Staple-bound softcover report entitled "Development and Evaluation of Simple Lunar Models for Apollo," prepared for NASA-MSC by Boeing's Aerospace Systems Division, 8.5 x 11, 192 pages, dated September 15, 1969. The report discusses the development and evaluation of four different lunar gravitational models for the Apollo missions. The abstract reads: "Four simplified lunar gravitational models have been developed for Apollo mission control on the basis of Lunar Orbiter and Apollo orbit element data. These models and four others provided by NASA MSC were evaluated by determining the accuracy in the predictions of orbit element variations. A five-coefficient model, R-6, provides the most accurate predictions when considering a wide range or orbital conditions, and it is the best model for the Apollo 12 mission." The report is filled with various charts, graphs, and tables associated with the development of such models. In very good to fine condition, with some creasing to the front cover, and the rear cover missing.
