The Spacecraft Data Analysis Team analyzed the engineering data transmitted from the spacecraft to evaluate the performance of the subsystems in flight. The Team was composed of one or more of the engineers responsible for each of the spacecraft subsystems, and a chairman. The Science Data Group was composed of the project scientist and certain other scientists associated with the experiments on board the spacecraft. This Group evaluated the data from the scientific experiments while Mariner was in flight and advised the Test Director on the scientific status of the mission. The Science Data Group was on continuous duty until 48 hours after launch, and at other times during the mission. During encounter with Venus, the Group was also in contact with the scientific experimenters from other participating organizations who were working with JPL. [Illustration: _Closed circuit television monitors are used for instant surveillance of the internal activities of the Operations Center._] A Tracking Data Analysis Group analyzed the tracking data to be used in orbit determination. They also assessed the performance of the DSIF facilities and equipment used to obtain the data. The Orbit Determination Group used the tracking data to produce estimates of the actual spacecraft trajectory, and to compute the spacecraft path with respect to the Earth, Venus, and the Sun. These calculations were made once each day before the midcourse maneuver, once a week during the cruise phase, and daily during and immediately after the planet encounter. The Operations Center was equipped with lighted boards on which the progress of the mission was displayed. This information included trajectory data, spacecraft performance, temperature and pressure readings, and other data telemetered from the spacecraft subsystems. Closed-circuit television was used for coordinating the activities of the SFOC. Operating personnel could use television monitors in four consoles which were linked to six fixed cameras viewing teletype page printers. The entire Operations Room could be kept under surveillance by the Project Manager, the Test Director, or the DSIF Operations Manager, using cameras controlled in “pan,” “tilt,” and “zoom.” CENTRAL COMPUTING FACILITY During the Mariner II mission, the JPL Central Computing Facility (CCF) processed approximately 13.1 million data words, or over 90 million binary bits of computer data. (Binary bit = a discrete unit of information intelligible to a digital computer. One data word = 7 binary bits.) In the four-month operation, about 100,000 tracking and telemetering data cards were received and processed, yielding over 1.2 million computer pages of tabulated, processed, and analyzed data for evaluation by the engineers and scientists. Approximately 1,000 miles of magnetic tape were used in the 1,056 rolls recorded by the DSIF.