Thinking about this after replying in the hoax forum.
The Parker Solar Probe and astrodynamics: Would general relativity have been used to calculate the orbital path. I understand that GR explains the precession of Mercury owning to the stronger gravitational field.
The physicist hand waving part of me wants to say yes, but the 0.000000000000001 % engineer in me says no as it was moving so quickly and second order effects could be ignored, and the mission was so short that orbital corrections could be applied using fuel. (I am assuming a short mission). But then you'd still need to know how to apply those corrections?
One of my favourite parts of Apollo 13 is 'Newton is in the driving seat.' 480 000 mph. He certainly was.