The Vega spacecraft were created as part of the international Venus-Halley project and are designed for studying two celestial objects when approaching them during the flyby – the planet Venus (with deploying landers on its surface and introducing balloon probes into its atmosphere) and Halley's Comet. Two spacecraft Vega-1 and Vega-2 were prepared for simultaneous participation in the mission. The Vega-1 and Vega-2 SC are completely identical in terms of objectives to be realized, flight trajectories, design, onboard systems and scientific equipment.
The launch of two identical spacecraft is intended not only to improve the overall reliability of the mission
accomplishment, but also to conduct contact studies of the surface of Venus in two different regions of
the planet, as well as to study Halley's Comet at different distances from the Sun.