Fragments from the Origins of the Solar System and our Interstellar Locale (FOSSIL): A Cometary, Asteroidal, and Interstellar Dust Mission Concept

Deciphering the composition of interstellar, cometary, and asteroidal dust offers an unparalleled opportunity to explore the origin and evolution of our solar system. The goal of the Fragments from the Origins of the Solar System and our Interstellar Locale (FOSSIL) mission is to confirm or disprove expectations that comets deliver fragments of pristine material, that is the most carbon rich and least aqueously altered matter from the early stages of solar system formation, as opposed to asteroidal matter that is heat-treated, carbon-poor, and aqueously altered. The FOSSIL mission concept is designed to unambiguously identify, and comprehensively explore the makeup of interstellar dust particles (ISD) flowing through our solar system today, delivering matter closest to the original solid building blocks of our solar system. The FOSSIL mission concept would comprehensively survey the compositional diversity of a broad range of bodies in our solar system and beyond, returning a powerful set of measurements to test the genetic relationships between the main reservoirs of primitive materials left over from planet formation. FOSSIL would be placed in an Earth-trailing orbit, carrying four state-of-the-art Dust Telescopes (DT) pointed anti-sunward to measure impacting dust particles' mass, composition, charge, and velocity vector. This approach connects decades of ground-based radar measurements of the speeds and directions of meteors from various sources, lacking compositional information, with decades of laboratory work on meteorites' compositions, similarly lacking dynamical information that would reveal their sources. Each DT consists of a Dust Trajectory Sensor (DTS) and an impact ionization reflectron-type time-of-flight (TOF) Composition Analyzer (CA). The DT has strong heritage from instruments already flown and in development: the Cosmic Dust Analyzer (CDA) onboard Cassini, the Lunar Dust Experiment (LDEX) onboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission, and the Surface Dust Analyzer (SUDA) instrument for the Europa Clipper mission. FOSSIL is a low-risk mission concept that would survey the composition of the solar system's primitive material at a cost far lower than sending probes to a representative sample of small bodies. FOSSIL would go beyond the in situ measurements from Giotto, Ulysses, Stardust, Rosetta, and Cassini, to enable a breakthrough in understanding how the fine dust from comets, asteroids, and interstellar space evolves in our solar system's largest visible structure, the Zodiacal Cloud.