Gene was very helpful to me when I was writing The Overview Effect. In particular, he, along with Edgar Mitchell, pointed out the differences in the astronaut experience between being in Low Earth Orbit and going to the moon. In Cernan's words:
"Being a quarter million miles out in space has to give you a different perspective. Anyone who denies it has missed something. Being in Earth orbit vs going out beyond must be separated. Philosophically, we really have had two different space programs." (1)
He goes on to talk about how the astronaut is moving rapidly around the Earth when in orbit, while he is moving away while on the way to the moon or on the way back from the moon. Then, of course, there is the experience of being on the surface of the moon and seeing our home planet in the sky.
Of that, Cernan said:
"When I was on the moon somewhere out there in the universe, I had to stop and also ask myself, 'Do you really know where you are in space and time and history?'" (2)
If you are interested in the distinction between the astronaut experience in LEO and on a lunar mission, I strongly recommend reading the interview with Gene Cernan in The Overview Effect.
You might also enjoy Cernan's book about his experiences, The Last Man on the Moon. https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=Eugene+Cernan
It is highly readable, and provides great insight not only into the Overview Effect aspects of the Apollo program but also what it was like to be an astronaut during the heady time of the late 60's and early 70's.
I find myself feeling increasing sadness as we lose more and more of the Apollo astronauts. There were not many of them to begin with, and each year seems to bring another passing. It is difficult to think of this elite group of people as mortal, but in a way that is the whole point of space exploration and the astronauts who carry it out: they are mortal and fallible, they are, well, human like the rest of us. And yet, as part of one of the greatest "central projects" of our time, they accomplished something that seems superhuman.
As we move out into the solar system, we should always remember that brave people like Eugene A. Cernan showed us the way and through their example, said, "You can do it, too."(1)
(1) The Overview Effect: Space Exploration and Human Evolution, F. White, AIAA, Reston, VA, 2014, p. 183.
(2) Ibid, p. 184.
(c) Copyright, Frank White, 2017, All Rights Reserved
The Overview Effect: Space Exploration and Human Evolution is available at aiaa.org and amazon.com