Planetary Science with an Interstellar Probe

The space science community has maintained an ongoing interest in exploration of interstellar space for several decades. In 2016, Congressional language encouraged NASA to take the enabling steps for an Interstellar scientific probe. In 2018, a study was initiated targeting 1000 AU within 50 years using current or near-term technology. The ultimate goal of this study is to define a mission that would be feasible to launch in the 2030's, enabling humanity to take the first explicit step in to interstellar space scientifically, technically and programmatically. Although the primary goal of an Interstellar Probe would be to understand the heliosphere and the very local interstellar medium (VLISM), a probe designed to exit the solar system and explore interstellar space provides a prime opportunity for planetary science. During the time period while traveling to interstellar space, flybys of critical science targets should be planned to maximize the science outcome of such a mission.

A gravity assist flyby of Jupiter is likely to be necessary and provides opportunities to study the magnetosphere and atmosphere of Jupiter as well as to image Jupiter's moons. This flyby should include coordinated observations with other spacecraft in the Jupiter system at the time of the encounter to maximize the science outcome. The mission will also plan as many close and distant flybys of other planets as the orbit trajectory allows. During distant flybys, imaging campaigns targeting surfaces and atmospheres would be of high value. Close flybys would permit in situ studies of atmospheric loss and solar wind interactions with these bodies. Of particular importance, we note that the New Horizons flyby of Pluto showed unexpected complexity in Pluto's surface processes, the distribution of volatiles on the surface and atmospheric chemistry and loss. This has clearly demonstrated the need for future exploration of the Pluto system and of other Kuiper Belt Objects (KBOs). KBOs represent thousands of unexplored worlds in our own solar system that can only be investigated through an ongoing multi-mission program. An Interstellar Probe could contribute to this effort with a flyby of at least one, ideally more than one, KBO. We will discuss specific KBOs along recommended trajectories and the challenge of observations taken at higher spacecraft velocities than the New Horizons flyby of Pluto.