A functional block diagram of the MM 69 power subsystem is shown in Figure 10. ... Actual flight data from MM VI of the Isc-Voc (open circuit voltage) transducer is shown in Figures 11 and 12. ... In addition, it is also planned to subject the spacecraft to several orbital trim maneuvers throughout the mission. ... VENUS/ MERCURY 1973 (MVM 73) One of the most interesting missions to be pursued in the 1973-1974 time period is the Venus gravity-assist mis. sion to the planet Mercury.