June 2, 2017
Ancient Earth-like lake on Mars could have been full of life
An ancient lake in Mars’ Gale Crater had physical and chemical properties extremely close to those found in similar bodies of water on Earth, and multiple environments in these areas could have supported life, according to research published Friday in the journal Science.
As part of the study, Stony Brook University geoscientist Dr. Joel Hurowitz and his colleagues analyzed data gathered from the Curiosity rover and determined that a lake previously found to have existed more than three billion years ago, different in composition at different depths.Specifically, they found the lake was stratified, meaning that its physical and/or chemical make-up would have been different in shallow waters than it was in deeper waters. In this case, the shallow water contained a greater amount of oxidizing agents than could be found at greater depths, and the deeper water contained higher amounts of reducing agents.
“These were different, co-existing environments in the same lake,” Dr. Hurowitz, an geoscientist and assistant professor at Stony Brook, said in a statement. “This type of oxidant stratification is a common feature of lakes on Earth, and now we have found it on Mars.”
In addition, the shallow water would have contained rocks formed from larger, dense grains, and the rocks in the deeper water formed from finer materials, the researchers reported. Dr. Hurowitz noted, because of these diverse environments, there would have been several chances for various microbes – including those that thrive in oxidant-rich conditions – to survive in the lake.
Microbes would have had ‘multiple niches to... choose from’
As part of their research, the authors used various geochemical and mineralogical analysis techniques and high-resolution imagery to observe the characteristics of rocks studied by Curiosity during the rover’s first 1300 Martian solar days (sols) of operation on the Red Planet, Space.com said.
The observations. Dr. Hurowitz told the website, spanned roughly 330 vertical feet (100 meters) of rock deposits – a thickness that he noted would require as many as 10 million years to form at the bottom of a terrestrial lake. They discovered that the shallow water would have been able to support microbes that thrive in oxygen-rich environments, while the deeper water may have been an ideal habitat for organisms that prefer an oxygen-poor environment.
More precisely, the researchers found that iron deposits located near the crater’s edges tended to be rusty, indicating that they were exposed to oxygen, explained New Scientist. Samples taken in the middle portion of the lake had not been oxidized, suggesting that the iron found there arrived in the groundwater by seeping into the lake from below, the website added.
“Oftentimes, lakes on Earth become chemically stratified in this same way,” Dr. Hurowitz told New Scientist, adding that the region was “not only... a very habitable environment on Mars” but that it was also home to “multiple sub-environments. If microbial life was present on Mars at that time, there would have been multiple niches for those microbes to pick and choose from.”
Image credit: NASA/JPL