 years, so I knew what to look for," Noffke added.
Although she pointed that her findings are not enough to confirm the existence of life on Mars, Chris McKay an associate editor at Astrobiology and a member of NASA's Ames Research Center, noted that Noffke's methodology strongly supports her argument.
"I've seen many papers that say 'Look, here's a pile of dirt on Mars, and here's a pile of dirt on Earth,'" he told Astrobiology Magazine. "And because they look the same, the same mechanism must have made each pile on the two planets."
"That's an easy argument to make, and it's typically not very convincing," he added. "However, Noffke's paper is the most carefully done analysis of the sort that I've seen, which is why it's the first of its kind published in Astrobiology."