Space sustainability is the idea of making sure that the space around Earth, like the moon and other planets, is used in a way that keeps it safe and healthy. This means that when people explore space, they do it in a way that doesn't damage the environment or use too many of the resources found there. This also means making sure that any materials taken from space, like soil or rocks, are used carefully and returned back to their original place when done. In this way, space can be protected for future generations to explore and enjoy.