KEYNOTE: EXPECTATIONS ABOUT LIFE ELSEWHERE IN THE SOLAR SYSTEM

The stage for life was set billions of years ago and we are on the verge of knowing what happened to its characters. Two convergent lines of evidence raise expectations that biological systems could occur beyond the confines of earth. The first is the detection of microbial life forms in terrestrial environments that may be similar to those on other solar system bodies. The second is NASA's spectacular discoveries of significant water reservoirs on Mars and Europa and evidence of liquid organic environments on other solar system bodies such as Titan. If we discover evidence of extraterrestrial past or present life, the next challenge will be to determine whether it originated and evolved independently versus sharing a common ancestry with microbial life-forms that dominate earth's biology. This task places new constaints on the importance of planetary protection and emphasizes the need to fully explore the true diversity of life on Earth.