The following is quite an informative and highly interesting article and paper and well worth the read. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Did 40-year-old Viking experiment discover life on Mars? October 21, 2016 by Lisa Zyga feature Please Register or Log in to view the hidden image! The Viking 2 Lander site, showing frost on the ground. This image was taken by Viking 2 in 1979. Credit: NASA; Viking 2 Lander image P-21873 (Phys.org)—In 1976, two Viking landers became the first spacecraft from Earth to touch down on Mars. They took the first high-resolution images of the planet, surveyed the planet's geographical features, and analyzed the geological composition of the atmosphere and surface. Perhaps most intriguingly, they also performed experiments that searched for signs of microbial life in Martian soil. Overall, these life-detection experiments produced surprising and contradictory results. One experiment, the Labeled Release (LR) experiment, showed that the Martian soil tested positive for metabolism—a sign that, on Earth, would almost certainly suggest the presence of life. However, a related experiment found no trace of organic material, suggesting the absence of life. With no organic substances, what could be, or seem to be, metabolizing? In the forty years since these experiments, scientists have been unable to reconcile the conflicting results, and the general consensus is that the Viking landers found no conclusive evidence of life on Mars. However, a small minority of scientists argues that the Viking results were positive for life on Mars. Read more at: http://phys.org/news/2016-10-year-old-viking-life-mars.html#jCp
http://online.liebertpub.com/doi/full/10.1089/ast.2015.1464 Astrobiology The Case for Extant Life on Mars and Its Possible Detection by the Viking Labeled Release Experiment: ABSTRACT The 1976 Viking Labeled Release (LR) experiment was positive for extant microbial life on the surface of Mars. Experiments on both Viking landers, 4000 miles apart, yielded similar, repeatable, positive responses. While the authors eventually concluded that the experiment detected martian life, this was and remains a highly controversial conclusion. Many believe that the martian environment is inimical to life and the LR responses were nonbiological, attributed to an as-yet-unidentified oxidant (or oxidants) in the martian soil. Unfortunately, no further metabolic experiments have been conducted on Mars. Instead, follow-on missions have sought to define the martian environment, mostly searching for signs of water. These missions have collected considerable data regarding Mars as a habitat, both past and present. The purpose of this article is to consider recent findings about martian water, methane, and organics that impact the case for extant life on Mars. Further, the biological explanation of the LR and recent nonbiological hypotheses are evaluated. It is concluded that extant life is a strong possibility, that abiotic interpretations of the LR data are not conclusive, and that, even setting our conclusion aside, biology should still be considered as an explanation for the LR experiment. Because of possible contamination of Mars by terrestrial microbes after Viking, we note that the LR data are the only data we will ever have on biologically pristine martian samples. Key Words: Extant life on Mars—Viking Labeled Release experiment—Astrobiology—Extraterrestrial life—Mars. Astrobiology 16, 798–810.
Certainly, most probably, that is correct. But like I said, an interesting article, that discusses what at first seemed like conflicting results, and then the discovery of organic matter by the MSL Curiosity, and how they arrived at their conclusions. A point to keep in mind with regard to further experiments and explorations is the following extract.... "Despite the positive outlook, Levin and Straat note that all future experiments will have an unavoidable drawback: the potential for contamination by previous landers. In this regard, the Viking landers were unique in that they were the only pristine Martian life-detection experiment that we will ever have".
Curiosity as a reminder has and did fuel further debate with the discovery of methane, chlorinated hydrocarbons, and other organic molecules. NB: A shame that the latest ESA venture appears to have been lost. Please Register or Log in to view the hidden image!
