The documents in this collection are all related to the development and systems engineering of the Viking Orbiter. They are arranged in fifteen series, and then chronologically within each series, except for the thirteenth series, Preshipment Review, in which the original order has been maintained. The series are: (1) Design and Readiness Reviews; (2) System Simulation; (3) Testing and Test Plan Documents; (4) Imaging Subsystem; (5) Telemetry System; (6) Tracking System; (7) Navigation; (8) Operations Plans; (9) Guidance and Control; (10) Orbiter Control Documents; (11) Modeling Documents; (12) Computer Command Subsystem; (13) Preshipment Review; (14) Launch Readiness Reviews; and (15) Miscellaneous Reports. A significant number of the test reports describe the shock and static testing of the orbiter components, electronic chassis, camera scan platform, attitude jet valves, propellant tanks, and electrical power system. Other test reports describe checkout of other of the orbiter's components and systems, including the imaging system and the Centaur release device. The collection also includes documents explaining engineering and development of operating systems for telemetry, tracking, orbit determination, navigation, and transmitting computer commands. Some of the testing was carried out on the "proof test model," a third orbiter used only for development purposes and never launched. Orbiter Control Documents comprise one series. These documents describe engineering reliability and quality control requirements, as well as the science data return plan, and the development of software macros for issuing computer commands. Also in this collection are reviews and status summaries of the orbiter systems and components prior to shipment, along with launch readiness statements. Most of the documents originate with the two agencies principally responsible for th orbiter development, the Jet Propulsion Laboratory, and Langley Research Center. In instances where there is an interface between the orbiter and the lander, some documents are authored by the contractor responsible building the lander, Martin Marietta Corporation. Most of the documents contain at least one identifying number, usually a Viking Orbiter Data Index number. These are usually written in pencil in the lower right-hand or left-hand corner of the first page of each document. The Archives has a nine-volume printout of Viking documents listed by Data Index number. The listing of index numbers, although in ascending sequential order, is discontinuous. Number series are repeated several times throughout the index.
