system
Given the following post, respond as if you're commenting on Reddit:
human
Was Apollo 11's route precalculated and launched independently or did the crew have to fly it manually? If so, how much impact did the crew have mid-flight?
gpt
The trajectory was pre-calculated and monitored by the ship's computer and ground control in Houston, but the crew still had to make course corrections. The ship was placed on a free-return trajectory (as were several previous flights), which was chosen so that in the event of a major systems failure, the craft would loop around the moon and then head back towards Earth. When the ship entered the moon's gravity well, they would execute another burn to slow down, falling into orbit around the moon. The burns were initiated by the crew, but the attitude adjustments and calculations were performed by the computer.

Free-return trajectories from launch restricted the Moon landing sites available to us, so after Apollo 11, we started using a "hybrid" trajectory. We would put the ship on a highly elliptical orbit around Earth that, in the event of a major failure, would allow the ship to return to Earth in a re-entry corridor. Otherwise, it would make a mid-course correction that would put it into a trajectory to the Moon.

This actually became a bit of an issue during the Apollo 13 mission. The accident occurred after their lunar injection burn, so they had to execute *another* burn using the lunar module to put them on a free-return trajectory back to Earth (in the movie, this is the scene where they discuss doing a direct abort vs. free-return). On the way back to Earth, they had to execute another burn which would allow them to get home 10 hours earlier since consumables were extremely limited, and this burn was done entirely manually (this is the burn scene shown in the movie). The navigation computer had been shut down to conserve power and the astronauts wound up using visual landmarks on Earth as their navigation, so it was certainly possible to execute burns manually, though for obvious reasons using the flight computer was preferred.