When NASA’s Viking landers conducted biological experiments on Mars in the 1970s, they reportedly found positive evidence of life, but may have accidentally drowned it in the process.
In the 1970s, NASA sent two Viking landers to Mars to search the planet for signs of life. Now, astrobiologist Dirk Schulze-Makuch claims that landers have indeed found evidence of microbial life forms on Mars, but may have accidentally destroyed them in the process.
“I dropped a suggestion that some people are sure to find provocative: that we actually found life on Mars nearly 50 years ago, but we inadvertently killed it,” says Schulz Makuch, professor of planetary habitability and astrobiology at the Technical University of Berlin in Berlin. Germany and former fellow at NASA’s Goddard Space Flight Center, writing for Big thought.
The Viking landers, two NASA space probes equipped with imaging technology and tools to test for life, landed on Mars in 1976. There, they began performing a series of biological tests that to this day remain the only experiments to test the existence of life. Life directly on another planet.
Unfortunately, these tests have shown contradictory results that have baffled researchers for decades.
For example, one such test found trace amounts of chlorinated organic matter. At the time, these organic materials were assumed to be the result of pollution from Earth, and were dismissed as, at best, inconclusive evidence of the existence of life.
But after subsequent explorations, such as those by the Phoenix lander and the Curiosity and Perseverance rovers, scientists now know that those chlorinated organics actually exist on Mars.
Schulz-Macuch believes that the same processes used to conduct the tests may have destroyed any evidence of life, which may be the reason for the confusing results of the experiments.
He says one of the tests involved adding water to combat soil samples to test for evidence of metabolism and photosynthesis. Scientists have been operating on the assumption that life on Mars would be similar to life on Earth, which would need exposure to water to survive.
But Mars is an incredibly barren planet. Although moist soil was “positive for life,” the introduction of water may have ultimately drowned out the organic microbes, which likely adapted to the dryness of their environment, Schulz-Makuch said.
“It would be as if an alien spaceship found you lost, half-dead in the desert, and your would-be rescuers decided, ‘Humans need water.’ Let’s put a human in the middle of the ocean to save them!” he writes.
In fact, in these tests, the evidence of life was strongest in the dry control process, in which no water was added to the soil samples.
Now, Schulz-Makuch suspects that Mars may be home to drought-adapted microbial life forms that contain hydrogen peroxide, allowing cells to draw water from the atmosphere.
While hydrogen peroxide is most often associated with highly concentrated forms used in cleaning and disinfection, many microbes in the human mouth produce it naturally, and some insects use solutions containing hydrogen peroxide as a defense mechanism.
This theory may help explain another experiment of the Vikings, which involved heating soil samples to separate out their materials. Recent analysis suggests that this process may have burned the organic matter that the experiment was designed to find.
If Martian cells contained hydrogen peroxide, Schulz-Macuch explains, the heat would not only have killed them, but caused the hydrogen peroxide to react with nearby organic compounds, producing carbon dioxide, which is likely what the Viking instruments were detecting.
In short, Schulze-Macuch says, the processes used to test soil samples for life on Mars — which have been used to claim no evidence of it — may in fact be responsible for the lack of evidence. He is not the only one who has made this claim.
According to the daily MailAnd in 2016, experts from Arizona State University and the National Institutes of Health released a study claiming that Viking’s findings “fit with a biological explanation” that life on Mars has adapted to survive in its dry environment.
In this study, the researchers injected soil samples from Viking chariots with nutrients and stored them in the dark for two months. The researchers found that the response of Martian soil was very similar to that of terrestrial soil.
These new findings indicate the need for another mission to Mars, with the primary goal of detecting life, says Scholz-Makuch.
“I can’t wait for a mission like this to begin,” he added.
After reading about the possibility of life on Mars, check out these 29 pictures of Mars that will blow your mind. Or read about how NASA prevented the Challenger from exploding.