title: Journey into the unknown beyond.
abstract: The Voyager 1 spacecraft has passed an important milestone. As is reported in papers in this issue, Voyager 1 has crossed the termination shock of the solar wind, where the wind abruptly decelerates to begin its merger into the local interstellar medium. The termination shock provided surprises; the region beyond is truly uncharted territory.
authors.affiliation: Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48109-2143, USA. lafisk@umich.edu
authors.forename: Len A
authors.initials: LA
authors.lastname: Fisk