This lecture by the instructor from eSpace at EPFL discusses the importance of sustainability in space activities, focusing on the challenges posed by space debris and the principles of space sustainability. It covers the guidelines for limiting space debris growth, the concept of passivation, and the design strategies for more sustainable missions, including reducing orbital lifetime and space debris removal initiatives. The lecture also explores the Space Sustainability Rating system, which evaluates missions based on various parameters to ensure long-term space sustainability.