This makes me very sad. Schirra was one of my favorite astronauts. One of the original Mercury 7.
He also flew with Tom Stafford in the Gemini program.
And he displayed huge brass balls by commanding the first flight of the Apollo Command Module after 3 of his fellow astronauts were incinerated in one.
He was the only astronaut to fly in all 3 programs. He was a pilot's pilot, a true pioneer, and a pretty funny guy.