The search for extraterrestrial life is the scientific obsession of our modern age. Whether sending probes throughout the solar system to search for signs of liquid water and remnants of microbial populations or operating sprawling listening stations begging for an echo of some distant radio transmission, humanity’s best and brightest minds want to prove humanity is not the only sentient life in the universe.
However, a two-year-old debate has resurfaced over whether humanity’s past space exploration might’ve destroyed what it so eagerly hopes to find: alien life.
A 2023 op-ed for Big Think, written by Dirk Schulze-Makuch, Ph.D., proposes that the NASA Viking landers of the 1970s potentially discovered signs of life on Mars—only for scientists to unintentionally destroy that evidence during experiments.
Now a professor at the Center for Astronomy and Astrophysics at Technische Universität Berlin, Schulze-Makuch says the Viking probes found small amounts of “chlorinated organics” (carbon-based molecules containing one or more chlorine atoms). Assuming they were Earth-born contamination from the Viking landers, NASA took no further notice.
More advanced Mars probes and rovers in the ensuing years have confirmed the presence of native organic compounds on the red planet in chlorinated form. Schulze-Makuch writes that life on Mars might have survived and adapted to an arid environment within salt rocks that absorbed water from the atmosphere. If that is the case, the Viking experiments that added Earth water to Martian soil samples might have destroyed the organics and killed off any microbes present.
Schulze-Makuch’ accusation that humanity missed or destroyed proof of life outside Earth generated ample controversy that continues today as we approach the 50th anniversary of the first Viking launch in August.
Chris McKay, Ph.D., a NASA astrogeophysicist and senior scientist, waves off any such fuss. He points out that the Viking landers didn’t find any clear-cut proof of microbes.
“The statement that Viking may have ‘found and killed’ life is incorrect because there is no evidence in the results that suggest Viking ‘found life’ of any sort,” McKay says. “The idea that adding water to a dried microbial community might cause a shock […] is not new. This was not unexpected by the Viking team […] since the understanding of life in saline, arid, and cold environments that informed the design and operation of the Viking biology experiments is virtually unchanged compared to the present.”
In other words, NASA was prepared for the possible shock to microbes or microbial remnants when “humidifying” or wetting the soil for testing. Still, Viking found no such life or remnants of it.
Over in Berlin, Schulze-Makuch stands by his thesis.
“Not much really changed on the scientific case (what I still propose happened),” Schulze-Makuch says. “I would only add that, with the recent discovery of alkanes (organic compounds consisting of single-bonded carbon and hydrogen atoms) by the Perseverance Mars rover […] that the case for Martian life becomes stronger.”
The professor adds that his team’s own research with extremophilic life (organisms surviving in extreme environments) shows that microbes can tolerate “high concentrations of chlorides, chlorates, and perchlorates (Martian chemical compounds containing a perchlorate ion that pose a human health hazard), all present on Mars.”
Schulze-Makuch urges anyone intrigued by his theories on signs of Martian life to read his updated paper published last September in the journal Nature Astronomy. In it, he doubles down on the Big Think report with the support of new evidence from more recent Mars probes.
John Scott Lewinski, MFA hustles around the world, writing for a network of publications recording a total monthly readership of more than 100 million people. As an author, he is represented by the Fineprint Literary Agency, New York.
