Final answer:
The main idea of 'Go, John Glenn' centers on the life and achievements of astronaut John Glenn, especially his groundbreaking orbit of Earth in 1962, which was a significant event during the Space Age.
Step-by-step explanation:
The main idea of Go, John Glenn is b) "The life and achievements of John Glenn". This is because the text focuses on the historical significance of John Glenn's contribution to space exploration, specifically highlighting his orbit around the Earth in February 1962, which marked a pivotal moment in the Space Age and the rivalry between the United States and the Soviet Union during the Cold War. The narrative might touch upon the various elements of space exploration, including the technological and human challenges involved, but the central theme revolves around John Glenn's personal journey and his role in the broader context of space exploration efforts by the United States.