Click For Photo: https://en.es-static.us/upl/2019/10/Viking-2-frost-on-rocks-and-soil-May-18-1979-cp-300x168.jpg
Water frost on Mars rocks and soil near the Viking 2 lander, May 18, 1979. Image via NASA/JPL/Ted Stryk/The Planetary Society.
Did NASA find evidence of life on Mars way back in the 1970s? That is a question that has been much debated for the past few decades, regarding the positive-yet-inconclusive results from the biology tests of the two Viking landers in 1976. Both landers reported positive results when the Martian soil was tested for the possible presence of microbes, but now, most scientists have concluded that those results were caused by unusual chemistry in the soil, not life.
Scientists - Gilbert - Levin - Investigator - Labeled
But not all scientists. Gilbert Levin, who was the principal investigator for the Labeled Release (LR) life detection experiment for both landers, still maintains that Viking really did discover life in the red sands of Mars after all. He outlined his stance in an opinion piece in Scientific American on October 10, 2019.
As Levin noted, both landers sent back positive results for the detection of microbial respiration:
July - LR - Results - Mars - Experiment
On July 30, 1976, the LR returned its initial results from Mars. Amazingly, they were positive. As the experiment progressed, a total of four positive results, supported by five varied controls, streamed down from the twin Viking spacecraft landed some 4,000 miles apart. The data curves signaled the detection of microbial respiration on the Red Planet. The curves from Mars were similar to those produced by LR tests of soils on Earth. It seemed we had answered that ultimate question.
The experiments seemed to be saying that there were living, breathing microbes in the Martian soil. But there was one big problem: neither lander had found organics in the soil, which any life would be made of and without which you couldn’t have life at all.
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