NASA’s Viking 1 lander may have killed life on Mars, claims scientist

A provocative theory from astrobiologist Dirk Schulze-Makuch of the Technische Universitat Berlin suggests that humans might have inadvertently wiped out Martian life nearly 50 years ago.

His claim dates back to the 1976 NASA Viking 1 mission, which saw two spacecraft land on Mars and conduct groundbreaking experiments to search for signs of life. These tests involved mixing Martian soil with water and nutrients, operating on the assumption that any life on Mars would require liquid water to survive, much like organisms on Earth.

At the time, initial findings hinted tantalizingly at the presence of life. Yet, after years of analysis and debate, scientists concluded the results were likely false positives. Schulze-Makuch, however, has a different take: the Viking landers might have actually found life but unintentionally killed it by drowning it in water.

Martian life may not have been water-based

Schulze-Makuch argues that life on Mars could be vastly different from what we expect. Instead of relying on water as we know it, Martian microbes might thrive in extremely dry conditions, drawing moisture from salty deposits. He points to examples on Earth, such as microbes living in the hyperarid Atacama Desert in Chile. These organisms survive by absorbing moisture from the atmosphere through salts, and similar mechanisms could be at play on Mars.

In his commentary for Nature, Schulze-Makuch suggests that NASA’s water-heavy experiments might have overwhelmed any existing Martian microbes. He proposes that life on Mars may use salts, like sodium chloride, to maintain hydration, and that future missions should focus on searching for these salts rather than only chasing water.

Rethinking the search for Martian life

NASA’s long-standing strategy has been to “follow the water” when hunting for life on Mars. Schulze-Makuch, however, believes it’s time to shift gears. He argues for a broader approach, suggesting that scientists should also investigate hydrated and hygroscopic (moisture-absorbing) compounds. The idea is to consider environments where life could exist without large amounts of liquid water.

In an interview with Space.com, Schulze-Makuch drew parallels between Mars and Earth’s driest regions. He recalled a study showing how heavy rainfall wiped out up to 80 per cent of native bacteria in the Atacama Desert because they couldn’t handle the sudden influx of water. Similarly, he speculates, the Viking landers’ experiments may have accidentally flooded and destroyed Martian microbes.

Time for a new mission?

Nearly five decades after the Viking missions, Schulze-Makuch believes it’s time for another attempt at finding Martian life, armed with our improved understanding of the planet’s environment. He suggests deploying various life-detection methods to gather more robust evidence. While his theory is speculative for now, it raises intriguing questions about our approach to exploring Mars.

Schulze-Makuch stresses the need for diverse, independent methods to detect life, hoping future missions could yield more definitive results. As we continue to explore the Red Planet, his ideas offer a fresh perspective on how we might finally answer one of humanity’s most enduring questions: is there life on Mars?