A team of researchers says that rocks in the Nili Fossae region of Mars may contain the fossilized remains of life.
The clay-carbonate rocks date back around four billion years to the Noachian period, and were analyzed using the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and images from the HiRISE spectrometer.
The results, says the team, show that the rocks are very similar to those found in the Pilbara region of Western Australia - which show signs of tiny fossils called stromatolites. They are some of the earliest remains of life on Earth.
The team found that the carbonate-bearing Martian rocks are very similar in composition. They are made up of hydrothermally altered ultramafic rocks, and are not pure Mg-carbonate. The implication is that, if life was present in the region, its remains would be likely to be preserved.
Moreover, the study explains that talc is present in close proximity to the carbonate locations - rather than previously suggested saponite - and that talc-carbonate alteration of high-Mg precursor rocks has taken place, showing that conditions in the region could have been suitable for life.
"We suggest that the associated hydrothermal activity would have provided sufficient energy for biological activity on early Mars at Nili Fossae," says SETI's Adrian J Brown.
"Furthermore, in the article we discuss the potential of the Archean volcanics of the East Pilbara region of Western Australia as an analog for the Nochian Nili Fossae on Mars. They indicate that biomarkers or evidence of living organisms, if produced at Nili, could have been preserved, as they have been in the North Pole Dome region of the Pilbara craton."
The research appears in Earth and Planetary Sciences. It "marks a significant finding in the Nili Fossae region of Mars, highlighting similarities between traces of life on early Earth and early Mars, and suggests a landing site for an exobiology mission to Mars," says editor Tilman Spohn.
Carbonate rocks were first discovered on Mars in 2008.