Grissom wrote in his posthumous 1968 book Gemini! that the realization of Project Mercury's end and the unlikelihood of his having another flight in that program prompted him to focus all of his efforts on the upcoming Gemini program.
U svojoj knjizi Gemini!, objavljenoj posthumno 1968., napisao je da ga je realizacija programa Mercury, s malim šansama da ostvari još jedan let u tom projektu, potakla da usredotoči sve svoje napore na nadolazeći program Gemini.