[4] The probe sent the first direct measurements proving that Venus was extremely hot, that its atmosphere was far denser than expected, and that it had lost most of its water long ago.

The flight program was planned to include two significant course corrections, for which purpose the station could receive and execute up to 127 different commands sent from the Earth.

[5] The front part of the carrier spacecraft contained a nearly spherical landing capsule 1 metre (3 ft 3 in) in diameter and weighing 383 kilograms (844 lb).

Compared to previous (failed) Venera probes, the capsule contained an improved heat shield that could withstand temperatures up to 11,000 °C (19,800 °F).

The centrifuge test caused cracking of electronic components and cable brackets, which were replaced shortly before launch.

Considering the possibility of such a landing, its designers made the lock of the capsule using sugar;[5][7][11] it was meant to dissolve in liquid water, releasing the transmitter antennas.

The transmitters were activated by the parachute deployment as soon as the outside pressure reached 0.6 standard atmospheres (61 kPa), which was thought to occur at the altitude about 26 kilometres (16 mi) above the surface of the planet.

[6][5] The capsule was equipped with a rechargeable battery with a capacity sufficient for 100 minutes of powering the measurement and transmitter systems.

[13] During entry into the Venusian atmosphere, the heat shield temperature rose to 11,000 °C (19,800 °F) and at one point the cabin deceleration reached 300 G.[14] The descent lasted 93 minutes.

The capsule deployed its parachute at an altitude of about 52 kilometres (32 mi), and started sending data on pressure, temperature and gas composition back to Earth.

At the end of the 26 kilometres (16 mi) descent, the temperature reached 262 °C (504 °F) and pressure increased to 22 standard atmospheres (2,200 kPa), and the signal transmission terminated.

[16][17] This result was quickly dismissed as inconsistent with the planetary diameter measured by radar,[18][19] and the pressure readings by the capsule were much lower than predicted by the recently developed models of the Venus atmosphere.

Because of the negligible humidity, the sugar lock system, employed on Venera 4 in case of a water landing, was abandoned in subsequent Venus probes.