Vega program
Soviet-led dual mission to Venus and Halley's Comet.
The Vega program sent two uncrewed spacecraft, Vega 1 and Vega 2, on a dual mission to Venus and Halley's Comet. Launched in December 1984, each probe released a lander and a balloon into Venus's atmosphere before flying past the comet. The mission was a multinational effort led by the Soviet Union.
Quick Facts
- Launch dates
- 15 and 21 December 1984
- Launch vehicle
- Proton 8K82K rocket
- Launch site
- Baikonur Cosmodrome, Tyuratam, Kazakh SSR
- Spacecraft mass
- 4,920 kg / 10,847 lb
- Venus arrival dates
- Vega 1 on 11 June 1985, Vega 2 on 15 June 1985
Facts from the source article.
The Vega spacecraft
The two Vega probes were identical 5VK spacecraft, a design based on earlier Venera models. Built by Lavochkin and designed at Babakin Space Center, each craft weighed 4,920 kg and used twin solar panels for power. Their instruments included cameras, spectrometers, magnetometers, and plasma probes. Both were three-axis stabilized and carried a dual bumper shield to protect against dust from Halley's comet.
The Venus mission
The twin Vega spacecraft reached Venus in June 1985, with Vega 1 arriving on the 11th and Vega 2 on the 15th. Each carried a spherical descent unit weighing 1500 kilograms and measuring 240 centimeters across, which was released days before arrival and entered the atmosphere without any active steering. Inside each unit were a lander and a balloon explorer. The landers were the same design used on the five previous Venera missions, equipped to study the atmosphere and surface with instruments for temperature and pressure, a UV spectrometer, a water concentration meter, a gas chromatograph, an X-ray spectrometer, a mass spectrometer, and a surface sampler. A strong wind jolt accidentally triggered the Vega 1 lander's surface experiments at 20 kilometers altitude, so they produced no results; it landed at 7.5 degrees north, 177.7 degrees east. The Vega 2 lander touched down at 03:00:50 UT on 15 June 1985 at 8.5 degrees south, 164.5 degrees east in eastern Aphrodite Terra, at an altitude 0.1 kilometers above the planet's mean radius. It measured 91 atmospheres of pressure and a temperature of 736 Kelvin, found the surface sample to be anorthosite-troctolite, and transmitted data for 56 minutes. The two balloon aerobots were meant to float at 54 kilometers altitude in the most active cloud layer. Their instrument packs, powered for 60 hours, measured temperature, pressure, wind speed, and aerosol density. The balloon envelopes were coated with polytetrafluoroethylene to resist Venus's corrosive atmosphere. Both balloons operated over 46 hours from injection to final transmission. They were spherical superpressure balloons 3.54 meters in diameter, filled with helium, with a 6.9-kilogram, 1.3-meter-long gondola attached by a 13-meter tether; the entire assembly weighed 21 kilograms.
The Halley mission
After their Venus flybys, the Vega probes used the planet's gravity to bend their paths toward Halley's Comet. Vega 1 passed closest on March 6 at roughly 8,890 kilometers from the comet's core, followed by Vega 2 on March 9 at 8,030 kilometers. Their most intense data collection lasted only the three hours nearest to each flyby, focusing on the nucleus's size, shape, temperature, and surface traits, along with the coma's structure, gas and dust composition, and how the comet interacted with the solar wind. Together, the two craft sent back around 1,500 pictures of Halley. The imaging system was built through a joint effort by the USSR, Hungary, France, and Czechoslovakia. Operations ended a few weeks after the comet encounters, and both spacecraft now orbit the sun.
More in Space Probes of ESA, Japan, China, India and the USSR
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