The paper dwells upon the security and long-term sustainability of space activities and introduces the main guidelines, approved by the UN General Assembly, as well as the guidelines, which did not receive consensus approval in the UN Committee on the Peaceful Uses of Outer Space. The challenges of the long-term sustainability of space activities for achieving the goals, objectives, and means of developing world cosmonautics and maintaining the status of the Russian Federation as a world space power are reflected. The study focuses on the problems and challenges associated with the man-made debris of near-Earth space, the delimitation of air and outer space, the need to organize space traffic control, which is inextricably linked with the deployment of multi-satellite orbital constellations. The issues of counteracting the asteroid-cometary hazard are touched upon. The research findings given in the paper should help representatives of the Russian space industry understand the problems, challenges, and essence of the long-term sustainability of space activities in conjunction with issues of ensuring its security.