[4] Mariner 5 also included some additional equipment that was not flown on Mariner 4, such as its Ultraviolet Photometer, two 50 MHz DFR antennas, a 423 MHz DFR antenna mounted on the end of one of the solar panels, and a deployable Sun-shade on the aft of the spacecraft for thermal control.

The UV Photometer was originally supposed to fly on Mariner 4 and would have been mounted to its TV Camera scan platform.

[5] Liftoff took place on June 14, 1967, from Cape Canaveral Air Force Station Launch Complex 12 on Atlas vehicle 5401.

Booster performance was normal through the Atlas portion of the launch and the first Agena burn, with all systems operating at the proper level.

During the second Agena burn, abnormal fluctuations in the engine chamber pressure occurred, however they did not preclude successful interplanetary injection.

There had been several occurrences of this behavior on previous NASA and Air Force launches and a program was initiated to correct it which led to a redesign of the Agena turbopump gearbox.

The Venera 4 and Mariner 5 data was subsequently analysed together under a combined Soviet–American working group of COSPAR in 1969,[6][7] an organization of early space cooperation.