Deciphering the silicate composition of Centaurs and small TNOs

Outer solar system small bodies (Centaurs, Comets, small TNOs) hold the residual ingredients from our young protosolar disk that are still observable today. Thus, by measuring their composition and distribution across the solar system we have the potential to unravel the scenario of our planetary system's formation and dynamical evolution, providing a benchmark to which other stellar systems can be compared. We propose performing spectroscopic observations with MIRI (over the 5-28 micron range) of 2 Centaurs and 2 small TNOs to constrain their silicate composition. We will observe a "less red" and a "very red" object within each population. Our proposed investigation will first enhance our understanding of the overall compositional diversity among primitive outer solar system small bodies, thereby complementing Cycle 1 observations of these bodies with NIRSpec. Second, we will provide critical information regarding the extent of radial mixing among primordial small bodies which took place during their early reorganization. Specifically, our measurements will allow us to confirm/refute the genetic link between outer (Centaurs, small TNOs) and inner (P/D type asteroids, Jupiter Trojans) solar system small bodies, as advocated by the Nice model. Finally, our proposed observations will provide unique constraints on the primordial heliocentric compositional gradient present in the outer (>10 AU) protosolar disk.