NASA scientists have found a new form of bacteria that they say has changed their notion of life as we’ve known it. The microbe, dubbed strain GFAJ-1, is able to substitute arsenic for phosphorus, a traditional element of life, in its cell structure. The discovery will lead to further research into the organic chemistry, the Earth’s evolution and disease mitigation. “The definition of life has just expanded,” said NASA’s Ed Weiler, NASA’s associate administrator for the Science Mission Directorate.”]