Post-fit NSB orbit sensitivity to dynamical model variations (DE, EPM, INPOP) in simulated orbit-fit tests, as well as the adopted actual observation weights serving as proxies for observation accuracy. Geocentric positional differences in the ICRF are presented in right ascension (α), declination (δ), and range (D) directions. The norm of the 3D differences (Δd) are also shown. The yellow region marks the approach window of currently planned Neptune missions (2040–2050).