This leather sheath held the Pickett 1006-T pocket slide rule belonging to Robert L. "Bob" Foster, an engineer who worked for McDonnell Aviation on Project Mercury (1959-1965) and Project Gemini (1965-1967). He also served as base manager, Deputy Director, and Director of Vandenberg Air Force Base during the late 1960s and as head of the Manned Orbiting Laboratory project in California. Although Foster would have relied on a full-sized slide rule for his real work, a pocket slide rule like the one for which this sheath was designed would have been used to make calculations in meetings or while away from his desk.

Slide rules illustrate the manner and pattern of work that was required to carry out NASA's early human spaceflight efforts. As a part of the social history of space exploration, it reminds us of the individual people and countless calculations that allowed the grand projects of human space exploration to happen.

Foster's daughter, Sally Foster-Chang, donated the slide rule and its accessories to the Museum in 2005 along with her father's engineer's jacket, her mother's charm bracelet, and a collection of her father's papers.