Back in the 1970s, two little spacecraft had the honor of becoming the first to land on the surface of Mars and send us back photos. For the first time, we were able to physically interact with the Martian surface and run experiments on our planetary neighbor.
Three of those experiments constituted our first attempt at sussing out life on the surface of the red planet.
The results were…confusing. According to a NASA webpage on the missions, “These experiments discovered unexpected and enigmatic chemical activity in the Martian soil, but provided no clear evidence for the presence of living microorganisms in soil near the landing sites.”
The conclusion drawn from those results and accepted by the vast majority of the scientific community was that we did not discover life on Mars. It may have been somewhere else on the planet, but what we detected was not a sign of life. Rather, the odd signal was assigned to the chemical behaviors of perchlorates. The burden-of-proof standard for extraterrestrial life is incredibly high—and for good reason—and the Viking tests did not meet it.
But the conclusions of those tests did not satisfy everyone. Dirk Schulze-Makuch, a researcher focused on astrobiology and planetary habitability, recently published an article on Big Think re-doubling a call that he and his fellow (now retired) scientist Joop Houtkooper have been putting out to the world for several years now—we need to follow up on the Viking results.
Houtkooper communicated with John Wenz for Popular Mechanics in 2015 about his position regarding life on Mars. “The final conclusion by NASA was that Mars was dead, the surface was oxidizing and therefore no life was possible,” Houtkooper said in an email. “One of the Principal Investigators, Gilbert Levin, who designed the Labeled Release Experiment, remained a dissenter to this day, stating repeatedly over the years that his experiment detected life.”
And this new piece continues the trend. In an article riddled with “perhaps-es,” “might-s,” and “assume-s,” Schulze-Makuch writes that he believes that we may, in fact, have discovered alien life on that first visit to Mars—and that we may have killed it in the process.
“Many of the Viking experiments involved applying water to the soil samples, which may explain the puzzling results,” Schulze-Makuch claimed in his article. “Perhaps the putative Martian microbes collected for the labelled release experiments couldn’t deal with that amount of water and died off after a while.”
Schulze-Makuch calls into question the context under which the conclusions of the Viking experiments were drawn. After all, we’ve learned a lot since the 1970s. For instance, we now know that Mars does have organic compounds of its own—though, in a different form. In the Viking experiments, organic compounds were dismissed as Earth contamination. We’ve also learned quite a bit about what the environment of Mars is actually like, allowing us to entertain the idea that life could survive using different mechanisms than originally hypothesized.
One of those different mechanisms has been at the center of Schulze-Makuch’s and Houtkooper’s hypothesis for some time. They believe that microorganisms on Mars—in the way that our cells are heavily comprised of water—may be instead heavily comprised of a mixture of water and hydrogen peroxide. This could allow life to exist at lower temperatures than expected, and if we then accidentally drowned that life during the Viking tests, it would offer an alternate explanation for the murky result.
But the proposal being put forth here is not “this is definitely what happened.” Most scientists don’t speak about their hypotheses in those black-and-white terms. Instead, Schulze-Makuch’s argument is that it may be time to re-do our initial experiments and see if Round 2 confirms or contradicts our initial conclusions.
In an age of high investiture in Martian exploration—one filled with rovers, (hopefully) a Sample Return Mission, and plans for an eventual human visit—Sulze-Makuch calls for a re-do. Which, to be fair, is incredibly common scientific practice. Replicating results to confirm their accuracy is one of the most important parts of the scientific process.
Most likely, if a re-do does get approved and funded, we will get the same results as we did in the original test. But confirmation is never a bad thing to have.
Associate News Editor
Jackie is a writer and editor from Pennsylvania. She’s especially fond of writing about space and physics, and loves sharing the weird wonders of the universe with anyone who wants to listen. She is supervised in her home office by her two cats.