Uy.M. Urlichich, S.A. Ezhov, V.M. Vatutin, E.P. Molotov, V.I. Grishin

With the assumption, that the habitable base is located at the dark (invisible) side of the Moon the Earth shall be invisible from the base territory. Therefore, the task of base communication with the Earth must be solved with the help of Lunar repeater-satellites injected into stationary orbits, from which the base territory and the Earth are visible simultaneously. However, due to singularities of the Moon and the Earth gravitational interaction the stationary orbits of the Moon are changeable and can not be used for location of repeater-satellites on them. The repeater-satellites for communication of the Lunar base at the dark side of the Moon with the Earth are proposed to be located in the libration points of the Earth - the Moon system, where the requirement of simultaneous visibility of the Earth and base territory is met. There are five libration points L1, L2, L3, L4, L5 (neutral points) in the Earth-the Moon system. The spacecraft in these points can retain its position relative to the Earth and the Moon using the engines only for comparatively small corrections of the trajectory (stabilization of the spacecraft). For the purpose to build the communication system the base-the Moon it is proposed to use the lunar repeater-satellites located in three points of libration - L2, L4, L5. The libration point L2 is located on the straight line the Earth - the Moon at the distance of 65.9 thousand km from the center of the Moon at the side opposite to the Earth. The libration point L4 is located in the orbit of the Moon advancing the Moon by 60º with respect to the motion direction. The libration point L5 is located in the Moon orbit with lagging from the Moon by 60º. The radio link for data exchange of the base with the Earth looks as follows: The first radio link the Earth - the repeater-satellite in the libration point L2 - relay communication station at the base territory; The second radio link the Earth - the repeater-satellite in the libration point L5 - repeater satellite in the libration point L2 - relay communication station. Availability of two radio links for the Earth and the base communication increases the reliability of communication system or improves its capacity during transmission of different data through the radio links. The communication system of the lunar base on the dark side of the Moon provides the solution of two principal tasks: Data exchange between the Earth and the lunar base what is necessary for supporting the life-sustaining activity of the base; Provision of the lunar base communication with mobile objects on the lunar surface - with cosmonauts and lunar rovers through the repeater-satellite in the libration point L2. The calculation results of the radio links - energy potential and throughput rate are given in the paper. These data confirm the realizability of declared communication system of the habitable lunar base located on the dark side of the Moon.