Life on Mars? Australian rocks could be clues to NASA rover.
Researchers studying Australian rocks say that only ancient microbes could have formed the rocks.
NASA’s Perseverance rover should find similarities when searching for rocks of the same age on Mars, they say.
Wheeled robots searching for evidence that biology took over the Red Planet early in history.
Scientists at the Natural History Museum in London, working with NASA, have described a series of domes in Western Australia with a variety of features, large and small, that undoubtedly appear to have been created by ancient microbes.
Persistence is exploring a large crater called Jezero and hopes to find a location next year that will show phenomena similar to those seen in Earth’s rock. These are preserved examples of what are called stromatolites.
They form over time when several millimeter-scale layers of bacteria and sediment build up in a large dome-like shape. These buildings today stand on the banks of a serene and nutrient-rich lake. However, examples from billions of years ago have been preserved in the Australian outback.
In fact, some of the Australian specimens identified by geologists represent some of the oldest living organisms on Earth.
Dr Kieron Hickman-Lewis and colleagues at the Natural History Museum (NHM) in London examined a particular set of stromatolites in detail.
They are the oldest yet undiscovered, part of the Dresser Formation in the Outback’s Pilbara region, dating back to 3.48 billion years ago.
They have few microbial fossils, and no organic (carbon-rich) compounds that might indicate past life. However, the NHM-led team believes they have succeeded in establishing a signature indicating the biological origin of the rock.
The researchers claim to have used a variety of high-resolution analysis and imaging techniques to detail the structures that can explain their existence solely through the activities of living organisms, as opposed to what might occur naturally in the environment.
A large-scale feature is the wavy upper surface of stromatolites, which occurs when photosynthetic microorganisms grow in the direction of light.
Fluctuations occur because biology does not grow at the same rate in all three dimensions.
At the microscopic scale, within the rock are small columns or columns that trace the connections between the individual “mats” of microbes that make up stromatolites.
Dr. “This is a strong and powerful representation of the microbial growth tissue we call the palisade structure,” explained Hickman-Lewis.
“We know many wall structures in modern Earth’s atmosphere. You can see examples of similar shapes and arrangements. And a lot happens between these domed growth layers.
As for Mars and the Perseverance rover, in satellite imagery, Jezero Crater appears to harbor deep lakes in the past. And on the rim of the crater are carbonate rocks that represent sediments deposited on the shore.
Did Jezero have microorganisms growing stromatolites in the calm, nutrient-rich shallow waters of the crater?
Timelines are no different from Earth. a little faster. Scientists believe that the lake existed about 3.7 billion years ago.
Patience will probably hit rock bottom by the end of next year. At that time we will be deploying gear to look for rocks that share some of the characteristics found in the Pilbara stromatolites.
Professor Carolyn Smith is Director of NHM’s Earth Science Collection and Dr. Like Hickman-Lewis, the rovers are on a mission.
She said she would use what she learned from Australia to investigate the part of the probe looking for the rover’s biological characteristics.
“We can use the rover’s imaging system to identify some of them, but it depends first on whether the stromatolites were there and how well they were preserved.
“Is it more conserved at the macro or micro scale? Is it ubiquitous, or could it be confined to a small area. So if we’re looking in the wrong place, we won’t see it.” she warned
A slam dunk identification of ancient biology in Jezero Crater is a long shot. It is more likely to find rock samples that represent good candidates for further study on Earth.
This is the main goal of persistence. Your job is to drill and store samples that you can collect on later missions and bring home for analysis.
Proving that life exists will be difficult, but Dr. Hickman-Lewis believes her team’s research has developed a template for doing just that. Gates, roads, bricks etc. are features built by people.
Similarly, stromatolites require numerous structural elements that allow us to identify the formation process and unravel its origins.”