According to scientist Dirk Schulze-Makuch, NASA may have inadvertently discovered life on Mars almost 50 years ago, but accidentally killed it before realizing what it was. Other experts are skeptical of these claims and consider them pure fantasy.
NASA ‘s Viking landers, which landed on Mars in 1976, may have sampled tiny, resilient life forms hidden within Martian rocks, Schulze-Makuch suggested in an article dated June 27th (ref.). If these extreme life forms existed, the lander experiments may have killed them before they were identified. “The tests conducted would have overwhelmed these potential microbes” Schulze-Makuch wrote.
“It is undoubtedly a hypothesis that some people will find quite provocative” Schulze-Makuch said. “But similar microbes live on Earth and could hypothetically exist on the Red Planet. So, they cannot take anything for granted” he added.
Viking Probe Experiments
Other scientists believe that the Viking results are much less ambiguous than Schulze-Makuch and his colleagues portray them. Each of the two Viking landers, Viking 1 and Viking 2, conducted four experiments on Mars:
- Gas Chromatograph-Mass Spectrometer (GCMS) experiment, which searched for organic or carbon-containing compounds in the soil.
- Labeled Release experiment, which tested metabolism by adding radioactively labeled nutrients to the soil.
- Pyrolytic Release experiment, which tested carbon fixation by potential photosynthetic organisms.
- Gas Exchange experiment, which tested metabolism by monitoring how essential life gases (oxygen, carbon dioxide, and nitrogen) changed in isolated soil samples.
Results of these experiments were perplexing and have continued to puzzle many scientists since then. Labeled Release and Pyrolytic Release experiments produced some results supporting the idea of life on Mars. In both experiments, slight changes in the concentrations of certain gases suggested some form of metabolism was occurring.
GCMS also found traces of chlorinated organic compounds (perchlorates), but at the time, mission scientists believed that these compounds were contaminated by cleaning products from Earth. Subsequent landers and rovers have shown that these organic compounds naturally exist on Mars. Gas Exchange experiment, considered the most crucial of the four, produced a negative result, leading most scientists to conclude that the Viking probes did not detect Martian life.
Blame it on Water
In 2007, NASA’s Phoenix lander found traces of perchlorate, a chemical used in fireworks, road flares, and explosives, which also naturally occurs in some Martian rocks. The general scientific consensus is that the presence of perchlorate can explain the gases detected in the original Viking mission results. “The Viking dilemma solved” said Chris McKay, a NASA astrobiologist.
In contrast, Schulze-Makuch believes that most of the experiments may have produced distorted results due to water. Both the Labeled Release, Pyrolytic Release, and Gas Exchange experiments involved adding water to the soil. “Given that Earth is a watery planet, it seemed reasonable that adding water could induce life to appear in the extremely dry Martian environment” Schulze-Makuch wrote. “In hindsight, this approach may have been too optimistic”.
In very dry terrestrial environments, extremophilic bacteria can survive in hygroscopic, extremely salty rocks by absorbing small amounts of water from the surrounding air. These rocks are also present on Mars. However, too much water can be lethal to these tiny organisms. In a 2018 study published in the journal Scientific Reports (ref.), researchers found that flooding in the desert can kill up to 85% of microbes that cannot adapt to extreme humidity.
New Doubts About Viking Mission Results
Therefore, adding water to any potential microbes in soil samples could have been devastating. Alberto Fairén, an astrobiologist at Cornell University and co-author of the 2018 study, said he completely agrees. Adding water in NASA ‘s Viking probe experiments could have killed potential life on Mars and led to contradictory results.
In fact, it is not the first time that scientists have suggested that the 1976 experiments may have inadvertently killed Martian microbes. In 2018, another group of researchers proposed that the soil samples were heated, triggering an unexpected chemical reaction. This reaction could have burned and killed all the microbes living in the samples.