This Chaillot Paper – which uses space exploration as a metaphor to demystify some of the concepts and challenges linked to cyber-related policymaking – focuses on the EU's cyber sanctions regime. The newly-established regime represents a significant achievement in the EU's ambition to defend the rules-based international order, and ensure broader global adherence to agreed norms of responsible behaviour in cyberspace. However, the growing complexity of cyber threats and the proliferation of malicious actors in the cyber domain indicate that the scale of the challenges ahead should not be underestimated. The EU's autonomous cyber sanctions regime constitutes a unique solution to the challenge of compliance with international law and norms of state behaviour. Taking account of the lessons derived from other sanctions regimes adopted by the EU in the past, the volume addresses a number of key issues relevant for ensuring the maximum effectiveness of the new regime. These include the problematic nature of attribution, state responsibility in cyberspace, listing and de-listing criteria, the principle of due diligence or the potential impact of cyber sanctions on the physical world.