In the meantime, the United States had succeeded with the Mariner 2 Venus probe and Mariner 4 Mars probe, and after a long string of lunar probe failures, Ranger 6 successfully impacted on the Moon (with a failed TV system), and Ranger 7 successfully sent back a series of TV pictures.

Among other design flaws they discovered was that the Venera landers, after being subjected to a centrifuge test, failed at half the G forces that they were supposed to handle.

The entry body contained a radio communication system, scientific instruments, electrical power sources, and medallions bearing the Coat of Arms of the Soviet Union.

[5][6] The power system for the carrier spacecraft was notable in that it was the first operational use of Gallium Arsenide (GaAs) solar cells in space.

GaAs solar cells, manufactured by Kvant [ru], were chosen because of their higher performance in high-temperature environments.