When it was announced last month that the Mars Odyssey satellite had found water ice beneath the planet’s frozen carbon dioxide south polar ice cap, Dr. Lidija Siller, a physicist from the University of Newcastle, England, felt excited. “I believe that the data I have explains how this water became trapped underneath the surface”,she said. Dr. Siller presented the results of her research – which involves studying photochemical reactions in ice – at the Condensed Matter physics conference held April 8, part of the Institute of Physics Congress in Brighton, England.