The 3MV planetary probe (short for 3rd generation Mars-Venus) is a designation for a common design used by early Soviet unmanned probes to Mars and Venus. It was an incremental improvement of earlier 2MV probes and was used for Zond 1, Zond 2 and Zond 3 missions to Mars as well as several Venera probes. It was standard practice of the Soviet space program to use standardized components as much as possible. All probes shared the same general characteristics and differed only in equipment necessary for specific missions. Each probe also incorporated improvements based on experience with earlier missions.It was superseded by the 4MV family.