According to astrobiologist Dirk Schulze-Makuch of the Technical University Berlin in Germany, an experiment to detect the signs of microbial life on Mars could have been deadly.
It behooves us, then, to consider thoroughly the ecology of Mars when designing future experiments. , Schulze-Makuch advises, that humanity ought to send another mission, dedicated primarily to the search for life, with these considerations in mind.
When they landed on Mars in 1976, the two Viking landers had a list of objectives. One of those was to perform a set of experiments designed to test the Martian dirt for biosignatures – traces of molecules that indicate the presence of life. To date, these have been the only dedicated biological experiments performed on Mars.
One of those experiments, the gas chromatograph-mass spectrometer (GCMS), found chlorinated organics. At the time, that result was interpreted as contamination from human cleaning products, and thus a null detection for signs of biology. We know now that chlorinated organics are native to Mars, although whether they are produced by biological or non-biological processes remains unknown.
There has been some speculation in recent years about the destructiveness of the Viking biological experiments. The GCMS needed to heat the samples to separate out the various materials therein. That, subsequent analysis revealed, could have incinerated the very organics it was hoping to find. Now, Schulze-Makuch suggests that other experiments could have destroyed evidence likewise; namely, the labeled release and pyrolytic release experiments, which involved infusing Martian samples with liquid, and then testing the results for evidence of metabolism and photosynthesis, respectively.