Distribution of asteroids across different spectral types. Panel (a) shows the fractions for all spectral types, while panel (b) focuses on those analogous to Phobos and Deimos (i.e., D, M, P, and Z types). Data are from Table 1 in Mahlke et al. (2022). Orbital class acronyms: NEA – near-Earth asteroids; MC – Mars-crosser; H – Hungaria; IMB – inner main belt; MMB – middle main belt; OMB – outer main belt; Cyb – Cybele; JT – Jovian trojans.