Fregat

 ( Rocket Stages ) 

Fregat () is an upper stage developed by Lavochkin for universal compatibility with a wide range of medium- and heavy-lift launch vehicles. Fregat has been used primarily with Soyuz and Zenit rockets, and entered operational service in February 2000.

Fregat uses a liquid rocket engine burning unsymmetrical dimethylhydrazine (UDMH) fuel and dinitrogen tetroxide () oxidizer, a pair of hypergolic propellants that ignite on contact. With a success rate of 97.3%, including two failures and one partial failure, Fregat is among the most reliable upper stages in operation. It has deployed more than 300 payloads into a variety of orbits and is capable of placing three or more spacecraft into distinct orbits during a single mission, owing to its ability to restart up to seven times and operate for a total burn duration of up to 1,350 seconds.

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Description The Fregat upper stage is a versatile and autonomous vehicle designed to inject large payloads into a range of orbits, including low, medium, and geosynchronous. Additionally, it serves as an escape stage for sending space probes on interplanetary missions, such as the Venus Express and Mars Express.

Developed by NPO Lavochkin in the 1990s, the Fregat features six spherical tanks—four for propellants and two for avionics—arranged in a circle. Its main engine is centrally positioned, allowing for a compact design with a diameter larger than its height. Structural support is provided by eight struts passing through the tanks, which also transfer thrust loads to the launcher. Fregat operates independently from the lower stages of its launch vehicle, with its own guidance, navigation, attitude control, tracking, and telemetry systems.

The Fregat’s design was largely based on the Satellite bus used in the Soviet Phobos program of the late 1980s, itself based on the architecture used for the Soviet lunar probes developed at NPO Lavochkin in the 1960s. Fregat also integrated several flight-proven subsystems and components from previous spacecraft and rockets. This approach ensured high reliability and accelerated development. Fregat was flight-qualified in February 2000 and successfully completed four missions that same year.

Currently used as the fourth stage on Soyuz launch vehicles, the Fregat’s S5.92 engine is capable of up to 25 ignitions, with seven demonstrated during flight. This allows it to execute complex mission profiles that would be impossible for the launch vehicle alone. The stage provides both three-axis and spin stabilization for spacecraft payloads. Fregat uses storable, hypergolic propellants—unsymmetrical dimethylhydrazine (UDMH) as fuel and dinitrogen tetroxide (, also called NTO or amyl) as the oxidizer, which ignite spontaneously upon contact. To date, Fregat has successfully deployed over 300 payloads into various orbits and remains the only upper stage capable of placing payloads into three or more distinct orbits in a single launch.

, adding a Fregat upper stage to a Soyuz-2 launch costs about .

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Fregat upper stage launch statistics

	1	2000/02/09	1001	Fregat	ST07	Soyuz-U	Full-size satellite layout, Inflatable Braking Device
	2	2000/03/20	1002	Fregat	ST08	Soyuz-U	Dumsat
	3	2000/07/16	1003	Fregat	ST09	Soyuz-U	Cluster FM6, Cluster FM7
4	2000/08/09	1004	Fregat	ST10	Soyuz-U	Cluster FM5, Cluster FM8
5	2003/06/02	1005	Fregat	ST11	Soyuz-FG	Mars Express, Beagle 2
6	2003/12/27	1006	Fregat	ST12	Soyuz-FG	AMOS-2
7	2005/08/13	1007	Fregat	ST13	Soyuz-FG	Galaxy 14
8	2005/11/09	1010	Fregat	ST14	Soyuz-FG	Venus Express
9	2005/12/28	1009	Fregat	ST15	Soyuz-FG	GIOVE-A
10	2006/10/19	1011	Fregat	ST16	Soyuz-2.1a	MetOp-A
11	2006/12/24	1012	Fregat	–	Soyuz-2.1a	Meridian № 11L
12	2006/12/27	1013	Fregat	ST17	Soyuz-2.1b	CoRoT
13	2007/05/29	1016	Fregat	ST18	Soyuz-FG	Globalstar M065, Globalstar M069, Globalstar M071, Globalstar M072
14	2007/10/20	1015	Fregat	ST19	Soyuz-FG	Globalstar M066, Globalstar M067, Globalstar M068, Globalstar M070
15	2007/12/14	1015-2	Fregat	ST20	Soyuz-FG	RADARSAT-2
16	2008/04/26	1008	Fregat	ST21	Soyuz-FG	GIOVE-B
17	2009/05/21	1018	Fregat	–	Soyuz-2.1a	Meridian № 12L
18	2009/09/17	1014	Fregat	–	Soyuz-2.1b	Meteor-M № 1, Sterkh, Universitetsky-Tatyana-2, UGATUSAT, BLITS, IRIS, Sumbandila
19	2010/10/19	1023	Fregat-M	ST22	Soyuz-2.1a	Globalstar M073, Globalstar M074, Globalstar M075, Globalstar M076, Globalstar M077, Globalstar M079
20	2010/11/02	1022	Fregat-M	–	Soyuz-2.1a	Meridian № 13L
21	2011/01/20	2001	Fregat-SB	–	Zenith-3SLBF	Elektro-L No.1
22	2011/02/26	1035	Fregat-M	–	Soyuz-2.1b	Glonass-K № 11L
23	2011/07/13	1024	Fregat-M	ST23	Soyuz-2.1a	Globalstar M081, Globalstar M083, Globalstar M085, Globalstar M088, Globalstar M089, Globalstar M091
24	2011/07/18	2002	Fregat-SB	–	Zenith-3SLBF	Spektr-R
25	2011/10/02	1045	Fregat-M	–	Soyuz-2.1b	Glonass-M № 742
26	2011/10/21	1030	Fregat-MT	VS01	Soyuz-ST-B	Galileo 1, Galileo 2
27	2011/11/28	1046	Fregat-M	–	Soyuz-2.1b	Glonass-M № 746
28	2011/12/17	1021	Fregat	VS02	Soyuz-ST-A	Pleiades-1A, ELISA W11, ELISA E12, ELISA W23, ELISA E24, SSOT
29	2011/12/23	1042	Fregat-M	–	Soyuz-2.1b	Meridian № 15L
30	2011/12/28	1027	Fregat-M	ST24	Soyuz-2.1a	Globalstar M080, Globalstar M082, Globalstar M084, Globalstar M086, Globalstar M090, Globalstar M092
31	2012/07/22	1019	Fregat	–	Soyuz-FG	Kanopus-V № 1, Zond-PP, BelKA, exactView-1, TET-1
32	2012/09/17	1037	Fregat-M	ST25	Soyuz-2.1a	MetOp-B
33	2012/10/12	1031	Fregat-MT	VS03	Soyuz-ST-B	Galileo 3, Galileo 4
34	2012/11/14	1034	Fregat-M	–	Soyuz-2.1a	Meridian № 16L
35	2012/12/02	1020	Fregat	VS04	Soyuz-ST-A	Pléiades-1B
36	2013/02/06	1029	Fregat-M	ST26	Soyuz-2.1a	Globalstar M078, Globalstar M093, Globalstar M094, Globalstar M095, Globalstar M096, Globalstar M097
37	2013/04/26	1047	Fregat-M	–	Soyuz-2.1b	Glonass-K № 747
38	2013/06/25	1041	Fregat-MT	VS05	Soyuz-ST-B	O3b FM1, O3b FM2, O3b FM4, O3b FM5
39	2013/12/19	1040	Fregat-MT	VS06	Soyuz-ST-B	Gaia spacecraft
40	2014/03/23	112-01	Fregat-M	–	Soyuz-2.1b	Glonass-M № 754
41	2014/04/03	1038	Fregat-M	VS07	Soyuz-ST-A	Sentinel-1A
42	2014/06/14	112-02	Fregat-M	–	Soyuz-2.1b	Glonass-M № 755
43	2014/07/08	1025	Fregat-M	–	Soyuz-2.1b	Meteor-M №2, Vernov, , UKube-1, TechDemoSat-1, SkySat-2, AISSat-2
44	2014/07/10	1032	Fregat-MT	VS08	Soyuz-ST-B	O3b FM3, O3b FM6, O3b FM7, O3b FM8
45	2014/08/22	1039	Fregat-MT	VS09	Soyuz-ST-B	Galileo 5, Galileo 6
46	2014/10/30	1026	Fregat-M	–	Soyuz-2.1a	Meridian № 17L
47	2014/11/30	1044	Fregat-M	–	Soyuz-2.1b	Glonass-K № 12L
48	2014/12/18	133-01	Fregat-MT	VS10	Soyuz-ST-B	O3b FM9, O3b FM10, O3b FM11, O3b FM12
49	2015/03/27	133-02	Fregat-MT	VS11	Soyuz-ST-B	Galileo 7, Galileo 8
50	2015/09/11	133-03	Fregat-MT	VS12	Soyuz-ST-B	Galileo 9, Galileo 10
51	2015/11/17	1033	Fregat-M	–	Soyuz-2.1b	EKS № 1
52	2015/12/11	2004	Fregat-SB	–	Zenith-3SLBF	Elektro-L No.2 № 2
53	2015/12/17	133-04	Fregat-MT	VS13	Soyuz-ST-B	Galileo 11, Galileo 12
54	2016/02/07	112-03	Fregat-MT	–	Soyuz-2.1b	Glonass-M № 751
55	2016/04/25	133-08	Fregat-M	VS14	Soyuz-ST-A	Sentinel-1B
56	2016/05/24	133-05	Fregat-MT	VS15	Soyuz-ST-B	Galileo 13, Galileo 14
57	2016/05/29	112-04	Fregat-M	–	Soyuz-2.1b	Glonass-M № 753
58	2017/01/28	133-07	Fregat-MT	VS16	Soyuz-ST-B	Hispasat 36W-1
59	2017/05/18	133-09	Fregat-M	VS17	Soyuz-ST-A	SES-15
60	2017/05/25	111–301	Fregat-M	–	Soyuz-2.1b	Tundra № 2
61	2017/07/14	122-02	Fregat-M	–	Soyuz-2.1a	Kanopus-V-IK, MKA-N № 1, MKA-N № 2, Mayak, Iskra-MAI-85, Ecuador UTE-YUZGU», Flying Laptop, TechnoSat, WNISAT-1R, NorSat-1, NorSat-2, Flock-2k 1...48, CICERO 1...3, Corvus-BC 1...2, Lemur-2 42...49, NanoACE
62	2017/09/22	112-05	Fregat-M	–	Soyuz-2.1b	Glonass-M № 752
63	2017/11/28		Fregat-M	–	Soyuz-2.1b	Meteor-M №2, Baumanets-2, LEO Vantage 2, Helios-Wire BIU, IDEA-OSG 1, AISSat-3, D-Star One, SEAM, Corvus-BC 3, Lemur-2 58...67
64	2017/12/26	2006	Fregat-SB	–	Zenith-3SLBF	Angosat-1
65	2018/02/01	122-03	Fregat-M	–	Soyuz-2.1a	Kanopus-V № 3, Kanopus-V № 4, Lemur-2 74, Lemur-2 75, Lemur-2 76, Lemur-2 77, S-Net A, S-Net B, S-Net C, S-Net D, D-Star One
66	2018/03/09	133-06	Fregat-MT	VS18	Soyuz-ST-B	O3b FM13, O3b FM14, O3b FM15, O3b FM16
67	2018/06/16	112-06	Fregat-M	–	Soyuz-2.1b	Glonass-M № 756
68	2018/11/03	112-08	Fregat-M	–	Soyuz-2.1b	Glonass-M № 757
69	2018/11/07	133-14	Fregat-M	VS19	Soyuz-ST-B	MetOp-C
70	2018/12/19	133-10	Fregat-M	VS20	Soyuz-ST-B	Composante Spatiale Optique
71	2018/12/27	122-06	Fregat-M	–	Soyuz-2.1a	Kanopus-V № 5, Kanopus-V № 6, GRUS-1, ZACube-2, Lume-1, Flock-3k 1...12, Lemur-2 88...95, D-Star One iSat, D-Star One Sparrow, UWE-4, ICEYE-Dummy, SAMSON-Dummy 1...3
72	2019/02/21	112-07	Fregat-M	–	Soyuz-2.1b	EgyptSat-A
73	2019/02/27	133-15	Fregat-M	VS21	Soyuz-ST-B	OneWeb-0006, OneWeb-0007, OneWeb-0008, OneWeb-0010, OneWeb-0011, OneWeb-0012
74	2019/04/04	133-17	Fregat-MT	VS22	Soyuz-ST-B	O3b FM17, O3b FM18, O3b FM19, O3b FM20
75	2019/05/27	112-09	Fregat-M	–	Soyuz-2.1b	Glonass-M № 758
76	2019/07/05	122-04	Fregat-M	–	Soyuz-2.1b	Meteor-M No.2 Sokrat VDNH-80 AmurSat SEAM-2.0 MTCube SONATE Beesat 9...13 MOVE-IIb TTU-101 Ecuador-UTE El Camino Real Lemur-2 100...107 NSLSat-1 JAISAT-1 EXOCONNECT LightSat Lucky-7 ICEYE X4 ICEYE X5 CarboNIX DoT 1
77	2019/07/30		Fregat-M	–	Soyuz-2.1a	Meridian № 18L
78	2019/09/26		Fregat-M	–	Soyuz-2.1b	Tundra № 3
79	2019/12/11	112-10	Fregat-M	–	Soyuz-2.1b	Glonass-M № 759
80	2019/12/18		Fregat-M	VS23	Soyuz-ST-A	COSMO-SkyMed CHEOPS EyeSat ANGELS OPS-SAT
81	2020/02/07		Fregat-M	ST27	Soyuz-2.1b	OneWeb (34 units)
82	2020/02/20		Fregat-M	–	Soyuz-2.1a	Meridian № 19L
83	2020/03/17		Fregat-M	–	Soyuz-2.1b	GLONASS-M №760
84	2020/03/21		Fregat-M	ST28	Soyuz-2.1b	OneWeb (34 units)
85	2020/12/29		Fregat	VS24	Soyuz ST-A	Falcon Eye 2
86	2021/02/28	122-07	Fregat-M	–	Soyuz-2.1b	Arktika-M №1
87	2021/03/22	122-05	Fregat-M	–	Soyuz-2.1a	CAS500-1 ELSA-d Target, Chaser DMSAT-1 Fukui Prefectural Satellite GRUS-1 × 3 ADELIS-SAMSON x 3 BeeSat × 4 Challenge One CubeSX-HSE CubeSX-Sirius-HSE GRBAlpha Hiber-3 Kepler-6,7 KMSL KSU_Cubesat LacunaSat-2b Shaheen Sat 17 NANOSATC-BR2 OrbiCraft-Zorkiy Pumbaa, Timon WildTrackCube-SIMBA 3B5GSAT UNISAT-7 BCCSAT-1 FEES DIY SMOG-1 STECCO
88	2021/03/25	123-05	Fregat	ST30	Soyuz-2.1b	OneWeb (36 units)
89	2021/04/25	123-11	Fregat	ST31	Soyuz-2.1b	OneWeb (36 units)
90	2021/05/28	123-10	Fregat	ST32	Soyuz-2.1b	OneWeb (36 units)
91	2021/07/01	112-15	Fregat	ST33	Soyuz-2.1b	OneWeb (36 units)
92	2021/08/21	123-03	Fregat	ST34	Soyuz-2.1b	OneWeb (34 units)
93	2021/09/14	123-05	Fregat	ST35	Soyuz-2.1b	OneWeb (34 units)
94	2021/10/14	123-14	Fregat	ST36	Soyuz-2.1b	OneWeb (36 units)
95	2021/11/25	111–305	Fregat	–	Soyuz-2.1b	EKS-5
96	2021/12/05	133-13	Fregat-MT	VS26	Soyuz ST-B	Galileo FOC FM23 Galileo FOC FM24
97	2021/12/27	123-04	Fregat	ST37	Soyuz-2.1b	OneWeb (36 units)
98	2022/02/05	111–401	Fregat	–	Soyuz-2.1a	Neitron №1
99	2022/02/10	133-19	Fregat-MT	VS27	Soyuz ST-B	OneWeb (34 units)
100	2022/03/22	111-?	Fregat	–	Soyuz-2.1a	Meridian-M 10 (20L)
101	2022/07/07	112-13	Fregat	–	Soyuz-2.1b	GLONASS-K 16
102	2022/08/09	123-06	Fregat	–	Soyuz-2.1b	Khayyam CubeXS-HSE-2 CYCLOPS Geoscan-Edelweiss ISOI KAI-1 KODIZ Kuzbass-300 MIET-AIS Polytech Universe-1, 2 ReshUCube-1 Siren Skoltech B1, B2 UTMN VIZARD-SS1
103	2022/10/10	112-16	Fregat	–	Soyuz-2.1b	GLONASS-K 17
104	2022/10/22	142-503	Fregat	–	Soyuz-2.1b	Gonets-M 23, 24, 25 Skif-D
105	2022/11/02	111-306	Fregat	–	Soyuz-2.1b	EKS-6
106	2022/11/28	112-??	Fregat	–	Soyuz-2.1b	GLONASS-M 761
107	2023/05/26	142-01	Fregat	–	Soyuz-2.1a	Kondor-FKA №1
108	2023/06/27	142-02	Fregat	–	Soyuz-2.1b	Meteor-M №2-3 Ahmat-1 ArcCube-01 A-SEANSAT-PG1 Avion BSUSat-2 CSTP-1.1, 1.2 Cube-SX-HSE-3 Impuls-1 Khors-1, 2 KuzGTU-1 Monitor-2, 3, 4 Nanosond-1 NORBI 2 PHI-Demo Polytech Universe-3 Rassvet-1 × 3 ReshUCube-2 SamSat-ION Saturn Sirius-SINP-3U SITRO-AIS × 8 StratoSat TK-1 Svyatobor-1 UmKa-1 UTMN-2 Vizard-meteo Yarilo-3, 4 Zorkiy-2M
109	2023/08/07	112-23	Fregat	–	Soyuz-2.1b	GLONASS-K2 13L
110	2023/08/10	122-10	Fregat	–	Soyuz-2.1b	Luna 25
111	2023/12/16	122-11	Fregat	–	Soyuz-2.1b	Arktika-M No. 2
112	2024/02/29	142-03	Fregat-M	–	Soyuz-2.1b	Meteor-M No.2-4 MARAFON-D-GVM Pars 1 SITRO-AIS × 16 Zorkiy-2M-2
113	2024/05/16	?	Fregat-M	–	Soyuz-2.1b	Nivelir-L №4 (Kosmos 2576) Rassvet-2 × 3 SITRO-AIS × 4 Zorkiy-2M-4 Zorkiy-2M-6
114	2024/11/04	142-601	Fregat-M	–	Soyuz-2.1b	Ionosfera-M №1 Ionosfera-M №2 Altair ArcticSat-1 ASRTU-2 CSTP-2.1, 2.11, 2.2 Gorizont Hod-Hod 1A HyperView-1G Khors 3, 4 Kolibri-S Kowsar Mordovia-IoT MTUCI-1 Nokhcho Norbi-3 Polytech Universe-4, 5 RTU MIREA 1 Ruzaevka-390 SamSat-ION 2 SIT-2086 SIT-HSE SITRO-AIS × 24 TUSUR-GO Vizard-ion Vladivostok-1 YUZGU-60 ZimSat-2

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Failures

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August 2014 failure The Arianespace-operated flight of a Fregat MT ended in failure on 22 August 2014 after the vehicle deposited two European Union/ESA Galileo navigation satellites into the wrong orbit. The lift off at 12:27:11 UTC from the Sinnamary near Kourou, French Guiana, appeared to go well. However, a failure was only apparent later when, after the second firing of the Fregat MT upper stage had taken place, the satellites were detected as being in the wrong orbit.

The Independent Inquiry Board formed to analyze the causes of the "anomaly" announced its definitive conclusions on 7 October 2014 following a meeting at Arianespace headquarters in Évry, near Paris. The failure occurred during the flight of the Fregat fourth stage. It occurred about 35 minutes after liftoff, at the beginning of the ballistic phase preceding the second ignition of this stage. The scenario that led to an error in the orbital injection of the satellites was precisely reconstructed, as follows:

• The orbital error resulted from an error in the thrust orientation of the main engine on the Fregat stage during its second powered phase.
• This orientation error was the result of the loss of inertial reference for the stage.
• This loss occurred when the stage's inertial system operated outside its authorized operating envelope, an excursion that was caused by the failure of two of Fregat's attitude control thrusters during the preceding ballistic phase.
• This failure was due to a temporary interruption of the joint hydrazine propellant supply to these thrusters.
• The interruption in the flow was caused by freezing of the hydrazine.
• The freezing resulted from the proximity of hydrazine and cold helium feed lines, these lines being connected by the same support structure, which acted as a thermal bridge.
• Ambiguities in the design documents allowed the installation of this type of thermal "bridge" between the two lines. In fact, such bridges have also been seen on other Fregat stages now under production at NPO Lavochkin.
• The design ambiguity is the result of not taking into account the relevant thermal transfers during the thermal analyses of the stage system design.

The root cause of the failure of flight VS09 is therefore a shortcoming in the system thermal analysis performed during stage design, and not an operator error during stage assembly.

Since 22 August 2014, Soyuz ST-B launch vehicles with Fregat-MT upper stages have performed three successful launches, six Galileo navigation satellites have been inserted into their target orbits in frame of Soyuz at the Guiana Space Centre ongoing ESA programme.

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July 2017 partial failure In July 2017, a Russian-operated rideshare flight of a Fregat upper stage ended with 9 of 72 small satellites dead-on-orbit.

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November 2017 failure The Russian-operated flight of a Fregat upper stage ended in failure after the vehicle deposited the upper stage, a Meteor MS-1 weather satellite, and 18 secondary back into Earth's atmosphere due to the first Fregat burn being ignited with the stage in the wrong orientation. The guidance computer on the Soyuz rocket's Fregat upper stage was mis-programmed, causing it to begin an unnecessary turn that left it in the wrong orientation for a critical engine burn required to enter orbit.

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Debris The Fregats did not have enough impulse capability to de-orbit themselves after placing their payload into orbit and so several have remained in orbit as space debris.

The Fregat-SB upper stage rocket used to launch the Russian Spektr-R satellite into orbit in 2011, broke into multiple pieces on May 8, 2020 creating even more debris than normal.

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Versions

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Fregat-M/Fregat-MT Fregat-M/Fregat-MT tanks have ball-shaped additions on the tops of the tanks. These additions increase the load capability of the propellant from to , without causing any other changes to the physical dimensions of the vehicle.

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Fregat-SB A version called Fregat-SB can be used with Zenit-2SB launch vehicle. This version is a variation of Fregat-M with a block of drop-off tanks ("SBB" or Сбрасываемый Блок Баков in Russian) which makes increased payload capability possible. The torus-shaped SBB weighs and contains up to of propellant. The total dry weight of the Fregat-SB (including SBB) is and the maximum propellant carrying capacity is .

Fregat-SB was launched for the first time on 20 January 2011, when it lifted the Elektro-L weather satellite into geosynchronous orbit.

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All versions data

+ Fregat Upper Stage Family
! Propellant (Max)

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External links

• Fregat page on the manufacturer site
• Vestnik NPO Im. S.A.Lavochkina, issue 1, 2014 - special issue dedicated to Fregat

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