Arianespace Soyuz ST-A successfully launches six satellites

by Chris Bergin and William Graham

Arianespace have launched their Soyuz ST-A from the European Spaceport “Centre Spatial Guyanais (CSG)” in Kourou, French Guiana. The veteran rocket successfully launched Pleiades, SSOT and four Elisa satellites into a Sun synchronous orbit, with launch occurring at the opening of the launch window at 02:03 GMT on Friday morning.

Soyuz Mission:

This was the second Soyuz to launch from the newly constructed launch site at Kourou, following the successful mission to loft two European “Galileo” navigation satellites into orbit via the Soyuz ST-B.

The veteran Soyuz launch vehicle is a descendent of the R-7 Semyorka, the world’s first intercontinental ballistic missile. The R-7 was designed by Sergei Korolev, and first flew in 1957. A modified version was used to launch the first satellite, Sputnik 1, on 4 October of that year.

The R-7 formed the basis for the Luna, Vostok, Voskhod, Molniya and Soyuz families of rockets, and to date all Soviet and Russian manned spaceflights have been launched using rockets derived from the R-7.

The Soyuz, which first flew in 1966, was a modification of the Voskhod rocket featuring an upgraded and lighter telemetry system, and more fuel efficient engines. It was initially used to launch only Soyuz spacecraft; however with the introduction of the Soyuz-U in 1973 it began to launch other satellites as well.

The Soyuz-U, which remains in service, is the most-flown orbital launch system ever developed, having made around 750 flights to date, plus around 90 more in the Soyuz-U2 configuration optimised to use synthetic propellant.

The Soyuz-2 was developed from the older Soyuz models, and features digital flight control systems and modernised engines. It first flew in 2004. Two variants are currently in service; the Soyuz-2-1a, and the Soyuz-2-1b which features an RD-0124 third stage engine which provides additional thrust. The RD-0124 was declared operational on 3 May 2011.

A third configuration, the Soyuz-2-1v, is currently under development and is expected to make its maiden flight next year. It features an NK-33 engine in place of the RD-108A used on the core stages of the other configurations, and does not include the strapon boosters used by other configurations.

The Soyuz-2 forms the basis for the Soyuz-ST rocket, which has been optimised to fly from Kourou, and also incorporates a flight termination system and a modified telemetry system.

The vehicle consists of four boosters (first stage), a central core (second stage), a third stage, and the restartable Fregat upper stage (fourth stage). Each vehicle also includes a payload adapter/dispenser and fairing.

The inaugural flight of the upgraded Soyuz 2-1b launch vehicle was successfully performed on December 27, 2006, launching the Corot scientific spacecraft for the French Centre National d’Etudes Spatiales.

As part of the Soyuz’ upgrades for its operations from the Spaceport, the launcher’s flight control system is modernized with a digital control system. This system incorporates a digital computer and inertial measurement unit that are based on proven technology – giving the Soyuz improved navigation accuracy and control capability.

The new digital control system provides a more flexible and efficient attitude control system, and it gives the additional flight control authority required when the new, enlarged Soyuz ST payload fairing is installed on the vehicle. In addition, it improves flight accuracy for the Soyuz’ first three stages, and provides the ability to perform in-flight roll maneuvers as well as in-plane yaw steering (dog-leg) maneuvers.

For this Soyuz – designated VS02 in Arianespace’s launcher family numbering sequence – the mixed payload consisted of France’s Pléiades 1 and the Chilean SSOT satellites for civilian and defense image gathering, along with four French ELISA micro-satellite demonstrators for defense-related electronic intelligence gathering (ELINT).
Pléiades 1 was deployed 55 minutes after Soyuz’ liftoff, followed four minutes later by the simultaneous release of all ELISA satellites. Completing the mission was the separation of SSOT, which occurred 3 hours, 26 minutes after liftoff.

France’s 970-kg Pléiades 1 dual-use imaging satellite and the 117-kg Chilean SSOT multi-role observation spacecraft, along with a cluster of four French ELISA demonstrator satellites for defense-related electronic intelligence gathering (ELINT), which weigh 120 kg each, marked a complicated mission profile for Arianespace.

These payloads were released into Sun-synchronous orbits in a multi-step process during the flight, involving the Soyuz’ Fregat upper stage carrying four propulsion burns, with a fifth to deorbit the stage.

The mission was Arianespace’s year-ending flight at the Spaceport, and comes less than two months after the company’s historic maiden launch of Soyuz from French Guiana in October. Also scheduled in 2011 is another Soyuz launch at Baikonur Cosmodrome with six Globalstar second-generation satellites, which is scheduled during the week of December 25 and will be conducted on behalf of Arianespace by its Starsem affiliate.

To date, Arianespace has logged seven missions in 2011. The five flights with its heavy-lift Ariane 5 during the year orbited eight telecommunications satellites (Arabsat-5C, ASTRA 1N, BSAT-3c/JCSAT-110R, GSAT-8, Intelsat New Dawn, SES-2, ST-2 and Yahsat Y1A), along with an Automated Transfer Vehicle for servicing of the International Space Station. 

The other two launches were Soyuz missions, one operating from Baikonur Cosmodrome with six of the Globalstar second-generation satellites, and Arianespace’s maiden flight of Soyuz from the Spaceport, which lofted two Galileo IOV (In-Orbit Validation) navigation satellites.

(Images via Arianespace)

Related Articles