Safeguarding international peace and security on a long-term basis and preventing of potential threats in the future are the main purposes of Public International Law as expressed in numerous international legal acts such as the Charter of the United Nations or SDGs (2016-2030). When it relates to space activities, the Outer Space Treaty serves the same purposes, even though many scholars call today for its modification. Recently, efforts to regulate space activities have been focused on the adaption of soft law. The newest example is the ongoing project on Guidelines for the Long-Term Sustainability of Outer Space Activities. The aim of the document is to create the necessary framework that will preserve outer space for current and future generations, so that it remains “an operationally stable and safe environment open for exploration, use and international cooperation in the interest of all countries…†(Scope and implementation, Part B). However, the endorsement of these Guidelines by the international community will require legal adjustments of several provisions in the five main outer space treaties. As already outlined by many experts, the current framework of international space law does not totally correspond to the scientific reality and technical progress made in the space domain. In this paper, the author points out that the difference between provisions of outer space treaties and current State practice in this sphere will inevitably lead to discrepancies in the “realization†of the Guidelines by the signatory parties to the five outer space treaties. Amendments to them are therefore necessary to maintain safe, sustainable and effective space activities at global level. The article will consist of 7 chapters and the purpose of the paper will be to highlight the necessary legal development for safety and effectiveness of outer space activities in the long-term, which including: a) solving the issue relating to the absence of space traffic management rules' and the challenge regarding space debris; b) the supersession the concept “launching State†for the “State of registry†as a safety and liability requirement; c) the necessity to adopt a Convention for the Unification of Certain Rules for Outer Space Activities (by analogy with the Montreal Convention of 1999 creating a uniform regime of liability of the international air transport operator) d) the introduction of unified and commonly agreed certification requirements in the sphere of use nuclear power sources; e) the negotiation of a consolidated UN Convention on International Space Law. The article is published in the framework of the grant of the Russian Foundation for Basic Research "BRICS and the Peaceful Uses of Outer Space" 17-03-00427. © 2018 by the International Astronautical Federation (IAF). All rights reserved.