Its mission was to serve as a communications relay for the lander and to explore cloud layers and atmospheric parameters with several instruments and experiments:[7] The orbiter consisted of a cylinder with two solar panel wings and a high gain parabolic antenna attached to the curved surface.

A bell-shaped unit holding propulsion systems was attached to the bottom of the cylinder, and mounted on top was a 2.4 metres (7 ft 10 in) sphere which held the landers.

This system, plus precooling prior to entry, permitted operation of the spacecraft for 65 minutes after landing.

During descent, heat dissipation and deceleration were accomplished sequentially by protective hemispheric shells, three parachutes, a disk-shaped drag brake, and a compressible, metal, doughnut-shaped, landing cushion.

Other measurements included atmospheric pressure at various heights, and temperature, and surface light levels.