Interstellar Probe: US Decadal Survey Recommendations and Strategic Next Steps

In 2022, a four-year, NASA-directed concept study on a pragmatic Interstellar Probe was completed by Johns Hopkins APL and submitted to the US Solar & Space Physics Decadal Survey. Released late 2024, the Decadal Survey Report recommended for the first time that the "NASA Science Mission Directorate (SMD) should develop a cross-divisional approach for planning, operation, and management of future projects and programs for interdisciplinary science. Specifically, ...support development of a mission to interstellar space". Interstellar Probe is a mission to escape the solar system to understand how the Sun upholds our protective magnetic bubble - the heliosphere. Targeting more than twice the distance of the Voyager mission, Interstellar Probe would explore completely new territory in the Very Local Interstellar Medium (VLISM) carrying a comprehensive suite of in-situ and remote instrumentation. On its escaping trajectory, flyby observations of unexplored dwarf planets and Kuiper Belt Objects would push our understanding of planetary system formation and evolution. Beyond the zodiacal cloud infrared measurements would uncover the extragalactic background light, providing new knowledge in to stellar and galactic formation. An Interstellar Probe is timely as recent findings indicate that the Sun is currently transitioning between two interstellar clouds. Furthermore, recent studies show that a few million years ago the heliosphere may have been wiped out for hundreds of thousands of years as it passed through a very dense interstellar cloud, pointing to a potentially game-changing role of the heliosphere in the evolution of our home in the galaxy. With Voyager going offline in the next few years, Interstellar Probe is also an urgent mission for NASA, for the US, and for the world as a whole. A trajectory through the forward hemisphere of the heliosphere would be accomplished by a launch in 2036-2042 using conventional chemical propulsion and a launch vehicle, such as the Space, Launch System, Falcon Heavy, or Starship. A Jupiter Gravity Assist would propel the 860-kg spacecraft to between 5 and 10 au/year with the first dwarf planet flyby as soon as 4 years after launch, and arriving in the VLISM after only 12-24 years. The spacecraft is designed to a 50-year nominal lifetime using modern-day technology with two next-generation Radioisotope Thermal Generators ensuring 300 We at end of nominal mission. Here, we present an overview of the mission, discuss the decadal recommendations, the need for cross-divisional approaches and the strategic roadmap toward launching Interstellar Probe in the coming decades.