VeGa-1/2 Venus lander
Credit: Andy Salmon
AKA: 5VS. Status: Cancelled 1985. Gross mass: 4,850 kg (10,690 lb).
5VS was a Venus orbiter which would act as a relay station for a big Soviet-French balloon. The balloon was to be dropped into the Venusian atmosphere by the 5VP probe as it flew by Venus. Thereafter the 5VP would head for Halley's comet.
The plan was to launch two 5VS probes in November 1984, followed by two 5VP probes on 6 and 11 December 1984.
The 5VP bus was able to carry only 50 kg of equipment to study Halley's comet. In 1981, while the development of both 5V versions was well underway, it was decided to cancel the 5VS orbiters and redesign the 5VP probes to expand the Halley research program (this may have been in response to the cancellation of the US Halley probe the same year). This resulted in a spacecraft code-named 5VK, later named Vega. On the Venus package the big Soviet-French balloon was replaced by a smaller Soviet-built balloon and a 4V-1 type lander (minus camera). The flyby bus was equipped with the same solar panels as Veneras-15 and 16 and now carried a scan platform with remote sensing instruments to study Halley as well as extra dust protection shields.