Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Zond 3, a member of the Soviet Zond program, was the first Zond spacecraft to successfully complete its mission (a Lunar flyby) and took a number of amazing photographs for its time. It is believed that Zond 3 was initially designed as a companion spacecraft to Zond 2 to be launched to Mars during the 1964 launch window. The opportunity to launch was missed, and the spacecraft was launched on a Mars trajectory as a spacecraft test, even though Mars was no longer attainable.The spacecraft design was similar to Zond 2, in addition to the imaging equipment it carried a magnetometer, ultraviolet (0.25 to 0.35 micrometre and 0.19 to 0.27 micrometre) and infrared (3 to 4 micrometre) spectrographs, radiation sensors (gas-discharge and scintillation counters), a radiotelescope and a micrometeoroid instrument. It also had an experimental ion engine.