An astrobiologist suggests that NASA's Viking missions in the 1970s may have inadvertently eliminated potential Martian life. The experiments, designed to detect life by introducing water, might have overwhelmed microbes adapted to Mars' hyperarid conditions.

Astrobiologist Dirk Schulze-Makuch from the Technische Universität Berlin in Germany believes that humans may have unintentionally killed all life on Mars in the 1970s. NASA's Viking 1 mission in 1975 saw two spacecraft land on the Red Planet's surface and conduct an experiment involving mixing water and nutrients with collected soil samples.

Dirk Schulze-Makuch is a scientist who thinks NASA's Viking landers could have inadvertently destroyed the life they were searching for. In this Q&A, we ask why.