August 2014 failure

The Arianespace-operated flight of a Fregat MT ended in failure on 22 August 2014 after the vehicle deposited two EU/ESA Galileo navigation satellites into the wrong orbit. The lift off at 12:27:11 UTC from the Sinnamary launch site 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.^[7]

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.^[8] 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.^[9]

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.^[10][11][12]

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.^[13]

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 cubesats back into Earth's atmosphere due to the first Fregat burn being ignited with the stage in the wrong orientation.^[14] 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.^[15]

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 5,350 kilograms (11,790 lb) to 6,640 kilograms (14,640 lb), without causing any other changes to the physical dimensions of the vehicle.^[2]

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 360 kg (790 lb) and contains up to 3,050 kg (6,720 lb) of propellant. The total dry weight of the Fregat-SB (including SBB) is 1,410 kg (3,110 lb) and the maximum propellant carrying capacity is 10,150 kg (22,380 lb).^[17]

Fregat-SB was launched for the first time on 20 January 2011, when it lifted the Elektro-L weather satellite into geosynchronous orbit.^[18]

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