In ancient stromatolites in Australia, NASA has found a blueprint for Mars exploration

NASA It works with its international partners to study ancient Earth as it relates to it Mars.

In June 2023, leaders of NASA’s Mars Exploration Program will join their counterparts from the Australian Space Agency (ESA).European Space Agency), and the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO) on a field expedition to visit some of the oldest convincing evidence of life on Earth.

“This science mission was a great opportunity for NASA to work with our international partners to study ancient Earth as it relates to Mars, which may have had a similar past,” said Eric Ianson, director of NASA’s Mars Exploration Program at NASA Headquarters in 2016. Washington. “The more we learn about the evolution of our planet, the more we can apply that knowledge to our characterization of the Red Planet.”

Glimpses of the past: a Pilbara geological treasure

The Pilbara, located in the outback of Western Australia, is one of the few places in the world that preserves an ancient geological record of our ancient planet. As the international community continues to work together to study Mars and prepare to take samples to bring back to Earth, these teams explored what our own backyard can teach us about searching for life elsewhere.

Members of NASA’s Mars Exploration Program, the European Space Agency, the Australian Space Agency and the Australian Commonwealth Scientific and Industrial Research Organization are in the Pilbara region of Western Australia to investigate “stromatolites”, the oldest confirmed fossilized life forms on Earth. They discuss the importance of geological context when choosing sampling sites and ensuring the integrity of the sample’s biological provenance while considering future mission plans to bring Mars samples to Earth. Image credit: NASA/Mike Tollion

“What we’re looking at here in Western Australia is known as stromatolite,” said Mitch Schulte, Mars Perseverance Rover program scientist at NASA Headquarters. “They are fossils from mats of microorganisms that lived about 3.5 billion years ago and whose presence has been recorded and preserved in the rock record for all this time.”

Due to geological processes that constantly reshape and recycle the Earth’s surface, it is extremely difficult to preserve stromatolites or other fossils on Earth for long periods of time, so only a portion of past life remains in the geological record. In the Pilbara region, the rock record has managed to remain intact over billions of years, creating geological outcrops that match the same age as we see on much of the surface of Mars. This makes the site a crucial proving ground for scientists and engineers to hone their skills in identifying signs of life in ancient environments.

The ‘egg-carton’ stromatolites of the 3.35 Ga Strelley Pool in the Trendall District of Western Australia. Image credit: NASA/Mike Tollion

Challenges in fossil detection

The international delegation spent the week-long expedition to the Pilbara looking at the difficulties of locating fossil evidence and how our expeditions use techniques, including making detailed contextual measurements, to overcome such challenges. Discussions centered around how difficult it is to find and confirm signs of past life in ancient rocks, even on a planet like Earth, where life is known to have gained a foothold.

“In order to be able to prove that a feature is biogenic, you not only need to be able to prove that life could create it, but you also need to be able to prove that the particular version of the feature was not created by something else,” says Lindsay Hayes. , deputy principal scientist for Mars Sample Returns and astrobiology program scientist at NASA Headquarters. “You have to understand what else is happening in the historical record of the rock section so you can understand what you’re looking at.”

The importance of geological context

The main theme of the field workshop was the importance of geological context when selecting sampling sites and ultimately confirming the integrity of the biological origin of the sample. The Pilbara is the perfect classroom for teams to study stromatolites that have stood the test of time and scientific rigor and understand what they might be looking for on Mars. The group investigated how the environment in which these signs of ancient life were found could have been favorable or unfavorable for the formation of biology.

NASA’s Perseverance Mars spacecraft has been traversing Jezero Crater, which contains an ancient river delta, since February 18, 2021, storing samples of rocks and regolith that may contain signs of ancient microbial life from this same 3- to 3.5-year-old period. Billion years. This mission’s exercises mimic what Perseverance does remotely, millions of miles away: identifying samples in the field and studying the surrounding area.

As we look to the next phase of the rover’s sampling campaign, the international community can use the information we’ve learned about the importance of environmental context on Earth to ensure that the most scientifically viable samples are collected in conjunction with the appropriate context. To make measurements that will answer our biggest scientific questions about Mars when it reaches Earth.

A step towards answering the final question

This astrobiology expedition paves the way for continued investigation and collaboration, as NASA’s Perseverance rover, the European Space Agency’s ExoMars program, and the two agencies’ joint Mars sample return missions will work together to try to answer humanity’s age-old question: Are we alone?