Astrobiology studies in the Hamersley Ranges look at early life on planet Earth

Astrobiology studies in the Hamersley Ranges look at early life on planet Earth

Astrobiology studies in the Hamersley Ranges look at early life on planet Earth

Updated 8 December 2017, 9:25 AEDT

Astrobiology researchers search for clues to how life evolved on Earth by studying geological forms in the Pilbara region of Western Australia.

Astrobiology researchers are searching for clues to how life evolved on Earth by studying geological forms in the Pilbara region of Western Australia.

"Astrobiology is a huge field. It has many aspects, looking for life out among the stars, probably more simplistic than intelligent life," PhD student Georgia Soares said.

"We look at life but we only have one example, which is back here on Earth.

"So we look at how it evolved through history and then see how that can be replicated in the stars and planets like Mars."

Ms Soares is studying the geological forms that exist alongside ancient stromatolites in the hills of the Pilbara region near Newman, WA.

Working on her doctorate alongside other scientists from the Centre for Astrobiology at the University of New South Wales, she looks closely at archaea, bacteria and silica forms that have the possibility of being an early branch of life on Earth before oxygen.

Some methanogens in the form of bacteria and archaea are associated with ancient cyanobacteria in stromatolites that appear in the remote Pilbara rocks.

Around 2.4 billion years ago the Earth experienced a global pollution event.

The atmosphere was filled with methane, the energy source for any life that existed then.

While oxygen is essential for life nowadays, it is traditionally a toxin and can be poisonous in large quantities.

Early life billions of years ago had to adapt to new conditions after methane in the atmosphere was replaced by oxygen.

Anything that could adapt became evolutionarily successful, as oxygen is also a huge energy source.

Life that could deal with oxygen as an energy supply was then set up for the future of planet Earth when the first "global pollution event" of oxygenation of the atmosphere occurred.

Stromatolites of Shark Bay

You can still see stromatolites in the shallow waters of Shark Bay today, but ancient geological forms also exist in the fossil-filled hillsides of the Hamersley Ranges near Karijini National Park.

"There are groups of microbes which live on the shallow sea floor and they get their energy from sunlight and they often get covered by sediment," Ms Soares said.

"So they grow through the sediment to see the sunlight.

"This forms layers and these layers come in the shapes of domes and columns and little cones, and eventually this builds up a great big reef."

For Ms Soares, the work of astrobiology is to go out and map the stromatolites, looking for evidence of how they grew and what environmental conditions existed in their lifetime.

Her team looks at questions such as, "Did they grow in an oxygenated environment? Did they evolve to adapt to oxygen? Did they become extinct because of oxygen?"

After lab analysis, the data can be compared to what is known of the history of other planets such as Mars.

Working in 40 degree heat of the Pilbara

Ms Soares spent part of the dry season wandering the rocky outcrops in search of samples to study back in the lab.

"It's 40 degrees, boiling hot in the mid-morning, standing out enjoying the nice breeze and looking out across the landscape, unbelievably beautiful country," she said.

"I'm looking at the red sand and all the hills and rocks and thinking, what could be out there? What opportunities are there for exploration of life back 2.4 billion years ago?"

Her first experience of the heat and harsh conditions came in her undergraduate Honours year.

"That was the first time I'd ever been to the Pilbara and the first time I'd properly experienced a dry outback Australia," she said.

"It was July when we went and it was super dry, completely different from everything I'd ever seen before in my life. It was just amazing."

Looking to find life forms on our ancient planet before life as we know it is exciting for a young student.

"We're working in a section of Earth's history that's just a bit younger than the huge banded iron formations of Karijini National Park," she said.

"[They] were laid down when free oxygen was just starting to accumulate in the atmosphere as the product of a micro metabolism, just like cyanobacteria today."

Methods she and her fellow colleagues use include getting core samples of the structures, dissolving them out of the rock, then looking at them under a 3D microscope.

She looks at the micro-structures, then the bigger structures to work out the morphology on the inside and outside.

Isotope analysis of the mineral gains in the structures and other detailed chemical investigations will be done down the track during her three-year PhD scholarship.

"My PhD is pretty much to figure out whether these things were alive and whether they were a different type of life from what we know," she said