Sustainability of outer space activities is the cornerstone of success in the modern international relations on the exploration and use of outer space. In 2018 UN COPUOS had to adopt the Guidelines for the long-term sustainability of outer space activities by the General Assembly Resolution but could not reach the consensus on the main provisions of the document. Some of States delegates suggested to endorse the Compendium of the approved guidelines, not finishing the draft process the whole document. This article explores the guidelines on the long-term sustainability and their importance, as well as defines future perspectives of its acceptance. Firstly, this paper includes the comprehensive analysis of the guidelines. Secondly, the research accumulates the data about the drafting process of the Guidelines and contains its rather-legal analysis from the proposals of different States. Thirdly, it strives to identify and predict whether the Guidelines will be approved or not in the future perspective. The research methodology rests on the UN COPUOS documents, soft law and national legislation of the States that are engaged in space activities on the issues, which have been touched on. The paper ends up with the conclusion that the Guidelines should be adopted in General Assembly Resolution and should become a basic document in the questions of sustainability, safety and longevity of outer space activities. 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. © 2020, Univelt Inc. All rights reserved.