Can living microbes travel between the planets, blown off one by a colossal asteroid impact, for example, and carried in debris to another? Some have suggested that life on Earth originated on Mars in just this way, but interesting work by electrical engineer Tom Dehel now offers an alternative. Dehel, who is also working on a law degree at Rutgers, was studying the Earth's electromagnetic fields and their impact on GPS satellite systems for the FAA when he realized that bacteria could be ejected from Earth by the kind of fields that create auroras. The work, presented at a meeting of the Committee on Space Research (COSPAR) in Beijing, was the subject of a recent New Scientist story by David Chandler. And it's intriguing because whereas asteroid impacts of the needed size were relatively rare even in the early Solar System, the electromagnetic fields in question are common. Dehel sees the possibility of bacteria floating in the upper atmosphere and reproducing there, evolving ways...

Jose Garcia writes from the wonderful Meme Therapy, where he's conducting another brain parade, this one asking science fiction writers and scientists a straightforward question: "Do you think it likely that the first discovery of extraterrestrial life will be made by a rover?" The answers to all of Jose's brain parade questions are stimulating and reflect a wide variety of perspectives, from Robert Zubrin's unqualified "No. It will be made by human explorers operating on the surface of Mars," to writer Peter Watts' call for widening the search from planets to comets and molecular dust clouds. Centauri Dreams' guess is that extraterrestrial life may well exist deep within the Martian soil, but the first conclusive proof of life beyond Earth will come by rover and in a more exotic place, such as one of the Galilean moons of Jupiter or, if we want to get truly exotic, in the bizarre deep freeze of Titan. Because this is by nature guesswork, I'm just playing a hunch that Mars is going...