The scientists feel, if there is a habitable niche, it is underground on the planet. Life anywhere else would leave atmospheric traces of gas produced by organisms. According to another theory cited by the scienctits, “a large meteorite may have sterilized life on Mars.” In December, NASA said the Sprint robot had discovered nearly pure silicon on Mars. The team feels this silicon forms near natural hot water sources or volcanic outlets, which give off natural gas. On Earth, living microbes are always found in such situations. The roving robots are still going despite having passed their expected performance life by three months.