Vega 2 (along with Vega 1) was a Soviet space probe part of the Vega program to explore Halley's Comet and Venus. The spacecraft was a development of the earlier Venera craft. The name VeGa (ВеГа) combines the first two letters of the Russian words for Venus (Венера: "Venera") and Halley (Галлея: "Galleya"). They were designed by Babakin Space Centre and constructed as 5VK by Lavochkin at Khimki. The craft was powered by large twin solar panels. Instruments included an antenna dish, cameras, spectrometer, infrared sounder, magnetometers (MISCHA) and plasma probes. The 4,840 kilograms (10,670 lb) craft was launched on top of a Proton-K from Baikonur Cosmodrome, Tyuratam, Kazakh SSR. Both Vega 1 and 2 were three-axis stabilized spacecraft. The spacecraft were equipped with a dual bumper shield for dust protection from Halley's Comet.

The descent module arrived at Venus on 15 June 1985, two days after being released from the Vega 2 flyby probe. The module, a 1,500 kilograms (3,300 lb), 240 centimetres (7.9 ft) diameter sphere, contained a surface lander and a balloon explorer. The flyby probe performed a gravitational assist maneuver using Venus, and continued its mission to intercept the comet.

The surface lander was identical to that of Vega 1 as well as the previous six Venera missions. The objective of the probe was the study of the atmosphere and the exposed surface of the planet. The scientific payload included a UV spectrometer, temperature and pressure sensors, a water concentration meter, a gas-phase chromatograph, an X-ray spectrometer, a mass spectrometer, and a surface sampling device. Several of these scientific tools (the UV spectrometer, the mass spectrograph, and the devices to measure pressure and temperature) were developed in collaboration with French scientists. Since the probe made a nighttime landing, no images were taken.

The Vega 2 lander touched down at 03:00:50 UT on 15 June 1985 at around 7°08′S 177°40′E / 7.14°S 177.67°E / -7.14; 177.67, in the northern region of Aphrodite Terra. The altitude of the touchdown site was 0.1 kilometres (330 ft) above the planetary mean radius. The measured pressure at the landing site was 91 atm and the temperature was 736 K (463 °C; 865 °F). The surface sample was found to be an anorthosite–troctolite rock, rarely found on Earth, but present in the lunar highlands, leading to the conclusion that the area was probably the oldest explored by any Venera vehicle. It transmitted data from the surface for 56 minutes.

The Vega 2 Lander/Balloon capsule entered the Venusian atmosphere (125 kilometres [78 mi] altitude) at 02:06:04 UT (Earth received time; Moscow time 05:06:04) on 15 June 1985 at roughly 11 kilometres per second (6.8 mi/s). At approximately 2:06:19 UT the parachute attached to the landing craft cap opened at an altitude of 64 kilometres (40 mi). The cap and parachute were released 15 seconds later at 63 kilometres (39 mi) altitude. The balloon package was pulled out of its compartment by parachute 40 seconds later at 61 kilometres (38 mi) altitude, at 7.45 degrees S, 179.8 degrees east. A second parachute opened at an altitude of 55 kilometres (34 mi), 200 seconds after entry, extracting the furled balloon.

The balloon was inflated 100 seconds later at 54 kilometres (34 mi) and the parachute and inflation system were jettisoned. The ballast was jettisoned when the balloon reached roughly 50 kilometres (31 mi) and the balloon floated back to a stable height between 53 and 54 kilometres (33 and 34 mi) some 15 to 25 minutes after entry. The mean stable height was 53.6 kilometres (33.3 mi), with a pressure of 535 millibars (535 hPa) and a temperature of 308–316 K (35–43 °C; 95–109 °F) in the middle, most active layer of the Venus three-tiered cloud system. The balloon drifted westward in the zonal wind flow with an average speed of about 66 metres per second (220 ft/s) at nearly constant latitude. The probe crossed the terminator from night to day at 9:10 UT on 16 June after traversing 7,400 kilometres (4,600 mi). The probe continued to operate in the daytime until the final transmission was received at 00:38 UT on 17 June from 7.5 S, 76.3 E after a total traverse distance of 11,100 kilometres (6,900 mi), about 29% of the planet's circumference. It is not known how much further the balloon traveled after the final communication.

After their encounters, the Vegas' motherships were redirected by Venus's gravity to intercept Halley's Comet.

The spacecraft initiated its encounter on March 7, 1986, by taking 100 photos of the comet from a distance of 14,000,000 kilometres (8,700,000 mi).