Space History

Tsiolkovsky is well known and is listed in many texts, lectures, etc. As
far as I know he did not work with hardware, but his intellectual
contributions were wonderful. O'Neill, of course made many intellectual
contributions but also built mass drivers. I am not sure of your points.
I think a pointwell worth making is that not only did Tsiolkovsky see much farther than did his contemporaries, he saw much better than do many present-day space thinkers. Like O'Neill, he was able to overcome the "planetary hang-up". Although he did write about landing men on Mars, he realized that orbital habitats (he called them "orbital mansion/greenhouses") and asteroid mining was where it's at. He realized how easy it would be to provide a substitute for planetary gravity simply by rotation, and also realized the advantages of having full and uninterrupted access to solar power.