Thus their formation and history is different and traces undisturbed galaxy evolution. The statistics of supernovae which can be seen to large lookback times, offers a very powerful way to study the distance scale and cosmology. This is already under way, but requires better instrumentation to make significant progress. Excellent images over wide fields are essential. There are surveys which will give us the statistics on the earliest times of galaxy formation, and the cosmic evolution of nuclear activity.
Present results are very exciting but lack statistics of large umnbers.
XMM survey follow-up for large numbers of distant clusters. The search for objects in the outer solar system bears on our understanding of the formation of planetary systems in general. Observations of young stars are a link between our own and other systems.