Since the launch of the first artificial satellite – Sputnik 1 – by the Soviet Union in 1957, and the landing of the first human on the Moon in 1969, astronauts and other spaceflight participants have travelled to the International Space Station, probes and rovers have explored the solar system and have landed on planets, comets and asteroids, and instruments, such as the Kepler Space Telescope, have discovered exoplanets. The next decade of space exploration will again take humans to the Moon, with the objective to go further towards Mars. New space activities are being developed by States and private entities that will involve space mining and human settlements on celestial bodies. These future space programmes will have to be conducted with caution in order not to unduly damage the unique and fragile space environment and to conduct space exploration in a sustainable way for present and future generations. In this context, this article examines the main provisions of the current international space legal framework applicable to the space environment. Since States are obligated to explore and use outer space in accordance with international law, we will assess which principles of international environmental law are possibly adaptable to space activities. We will also address the relevant international guidelines and policies in the field of planetary protection, in particular the Committee on Space Researchs (COSPAR’s) Planetary Protection Policy (PPP).