Life on Mars? Clues Hidden in Martian Salts
The secrets to ancient life on the Red Planet may be locked within tiny, durable crystals.
For centuries, humanity has gazed at the red dot in the night sky and wondered: Are we alone? While today's Mars is a barren, frozen desert, evidence now suggests that billions of years ago, it was a world with flowing water and a thicker atmosphere—a place potentially teeming with life. If ancient microbes ever called Mars home, where would their traces remain? Scientists are now turning their attention to a surprising keeper of secrets: sulfate minerals, common salts on the Martian surface, which may have preserved the molecular fingerprints of life for eons.
Why Lipids? The Ultimate Time Capsules
Geostable
Lipids are among the most durable biomolecules on Earth 2
Distinct Fingerprint
Different microorganisms produce unique lipid patterns 1
Long-Lasting
Can retain information for billions of years 2
Imagine a microscopic Martian organism. When it died, its soft parts would have rapidly decomposed. But its cell membrane, the sturdy barrier that held it together, was built from lipid molecules. These are fatty acids and related compounds that are incredibly resilient.
"Lipids are among the most geostable biomolecules on Earth," scientists note, and their hydrocarbon skeletons can retain diagnostic information about their biological source for thousands of millions of years 2 . This makes them ideal candidates in the search for life on Mars, where any potential organisms would have existed billions of years in the past.
Lipids provide a distinct "fingerprint" because different types of microorganisms produce different lipid patterns. Furthermore, they are relatively resistant to harsh environmental conditions and can be preserved over geological timescales 1 . On a planet like Mars, which has been subjected to intense radiation and oxidation, this durability is not just a bonus—it's a necessity.
Mars's Salty Archives: A Window to a Wet Past
The story of Mars is divided into three broad geological periods. The Noachian period (around 4 billion years ago) was the most habitable, with a warmer climate and widespread liquid water 1 2 . This was followed by the Hesperian, when the planet began to freeze, and the current Amazonian, characterized by hyperarid and cold conditions 2 .
Robotic missions have confirmed that between the late Noachian and late Hesperian, vast salt deposits formed across Mars 1 . In particular, the Gale crater, explored by NASA's Curiosity rover, is rich in calcium and magnesium sulfates 1 . These sulfates are evaporites, meaning they crystallized from evaporating water, much like salt crusts on Earth. They mark the spots where the last widespread lakes and streams on Mars once existed.
Noachian Period
~4 billion years ago
Warm climate, liquid water, potentially habitable
Hesperian Period
~3.7-3.0 billion years ago
Planet begins to freeze, sulfate deposits form
Amazonian Period
~3.0 billion years ago - present
Hyperarid, cold desert conditions
Terrestrial Analogues
On Earth, such salts are known to protect microbial life and its molecular remains for millions of years 1 . The crystals can entomb and shield organic matter from destructive forces like radiation.
High-Priority Targets
Therefore, Martian sulfate deposits are now considered one of the most compelling targets in the search for evidence of past life.
A Groundbreaking Experiment: Recreating Mars in a Lab
To test whether sulfates could truly preserve lipids under Mars-like conditions, scientists designed an innovative experiment. The goal was straightforward but critical: to simulate the Martian environment and see if lipid biomarkers could survive inside sulfate crystals.
The Experimental Method, Step-by-Step:
1. Source Analog Microbes
Researchers began with microorganisms isolated from terrestrial "Mars analogue" sites, such as the magnesium sulfate-rich waters of Basque Lake 1 .
2. Create Martian Crystals
The researchers then entombed these microbes within artificial sulfate crystals by evaporating experimental brine under low atmospheric pressure 1 .
3. Simulate Martian Assault
The crystals were placed inside "The Open University's Mars chamber" and exposed to UV radiation and atmospheric conditions identical to Mars 1 .
| Reagent / Material | Function in the Experiment |
|---|---|
| Artificial Sulfate Brine | Recreates the chemical environment of ancient Martian water bodies to grow crystals 1 . |
| Mars Simulation Chamber | Replicates the destructive surface conditions of Mars (low pressure, UV radiation) 1 . |
| Py-GC-MS (Pyrolysis-Gas Chromatography-Mass Spectrometry) | The core analytical instrument that heats samples, separates the released molecules, and identifies them by mass 1 6 . |
| MTBSTFA (Derivatization Chemical) | A chemical reagent used to make refractory (stubborn) organic molecules volatile enough for GC-MS analysis . |
What the Crystals Revealed: A Hopeful Outlook
While the specific numerical results of the Mars chamber simulation are detailed in the scientific literature, the overarching finding is promising: sulfate minerals can act as viable substrates for the long-term preservation of lipids, even when exposed to Mars-like radiative and atmospheric conditions 1 .
This laboratory success is bolstered by real-world data from terrestrial analogues. A study of an acidic, iron-sulfate-rich stream in Dorset, UK—a mineralogical analogue for Mars—found that lipids were exceptionally well-preserved in goethite, an iron oxide mineral that often forms from the transformation of sulfates like jarosite 8 . The study concluded that "concentrations of lipids, and particularly alkanoic or 'fatty' acids, are highest in goethite layers" 8 . This suggests that on Mars, missions should prioritize detecting fatty acids in iron oxides and hydroxides associated with sulfur-rich environments.
| Mineral Host | Lipid Preservation Quality | Implication for Mars |
|---|---|---|
| Goethite (Iron Oxyhydroxide) | High concentration of lipids; retains biogenic signatures 8 . | A high-priority target. Often forms from sulfates and is excellent at preserving biosignatures. |
| Jarosite (Iron Sulfate) | Lower abundance and diversity of lipids 8 . | Indicates more acidic, lower water activity environments less favorable for life, but still preservative. |
| Quartz Sand & Clay | Paucity of lipids 8 . | Less effective at shielding organic molecules from destruction compared to iron-based minerals. |
From the Lab to Mars: Robotic Explorers on the Hunt
The theoretical and experimental work is already being put into practice on the surface of Mars.
Curiosity Rover
NASA's Curiosity rover has made significant strides. In 2025, researchers announced that the rover had detected the largest organic molecules yet found on Mars—decane, undecane, and dodecane—in a 3.7-billion-year-old mudstone sample from Gale crater. Scientists hypothesize these are fragments of fatty acids that were preserved in the rock 3 . This finding suggests that prebiotic or biological chemistry on Mars may have been more advanced than previously thought.
Perseverance Rover
Meanwhile, NASA's Perseverance rover is collecting samples from the Jezero Crater, an ancient lakebed. It has identified rocks rich in clay, sulfur, and phosphate—a combination that, on Earth, is an excellent preserver of microbial life 7 . A rock dubbed "Cheyava Falls" was found to contain a distinct pattern of minerals, including vivianite and greigite, which on Earth are frequently associated with microbial activity 7 . These samples are slated for return to Earth in the Mars Sample Return campaign in the 2030s, where they can be analyzed with the most powerful terrestrial instruments 4 6 .
| Mission / Instrument | Key Goals & Discoveries | Detection Method |
|---|---|---|
| Curiosity Rover (SAM instrument) | Detected large organic molecules (potential fatty acid fragments) in Gale crater 3 . | Pyrolysis-GC-MS 1 . |
| Perseverance Rover | Collecting rock cores from Jezero Crater for future return to Earth; identified mineral assemblages indicative of potential biosignatures 4 7 . | On-board caching; remote sensing with PIXL and SHERLOC instruments 7 . |
| ExoMars Rosalind Franklin Rover (MOMA instrument) | Future rover (launch planned for 2028) capable of drilling 2 meters down to sample soil protected from surface radiation 4 . | Pyrolysis-GC-MS and Laser Desorption-MS 6 . |
The Future of the Hunt
The quest to find life's traces on Mars is a painstaking process of connecting dots across millions of miles and billions of years. The evidence gathered so far is compelling: the environment was right, the preserving minerals are present, and the chemical building blocks of life exist.
"Our study proves that, even today, by analyzing Mars samples we could detect chemical signatures of past life, if it ever existed on Mars," said Caroline Freissinet, a lead scientist on the Curiosity mission 3 .
The next great leap will come when the Perseverance rover's samples are returned to Earth. Here, free from the size and power constraints of rover-based instruments, these precious cores of Martian sulfate and rock can be interrogated for the definitive lipid fingerprint that would finally answer one of humanity's oldest questions: Were we ever alone?