Interference phenomena affecting the performance and availability of an Earth-space system are of utmost importance for the reliable design of a satellite communication network. Commercial satellite networks operate or will operate at Ku, Ka, and V frequency bands, in which rain is the dominant fading mechanism. Nominal interference induced on an Earth-space link by an adjacent satellite network operating at the same frequency is further aggravated because of the potential existing differential rain attenuation, as well as the rain and ice crystals depolarization valid for a frequency reuse system. In the present paper, an existing model, predicting the degradation of the total carrier-to-interference ratio under rain fade conditions, is properly modified considering interference effects by two adjacent satellites. The method is based on a convective rain cell model and the lognormal assumption for the point rain rate statistics. The obtained numerical results indicate the significant impact of the second interfering satellite on the aggravation of radio interference effects. Also presented are some simple mathematical formulas for the prediction of the carrier-to-interference ratio, based on the above theoretical results, appropriate for use by the system designer for back of the envelope computations.