Ten probes successfully landed on the surface of the planet, including the two Vega program and Venera-Halley probes , while thirteen probes successfully entered the Venusian atmosphere. Due to the extreme surface conditions on Venus , the probes could only survive for a short period on the surface, with times ranging from 23 minutes to two hours. The Venera program established a number of precedents in space exploration, among them being the first human-made devices to enter the atmosphere of another planet Venera 4 on October 18, , the first to make a soft landing on another planet Venera 7 on December 15, , the first to return images from another planet's surface Venera 9 on June 8, , and the first to perform high-resolution radar mapping scans Venera 15 on June 2, The first Soviet attempt at a flyby probe to Venus was launched on February 4, , but failed to leave Earth orbit. In keeping with the Soviet policy at that time of not announcing details of failed missions, the launch was announced under the name Tyazhely Sputnik "Heavy Satellite".
It consisted of an orbiter and a lander. The orbiter entered Venus orbit on October 20, Its mission was to act as a communications relay for the lander and to explore cloud layers and atmospheric parameters with several instruments and experiments. It performed 17 survey missions from October 26, to December 25, The orbiter consisted of a cylinder with two solar panel wings and a high gain parabolic antenna attached to the curved surface. A bell-shaped unit holding propulsion systems was attached to the bottom of the cylinder, and mounted on top was a 2. The lander was encased in a spherical shell before landing to help protect it from the heat of entry as it slowed from