THE SPACEFRAME
The design engineers were forced to work within the framework of the earlier spacecraft technology because of the time restrictions, but Mariner I and II could weigh only about half as much as the Ranger spacecraft and just over one-third as much as the planned Mariner A.
Mariner spacecraft with solar panels, microwave radiometer, and directional antenna extended in flight position. Principal components are shown.
ROLL AXIS OMNIANTENNA MAGNETOMETER SENSOR PARTICLE FLUX DETECTORS (GEIGER TUBES) RADIOMETER REFERENCE HORNS MICROWAVE RADIOMETER INFRARED RADIOMETER ION-CHAMBER COSMIC DUST DETECTOR EARTH SENSOR SOLAR PANEL COMMAND ANTENNA SOLAR SAIL ATTITUDE CONTROL GAS BOTTLES SOLAR PLASMA DETECTOR DIRECTIONAL ANTENNA
The basic structural unit of Mariner was a hexagonal frame made of magnesium and aluminum, to which was attached an aluminum superstructure, a liquid-propelled rocket engine for midcourse trajectory correction, six rectangular chassis mounted one on each face of the hexagonal structure, a high-gain directional antenna, the Sun sensors, and gas jets for control of the spacecraft’s attitude.
The tubular, truss-type superstructure extended upward from the base hexagon. It provided support for the solar panels while latched under the shroud during the launch phase, and for the radiometers, the magnetometer, and the nondirectional antenna, which was mounted at the top of the structure. The superstructure was designed to be as light as possible, yet be capable of withstanding the predicted load stresses.
The six magnesium chassis mounted to the base hexagon housed the following equipment: the electronics circuits for the six scientific experiments, the communications system electronics; the data encoder (for processing data before telemetering it to the Earth) and the command electronics; the attitude control, digital computer, and timing sequencer circuits; a power control and battery charger assembly; and the battery assembly.
The allotment of weights for Mariner II forced rigid limitation in the structural design of the spacecraft. As launched, the weights of the major spacecraft subsystems were as follows:
| Structure | 77 pounds |
| Solar panels | 48 pounds |
| Electronics | 146 pounds |
| Propulsion | 32 pounds |
| Battery | 33 pounds |
| Scientific experiments | 41 pounds |
| Miscellaneous equipment | 70 pounds |
| Gross weight | 447 pounds |