I remember those days, but I don't really remember High Flight. I do remember the Star Spangled Banner with an image of the flag and, I believe sometime after the moon landing, there was the image of earth from space (or maybe it was before the moon landing). Anyway, I do recall the days when stations went off the air at midnight till 6 am.
By the way, we had four stations -- ABC, CBS an NBC plus the "educational television," known now as PBS. Back then the channel really did educate, at least during the day. I remember lectures in science and mathematics in particular.