Methods are provided for predicting uplink interference potential to a mobile satellite system (MSS) generated by ancillary terrestrial components (ATCs) of an ancillary terrestrial network (ATN) and/or ATC radioterminals that are configured to terrestrially use/reuse satellite frequencies that are used and/or authorized for use by a MSS. The methods include measuring power transmitted by and/or received at one or more radioterminals communicating with one or more terrestrial networks and/or transmitted by and/or received at the one or more terrestrial networks communicating with the one or more radioterminals using terrestrial frequencies that are at least partially outside a range of the satellite frequencies. Uplink interference potential to the MSS generated by terrestrial use/reuse of satellite frequencies by the ATN and/or the ATC radioterminals is predicted responsive to the measured power. Related ancillary terrestrial networks are also described.