Internet and Science: Roscosmos publishes declassified documents about the space probe “Venera 8” for the first time

Half a century ago on July 22, 1972 a lander of the Soviet space probe Venera 8, built at the Lavochkin Research and Production Association (a part of the State Space Corporation Roscosmos) landed on Venus and transmitted data about the planet’s atmosphere, light level on its surface and the nature of Venus’ resources to scientists.

Roscosmos publishes parts of declassified documents about the preparation and organization of this flight.

The probe Venera 8 was launched on March 27, 1972 at 07:15:06 Moscow time from the Baikonur Cosmodrome via the Molniya-M rocket. During the flight to the Morning Star, the trajectory of the spacecraft was corrected on April 6.

The spacecraft reached the planet on July 22. The lander separated from the orbiter, which resulted in it experiencing overloads up to 335 g and reducing speed from 11.6 km/s to 250 m/s in the process of the aerodynamic braking in the atmosphere. At the altitude of approximately 55 km, a parachute opened and the transmission of data from the lander began. After 55 minutes of slow landing at the vertical speed 8.3 m/s in the atmosphere via parachute, the device landed on the Venus’ surface in sunlight at 10°S 335°E at 12:28:40 Moscow time.

The transmission of data from the lander continued for 50 minutes 11 seconds after the landing. Data from the scientific devices has shown that the surface temperature and pressure near the landing site of Venera 8 were 470±8°С and 90±1.5 atmospheres, respectively, while the light level at the Sun angle 5.5° was 350±150 lx. During the descend at altitudes of about 46 and 33 km, a volume content of 0.01–0.1% ammonia was recorded in the atmosphere, and at altitudes of 50 and 0-11 km, the wind speed was 50-60 and 0-2 m/s, respectively. It was concluded that the surface layer of the planet in the area of the landing site of the spacecraft is quite loose with a soil density of 1.4 g/cm3 and that the soil itself resembled terrestrial granite rocks.

In comparison with the previous probe Venera 7, Venera 8 has barely undergone any changes. The main modifications have been made on its lander, among which – the development of a thinner wall of the instrument compartment, installation of a shock-absorbing device and refinement of the antenna-feeder system.