PULLMAN – WSU Astrobiologist Dirk Schulze-Makuch asserts that life on an alien world might well have been celebrated nearly 35 years ago in a new book, “We Are Not Alone: Why We Have Already Found Extraterrestrial Life,” written in collaboration with science writer David Darling and published last month by Oneworld Publications.
With a hindsight made possible by four subsequent decades of scientific research, Schulze-Makuch and Darling commence their hunt for alien life on the planet Mars in 1976, when NASA first placed two Viking landers on the planet’s surface to test the soil for Martian microbes. Although the eventual scientific consensus would become that the landers’ life-detection mission proved a failure, the authors’ careful reconstruction of events demonstrates how, at the time, the actual experimental results were considered confusing and ambiguous.
“Taken as a whole, the early Viking data were perplexing,” says Schulze-Makuch. “Mars was giving definite signs of life, but these seemed to be mixed up with some sort of exotic chemical reactions.”
While a few mission scientists believed the Viking data to be consistent with biological activity, the authors write that the consensus within the Viking science team and NASA shifted toward a chemical, or non-biological, explanation.
“The idea that the Viking results were caused by highly oxidizing compounds born of the interaction between ultraviolet radiation and the Martian soil became the paradigm of choice,” write Schulze-Makuch and Darling. “This was despite the fact the theory failed to explain a number of key observations.”
By revisiting the same Viking data with an eye to our contemporary understanding of Martian climate and geology, and by applying also what we now know about the impressive diversity and resilience of microbial life on Earth, the authors challenge these prevailing assumptions with tantalizing new insights that bode far more optimistically about the possibility of Martian life, either now or in some ancient past.
The fundamental problem with the Viking experiments, they conclude, was that the Viking mission – still the only spacecraft ever designed to search for life on an alien world – “was built to look for the kind of microbes with which scientists were most familiar in the 1970s.”
But in fact, there is little reason to believe that organisms that have adapted and evolved under alien conditions on the Red Planet would exploit the same biochemistry and evoke the same chemical responses as terrestrial microbes, the authors argue.
Schulze-Makuch hypothesizes that Mars is home to microbe-like organisms that use a mixture of water and hydrogen peroxide as their internal fluid. He says that despite hydrogen peroxide’s reputation as a powerful disinfectant, the fluid is also compatible with biological processes if it is accompanied by stabilizing compounds that protect cells from its harmful effects. It performs useful functions inside cells of many terrestrial organisms, including mammals. Some soil microbes tolerate high levels of H2O2 in their surroundings, and the species Acetobacter peroxidans uses hydrogen peroxide in its metabolism.
Possibly the most vivid use of hydrogen peroxide by an Earth organism is performed by the bombardier beetle (Brachinus), which produces a solution of 25 percent hydrogen peroxide in water as a defensive spray. The noxious liquid shoots from a special chamber at the beetle’s rear end when the beetle is threatened.
Schulze-Makuch reasons that scientists working on the Viking projects weren’t looking for organisms that rely on hydrogen peroxide, because at the time nobody was aware that such organisms could exist. The study of extremophiles – organisms that thrive in conditions of extreme temperatures or chemical environments – has just taken off since the 1990s, well after the Viking experiments were conducted.
And perhaps most significantly, the authors contend that hydrogen peroxide-containing organisms would have produced almost all of the results observed in the Viking experiments.
But while the authors provide evidence for alien life on Mars, “We Are Not Alone” goes on to provide compelling reasons that there are multiple places for extraterrestrial life within our solar system and beyond. Expertly probing the latest scientific research, including from the Phoenix probe in 2008, Schulze-Makuch and Darling discuss the controversial findings from Martian meteorites to the promising environment of Saturn’s moon Titan, describing how persistent and resilient forms of life could well emerge under a variety of conditions and across a host of alien worlds.
In addition to theorizing about life on other planets, Schulze-Makuch, an associate professor with the WSU School of Earth and Environmental Sciences, does research on the movement of microbes and viruses through groundwater. He holds a patent for a mineral-based filtering system that blocks viruses and E. coli bacteria from entering wells.