Today marks 50 years since the Viking 1 spacecraft successfully landed on Mars on 20 July 1976, a milestone being examined amid renewed questions about whether the mission overlooked evidence of extraterrestrial life.
Steven Benner, a chemist and former Harvard professor, has published a new book titled “Meet the Neighbours” in which he contends that NASA scientists misinterpreted data from the Viking missions’ life-detection experiments. Benner argues that the scientific community has operated under an incorrect assumption that Viking found no evidence of microbial life on Mars. He attributes this partly to scientists’ reluctance to announce groundbreaking discoveries without absolute certainty, making them more cautious about reporting positive findings than negative ones. According to Benner’s analysis, while conducting peer reviews of NASA grants at the Lunar and Planetary Institute in Houston, he discovered discrepancies in the original 1976 Viking mission logs that suggested chemical activity indicative of organic materials was detected but dismissed as contamination.
The crux of Benner’s argument centers on the Gas Chromatography-Mass Spectrometry (GC-MS) experiment conducted by Viking, which was designed to detect organic materials in Martian soil. Benner maintains that the experiment did detect trace organic compounds, but scientists could not explain these findings and rejected them as contaminants. His position gained further support decades later when NASA’s Phoenix lander discovered in 2008 that perchlorates—chemicals that destroy organic materials when heated—were present in Martian soil. Since the 1970s GC-MS experiment heated samples to 500 degrees Celsius, such extreme temperatures would have destroyed most organic matter, potentially explaining why organic traces were detected but misinterpreted.
If Benner’s interpretation proves correct, the implications would be profound. He suggests that discovering life on Mars would indicate either an independent origin of life or evidence of panspermia, the transfer of material between planets. Either scenario would suggest that microbial life is widespread throughout the galaxy on rocky planets similar to Earth and Mars. Benner emphasizes that this conclusion would fundamentally reshape humanity’s understanding of life’s prevalence in the universe and would have guided different research priorities for subsequent Mars missions, which have instead focused on searching for water, habitability, and signs of ancient rather than extant life.
Benner’s claims have not gone uncontested within the scientific community. Other researchers, including the late Dr. Gilbert V. Levin, who designed one of the Viking life-detection tests, and Mexican astrobiologist Rafael Navarro-Gonzalez, have previously made similar arguments. However, Benner acknowledges that the scientific community remains divided on the issue, with some supporting his work and others concerned about potential negative public perception or impacts on funding. NASA declined to comment on the outside research, and the European Space Agency stated it was not aware of Benner’s publication. Despite the controversy, Benner remains committed to pursuing further examination of his conclusions.