The global nature of the interaction of our heliosphere and the Local Interstellar Medium (LISM) remains one of the most outstanding space physics problems of today. Voyager 1 and 2 are nearing their end of operations well inside of 200 AU and have uncovered a completely new regime of physical interactions. Anomalous Cosmic Rays (ACR) are not accelerated at the Termination Shock as anticipated, the force upholding the heliosheath against the LISM has eluded the in-situ measurements, significant shielding of Galactic Cosmic Rays (GCRs) appears in an extremely thin boundary layer at the Heliopause (HP), UV observations reveal a surprisingly dense wall of neutral hydrogen outside of the heliosphere, and the entire magnetic topology even well beyond the HP goes against all previous expectations. At the same time, IBEX and Cassini have obtained complementary “inside-out” ENA images of the heliospheric boundary region that cannot be fully explained.
An Interstellar Probe through the boundaries of the heliosphere, in to the LISM would be the first dedicated mission to venture into this largely unexplored frontier of space. With a dedicated suite of in-situ and remote-sensing instrumentation, such a probe would not only open the door for this new regime of space physics, but would also send us back the very first images from the outside of the global structure of the heliosphere that, in context with the in-situ measurements, would enable a quantum leap in understanding the global nature of our own habitable astrosphere. Traveling beyond the HP would offer the first sampling of the properties of the Local Interstellar Cloud and interstellar dust that are completely new scientific territories. As such, an Interstellar Probe would represent humanity’s first step in to the galaxy and become the furthest space exploration ever undertaken.
Relatively modest contributions from the Planetary Sciences and Astrophysics would offer historic science returns, including a flyby of one or two Kuiper Belt Objects, first insights in to the structure of the circum-solar dust disk, and the first measurements of the Extra-galactic Background Light beyond the obscuring Zodiacal cloud.
Although the idea of an Interstellar Probe has been discussed and studied since 1960, the lack of propulsion technologies and launch vehicles have presented a stumbling block to realize these concepts. With recent developments of conventional launch vehicle and kick stages, this bottleneck is being removed. Several international ongoing studies are developing realistic mission concepts using available or near-term technology, including the Pragmatic Interstellar Probe Study funded by NASA, the Interstellar Heliopause Probe project in Europe, and a study of dual probes to the boundaries of the Heliosphere under the Chinese Academy of Sciences.
This session welcomes discussions on the current state of understanding and outstanding science questions that could be addressed by missions to the LISM, and reports on realistic design concepts, enabling technologies, and programmatic challenges.