The Small Interstellar Probe m1ss1on would be designed to cross the solar wind
termination shock and the heliopause, and make a significant penetration into nearby
interstellar space. The principal scientific objectives of this mission would be to explore the
structure of the heliosphere, to investigate its interaction with the interstellar medium, and to
explore the nature of the interstellar medium itself. These studies would be carried out by a
~200 kg spacecraft carrying a scientific payload designed to make comprehensive, in situ
measurements of both heliospheric and interstellar plasma, fields, energetic particles, gas, and
dust. New trajectory calculations indicate significantly improved performance over earlier
studies with larger spacecraft, including spacecraft velocities ranging from -6 to -14 AU/yr.,
depending on trajectory and launch vehicle