Short answers, pulled from the story.
Space advocacy means supporting human activity in outer space, covering goals that range from orbital flight and space exploration to the commercialization and colonization of space. Advocacy organizations typically educate the public, lobby governments for increased funding, and support private space activities.
The first space advocacy groups formed in the 1920s, primarily among members of the Russian, American, British, and German scientific communities. Starting in the 1930s these groups began sharing their plans with governments and the public.
The Space Exploration Alliance is a coalition of major US non-profit space organizations formed in 2004 to advocate for the exploration and development of outer space to members of Congress. It organizes an annual Legislative Blitz encouraging space enthusiasts to call, email, or personally visit their Congressperson's office.
Daniel Deudney's book Dark Skies identified the Braun-Tsiolkovsky paradigm, which focuses on migration and militarization of space, and the Clarke-Sagan paradigm, which focuses on space exploration. These two frameworks represent distinct and sometimes competing visions for humanity's future beyond Earth.
Critics including those associated with the JustSpace Alliance and Lucianne Walkowicz argue that dominant space advocacy applies settler colonialism and manifest destiny ideology to outer space. Joon Yun has argued that framing space as a solution to problems like pollution is an imperialist narrative, and international space law declaring space the "province of all mankind" has been criticized as still lacking in genuine equity.
The British Interplanetary Society, founded in 1933 in the United Kingdom, is among the oldest continuously active space advocacy groups. It has been running technical studies since the 1930s, including a detailed interstellar probe study called Daedalus completed in the 1970s.