“…Nonetheless, this may not mean that captured objects or debris originating from them did not leave their mark on Callisto and Iapetus (and the outer satellites of Uranus). It is possible that the leading and trailing asymmetries present in the outer uranian satellites (Buratti and Mosher, 1991), perhaps Callisto (Bell, 1984), and Iapetus (Buratti et al, 2002, and references therein) may be the result of interactions with material originating from retrograde satellites exterior to their orbits (Cruikshank et al, 1983). Buratti et al (2002) argue in favor of this alternative to explain the extreme leading and trailing composition asymmetry of Iapetus.…”