In 1976, NASA’s Viking 1 mission deployed two spacecraft to the Martian surface to to investigate the Red Planet and search for signs of life. These experiments involved mixing water and nutrients with soil samples collected from Mars, based on the assumption that life would require liquid water to survive—similar to life on Earth.
Initial results hinted at the possibility of life, but after decades of debate, most researchers concluded that the findings were likely false positives.
Now, Schulze-Makuch has proposed a radical theory that the Viking landers may have indeed encountered Martian life, but inadvertently destroyed it by overwhelming it with water.
In a commentary for Nature, Schulze-Makuch wrote that potential Martian life might survive in hyperarid conditions by relying on salts to draw moisture from the atmosphere—similar to microbes found in extreme environments like Chileâ€s Atacama Desert. “The experiments performed by NASAâ€s Viking landers may have accidentally killed Martian life by applying too much water,†he explained.
This hypothesis challenges NASA’s longstanding strategy of “following the water†to search for extraterrestrial life. Schulze-Makuch argues that instead of prioritizing liquid water, future missions should also target hygroscopic salts—compounds that absorb atmospheric moisture. Sodium chloride, the primary salt on Mars, could potentially sustain microbial life, similar to certain bacteria that thrive in brine solutions on Earth.The researcher likened the Viking experimentâ€s potential impact on Martian microbes to an incident in the Atacama Desert, where torrential rain killed 70–80% of indigenous bacteria, as they couldnâ€t adapt to an influx of water.Nearly 50 years after the Viking missions, Schulze-Makuch calls for renewed efforts to detect life on Mars, incorporating updated methods and knowledge about the planetâ€s extreme environment. “It is time for another life-detection mission,” he emphasized, while acknowledging that his theory remains speculative. “To build convincing evidence, we need multiple, independent methods of life detection.”
