Felisa Wolfe-Simon, a lead researcher and NASA astrobiology research fellow, speaks during a press conference, Thursday, Dec. 2, 2010, at NASA Headquarters in Washington. NASA-funded astrobiology research has changed the fundamental knowledge about what comprises all known life on Earth. Researchers conducting tests in the harsh environment of Mono Lake in California have discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. Photo Credit: (NASA/Paul E. Alers)
