The 1967 Outer Space Treaty (formally the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies) is the foundational international treaty governing space activity, in force since October 1967.
Article IX is the legal basis for COSPAR’s Planetary Protection Policy — the obligation to avoid harmful contamination of celestial bodies and adverse changes to the Earth environment from extraterrestrial matter. The 2026 COSPAR icy-worlds policy update (icy-worlds-protection-policy) extends this Article IX lineage.