Venera/Vega series, 1975-1985

The Venus objectives of the 3MV series were fulfilled when Venera 7 and 8 both survived landing and provided data on surface conditions. This led to the decision to design a new spacecraft for more extensive operations on the surface of this planet. For the first time since the initial launch to Venus in 1961, a launch opportunity was skipped in 1973 to devote the time to developing a new, heavier, more complex and capable Venus orbiter/lander system based on the Proton-launched Mars spacecraft. The success of the American Mariner 9 orbiter in 1971, and the anticipated superior capability of that nation’s Viking landers to be launched in 1975, led to the decision to focus the mote expensive Proton-launched missions on Venus rather than Mars in the immediate future.

The new Venera orbiter was nearly identical to the Mars orbiter, with changes in solar panel size and thermal design. But the entry vehicle was significantly different. The thicker, deeper atmosphere of Venus allowed for a simpler entry and landing system consisting of a large, hollow, spherical entry vessel containing the lander and parachute system. Pairs of spacecraft were launched on three launch windows, and all were successful, the Venera 9 and 10 orbiter /landers in 1975, the Venera 11 and 12 flyby/landers in 1978. and the Venera 13 and 14 flyby/landers in 1981. Not only did the Venera 9 lander provide the first imagery and composition measurements from the surface, the parent spacecraft was the first successful Venus orbiter. Flight energy requirements in 1978 and 1981 did not allow for orbiters. In 1983 the lander module was replaced with an imaging radar, and the Venera 15 and 16 orbiters were successful in providing the first radar imagery of the surface of the planet.

Nearly simultaneously with the 1983 radar mission, another flyby/lander mission was being prepared in a French partnership to deploy a large balloon which would be equipped with a comprehensive science payload and drift around the planet in the cloud deck. But when it was recognized that the flyby spacecraft could be retargeted to Halley’s comet after releasing the entry vehicle for Venus, the flyby spacecraft payload was redesigned for Ilalley, the balloon significantly descoped. a lander added, and the launch date adjusted to provide encounters with both Venus and Ilalley. Renamed Vega 1 and Vega 2, all aspects of these missions were carried out very successfully at both targets.