The Mariner 4 spacecraft consisted of an octagonal magnesium frame, across a diagonal and high. Four solar panels were attached to the top of the frame with an end-to-end span of , including solar pressure vanes which extended from the ends. A elliptical high-gain parabolic antenna was mounted at the top of the frame as well. An omnidirectional low-gain antenna was mounted on a tall mast next to the high-gain antenna. The overall height of the spacecraft was . The octagonal frame housed the electronic equipment, cabling, midcourse propulsion system, and attitude control gas supplies and regulators.