[TaylorAlexander]

Not Voyager but here’s code from the Apollo program: https://github.com/chrislgarry/Apollo-11/

[KineticLensman]

Highly recommend 'Sunburst and Luminary: An Apollo Memoir' by Don Eyles who gives a programmer's perspective on the software aspects of Apollo. Some of which were fairly nail-biting, especially when they occurred in-flight.

[DylanSp]

Seconding this recommendation, it's a fascinating book.