Not so long ago it was unthinkable for respectable scientists to talk about life on Mars. Such talk was best left to X-Files fans. But no longer. Evidence is building to suggest biological processes might be operating on the red planet, and life on Mars, many scientists believe, is now more a likelihood than merely a possibility. “The life on Mars issue has recently undergone a paradigm shift,” said Ian Wright, an astrobiologist at the Planetary and Space Sciences Research Institute at the Open University in Britain, “to the extent now that one can talk about the possibility of present life on Mars without risking scientific suicide.” Much of the excitement is due to the work of Vittorio Formisano, head of research at Italy’s Institute of Physics and Interplanetary Space.