I highly recommend reading the book Chasing New Horizons by Alan Stern[0]. It is a great insight into years of work it takes to get a mission like New Horizons going. It is a very well written book and I could not put it down until finished.

[0] https://www.amazon.com/Chasing-New-Horizons-Inside-Mission/d...

Since Pluto is clearly Planet Nine, I'm assuming this was written before 1930.

(I'm only being a little facetious. According to https://www.amazon.com/Chasing-New-Horizons-Inside-Mission-e..., plenty of scientists consider Pluto a planet still.)