The Vega program was a series of Venus missions that also took advantage of the appearance of comet 1P/Halley in 1986. They had a mission to investigate Venus and also flyby Halleys Comet. The flyby of Halleys Comet had been a mission change in the Venera program following on from the cancellation of the American Halley mission in 1981. A later Venera mission was cancelled and the Venus part of the Vega 1 mission was reduced, because of this, the craft was designated Vega, a contraction of Venera and Gallei. The spacecraft design was based on the previous Venera 9 and Venera 10 missions, the two spacecraft were launched on December 15 and 21,1984, respectively. With their redesignated dual missions, the Vega probes became part of the Halley Armada, Vega 1 and Vega 2 were identical sister ships. The spacecraft was a development of the earlier Venera craft and they were designed by Babakin Space Center and constructed as 5VK by Lavochkin at Khimki. The craft was powered by large solar panels and instruments included an antenna dish, cameras, spectrometer, infrared sounder, magnetometers. The 4,920 kg craft was launched by a Proton 8K82K rocket from Baikonur Cosmodrome, Tyuratam, both Vega 1 and Vega 2 were three-axis stabilized spacecraft. The spacecraft were equipped with a dual bumper shield for dust protection from Halleys comet, the units were released some days before each arrived at Venus and entered the atmosphere without active inclination changes. Each contained a lander and a balloon explorer, the Vega 1 landers surface experiments were inadvertently activated at 20 km from the surface by an especially hard wind jolt, and so failed to provide results. The Vega 2 lander touched down at 03,00,50 UT on June 15,1985 at 8. 5° S,164. 5° E, the altitude of the touchdown site was 0.1 km above the planetary mean radius. The measured pressure at the site was 91 atm and the temperature was 736 K. The surface sample was found to be an anorthosite-troctolite, the lander transmitted data from the surface for 56 minutes. The instrument pack had enough power for sixty hours of operation and measured temperature, pressure, wind speed. The balloon envelopes were surfaced with polytetrafluoroethylene to resist attack by the corrosive atmosphere, both Vega-1 and Vega-2 balloons operated for more than 46 hrs from injection to the final transmission. The balloons were spherical superpressure types with a diameter of 3.54 metres, a gondola assembly weighing 6.9 kilograms and 1.3 meters long was connected to the balloon envelope by a tether 13 metres long. Total mass of the assembly was 21 kilograms
Vega mission description
Vega solar system probe bus and landing apparatus (model)
Position of Vega landing sites. Red points denote sites returning images from the surface, black central dots sites of surface sample analysis. Map based on mapping from Pioneer Venus Orbiter, Magellan and Venera 15/16.
Vega balloon probe on display at the Udvar-Hazy Center of the Smithsonian Institution. Photo by Geoffrey A. Landis.