Life on Mars Viking mission claims are once again at the center of scientific debate, as a prominent scientist argues that NASA may have misinterpreted crucial data collected nearly half a century ago. According to this view, evidence of life on Mars may have already been discovered in the 1970s—but was dismissed due to flawed assumptions.
Some researchers now believe that the long-standing conclusion that “no life was found on Mars” is not based on the absence of evidence, but rather on how the data from NASA’s Viking missions were interpreted.
What the Viking Missions Actually Detected
NASA’s Viking 1 and Viking 2 landers touched down on Mars in 1976. Each lander carried three separate experiments specifically designed to detect signs of microbial life. Remarkably, all three experiments produced results that could be interpreted as positive.
However, one instrument—the Gas Chromatograph–Mass Spectrometer (GC-MS)—failed to detect organic molecules in Martian soil. This single result became decisive. Viking Project lead scientist Gerald Soffen famously concluded: “If there is no body, there is no life.”
That statement shaped scientific thinking for decades and became standard teaching in textbooks worldwide.
A New Interpretation of Old Data
Now, chemist Professor Steve Benner from the Foundation for Applied Molecular Evolution in Florida says the Viking data tells a very different story. According to Benner, the problem was not what the instruments detected, but how the results were explained.
During the GC-MS experiment, Martian soil samples were first heated to 120°C to remove carbon dioxide, then raised to 630°C to vaporize any organic material. Instead of complex organic molecules, scientists observed a second burst of carbon dioxide along with small amounts of methyl chloride and methylene chloride.
At the time, NASA scientists believed this meant a powerful oxidizing substance on Mars had destroyed any organics. The methyl chloride was dismissed as contamination from Earth-based cleaning chemicals.
Benner strongly disputes this explanation.
“Methyl chloride is not a cleaning solvent,” he explains. “It is a gas that boils at minus 24 degrees Celsius.”
The Missing Piece: Perchlorate
The mystery remained unresolved until 2008, when NASA’s Phoenix mission discovered perchlorate in Martian soil. Perchlorate is a strong oxidizer capable of breaking down organic material over long periods.
Then, in 2010, astrobiologist Rafael Navarro-González demonstrated that heating organic matter in the presence of perchlorate produces almost exactly what Viking detected: about 99% carbon dioxide and 1% methyl chloride.
According to Benner, this experiment perfectly matches the Viking GC-MS results and suggests that organic material may have been present all along.
Did Viking Experiments Detect Life After All?
If organic molecules were indeed present, the positive signals from Viking’s three biology experiments become far more significant. This would mean there was no need to assume the existence of an unknown, ultra-powerful oxidizer that has never been found since.
One of the strongest supporters of this view was Gil Levin, the lead scientist of the Labeled Release experiment. Levin consistently argued throughout his life that Viking had detected living microbes on Mars.
A New Model for Martian Microbes
Benner and his team have gone even further by developing a theoretical model for what Martian life might look like. Known as the BARSOOM model, it suggests that Martian microbes could be photosynthetic bacteria.
In this model, microbes produce oxygen during the day and enter a dormant state at night. They may store oxygen internally and reuse it later, which could explain why Viking’s Gas Exchange experiment detected oxygen release from the soil.
A Scientific Debate Reopened
According to Benner, the misinterpretation of GC-MS data may have set Mars life research back by 50 years. Instead of open scientific debate, the conclusion that “Viking found no life” became accepted dogma.
As the 50th anniversary of the Viking landings approaches, Benner is calling for a transparent re-examination of the original data. He argues that science advances by questioning assumptions—not by protecting conclusions.
The life on Mars Viking mission debate, once considered closed, may now be entering a new and critical chapter.
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