Scientists have discovered biosignatures on Earth that look extremely similar to deposits seen on Mars – and may hint at past life on the Red Planet.

The tantalizing research was published last week in the journal Nature Communications, led by Steve Ruff and Jack Farmer of Arizona State University (ASU). They studied outflows from hot springs in El Tatio, Chile, near the edge of the Atacama Desert, one of the most Mars-like places on Earth.

These particular springs are among the highest on our planet, at an altitude of 4,300 meters (14,000 feet). But what had first piqued the scientists’ attention was a seemingly similar location on Mars explored by NASA’s Spirit rover in 2007.

This location is called Home Plate, located in the 3 to 4 billion-year-old Gusev Crater. Next to the Home Plate’s eastern edge, the rover uncovered silica deposits near what is thought to have been an ancient hot spring when one of its wheels failed and was dragged along, digging up material.

Spirit would later become defunct by 2010 owing to its faulty wheel, but this particular discovery has come to the fore again. The researchers found that silica nodules seen by Spirit seem to resemble some at El Tatio, implying they were formed by a similar process – namely, by microbial organisms.

“We went to El Tatio looking for comparisons with the features found by Spirit at Home Plate,” Ruff said in a statement. “Our results show that the conditions at El Tatio produce silica deposits with characteristics that are among the most Mars-like of any silica deposits on Earth.”

Now, it’s definitely too early to jump to any conclusions yet, but it’s certainly an exciting discovery. And it’s all the more interesting because a new rover may revisit this location in the near future.

Spirit’s Gusev Crater is currently being considered as a potential landing site for NASA’s upcoming 2020 Mars rover, which will attempt to determine if life ever existed on the Red Planet. With that in mind, one of the requirements for the landing site is the potential for biosignatures to have been preserved.

The current favored landing site is a dry ancient lake in the Jerezo Crater, but if this latest research proves correct, it would mean there could very well be biosignatures in the Gusev Crater. Why take a chance on a new location when another looks so promising?

In their paper, the researchers note that biological processes are not the definitive explanation for the structures seen by Spirit. But it could be intriguing enough to deserve more investigation, at least.

“Although fully abiotic [physical] processes are not ruled out for the Martian silica structures, they satisfy an a priori definition of potential biosignatures,” they wrote.

^{Image in text: Silica deposits in Gusev Crater (left) compared to those in El Tatio, Chile (right). Ruff/Farmer/Nature}