Zond 3

Zond 3 was a 1965 space probe intended to be sent toward Mars^[1] as a spacecraft test. It was a member of the Soviet Zond program sharing designation Zond, while being part of Mars 3MV project. It was unrelated to Zond spacecraft designed for manned circumlunar mission (Soyuz 7K-L1). Zond 3 completed a successful Lunar flyby, taking a number of good quality 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.

History

Zond 3 was a repeat of a mission that failed in late 1963 intended to test communication at distances equivalent to the distances experienced by Mars and Earth.^[2] It passed by Earth's moon, the Moon, in 33 hours and communication ended when it was at a distance of 150 million kilometers from the Earth.^[3] The spacecraft was a 3MV-4 type and launched into space on a 8K78 Molniya rocket on July 18, 1965.^[4] It operated for 228 days, roughly equivalent to the time needed to survive a journey to Mars and exceeding that needed for Venus.^[4]

The Zond 3 took pictures of the Moon on film which were then scanned and returned by radio signal back to Earth; it took 25 exposures in visible light and three more for an ultraviolet spectrometer.^[4] The images it took could be re-transmitted, and the most distant re-transmission was on October 23, 1965 at a distance of 31.5 million km from the Earth.^[4]

Spacecraft design

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.

Mission

Mosaic of all the Zond 3 images created with modern image processing tools.

The spacecraft, a Mars 3MV-4A, was launched from a Tyazheliy Sputnik (65-056B) earth orbiting platform towards the Moon and interplanetary space. The spacecraft was equipped with an f/106 mm camera and TV system that provided automatic inflight film processing. On July 20 lunar flyby occurred approximately 39 hours after launch at a closest approach of 9200 km. 23 photographs and 3 ultraviolet spectra of very good quality were taken of the lunar farside from distances of 11,570 to 9960 km over a period of 68 minutes. The photos covered 19,000,000 km² of the lunar surface. Zond 3 proceeded on a Mars trajectory, but not at a time when planetary encounter would occur. To test telemetry, the images were rewound and transmitted at 2.2 million km, 31.5 million km and possibly again at greater distances, thus proving the ability of the communications system. The subsequent transmissions were also at a higher data rate.^[5] The mission was ended and radio contact ceased when it was at a distance of 150 million km.

This article was originally based on material from NASA (NSSDC) information on Zond 3

References

External links

• Zarya - Zond 3
• Soviet Lunar Images
• Processed images from the Zond 3 mission

Zond program
3MV based missions	Zond 1 Zond 2 Zond 3
Soyuz 7K-L1/L1S	Kosmos 146 Kosmos 154 Zond 1967A Zond 1967B Zond 4 Zond 1968A Zond 1968B Zond 5 Zond 6 Zond 1969A Zond-M 1 Zond-M 2 Zond 7 Zond 8 Zond 9 Zond 10