Zenit (launcher)

A Zenit-3 SLB in Baikonur

Zenit-2 in Baikonur, December 10, 2001

The side boosters of the Energija rocket each form the first stage of a Zenit rocket

Sea launch platform in Long Beach Harbor

The Zenit [ zeːˈnɪt ] ( Ukrainian Зеніт; Russian Зени́т ) is a Ukrainian launcher that was used from 1985 to 2017 . It was originally developed between 1976 and 1985 as the first stage for the Energija rocket - in a single-stage variant as a booster called the Zenit-1 - but, equipped with an upper stage, was also used as an independent launcher.

The Zenit was largely made in Dnipro , Ukraine , so it has been considered Ukrainian since the fall of the Soviet Union , while some key components, such as the first stage engines, were made in Russia . It was initially used by Russia to launch military and earth exploration satellites, and later also for launching scientific and commercial satellites. A replacement by the all-Russian, so far unsuccessful Angara missile was planned. Today Russia is working on the Soyuz-5 , which is partly based on Zenit technology.

The Zenit was the most advanced launcher available to Russia and Ukraine. It was also considered one of the most modern worldwide; so the new US use Atlas rockets a derivative of the Zenit RD-180 - main engine . However, as a result of the Ukraine conflict, Russia stopped cooperation with Ukraine in the field of space travel.

Zenith-2

A two-stage version of the Zenit, developed by the Yuzhnoye design office in Dnepropetrovsk, was called Zenit-2 ( GRAU index 11K77). It was in the performance class between the Soyuz with 7 t in near-earth orbit and the Proton with 21 t at around 13.7 t ( Baikonur launch site ). The first take-off took place on April 13, 1985, the last on November 8, 2011. The Zenit-2 was 57 m high and 3.9 m in diameter, the take-off mass was around 460 t. The first stage used an RD-171 engine equipped with four combustion chambers , which developed a thrust of 7259 kN on the ground and is still the most powerful liquid rocket engine ever used. The performance of the RD-171 even surpassed the F-1 main engine of the American Saturn V moon rocket. A version with two combustion chambers is used as a lower thrust RD-180 engine in the American Atlas III and Atlas V rockets, and a version with one combustion chamber as the RD-191 in the Angara . When used as a booster for the Energija, the Zenit received an RD-170 engine that had fewer control options than the RD-171, and which should also be able to be used several times, since the boosters were to be recovered and reused. The second stage of the Zenit used the RD-120 as the main engine (not to be confused with the RD-0120 from Energija) and four RD-8 engines for attitude control. The first and second stages both worked with liquid oxygen (LOX) and the kerosene type RP-1 . The Zenit was the first Soviet rocket to receive an adaptive control system that reacts to disturbing factors (e.g. wind) in flight and can be reprogrammed from Earth.

After its first use, the Zenit was supposed to replace the Soyuz rocket in manned space travel. It was supposed to put the newly developed spaceship Sarja (not to be confused with the ISS module of the same name ), which should weigh around 15 t and could have carried up to eight space travelers, into orbit. In Baikonur , towers were built for cosmonauts to board the rocket, but they were never used after the collapse of the Soviet Union. The development of the spaceship was stopped at a very early stage in 1989. A Zenit launch facility in Plesetsk was never completed due to lack of funds. The facility was later converted to launch Angara missiles.

RD-171 engine of the Zenit

By 2007 only 28 of the 37 missions of the Zenit-2 were completely successful. The worst accident occurred on October 4, 1990, when a Zenit-2 exploded three seconds after takeoff, completely destroying one of the two launch pads. The money to rebuild the plant was missing, however. The Zenit-2 had its first commercial use on September 9, 1998, when it was supposed to carry 12 Globalstar satellites into space. But the second stage of the rocket failed, whereupon it crashed on the ground together with the expensive cargo after a few minutes of flight.

The modified Zenit-2M was launched for the first time in June 2007 (some sources, including official sources, continue to use the name Zenit-2). During this launch, the rocket launched a military payload from Baikonur into low-earth orbit. The Zenit-2M took over some modifications already integrated in the Zenit-3SL, such as: B. the improved control system. The main engines of the first stage were also modified and should now deliver more thrust. These were now called RD-171M. The commercial version of the two-stage Zenit-2M has been marketed since 2007 under the name Zenit-2SLB as part of the land launch project for take-offs from Baikonur. However, the Zenit-2 has been unsuccessful since 2007 and only takes off once.

Zenith-3

Zenit-3 is a three-stage version of the Zenit, which was used to deploy satellites in geostationary transfer orbits (GTO). The Sea Launch company deployed the three-stage Zenit 3SL rocket, with the abbreviation SL standing for S ea L aunch. A floating, converted drilling platform was used as the launch site, which is positioned near Kiritimati for launch . Due to the proximity of the launch site to the equator , the payload capacity of the rocket increased compared to Baikonur, so that a Zenit-3SL can bring satellites up to 6 t in a geotransfer orbit. The first two stages of the rocket are identical to those of a Zenit-2 except for a few small modifications. As a third step, the of the Russian company RKK Energia built Block DM-SL used that on the Blok DM of proton based missile, but other uses with LOX / kerosene fuels. The payload capacity for the geostationary transfer orbit was initially 5,250 kg and could be increased to 6,066 kg through some modifications. The engines were modified (especially the engine of the DM-SL block), the fuel load of all three stages increased and the empty weight of the stages decreased at the same time. The new rocket (without the third stage) is also called the Zenit-2S.

The first flight of the Zenit-3SL with a dummy satellite took place on March 28, 1999, the first commercial flight followed in the same year. Up to the last flight on May 26, 2014, Zenit-3SL completed a total of 35 missions, three of which failed and one of which was considered a partial success (the third stage did not reach the intended orbit, but the satellite was able to reach orbit with its own engines). Since the rocket launch site was outside the CIS , the launches were not subject to the CoCom regulations . It is estimated that starting a Zenit 3SL would cost customers around $ 90 million.

When attempting to launch the NSS-8 communications satellite on January 30, 2007 , a Zenit 3SL launcher exploded directly on the “Odyssey” launch platform. The platform suffered limited damage and was already manned by the full crew on February 1, 2007, who, as always, had withdrawn to the "Sea Launch Commander" during take-off. A metal part in a fuel pump was found to be the cause of the explosion. On January 15, 2008, the first launch took place after the accident with the Thuraya 3 telecommunications satellite , which was successful.

Under the name Land Launch , the three-stage Zenit-3SLB brought satellites from Baikonur into the geostationary transfer orbit (GTO). For this, the Zenit-3SL was slightly modified (the first two stages then correspond to the Zenit-2M) and started from the Zenit-2 launch system. Because of the less favorable location of the Baikonur Cosmodrome, the rocket could only carry 3.6 t into the GTO. The advantage of the land launch, however, was that the start-up costs are significantly lower than for a start from sea. The first of six Land Launch Zenit-3SLB launches took place on April 28, 2008, the last on December 11, 2015.

Another three-stage version called Zenit-3F uses the Fregat-SB upper stage instead of the DM-SL block. The stage is derived from the Fregat used on Soyuz missiles, but has additional drop-off fuel tanks. It can thus take up more fuel and transport heavier payloads into high orbits. This version of the Zenit flew three times from Baikonur since January 20, 2011, but was not marketed by Land Launch .

The only open Zenit launch order is the launch of the Ukrainian satellite Lybid with a Zenit-3F from Baikonur.

Dates of the zenith

version	Zenit-1 ( Energija booster)	Zenith-2	Zenit-3SL	Zenit-2SLB	Zenit-3SLB
Takeoff mass ( t )	372.6	460	472	450-460	462-466
Height (maximum) (m)	39.46	57	59.6	57.4	58.65
Launch site	Baikonur		Odyssey platform	Baikonur
Payload ( LEO 200 km) ( t )	-	13.7	6.1 (for structural reasons)	13,920	5 (for structural reasons)
Payload ( GTO ) ( t )	-		6,066	-	3.6
Payload ( GEO ) ( t )	-		2.9	-	?
First flight	May 15, 1987	April 13, 1985	March 28, 1999	-	April 28, 2008
1st stage
Engine	RD-170	RD-171
Length (m)	39.46	?	32.9
Diameter (m)	3.9
Mass ( t )	372.6 (empty 65.6)	352.7 (empty 33.9)	354.58	354.35 (empty 27.564)
Thrust (max) ( kN )	7259 (7908 in vacuum)
Burning time (s)	≈ 135	?	≈ 144	140-150
fuel	LOX / kerosene
2nd stage
Engine	-	RD-120 + RD-8
Length (m)	-	?	10.4
Diameter (m)	-	3.9
Mass ( t )	-	89.9 (empty 9.3)	90.76	90.85 (empty 8.367)	90.79 (empty 8.307)
Thrust (max) ( kN )	-	834 + 78	912 + 79.5
Burning time (s)	-	?	≈ 360	300-1100	360-370
fuel	-	LOX / kerosene
3rd stage
Engine	-	-	11D58M	-	11D58M
Length (m)	-	-	5.93	-	5.93
Diameter (m)	-	-	3.7	-	3.7
Mass ( t )	-	-	19.7	-	17.8 (empty 3.2)
Thrust (max) ( kN )	-	-	79.5	-	79.5
Burning time (s)	-	-	≈ 700	-	≈ 600
fuel	-	-	LOX / kerosene	-	LOX / kerosene
Payload fairing
Length (m)	-	13.7	11.39	13.7	10.4
Diameter (m)	-	3.9	4.15	3.9	4.1

Start list

• List of Zenit rocket launches

Web links

Commons : Zenit  - album with pictures, videos and audio files

• Bernd Leitenberger: The Zenit launcher
• Zenit launch vehicle on the Russian Space Web (English)
• Rocket Segment Overview ( Memento from March 26, 2018 in the Internet Archive )
• Rocket launcher "Zenit" (11К77) at Buran-energia.com (English)
• Technologies - Zenit on the website of the Ukrainian manufacturer KB Yuzhnoye (English)
• Zenit family on skyrocket.de (English)

swell

1. ↑ Sea Launch: Sea Launch Assesses Status and Plans for Next Steps ( Memento of February 3, 2007 in the Internet Archive ), February 1, 2007
2. ↑ Cause of the false start of the Zenit-3SL - failure of an engine ( memento from April 17, 2013 in the web archive archive.today ), RIA novosti , March 13, 2007, accessed on October 26, 2011
3. ^ Thuraya-3. Sea launch, archived from the original on April 22, 2014 ; accessed on February 20, 2014 .