Fifty years after NASA's Viking 1 lander touched down on Mars on July 20, 1976, a leading scientist argues that the mission may have overlooked evidence of microbial life. Chemist and former Harvard professor Steven Benner claims in his new book, Meet the Neighbours, that data from the Viking missions' life-detection experiments was misinterpreted, potentially missing signs of extant life on the Red Planet.
The Viking Missions and Their Legacy
Viking 1 and its successor, Viking 2, operated for over six years, returning more than 50,000 images and mapping 97% of the Martian surface. Their life-detection experiments were designed to search for microorganisms. At the time, Viking chief scientist Gerald Soffen declared, "No bodies, no life," and NASA's website states that Viking "provided no definitive evidence for the presence of living microorganisms." However, Benner contends that this conclusion was premature.
Benner's Alternative Interpretation
Benner, who holds degrees from Yale and Harvard and has worked with NASA, discovered what he calls "missed" evidence while reviewing original Viking mission logs at NASA's Lunar and Planetary Institute in Houston in 1999. He argues that the Gas Chromatography-Mass Spectrometry (GC-MS) experiment, which heated Martian soil to 500°C to detect organic materials, may have destroyed them. In 2008, NASA's Phoenix lander found perchlorates in Martian soil, chemicals that break down organics when heated, supporting Benner's claim that the Viking GC-MS could have missed organic matter.
Implications of Life on Mars
If Benner is correct, the consequences are vast. He suggests two possibilities: an independent origin of life on Mars, implying life is common across the galaxy, or interstellar panspermia, where life transfers between planets via meteorites. "If we get two for two, life origin on Mars and Earth, it suggests there is microbial life all over the galaxy," Benner said. He compares it to a casino: "If your first casino hand is a straight flush, you're just lucky. If your second is also a straight flush, you know the deck is rigged."
Scientific Community Divided
Benner is not alone in his views. Dr. Gilbert V. Levin, who designed one of the Viking life-detection tests, argued for decades that the mission found life, though he was marginalized. The late astrobiologist Rafael Navarro-Gonzalez also found that Viking may have been "blind to low levels of organics" based on soil studies in Chile's Atacama Desert. Benner acknowledges that the community is divided: "Some say, 'Good guy, Steven. Well done for going out there and taking the arrows.' Others are worried about the impact on public perceptions of space."
NASA's Response and Future Directions
NASA declined to comment on Benner's research, and the European Space Agency said it was "not aware" of his publication. Benner asserts that since the Viking missions, focus has shifted to searching for water and ancient life, rather than extant life. He claims that NASA's Astrobiology Institute, where he worked from 1999, decided that "no experiment will fly if it is going to look for extant life on Mars," interpreting Viking as a mistake. Benner says he will continue to push for acknowledgment: "I'm not going to stop until [NASA head] Jared Isaacman goes on television and acknowledges the issue."
