We often think about interstellar probes only in the context of what they find at the end of their journeys -- astrobiologically interesting planets seem to be the whole story. But not so fast. As Ian Crawford (University of London) notes in a recent paper, there are quite a few fascinating -- and indeed critical -- things we need to learn about interstellar space itself, in this case what is known as the Local Interstellar Medium (LISM). Crawford, who has been analyzing these matters for the Project Icarus team, notes how much we've learned about the LISM since the Daedalus days. The new paper grows out of Crawford's presentation at the British Interplanetary Society symposium 'Project Daedalus - Three Decades On,' which was held last September in London. It reflects his thinking on interstellar probes in relation to planetary and stellar studies and astrobiology as well as the nature of the medium through which the probe will fly. But today I want to focus on the LISM because what...