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3MV (Zond)


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Flight beyond the ecliptic

The one of a kind mission of Kosmos-21

Previous chapter: Origin of the 3MV project

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On October 31, 1963, top industry officials reported to the Kremlin that the first "probe vehicle" or "Zond" for an Earth-return mission had been completed, while the assembly of the second Zond was in its final stages. Both spacecraft were described as identical to the third-generation Mars-Venus probes, 3MV. The astronomical launch window for these two missions was expected to close around Nov. 19, 1963, even though currently available documents provide no criteria which limited the launch window. According to the report, both spacecraft were intended for a deep-space flight concluding with a return to Earth.

The Zond probe would first be inserted into an initial parking orbit around the Earth by a 8K78M (Molniya) rocket. Then, the fourth stage (Block L) of the rocket still attached to the probe would fire, inserting its payload into a solar orbit and tilting its inclination toward the ecliptic (orbital plane of the Earth around the Sun) by five degrees. As a result, the spacecraft would start climbing above the ecliptic plane.

Three months after the launch and a quarter of a revolution around the Sun, the probe would reach a maximum distance of 12-16 million kilometers away from Earth. After that, the spacecraft would start its descent back toward the ecliptic plane, while simultaneously drifting toward Earth. Six months later, when the orbit of the Earth and that of the probe crossed again on the opposite side of the Sun, the spacecraft would rendezvous with the Earth, after having completed a half an orbit around the Sun. At that point, a 270-kilogram lander would parachute back to Earth, testing high-speed return from interplanetary space.

To ensure a landing in the prescribed area, two orbit-correction maneuvers would have to be conducted on the ninth day of the mission and 10-15 days before landing on Earth. The exact direction and the Delta V (burn duration) of the orbital maneuvers would have to be calculated based on measurements of the probe's actual trajectory. A ground station near Yevpatoria, NIP-16, would be used for tracking, flight control and downlinks of scientific information from the probe. Other ground stations of the Soviet Ministry of Defense would be used to receive telemetry and track the vehicle during its Earth-orbiting phase of the flight. (509)

Zond-1 becomes Kosmos-21

The first Zond vehicle arrived in Tyuratam on October 28 (202) and the Soviet government gave a green light to its mission on November 4, 1963. As it was already a tradition, the decree that gave the formal "go ahead" to the launch also approved a public announcement, which would be released after the successful departure of the spacecraft from the Earth orbit. This announcement would identify the mission as Zond-1. The exact liftoff date remained blank, to be filled only after the successful departure of the probe. In case of the failure of the mission in the initial parking orbit, another draft of the public announcement was prepared identifying the spacecraft as Kosmos. The mission would be launched and fly in accordance with the plan proposed on October 31. (509) If everything went as planned, the spacecraft would return to Earth in May 1964.

On Nov. 11, 1963, at 09:23:34 Moscow Time, the USSR launched what is now believed have been the 3MV-1A No. 2 vehicle. The liftoff went smoothly, however an anomaly during the separation between the third stage of the Molniya rocket and the Block L fourth stage apparently led to the failure of the Block L's propulsion system. (202) p. 125. According to one source, the firing of the fourth stage took place, while the spacecraft was in a wrong orientation. (52) In any case, the spacecraft was left stranded in a 229 by 195-kilometer orbit with an inclination of 64.83 degrees toward the Equator. (2) Accordingly, the USSR officially announced the mission as Kosmos-21 and never revealed its true destination. According to Western radar data, a single object, most likely representing the stack of Block L and the probe, plunged back to Earth on November 15. (227) Based on similarities of the flight profile to previous Soviet launches, Western sources determined that this mission had been targeting the Moon and was possibly preparing a flight to Venus. (185) For lack of a better information, it remained so for decades.

The confusion surrounding the mission of Kosmos-21 was further exacerbated in 1996 by the the official history of RKK Energia, the company that succeeded Korolev's OKB-1 design bureau. The publication claimed that the November 11, 1963, probe was targeting Mars, even though the timing of the launch was far outside of the available biannual window for reaching the Red Planet! (52) A number of other post-Soviet sources have corroborated this information. (202) Only in 2011, did newly published documents allow to identify the true flight plan of Kosmos-21. (509) If anything, it proves that official histories are prone to errors like any other sources.

Next chapter: Mission of 3MV-1A No. 4A spacecraft


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Kosmos-21 mission at a glance:


3MV-1A No. 2 (Zond) Kosmos-21

Launch vehicle

8K78 (Molniya) No. G15000-17 or G103-18 or G15000-06 (202)

Launch date

1963 Nov. 11, 09:23:34 Moscow Time

Flight plan

Flight beyond the ecliptic and return to Earth

Flight status

Failed in Earth orbit

Date of reentry

1963 Nov. 15

Planned Earth return and landing date

1964 May


Article by Anatoly Zak; last update: April 1, 2014

Page editor: Alain Chabot; last edit: March 31, 2014

All rights reserved





A 3MV-1 (Mars-Venus) spacecraft configured for the mission to Venus. 3MV-4 No. 4 spacecraft was officially announced as Venera-2, 3MV-3 No. 1 as Venera-3. Copyright © 2000, 2011 Anatoly Zak


A Block L fourth stage (foreground) and the Block I third stage of the 8K78 (Molniya) rocket during the assembly. Credit: RKK Energia


A 8K78 (Molniya) rocket moments before liftoff from Tyuratam. Credit: RKK Energia











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