A group of space explorers visit a newly discovered planet. They observe it from a distance, careful not to interfere with its cultures (along the lines of Starfleet Prime Directive, from Star Trek).Wow, I hadn't realized that this idea went as far back as 2003.
A team lands on the planet to observe. Inadvertantly they affect the local culture, who builds a religion around them. When it is time for the team to leave, several members remain behind to try to fix the damage, unobtrusively.
I am pleased with what this idea has evolved into. Starting with just that idea, I now have a title, a setting, and an ensemble of characters who have names, history, and goals. I have written enough content to fill a chapter.
At the same time I am disheartened that this process is coming so slowly. I mean, after a year of writing, I am still working on the first chapter. At this pace it will take me a decade to finish.