Danny Dunn and the Anti-Gravity Paint (Danny Dunn, # 1)
by Jay Williams, Raymond Abrashkin, Ezra Jack Keats
I mostly remember the absurdity of reading this book as a kid in the 1990s and trying to wrap my head around this being a "scientific" depiction of what space travel was going to be like, in checks notes 1956. You know, just casually making a gravitational slingshot around Saturn after accidentally launching my weird grandfathery stepdad's spaceship.
Also, Danny has to write "Space travel isn't possible" 500 times for his teacher at the beginning of the book. On what planet is this considered educational??
Super duper pulp, I bet it would be a fun reread.