Ascientist recently claimed that NASA may have inadvertently discovered life on Mars almost 50 years ago and then killed A it before realising what it was. But other experts are split on whether the new claims are a farfetched fantasy or an intriguing possible explanation for some puzzling past experiments. After landing on the Red Planet in 1976, NASA’s Viking landers may have sampled tiny, dry-resistant life forms hiding inside Martian rocks, Dirk Schulze-Makuch, an astrobiologist at Technical University Berlin, suggested in a 27 June article. If these extreme life forms did and continue to exist, the experiments carried out by the landers may have killed them before they were identified, because the tests would have “overwhelmed these potential microbes,” Schulze-Makuch said.
This is “a suggestion that some people surely will find provocative,” Schulze-Makuch said. But similar microbes do live on Earth and could live on the Red Planet, so they can’t be discounted,. However, others believe the Viking results are far less ambiguous. Each of the Viking landers – Viking 1 and 2 – carried out four experiments on Mars: the gas chromatography-mass spectrometry (GCMS) experiment, which looked for organic, or carbon-containing, compounds in Martian soil; the labelled release experiment, which tested for metabolism by adding radioactively traced nutrients to the soil; the pyrolytic release experiment, which tested for carbon fixation by potential photosynthetic organisms, and the gas exchange experiment, which tested for metabolism by monitoring how gases that are known to be key to life changed surrounding isolated soil samples.
The results of the Viking experiments were confusing and have continued to perplex scientists ever since. The labelled release and pyrolytic release experiments produced some results that supported the idea of life on Mars. In both experiments, small changes in the concentrations of some gases hinted that some sort of metabolism was taking place. GCMS also found some traces of chlorinated organic compounds, but at the time mission scientists believed the compounds were contamination from cleaning products used on Earth. Subsequent landers and rovers have since proved that these organic compounds occur naturally on Mars. However, the gas exchange experiment, which was deemed the most important of the four, produced a negative result, leading most scientists to eventually conclude that the Viking experiments didn’t detect life.
Schulze-Makuch believes most of the experiments may have produced skewed results because they used too much water. The labelled release, pyrolytic release and gas exchange experiments
