Vega 1 flew by Venus on June 11, 1985, and dropped a science capsule and a high-altitude, balloon-borne payload to the Venusian surface. The capsule landed safely and relayed pictures and other scientific data for two hours. At the same time, the helium-filled balloon carrying scientific instruments hovered in the atmosphere of Venus for two days at an altitude of about thirty-one miles (fifty kilometers). During that time, the balloon was blown more than 6,200 miles (10,000 kilometers) from its original position. The instruments gathered valuable scientific data about the temperature, pressure, and wind speeds of the Venusian atmosphere. The entire capsule-and-balloon scientific sequence was repeated a few days later by Vega 2.

After releasing their scientific payloads at Venus, the Vega spacecraft then used Venus as a gravitational slingshot, propelling them on an intercept course with Comet Halley. On March 6, 1986, Vega 1 came within 5,600 miles (9,000 kilometers) of the comet’s nucleus; Vega 2 had its closest approach three days later. The two probes collected substantial scientific data on the comet; some of the data was used by the European Space Agency to reposition the Giotto probe to the comet. After passing Comet Halley, the Vega spacecraft remained in orbit around the Sun until they were shut down in early 1987.