From observations and theory we know that the unshocked solar wind extends at least 80 AU from the Sun but likely no more than ∼100 AU in the region from which the local interstellar wind blows. The much larger region of the shocked solar wind and heliosheath extend out to at least several hundred AU, and fast neutrals from charge‐exchanged supersonic solar wind protons disturb the very local interstellar medium to ∼500 AU or more. Thus to really understand the interaction of the solar wind with the local external medium, a properly‐instrumented, in situ probe to this region of space is required. For more than 20 years, an “Interstellar Precursor Mission” has been discussed as a high priority for multiple scientific objectives. The chief difficulty with actually carrying out such a mission is the need for reaching significant penetration into the interstellar medium (∼1000 Astronomical Units (AU)) within the working lifetime of the initiators (<50 years). We have revisited an old idea for implementing such a mission. The probe and its perihelion carrier are launched initially to Jupiter as a combined package and then fall to the Sun where a large propulsive &squarelg;V maneuver propels the package on a high‐energy, ballistic escape trajectory from the solar system. Outbound in deep space, the two separate, and the probe takes data with its onboard instruments and autonomously downlinks the data to Earth at regular intervals. The implementation requires a low‐mass, highly‐integrated spacecraft to make use of available expendable launch vehicles. We provide a first‐order cut at many of the engineering realities associated with such a mission. These separate into (1) the systems constraints imposed on the perihelion package by the combination of the propulsion system, carrying the needed propellant into perihelion, and the associated thermal and mechanical constraints, and (2) the requirements of power, autonomous operations, and data downlink from the probe itself. We find that many of the requirements for a low‐mass probe that operates autonomously for this mission are common for either this propulsion concept or more advanced low‐thrust concepts, e.g., solar sails and ion propulsion. We describe an implementation that could make such a mission into reality in the next 10 to 20 years. © 2003 American Institute of Physics