Yesterday, Europa floated on the giant screen next to Dr. Christopher Chyba, the Carl Sagan Chair for the Study of Life in the Universe at the SETI Institute. Chyba described our current understanding of Europa, using photographs and evidence from the Voyager and Galileo missions to Jupiter. Like other solar system bodies, Europa is about 4.5 billion years old, but recent analysis of the crater density on its icy surface reveals that Europa is very geologically activethe surface is only about 50 million years old. The pull and tug of Jupiters gravity and magnetic fields keep Europas subsurface ocean liquid, and drive the surface recycling system. The hunt for life as we know it guides us toward places where there is liquid water, and Europa is certainly one of those. Chyba closed with a vivid photograph of giant, terrestrial tubeworms that live on hydrogen sulfide near Earths seafloor volcanic vents. He asked us to imagine seafloor life on Europa; something that until a few years ago we simply did not imagine existed here on Earth.

Today Im looking forward to the debate about the ancient fossils found in Australian rock. Dr. Bill Schopf of UCLA speaks first, defending his discovery of microfossils in samples from Australia. Dr. Martin Brasier of University of Oxford, UK, follows with an oral presentation that questions Schopfs evidence and conclusions. At first glance, this may seem a touch obscure, but its at the heart of good science. Its all about the careful collection of observations and evidence followed by the interpretation and defense in the public forum of the scientific community. This argument carries on the debate that has already been published in the prestigious journal, Nature, this spring. Now, these scientists will present for their colleagues. Like the argument that swirled and continues to eddy around photographs of minute structures in the Martian meteorite, ALH840001, the evidence for these Australian microfossils is strongly debated. Its the very stuff of scientific discovery and progress, and points to the challenges of identifying and understanding life here on Earth and beyond.

And what was I looking forward to on Wednesday, April 10? Dr. Jill Tarter, the Oliver Chair for the Study of SETI at the Institute will present "SETI: Pulling Signals Out of Cosmic Noise." There are more than a dozen privately funded SETI projects worldwide, including the worlds largest distributed computing project currently running. As one legitimate scientific method of attempting to answer the "Are we alone?" question posed by NAI, searching for evidence of technological civilizations offers a different, appealing and popular approach. Tarter will share the current state and future of SETI projects and future telescopes. As a private endeavor, SETI thrives and I expect will be well received by the astrobiologists.