Whitepaper #222 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: basic research. Additional topics: outer heliosphere; space-based missions/projects.
The heliospheric community needs an interstellar probe. An interstellar probe with a proper onboard magnetometer would provide observational data to answer many questions about the magnetic field in the heliosphere, including the effect of magnetic reconnection on ion acceleration in the heliosheath and the draping of the interstellar magnetic field around the heliopause.