Henry Fountain's column in the Science Times observes that the radiation levels on Mars from solar and cosmic sources are so high that astronauts there for three days would recieve the maximum safe radiation dose for a lifetime, based on measurements from the Mars Odyssey probe. SPF 6 X 10^23 lotion, anyone?[New York Times: Science]

The difference in radiation exposures between Mars Odyssey and the International Space Station indicates one thing to me: it's good to have a liquid iron planetary core that creates a magnetic field. Elsewise, we'd all be as fried as microwaved popcorn by now.