Orbit Design for the Millimetron Space Observatory

Millimetron is a space observatory for millimeter and sub-millimeter observations planned for launch around 2030. The 10-meter diameter space unfolded telescope will be cooled down to 10~K and operated in the vicinity of Lagrange point L2. Mission lifetime is 10 years and it includes astronomical observations in two modes: as a space-ground interferometer and as a single-dish telescope. This paper presents the results of the Millimetron space observatory orbit design that takes into account technical and scientific requirements and constraints. It covers the computation of suitable operational orbits, the selection of an orbit, and the transfer from Earth. Furthermore, scientific objectives are demonstrated through VLBI visibility simulation and image reconstruction. Unlike previous works that used analytical methods, this work employs numerical integration for orbital design. Based on the orbital design methods developed in this work, we calculate the exact dates for departure, halo formation, and trajectory correction. Additionally, we investigate the existence of the short baseline projection and its specific dates for VLBI mode and show the feasibility of scientific objectives through VLBI visibility simulation and image reconstruction.