Astrobiologist Dirk Schulze-Makuch, from the Technische Universität Berlin in Germany, believes that humans may have unintentionally killed life on Mars in the 1970s.

NASA’s Viking 1 mission in 1976 saw two spacecraft land on the Red Planet’s surface and conduct an experiment involving mixing water and nutrients with collected soil samples. The assumption at the time was that life on Mars would behave the same way as it does on Earth, relying on liquid water to survive.

As Space.com reports, early results gave researchers a tantalizing hint at the possibility of life on the Red Planet — but despite decades of debate, they’ve since largely concluded that their readings were a false positive.

Schulze-Makuch, however, takes this thorny debate one step further, suggesting that the Viking landers may have indeed found life on Mars — but accidentally killed it with its water-based life-hunting experiments.

That’s because he argues life on Mars may be relying on salt deposits, much like the organisms that live in the driest places on Earth, such as the microbes habitating the Atacama Desert in Chile.

“In hyperarid environments, life can obtain water through salts that draw moisture from the atmosphere,”  Schulze-Makuch wrote in a commentary for the journal Nature. “These salts, then, should be a focus of searches for life on Mars.”

“The experiments performed by NASA’s Viking landers may have accidentally killed Martian life by applying too much water,” he added.

The astrobiologist’s hypothesis rebuffs the assumption that NASA scientists made in the 1970s that life needs liquid water to survive.

“If these inferences about organisms surviving in hyperarid Martian conditions are correct, then rather than ‘follow the water,’ which has long been NASA’s strategy in searching for life on the Red Planet, we should in addition follow hydrated and hygroscopic compounds — salts — as a way to locate microbial life,” Schulze-Makuch wrote.

In an interview with Space.com, the researcher suggested that the idea of using table salt to create a brine, in which “certain bacteria thrive,” could be roughly applied to life on Mars as well.

“The main salt on Mars appears to be sodium chloride,” he told the publication, “which means this idea could work.”

Schulze-Makuch recalled a study that found that torrential rain killed 70 to 80 percent of indigenous bacteria in a region of the Atacama Desert because they “couldn’t handle that much water so suddenly.” In a similar vein, the Viking landers may have inadvertently killed any sign of life during their experiments.

“Nearly 50 years after the Viking biology experiments, it is time for another life detection mission — now that we have a much better understanding of the Martian environment,” Schulze-Makuch wrote in his commentary.

But for now, this all remains theory.

“To make a long story short, we would want to have several different kinds of life-detection methods that are independent of each other, and from there, we could come up with more convincing data,” Schulze-Makuch told Space.com.

More on life on Mars: Life on Mars May be Trapped Under Ice, NASA Researchers Suggest

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