Space exploration conjures up awe and excitement, but it’s also about making hard choices, especially once we leave the solar system. Because of my human rights background, I was interested in knowing what our absolute red lines would be if we were trying to save our species from extinction. What would we agree never to do in deep space? What line would we never cross? So I told the story from the point of view of people who created the line, and those who were living on the other side of it. Here on Earth we decided that we would not tolerate certain acts. We had also agreed not to allow any one country to claim property in space.