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Soyuz-5 development in 2017


Origin of the Zenit rocket

The Zenit rocket became the latest and the most advanced launch vehicle developed in the former Soviet Union in the 20th Century.

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The development of the 11K77 launch vehicle, known today as Zenit-2, started at the beginning of the 1970s in the apparent attempt to create a "standartized" family of light, medium and heavy lauchers.

According to KB Yuzhnoe sources, the design bureau considered a family of three launchers in its bid for the government assignment to create a "standard" family of launchers:

  • 11K55 light-weight vehicle
  • 11K77 medium-lift vehicle
  • 11K37 heavy-lift vehicle

All three vehicles were designed to share propulsion and control systems, booster and upper stages, processing and launch facilities. For the 11K37 vehicle KBTM bureau's Department 8 (PKO-8) studied a launch complex with the vertical assembly of the vehicle on the launch pad. It would be the first precedent for this type of launch processing in the USSR. The design experience was later applied toward the Angara project. (103)

A three-booster 11K37 vehicle would use RD-170 engine on each of its pair of strap-on boosters. The core stage would ignite in stratosphere, everal seconds before separation of two strap-ons.

Out of three proposals, the Soviet space forces, VKS, was primarily interested in the 11K77 version, to which KB Yuzhnoe gave a priority in development. The preliminary design of the 11K77 vehicle was completed in April 1974. However in 1975, the original configuration of the rocket, featuring multi-modular architecture, was abandoned in favor of a single-module booster.

On March 16, 1976, the Soviet government officially approved the development of the 11K77 Zenit project. In agreement with NPO Energia, the Zenit's first stage was chosen as a base for the strap-on boosters of the Energia super heavy-lift launcher. The original plans called for the first test launch of the Zenit rocket in 1982.

Sometime in the second half of the 1970s, the Ministry of the General Machine Building, overseeing space industry in the USSR, also proposed the Zenit as a launch vehicle for a super-secret Tselina-2 electronic intelligence satellites, also in the development at the time.

However, the developers of the super-powerful engine of the first stage for Zenit run into considerable trouble. Between 1981 and 1983, the problems plagued the test firings of the RD-171 engine. One of the solutions proposed at the time called for the use of one-chamber engines from the first stage of the N1 rocket.

On top of the difficulties with the engine development, the financial problems in the industry in the mid-1980s further slowed down the program.

The construction of the launch complex for Zenit-2 in Baikonur started in 1978 and the first launch pad was declared operational in December 1983.

The testing of the Zenit launcher was officially completed in December 1987.

In December 1990, with completion of the second (left) launch pad in Baikonur, the complex of the Zenit-2 rocket and Tselina-2 spacecraft was officially accepted into armaments.

In the 1990s, the RKK Energia started the negotiations with the potential partners on forming a joint venture with a purpose of launching commercial payloads from a floating platform. The project became known as Sea Launch.

In June 2001, Sea Launch officials announced that they offered NASA to use the Zenit rocket and its ocean-based platform to transport cargo to the ISS.

After 2000, KB Yuzhnoe also briefly considered upgrading the Zenit rocket with a second side booster, which could be used on the Sea Launch platform. It could deliver around 25 tons of payload into the low Earth's orbit. A three-booster version of the rocket was also evaluated for delivering between 30 and 38 tons. Finally, a four-booster variant would have an estimated payload of 54 tons.

In mid-2000s, three-, four- and five-booster architectures for Zenit upgrades were under consideration leading to proposals for the Russian-Ukrainian Sodruzhestvo rocket around 2012.

Crimean crisis

In 2014, the Russian annexation of Crimea and the resulting conflict in the East of Ukraine dealt a blow to all Russian-Ukrainian economic ties, including space cooperation. The production of the Zenit rocket was virtually frozen leaving the future of the launch vehicle in limbo.


Overview of the Zenit launch vehicle family:

Manufacturer index
US designation
Sheldon designation
Notes, payloads
Not developed
Not developed
Zenit-1 (Energia's first stage)
Tselina-2, Orlets, Yenisei-2, Okean-O
Sea Launch-based three-stage rocket
Land Launch-based
Land Launch-based three-stage rocket with Block DM-SLB third stage
Zenit-2SLB with Fregat-SB as the third stage


Specifications of the Zenit-2 rocket (two booster stages):

Number of stages
Length of the vehicle

57 - 61.64 meters

3.9 meters
Mass (fueled)
459 tons
Oxidizer Liquid oxygen
First launch 1985
Launch sites Baikonur (two pads: Site 45)
Stage I -
Stage I mass

349 tons

Stage I dry mass

29 tons

Stage I length

32.9 meters

Stage I diameter 3.9 meters
Stage I burn time ~143 seconds from launch
Stage I propulsion

1 (one) four-chamber RD-171 engine (11D520)

Stage II -
Stage II mass (fueled)

89.5 tons

Stage II dry mass

8.9 tons

Stage II length

10.4 meters

Stage II diameter 3.9 meters
Stage II burn time 249 seconds (main engine)
2nd stage propulsion
  • 1 one-chamber RD-120 engine (11D123)
  • 1 four-chamber 11D513 steering engine
Launch system

ground-based: (8U259)

Payload to 200-km circular orbit from Baikonur
  • 13.74 tons to 51-degree
  • 11.38 tons to 99-degree sun-synchronous orbit


Zenit development cooperation:

Element Developer Chief-designer Location
Overall design
KB Yuzhnoe
V. F. Utkin
L. Kuchma
Propulsion units (1st and 2nd stage)
V. Glushko
3rd stage
RKK Energia
Y.P. Semenov
Podlipki (Korolev)
Flight control system
N.A. Pilyugin
Launch complex (surface)
KB Transmash
V.N. Soloviev


Next chapter: Zenit's first stage


This page is maintained by Anatoly Zak

Last update: August 13, 2018

All rights reserved


A fully-assembled Zenit-2 booster is used for personnel training in the assembly building in Baikonur. Copyright © 2000 Anatoly Zak


The 11K55 project -- the "light" version of the Zenit launcher. Credit: KB Yuzhnoe


The 11K37 project -- the "heavy" version of the Zenit. Credit: KB Yuzhnoe


A cutaway view of the three-stage Zenit-3 launch vehicle, equipped with Block-D upper stage. Zenit-3 would be able to deliver one (1) ton of payload to the geostationary orbit after its launch from Baikonur. Zenit-3 has never flown from Baikonur but, later became a base for the Sea Launch project. Copyright © 2001

Svityaz launcher

The Svityaz project -- the air-launched version of the Zenit rocket, carried on top of a Mriya transport plane. Credit: KB Yuzhnoe


After year 2000, KB Yuzhnoe in Dnepropetrovsk, Ukraine, considered upgrading the Zenit rocket for the Sea Launch venture with a second asymmetrical booster, as well as building a three-booster configuration. Copyright © 2013 Anatoly Zak


The RD-170 engine powered the first stage of the Energia rocket. Copyright © 2005 Anatoly Zak


The RD-120 (11D123) engine powers the second stage of the Zenit launcher. Copyright © 2001 Anatoly Zak


An adapter built by RKK Energia's manufacturing arm for the Zenit rocket used in the Land Launch venture. Copyright © 2011 Anatoly Zak