Mars Viking Orbiter High-Gain Antenna Mount

with rectangular wave-guide running from dish mount on left to spacecraft on right and passing through central 2-axis gimbal (for rotating from launch storage to deployment and pointing).

The various parts have Serial Number 003 and 004, so I wonder if it’s a flight spare (Viking 1 and 2 landed successfully on Mars in 1976, the first craft to do so).

From NASA Facts: Viking Mission to Mars: “The main orbiter communications system was a two-way, S-band, high-rate radio link providing Earth command, radio tracking and science and engineering data return. This link used either a steerable 1.5-meter (59-inch) dish high-gain antenna or an omni-direc- tional low-gain antenna, both of them on the orbiter. The low-gain antenna was used to send and receive near Earth, and the high-gain antenna was used as the orbiter journeyed farther from Earth.

S-band transmission rates varied from 8.3 or 33.3 bits per second for engineering data to 2,000 to 16,000 bits per second for lander and orbiter science data.
Relay from the lander was achieved through an antenna mounted on the outer edge of a solar panel. It was activated before separation and received from the lander through separation, entry, landing and surface operations. The bit rate during entry and landing was 4,000 bits per second; landed rate was 16,000 bits per second.

Data were stored aboard the orbiter on two eight- track digital tape recorders. Seven tracks were used for picture data and the eighth track for infrared data or relayed lander data. Each recorder could store 640 million bits.

Data collected by the orbiter, including lander data, were converted into digital form by the flight data subsystem and routed to the communications subsystem for transmission or to the tape recorders for storage.”

Part of the Future Ventures’ 🚀 Space Collection.