Rethinking Viking: The Life on Mars Debate Rages On

Former Viking scientist, Gilbert Levin, believes that Viking voyager had already found microbial life on Martian soil. Levin's technique for proving this was by taking Martian soil placing it in a nutrition solution with Carbon 14, a radioactive isotope of Carbon 12. As a result, if there are any living organisms in the soil, then the organisms will ingest the Carbon 14, and they will be visible. However, NASA counters Levin claim, by stating that no results were found and that the landing site of Viking was a hot desert like terrain, hence, making unlikely to find life in such a location. The debate revolves around whether the data collected should be voided or is to be considered viable information to prove that there is life on mars.
http://www.space.com/news/spacehistory/rethinking_viking_010720-2.html