Zond 2
Zond 2 was a Soviet space probe launched on November 30, 1964, as part of the Zond program. It was intended to perform a flyby of Mars and act as a test flight for future planetary probes.
The spacecraft carried a suite of scientific instruments, including a magnetometer, spectroreflectometer for studying infrared and ultraviolet radiation, instruments for detecting cosmic rays and plasma, and a camera.
Communication was lost with Zond 2 sometime in May 1965, before its planned Mars encounter. While the exact cause of the failure remains unknown, it is believed to be related to a malfunction in the spacecraft's attitude control system. Despite the communication loss, Zond 2 continued its trajectory and passed by Mars on August 6, 1965, at a distance of approximately 1,500 kilometers. No data was returned from the flyby.
Although Zond 2 was ultimately unsuccessful in its primary mission, it provided valuable experience in deep space navigation and spacecraft design, contributing to the development of later Soviet planetary probes.