Soyuz-2

Soyuz-2 (Союз-2) (GRAU index 14A14) is a modernised version of the is an expendable medium-lift launch vehicle and the seventh major version in the Soyuz family. It includes key enhancements over its predecessors including improved engines along with digital flight control and telemetry systems, enabling launches from fixed platforms and the use of large payload fairings.

In its standard configuration, Soyuz-2 is a three-stage launch vehicle designed for low Earth orbit missions. Notably, its stage numbering differs from some rockets. The boosters are considered its the first stage, while the central core is the second. For higher orbits like Molniya or geosynchronous, an optional upper stage can be added. The most common upper stage is the Fregat, but the Volga is also an option. These upper stages have their own independent flight control and telemetry systems.

The Soyuz-2 rocket utilizes the existing facilities as its R-7 derived predecessors, Site 31 at the Baikonur Cosmodrome in Kazakhstan and Site 43 at the Plesetsk Cosmodrome in northwestern Russia. Additional launch locations opened at the Ensemble de Lancement Soyouz at the Guiana Space Centre in French Guiana in 2011 and the Site 1S at the Vostochny Cosmodrome in eastern Russia in 2016. However, Soyuz-2 launches from Guiana were suspended in 2022 after the Russian invasion of Ukraine.

The Soyuz-2 family has two major variants, with the Soyuz-2.1a being the base version that first launched on 8 November 2004. The Soyuz-2.1b, with a 15 percent more powerful third stage, followed on 27 December 2006. Soyuz rockets that use a larger payload fairing are called the Soyuz ST-A or Soyuz ST-B. The derivative Soyuz-2.1v with a more powerful core stage and no boosters was introduced in December 2013.

The Soyuz-2 has replaced the Molniya-M, Soyuz-U and Soyuz-FG since 2010, 2017 and 2019 respectively.

Soyuz-2.1a
The Soyuz-2.1a incorporates upgraded RD-107A engines on both booster and core stages, that have improved injection systems, to enhance overall performance.

The 2.1a also has a digital flight control system, replacing the analog system used on prior Soyuz models. This system allows the vehicle to adjust its trajectory in-flight (a capability the analog system lacked) eliminating the requirement for a complex rotating launchpad. The digital flight control system also unlocks the potential for deploying larger commercial satellites housed within wider and longer payload fairings. These fairings introduce too much aerodynamic instability for the old analog system to handle. The RD-110 engine remains in use for the third stage. When configured with the larger ST fairing, the Soyuz 2.1a is sometimes called Soyuz ST-A.

The first launch of a Soyuz-2.1a took place from Plesetsk Cosmodrome Site 43 on 8 November 2004 with a boilerplate payload, simulating the size and weight of a Zenit-8 spy satellite. The first launch of a Soyuz ST-A took place from Guiana Space Centre on 17 December 2011 carrying four satellites (including Pléiades-HR 1A, SSOT and ELISA).

Soyuz-2.1b
The Soyuz-2.1b has all the same features as the Soyuz-2.1a, but uses an upgraded engine (RD-0124) on the third stage, which greatly increases specific impulse (326 to 359 seconds), improving payload capability to LEO from 7200 kg to 8200 kg. When configured with the larger ST fairing, the Soyuz 2.1b is sometimes called Soyuz ST-B.

The first launch of a Soyuz-2.1b took place from Plesetsk Cosmodrome Site 43 on 26 July 2008 with a classified military payload. The first launch of a Soyuz ST-B took place from Guiana Space Centre on 21 October 2011 carrying two Galileo satellites.

Guiana Space Centre
To accommodate the conditions and requirements of the Guiana Space Centre (CSG), Soyuz rockets underwent several key modifications. These adaptations ensure the vehicle's optimal performance and safety within the tropical environment.

Launch Infrastructure and Payload Integration

 * Mobile Service Tower: Unlike other Soyuz launch complexes, the ELS employed a mobile service tower that enabled vertical payload integration directly on the launchpad.
 * European Payload Adapters: Launch vehicles used European-supplied payload adapters, enhancing compatibility with a broader range of spacecraft.
 * Engine Ignition: At the ELS, the engines of the boosters and first stage were pyrotechnically ignited. At other Soyuz launch complexes, engines are chemically ignited.

Enhanced Safety Systems

 * European Safeguard Kit (Kit de Sauvegarde Européenne): This system can locate the rocket in real-time and, if necessary, transmit a flight termination signal, ensuring the safe destruction of the vehicle in the event of an anomaly.
 * Destruct System for Boosters and Core Stage: Boosters and core stage are equipped with pyrotechnic devices to ensure they sink in the ocean for disposal after flight.
 * S-Band Telemetry System Adaptation: The S band telemetry system is modified to operate on the Inter-Range Instrumentation Group standard used at the CSG.

Environmental Adaptation

 * Tropical Climate Adaptation: The air conditioning system is adapted to keep the payload cool inside the faring, and protective measures are added to reduce icing when loading cryogenic fluids in the humid environment.
 * Pest Control: To avoid potential wildlife intrusions, all cavities and openings within the rocket were studied and certified to be adequately sealed against insects and rodents.

Vostochny Cosmodrome
Modifications for the Vostochny Cosmodrome version includes:
 * New and upgraded computer, N.A.Semikhatov NPO Automatika's Malachite-7, with six times more performance, better obsolescence protection, reduced weight.
 * The new computer enabled a significant reduction on the cable network complexity thanks to multiplexing lines and using common buses.
 * New nickel-cadmium batteries that eliminate the need for a dedicated battery charging station.
 * The inclusion of on-board video system, that will enable real-time views of the launch.
 * Since the launch pad at Vostochny also has a mobile gantry for vertical payload integration, similar to the ELS at Guiana, it has the necessary piping to direct the oxygen purges outside the gantry.

On 1 October 2015, it was announced that parts of the assembly complex for the Soyuz-2 at Vostochny Cosmodrome were designed for a different modification of the rocket and are too small, so that the planned first launch in December 2015 was under question. The first launch occurred on 28 April 2016 at 02:01:21 UTC.

Suborbital test flight
On 8 November 2004, at 18:30 UTC, the first Soyuz-2 carrier rocket, in the Soyuz-2.1a configuration, was launched from the Plesetsk Cosmodrome in Russia. The rocket followed a sub-orbital trajectory, with the third stage and boilerplate payload re-entering over the Pacific Ocean.

Maiden launch
The first attempt at launching a Soyuz-2 to orbit, with the MetOp-A satellite, occurred on 17 July 2006. It was scrubbed two hours before the launch by an automatic sequence, after the onboard computer failed to check the launch azimuth. Fuelling of the rocket was underway at the time, and all launch complex equipment and on-board preliminary checks had proceeded without incident. The rocket was left fuelled on the launch pad, for the next attempt on 18 July 2006. Launch was eventually conducted on 19 October 2006.

First crewed mission
First crewed launch of Soyuz-2 took place at 9 April 2020, carrying Soyuz MS-16 to the ISS.

Naphthyl fuel
Following successful ground testing, a naphthyl fueled Soyuz-2.1b launch took place on 22 October 2022 at Vostochny. Naphthyl is an environmentally safe hydrocarbon fuel with fewer aromatic compounds than kerosene, that also slightly improves engine performance. There are only minor differences in thermal properties, viscosity, and surface tension, so this did not require significant engine changes.

Launch statistics
Since 2006, Soyuz-2 rockets have accumulated a total of 177 launches, 170  of which were successful, yielding a   success rate.