A highly engaged group of conspiracy theorists can override a fact-based endeavor’s internet ads.

This was a lesson that Benedict Redgrove, a photographer, said he took away from his recent attempt to advertise his space photo project on Facebook and Instagram.

Another lesson was that flat earthers and lunar landing deniers can be difficult to avoid, even when you try.

Nine years into his project photographing space artifacts for a self-published book and exhibit, Mr. Redgrove realized that he needed cash. The project involves photographing the artifacts and objects associated with space travel — the suits, the gloves, the helmets and the rubber stamps for imprinting astronauts’ names on their spacesuits.