Kleckner was part of a mission to Rudimon, a planet ravaged by decades of war and now beginning a fledgling peace. The Enterprise began a program to rebuild the Rudimonian’s infrastructure to inspire the peace to continue. After completing an initial survey, large numbers of the crew including Kleckner were located in the most populated city on Rudimon for training medical specialists, improving educational techniques, and upgrading the city’s power plant. Suddenly a crude, outdated nuclear engine beneath the city blew up, killing or injuring 120 members of the crew. Kleckner was one of 63 who were killed.