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High in the mountains of northern Chile, there is a place where almost nothing can live. This location is called Salar de Pajonales. It sits at an altitude of 3,500 meters above sea level in the Andean Altiplano. The environment here is known for its savage and severe extremes. The temperature changes wildly throughout the day. In the cold, the air drops to negative 23 degrees Celsius. In the heat, it rises to 26 degrees Celsius. The air is filled with solar radiation that ranks among the highest found anywhere on Earth. Rain is so rare that it barely shows up on weather instruments. Strong winds also tear across the flat surface at speeds faster than 100 kilometers per hour.
Yet, despite these harsh conditions, life is present. This life is not just surviving; it is thriving. Even more remarkably, it is leaving a detailed record of its existence that stretches back thousands of years. A new study published in the journal Frontiers in Astronomy and Space Sciences has uncovered a surprising secret within this ancient landscape. The study reveals that ancient stromatolites made of gypsum are hiding a dual history. Gypsum is the same calcium sulphate mineral found in the plaster walls of a newly renovated home. In this high-altitude salt flat, these rock structures contain fossilized biosignatures from the distant past alongside living microbial communities from the present day. These two worlds exist within millimeters of each other, separated only by thin layers of crystal.
To understand the importance of these findings, one must understand what stromatolites are. Stromatolites are layered rock structures that are built up over vast periods of time by communities of microorganisms. They represent some of the oldest evidence of life on Earth. In fact, examples of these structures date back 3.5 billion years. The stromatolites found at Salar de Pajonales are far younger. Scientists estimate they are probably between 4,000 and 6,400 years old. However, what makes them scientifically extraordinary is not their age, but what they contain within their layers.
In the deeper layers of the gypsum, researchers found the glassy remains of microscopic algae. Along with these remains, they identified preserved filamentous cell structures. They also found tell-tale chemical signatures that prove ancient photosynthesis once took place here. These are fossils, entombed in crystal during a much wetter period in the salt flat's history. Back then, a lagoon once covered the site, allowing these ancient organisms to flourish before the water dried up and the crystals formed around them.
Just a few millimeters higher up, in the near surface layers of the same rocks, something entirely different is happening. Active communities of some of the toughest photosynthetic organisms known are alive today. They are carrying out photosynthesis right now, hidden beneath the gypsum surface. In this specific spot, they are shielded from the worst of the ultraviolet radiation and the drying air above. The gypsum itself is optically translucent. This unique property allows just enough light to pass through to power photosynthesis. At the same time, the crystal structure retains tiny amounts of water, providing a lifeline for microbes even during the driest months of the year.
An interesting discovery, you might ask, but why does any of this matter beyond Chile? The answer lies up in space. One of our nearest planetary neighbors, Mars, has gypsum as well. In fact, it has a lot of it. Orbital surveys have detected widespread sulphate deposits across the Martian surface. NASA's Perseverance rover has been examining calcium sulphate minerals in Jezero Crater in great detail. If gypsum can preserve biosignatures for thousands of years on Earth under conditions as extreme as those in the Andes, it raises a tantalizing possibility. Similar deposits on Mars might be holding onto evidence of ancient life, waiting to be found.
The researchers are careful to note that finding biosignatures in Martian gypsum would not be straightforward. Preservation is not guaranteed because the chemical alteration of minerals over time can degrade organic evidence. However, the Salar de Pajonales offers a working model for what to look for and where to look. It provides a concrete example of how life can hide in stone and how that record can be kept safe for millennia.
In a universe that seems increasingly indifferent to life, a salt flat in the Andes is quietly making a powerful case. It argues that biology finds a way wherever it can. Furthermore, it suggests that the crystals that seem to entomb life might one day tell us whether biology ever did the same on Mars. This study transforms a remote and hostile environment into a key for understanding the history of our solar system. The connection between the ancient algae in Chile and the potential for life on Mars is now a concrete scientific target.
The study highlights a delicate balance between destruction and preservation. The same forces that create the harsh desert environment also create the conditions for perfect preservation. The extreme dryness prevents decay, while the crystal formation seals the evidence inside. This duality is central to the search for life beyond Earth. By studying the Salar de Pajonales, scientists are learning to read the language of stone. They are learning to recognize the faint traces of life that might have been buried for thousands, or even millions, of years.
As technology improves, the tools available for exploring these environments become more sophisticated. Rovers like Perseverance carry instruments that can analyze chemical compositions with incredible precision. These machines can look for the specific chemical signatures mentioned in the study. They can detect the subtle changes in mineral structures that indicate biological activity. The work in the Andes provides a roadmap for these missions. It tells scientists exactly what features to prioritize when scanning the Martian landscape.
The implications of this research extend far beyond the study itself. It touches on the fundamental question of whether life is unique to Earth or if it is a common feature of the universe. If life can survive and leave a record in the most extreme places on our own planet, the chances of it existing elsewhere increase significantly. The Salar de Pajonales serves as a natural laboratory, a place where the past and present converge in a single rock formation.
The story of the salt flat is a story of resilience. It is a reminder that life is persistent and that it will find a way to endure against overwhelming odds. The gypsum acts as a silent witness to this struggle and triumph. It holds the secrets of ancient algae and supports modern microbes in the same small space. As we look to the stars, we carry this knowledge with us. We look at Mars with new eyes, seeing not just red rock and dust, but potential history. The crystals that once trapped life in the Andes may now be the key to unlocking the secrets of the Red Planet.
The research published in Frontiers in Astronomy and Space Sciences has opened a new chapter in astrobiology. It bridges the gap between Earth science and space exploration. The findings encourage scientists to look deeper, literally and figuratively, at the surfaces of other worlds. The Salar de Pajonales is no longer just a place of harsh extremes; it is a beacon of hope for the search for extraterrestrial life. It proves that the record of life can survive where we least expect it. And as we continue to explore, we may find that the universe is far more alive than we ever imagined.