A 1-pulse-per-minute signal was provided for such launch sequence events as the extension of the solar panels 44 minutes after launch, turning on power for the attitude control subsystem one hour after launch, and for certain velocity correction commands during the midcourse maneuver.
The spacecraft used two antennas for communication. The omni-antenna (top) was utilized when the directional antenna (bottom) could not be pointed at the Earth.
This command antenna (on solar panel) was used to receive maneuver commands.
A 1-pulse-per-second signal was generated as a reference during the roll and pitch maneuvers in the midcourse trajectory correction phase. One pulse was generated every 3.3 hours in order to initiate the command to orient the directional antenna on the Earth at 167 hours after launch.
Finally, one pulse every 16.7 hours was used to readjust the Earth-oriented direction of the antenna throughout the flight.
TELECOMMUNICATIONS: RELAYING THE DATA
The telecommunications subsystem enabled Mariner to receive and to decode commands from the Earth, to encode and to transmit information concerning space and Mariner’s own functioning, and to provide a means for precise measurement of the spacecraft’s velocity and position relative to the Earth. The spacecraft accomplished all these functions using only 3 watts of transmitted power up to a maximum range of 53.9 million miles.
A data encoder unit, with CC&S sequencing, timed the three phases of Mariner’s journey: (1) In the launch mode, only engineering data on spacecraft performance were transmitted; (2) during the cruise mode, information concerning space and Mariner’s own functioning was transmitted; and (3) while the spacecraft was in the vicinity of Venus, only scientific information concerning the planet was to be transmitted. (The CC&S failed to start the third mode automatically and it was initiated by radio command from the Earth.) After the encounter with Venus, Mariner was programmed to switch back to the cruise mode for handling both engineering and science data (this sequence was also commanded by Earth radio).