NASA’s Perseverance rover has made a stunning discovery on Mars that has scientists excited about the possibility of ancient microbial life on the Red Planet. On July 21, 2024, the rover spotted an unusual rock, nicknamed “Cheyava Falls”, that shows signs it may have once hosted all the key ingredients necessary for life as we know it.
The Discovery
While exploring a dry ancient riverbed in Jezero Crater, Perseverance came across a partially buried 3.5 billion-year-old sedimentary rock with some very intriguing features:
- White streaks: These streaks hint that water once flowed through the rock. Perseverance detected hydrated calcium sulfate, evidence that the rock interacted with water in the past.
- Organic molecules: The rover detected carbon-based organic compounds within the rock. Organics are considered the building blocks of life.
- Leopard-like spots: Most intriguingly, the rock features a smattering of black and white spots along its surface that resemble a leopard’s coat. On Earth, such spots mainly form in two ways – from microbes or through chemical reactions that can provide energy for life.
The spots consist of iron and phosphate surrounded by black rings, a pattern seen on Earth as a result of microbe-led chemical reactions. “These spots are a big surprise,” said David Flannery, an astrobiologist on the Perseverance team. “On Earth, these types of features in rocks are often associated with the fossilized record of microbes living in the subsurface.”
Essentially, this single rock shows evidence that it once had liquid water, organic molecules, and a potential energy source that could have sustained ancient microbes. It’s the first time a rock with all three of life’s key ingredients has been found in the same place on Mars.
Bringing Cheyava Falls Back to Earth
To determine if the leopard spots and organics in the rock are truly signs of ancient life, scientists need to study Cheyava Falls more closely. Perseverance has already collected a sample which NASA plans to retrieve and return to Earth through the upcoming Mars Sample Return mission.
On Earth, the rock could be analyzed with powerful laboratory instruments to learn more details about its composition, how it formed, and its history on the Martian surface. Studying Cheyava Falls in context with Perseverance’s other collected samples could also paint a broader picture of Mars’ ancient environment and habitability.
However, the Mars Sample Return mission has faced recent challenges. Originally planned to cost $5 billion and launch in 2026, budget overruns and delays have pushed the price tag to over $11 billion with a new timeline stretching to 2040. NASA is currently evaluating more affordable options to retrieve the samples sooner, including considering bids from private companies.
An Important Discovery, Regardless of Outcome
Even if further analysis reveals the leopard spots and organics were produced through non-biological means, Cheyava Falls would still be a groundbreaking discovery. At a minimum, it would expand our understanding of how the ingredients for life could have formed on early Mars without life itself.
The rock could also provide clues about how long habitable conditions might have persisted on ancient Mars. Some scientists hypothesize that as Mars dried out billions of years ago, rocks containing hydrated minerals like the calcium sulfate in Cheyava Falls could have been one of the last refuges for microbial life.
“Cheyava Falls is the most puzzling, complex, and potentially important rock yet investigated by Perseverance,” said Ken Farley, Perseverance’s project scientist. “On the one hand, we have our first compelling detection of organic material, distinctive colorful spots indicative of chemical reactions that microbial life could use as an energy source, and clear evidence that water, necessary for life, once passed through the rock. On the other hand, we have been unable to determine exactly how the rock formed and to what extent nearby rocks may have heated Cheyava Falls and contributed to these features.”
The Search for Life Continues
Perseverance will continue exploring Jezero Crater and collecting promising samples as NASA works to finalize plans to retrieve those samples in the coming years. With each new discovery, we learn more about Mars’ ancient past and its potential to have once harbored life.
The Cheyava Falls rock is arguably the most compelling evidence yet that some form of life could have once existed on the Red Planet. But definitive proof of ancient Martian life will likely require intensive study of the rock and other samples back on Earth. One thing is certain – the groundbreaking discoveries by Perseverance have brought us closer than ever before to answering the profound question of whether life once existed beyond Earth.
