Deepening suspicion that there is or was life in Mars, a study based on images and data captured by the NASA rover Curiosity says that Mars had Earth-like soils comparable with soils in Antarctic Dry Valleys and Chile's Atacama desert some 3.7 billion years ago.
Recent images from Curiosity from the impact Gale Crater reveal Earth-like soil profiles with cracked surfaces lined with sulfate, ellipsoidal hollows and concentrations of sulfate comparable with soils in Antarctic Dry Valleys and Chile's Atacama Desert, said author of the study Gregory Retallack, a geologist at University of Oregon in the US.
The soil deep in the crater dating to some 3.7 billion years ago contains evidence that Mars was once much warmer and wetter, Retallack added.
The potential discovery of these fossilised soils in the Gale Crater dramatically increases the possibility that Mars has microbes, said Malcolm Walter, who was not involved in the research, from Australian Centre for Astrobiology.
"There is a real possibility that there is or was life on Mars," he added.
Retallack studied mineral and chemical data published by researchers closely tied with the Curiosity mission.
"The pictures were the first clue, but then all the data really nailed it," Retallack said.
The key to this discovery has been the superb chemical and mineral analytical capability of the Curiosity Rover, which is an order of magnitude improvement over earlier generations of rovers.
"The new data show clear chemical weathering trends, and clay accumulation at the expense of the mineral olivine, as expected in soils on Earth. Phosphorus depletion within the profiles is especially tantalising, because it attributed to microbial activity on Earth," Retallack said.
The ancient soils, he said, do not prove that Mars once contained life, but they do add to growing evidence that an early wetter and warmer Mars was more habitable than the planet has been in the past three billion years.
The study is forthcoming in the journal Geology.
