Fingerprint of life on Mars?

Like a bombshell in the scientific community, the news broke a few days ago that NASA's Mars rover "Curiosity" had found organic molecules on the Red Planet. "This sensational discovery will further fuel the search for life on Mars," said Prof. Dr. Dirk Schulze-Makuch, astrobiologist from TU Berlin and adjunct professor at Arizona State and Washington State University. He had suspected such occurrences on Mars for some time. The new discoveries confirm his suspicions. Schulze-Makuch recently demonstrated in elaborate studies that active cell communities can survive in the Martian-like landscape of the Atacama Desert, which can endure in one of the driest places on Earth until minimal amounts of water reactivate their metabolic activities.

"Of course, there is no rain on Mars," said Schulze-Makuch. "But there is also liquid water there in the form of water films on minerals, fog, groundwater, and even occasionally through nocturnal snowfall. In this regard, the hyper-arid core zone of the Atacama Desert, where we discovered a temporarily habitable habitat with short-term active microbes, can serve as a model for Mars." His colleague Jen Eigenbrode from the Goddard Space Flight Center and his colleague Christopher Webster from Caltech were able to detect many different organic substances as well as methane for the first time using the SAM instruments (Sample Analysis at Mars) on the Curiosity Rover. The rover had collected the samples in Gale Crater, where it has been working for six years. The investigations focused on an ancient lake that existed around 3.5 billion years ago and thus represents a kind of geological "memory."

"Of course, organic molecules could also have arrived on Mars through inorganic processes, such as by a meteorite impact," said Schulze-Makuch. "But the diversity and number of molecules suggest they are decay products of microorganisms. On the surface, biological molecules like protein compounds would break down quickly due to radiation. However, sulfate compounds were also found, which help preserve organic molecules under these inhospitable conditions. So, one can imagine what might be found in even deeper layers of the soil."

Earlier studies, according to Schulze-Makuch, had established that the former Martian lake was a habitable, i.e., inhabitable zone. "So if we now find organic material there, we can formulate the scientific hypothesis that Mars once had an early ecosystem."

Dirk Schulze-Makuch has published nearly 200 papers dealing with astrobiology and planetary habitability. His latest book, "The Cosmic Zoo: Complex Life on Many Worlds," was published at the end of 2017. Regarding the recent discovery of organic substances by the "Curiosity Rover," he wrote a blog in the science magazine (open access) Air & Space Smithsonian: "Fingerprints of Martian Life – Recent discoveries by the Curiosity rover reset the debate about life on Mars."