A series of Soviet robotic space probes "Venera" actively pursued Venus exploration.
On November 12 and 16, 1965, two spacecraft “Venera-2” and “Venera-3” were launched. A television system and scientific tools were installed on Venera-2. At a distance of 24,000 km, the control system of the station was out of order even before it reached the planet. The Venera-3 station consisted of an orbital compartment and a descent vehicle. On March 1, 1966, the station reached Venus and crashed into its surface. Venera 3 was the first spacecraft to reach the surface of another planet. "Venera-2" and "Venera-3" failed to transmit data about Venus, but scientific data on outer space and near-planetary space were obtained in the year of the quiet Sun.
In October 1967, Venera-4 delivered a spherical descent vehicle to Venus, which with the help of a parachute system was descending into the night side of the planet for 93 minutes. Entering the atmosphere, the probe began to measure the temperature, density, pressure and chemical composition of the Venus atmosphere.
The scientific devices of the Venera-4 showed that Venus had no radiation belts, and the planet's magnetic field turned out to be 3000 times weaker than the Earth's magnetic field. The hydrogen corona of Venus was discovered with the help of an ultraviolet radiation indicator from the Sun. The atmosphere of Venus was found to be 90% carbon dioxide. Initially, scientists assumed that the pressure on the surface of Venus could reach 10 bars (much less than the true value - 90 bars), so the spacecraft was designed to overcome 20 bars, but as a result it was crushed at an altitude of 28 km from the surface. On the basis of his measurements, the model of the atmosphere of Venus was completely revised and a new estimate of the pressure at the surface was obtained - about 100 bars.
However, there was no time to alter the Venera-5 and Venera-6 descent vehicles, and they flew with similar descent vehicles, but the area of their braking parachutes was reduced to 12 м², which allowed them to reach deeper layers of the atmosphere and continue to determine its chemical composition. As new data on Venus came to light, spacecraft were altered in order to adapt to the extreme conditions of the planet.
On 15 December 1970, Venera 7 became the first spacecraft to soft land on another planet. The lander was designed to be able to survive pressure of up to 180 bars, which allowed it to reach the surface in working order.
Venera 8 confirmed that the temperature on the surface of Venus was 475 °C. By calculating the illumination on the surface of Venus, the spacecraft determined that it is possible to take photos there.
On June 8 and 14, 1975, two spacecraft "Venera - 9" and "Venera - 10" were launched. They executed a soft landing and were the first to take black and white photographs of the surface of Venus in the world.
On December 25, 1978 two spacecraft "Venera - 11" and "Venera - 12" soft landed on the surface of Venus. They were unable to take images because the protective covers of the cameras could not open.
In March 1982, two identical space probes "Venera - 13" and 5 days after "Venera - 14" soft landed on Venus. These spacecraft were the first to take panoramic color images of the surrounding landscape of Venus. With the help of an automatic drill, soil samples were taken, then placed for research in a special chamber inside the space probe. For the first time in astronautics, the chemical composition of soil samples was investigated with an X-ray fluorescence spectrometer. During the descent, the probes recorded numerous electrical discharges. Moreover, the robotic space probes were equipped with microphones and were the first to record sound from the surface of another planet. Scientists believed that there was a sound of thunder and lightning in the recording against the backdrop of wind noise and ground drilling. After the signal, you will be able to listen to this short recording.