OrbitalHub

Credits: ESA – S. Corvaja 2007

CNES and ESA signed the development contract to build the launch facilities for Soyuz at the Guiana Space Centre on July 19, 2005. The Soyuz launcher will give Europe medium-lift capability and will complete the range of launchers operated by Arianespace, which includes the Ariane 5 heavy-lift launcher and the Vega small launcher.

The Soyuz launchers that will liftoff from Kourou have a number of improvements: an updated digital flight control system, an increased-performance third stage, and the larger Soyuz ST payload fairing.

The launcher has a length of 46.2 meters, a diameter of 10.3 meters, and a liftoff mass of 308 tons. Due to the position of the launch site, close to the equator, the payload capacity of the launcher has increased significantly: 3,150 kg to a geostationary orbit, and 4,900 kg to a sun-synchronous orbit, with a circular altitude of 820 km.

Soyuz is a reliable, four-stage launch vehicle, which has been in production since 1957 and has accounted for more than 1,700 missions to date.

The first stage is composed of the four boosters that are assembled around the central core of the launcher. The RD-107A engines installed on the boosters use liquid oxygen and kerosene as propellant combination. Each engine has four combustion chambers and four nozzles. One aerofin and two movable vernier thrusters per engine are used for the three-axis flight control.

Credits: ESA – S. Corvaja 2008

The second stage consists of the central core surrounded by the boosters. It uses the same propellant combination for powering the RD-108A engine with four combustion chambers and nozzles.

Four vernier thrusters are used for three-axis flight control, after the boosters of the first stage are jettisoned during flight.

The engines of the first two stages are ignited 20 seconds before liftoff. The reason for this is that the launch procedures include monitoring the engine health parameters just before liftoff, while the engines are operating at an intermediate level of thrust. This reminds me of the SpaceX Falcon 1 booster launch procedures. SpaceX engineers perform a similar monitoring procedure for the Merlin engine just before the Falcon 1 liftoff.

The third stage utilizes a RD-0124 engine, also powered by liquid oxygen and kerosene. The liquid oxygen and kerosene tanks are pressurized using helium stored in vessels located in the liquid oxygen tank. The avionics module of the launcher is carried by this stage. The new flight control system improves the accuracy and the control capability for the launcher, as additional flight control authority is needed for the enlarged payload fairing.

Credits: ESA – S. Corvaja 2008

The upper stage of the Soyuz launcher is called Fregat. Fregat is an autonomous and flexible upper stage with its own guidance, navigation, control, tracking, and telemetry systems. It was designed to operate as an orbital vehicle, and it extends the launch capabilities of the Soyuz launcher to medium-Earth orbits, Sun-synchronous orbits, geostationary transfer orbits, and Earth escape trajectories.

The Fregat stage can be restarted up to 20 times in flight, it can provide three-axis stabilization, and perform a spin-up of the spacecraft payload. Fregat uses a bi-propellant propulsion system: UDMH (unsymmetrical dimethylhydrazine) and NTO (nitrogen tetroxide).

The payload fairing is the most visible change to the Soyuz launcher. The new Soyuz fairing has a diameter of 4.11 meters and a length of 11.4 meters. The fairing is based on the configuration used for Ariane 4 vehicles.

The construction of the Soyuz launch base in French Guiana started in early 2007. At the groundbreaking ceremony on February 26, 2007, a number of European space industry officials were present: Jean-Jacques Dordain – ESA Director General, Yannick d’Escatha – President of CNES, Jean-Yves Le Gall – Director General of Arianespace, and Anatoly Perminov – Head of Roscosmos.

In 2007, Arianespace ordered four Soyuz launchers for the early launch missions that are scheduled for the second half of 2009. A contract was also signed in September 2008 for 10 more Soyuz launch vehicles.

The Soyuz launch missions that are scheduled for 2009 signal the beginning of a new chapter in ESA-Russian relations. Stay tuned for more information about the Soyuz launches from French Guiana!