| Abstract |
During its twenty revolutions around the galactic core, our Sun and its protective magnetic bubble have plowed through dramatically different interstellar environments and witnessed several supernovae along its evolutionary path. Extreme ranges of interstellar plasma and gas have resulted in very different sizes and interaction regimes of the heliosphere. The resulting drastic alterations in the exposures of the inner solar system to high-energy galactic cosmic rays and interstellar dust have likely had far-reaching consequences on elemental and isotopic composition, atmospheric chemistry and perhaps even biological evolution. Today, our protective magnetic bubble -the Heliosphere - is leaving the Local Interstellar Cloud and will enter a completely new environment of interstellar space on very short galactic times scales (<1000 years) that, again will change the entire heliospheric interaction and shielding from interstellar matter. An Interstellar Probe on a fast trajectory through the heliospheric boundary in to the Very Local Interstellar Medium (VLISM) would provide answers to what physics upholds the boundary, how it responds under dynamic influences of our solar cycle, and ultimately sample the unexplored VLISM to understand how our habitable system has evolved through its galactic journey, and what will happen in the future. As such, an Interstellar Probe would represent humanity’s first step into the galaxy to understand our home within it.
A four-year NASA-funded mission concept study of a pragmatic Interstellar Probe has now been completed and has culminated in a >500-page report (interstellarprobe.jhuapl.edu) marking the most complete study of an Interstellar Probe ever done. The idea of an Interstellar Probe dates back to the 1960’s, when also the ideas were formed of a probe to the Sun and its poles. An international team of scientists and a team of engineers at the Johns Hopkins University Applied Physics Laboratory have studied the pragmatic mission concept that would make a launch in the 2030’s a reality. Detailed staging analyses using the upcoming SLS Block 2 have demonstrated that asymptotic speeds in excess of 7.0 Astronomical Units per Year (au) are already possible with a Jupiter Gravity Assist. Equipped with dedicated instrumentation, Interstellar Probe would measure particles, fields and waves starting already shortly after launch to understand the physical processes that build up the heliosphere and shields us from interstellar dust and galactic cosmic rays. Beyond the heliopause, Interstellar Probe would obtain the first unique images of the heliosphere from the outside and be given direct access to the unshielded properties of the VLISM, including the interstellar magnetic field, plasma, dust and gas that would tell us about the present state of the interstellar cloud and what may lie ahead. Here, we give an overview of the pragmatic Interstellar Probe concept and the science discoveries that await along the journey, spanning not only the heliosphere and VLISM, but also exploration of Kuiper Belt Objects, the circum-solar dust disk and the extra-galactic background light.
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