Vega Project

Abstract

Vega was the last successful deep space mission of the Soviet space program. It was built on the legacy of the Venera‐9 to Venera‐16 series of spacecraft launched, starting in 1975, to study Venus. In its last encounter (1986), Halley's comet's perihelion was much closer to Venus than to Earth. That created a unique opportunity to launch Vega during the astronomical window for Venus (December 1984) and to use that planet's gravity assist for redirecting the craft to the comet. Using such a choice of spacecraft trajectory, it was decided to combine a scenario to explore Venus with a Halley's comet encounter by employing a two‐element space vehicle: a planetary reentry module, carrying the Venus Lander and balloon, and a Halley flyby probe. The integrated mission was called Vega, a contraction of the Russian words “Venera” (Venus) and “Gallei” (Halley) and was conducted by the Soviet Union and a number of other countries within the framework of an Intercosmos program. The Vega mission comprised two identical spacecraft, Vega 1 and Vega 2. This was a standard approach in the Soviet Union, aimed primarily at increasing the overall reliability of the mission. In addition, if both flybys were successful, there would be a significant increase in the scientific return, which was particularly valuable considering the expected variability of the comet's activity. The Vega project was truly international. The spacecraft production and launch operation were controlled by the Soviet aerospace agency (at that time called the Ministry of General Machine Building), but the scientific program and its payload were coordinated by the International Science and Technical Committee (ISTC), representing scientific institutions and space agencies from nine countries. The ISTC designed the Vega mission program to optimize international efforts related to the Halley's comet campaign, which included the European Giotto and the Japanese Suisei and Sakigake space missions. This article discusses the launch of the two spacecraft and these encounters with Halley's comet: The mission was scientifically highly successful.