Short answers, pulled from the story.
The Vega program was a Soviet-led series of Venus missions that also flew by Halley's Comet during its 1985-1986 perihelion. Vega 1 and Vega 2 each deployed a lander and a balloon probe at Venus before redirecting to photograph Halley's Comet, returning about 1,500 images of the nucleus.
The dual mission arose after the cancellation of the American Halley mission in 1981. Soviet planners modified a planned Venera Venus mission to also intercept the comet, using Venus's gravity to redirect the spacecraft toward Halley after the Venus encounter.
The Vega balloon probes were 3.54-meter helium-filled spherical aerobots designed to float at 54 kilometers altitude in the Venusian cloud layer. They were the first human-made aircraft to fly on a planet other than Earth, and that distinction held until NASA's Ingenuity helicopter flew on Mars in 2021.
Vega 2's lander touched down in eastern Aphrodite Terra on the 15th of June 1985 and measured a surface pressure of 91 atmospheres and a temperature of 736 Kelvin. A surface sample was identified as anorthosite-troctolite, and the lander transmitted data from the surface for 56 minutes.
Vega 1 passed about 8,890 kilometers from Halley's nucleus on the 6th of March 1986, and Vega 2 came within 8,030 kilometers on the 9th of March 1986. The data-intensive examination covered only the three hours around each closest approach.
The Vega program was a cooperative effort involving the Soviet Union, Austria, Bulgaria, France, Hungary, the German Democratic Republic, Poland, Czechoslovakia, and the Federal Republic of Germany. The Soviet Union provided the spacecraft and launch vehicles, while partner nations contributed instruments and scientific expertise.