[3] Following retirement from the aerospace industry, Clemons was a consultant and a professional writer as well as a speaker and presenter on NASA's space programs.

[5][6] Following Apollo, at IBM Federal Systems in Houston, he was the overall program manager for the development of the onboard software for NASA's Space Shuttle.

In the 1990s and 2000s, Clemons was Senior Vice President of Engineering at Lockheed Martin Air Traffic Control Company in Rockville, Maryland.

[11] His organization designed and implemented the hardware and software required to support the modernization of the FAA's nationwide Air Traffic Control computer systems,[12] and the United Kingdom's London Area Air Traffic Control Centre, as well as systems in Scotland, Eastern Europe, South America, and New Zealand.

His non-fiction book Safely to Earth: The Men and Women Who Brought the Astronauts Home, a memoir of his time on NASA's Apollo and Space Shuttle programs, was published by University Press of Florida in September 2018.