NASA hasn’t found life on Mars yet – but signs are promising

Is Life on Mars a Reality?

The direct answer is no. However, NASA’s Perseverance rover has unearthed intriguing clues in ancient rock formations that suggest life may have existed on Mars billions of years ago. Recent findings reveal small nodules of unusual minerals embedded in various clay-rich rocks that might hint at biological origins.

As thrilling as this evidence may be, it is essential to tread carefully. Astrobiologists utilize a seven-step scale known as the Confidence of Life Detection to quantify the quality of such evidence. Currently, even when considering previous discoveries alongside the recent revelations, we find ourselves firmly at step one of this scale.

What Exactly Has NASA Discovered?

In its quest last year, Perseverance explored the ancient lakebed of Bright Angel in Jezero Crater, where it stumbled upon a rock displaying distinctive markings referred to as “leopard spots” and “poppy seeds.” In Earth’s geological context, these formations are often indicators of ancient microbial activity. Leopard spots consist of millimeter-sized dark blobs surrounded by a circular rim, while poppy seeds signify even smaller dark speckles.

Both these formations have been documented in a rock now dubbed Cheyava Falls, named after a waterfall in the Grand Canyon. They are found sandwiched between layers of calcium sulfate—a mineral typically indicative of water presence, a vital prerequisite for life.

Recently, NASA announced additional captivating discoveries from clay-rich samples at two sites—Sapphire Canyon within Bright Angel and another site called Masonic Temple. These samples reveal tiny, green-tinted specks of chemically reduced iron phosphate and iron sulfide minerals.

Why Are These Findings Significant?

On Earth, the geological features known as leopard spots and poppy seeds are often associated with microbial life. The redox reactions pivotal for microbial energy production result in the deposition of colored iron and sulfur minerals in their reduced forms—those having gained electrons. The features on Cheyava Falls may have been created by microbes or through processes involving high-temperature reactions not connected to biological activity.

However, analysis conducted with Perseverance’s onboard instruments earlier this year revealed that the markings contain minerals in a reduced state, increasing the likelihood of a biological explanation. Furthermore, the new rocks exhibit uneven distributions of reduced material, correlating distinctly with levels of organic compounds—providing compelling evidence that these could stem from once-living organisms.

According to Joel Hurowitz from Stony Brook University and colleagues, in a study published today in the journal Nature, the Bright Angel formation holds textures and organic signatures that may represent genuine “potential biosignatures.” Nonetheless, they underscore that definitive proof of life on Mars has yet to be established.

What Steps Can Confirm These Findings?

With our current exploratory missions extensively analyzing Cheyava Falls and the new samples on Mars, the next monumental step would be to bring these samples back to Earth for in-depth studies.

Perseverance is designed to collect and store intriguing samples to eventually transfer to a future mission tasked with the retrieval of these materials. However, complications arising from budget cuts proposed by former US President Donald Trump might threaten the viability of the Mars Sample Return mission, leaving sampled materials stranded on Mars without further analysis.

Team member Sanjeev Gupta from Imperial College London expressed optimism that this latest discovery bolsters the argument for renewed funding towards a sample return mission. “This is the first time we’ve seen indications that suggest biological processes may have been at work, amplifying the excitement,” he said. “It is crucial that we bring these samples back.”

Ultimately, returning samples from Mars to Earth, including those from Sapphire Canyon, would provide the most promising chance of elucidating the processes responsible for these remarkable features.

Can We Explore More from Mars?

Life on Earth spread rapidly when it first emerged, so even without a sample-return mission, we can expand our search for recurrent patterns. Are there additional rocks exhibiting similar features?

“Currently, we’re venturing beyond Jezero Crater to investigate ancient rocks for evidence of similar processes or characteristics. We might revisit the original sites to seek further occurrences,” Gupta stated. “However, the key factor remains the retrieval of samples for thorough analysis back on Earth.”