Arianespace Soyuz ST-B in debut launch from CSG with two Galileo IOVs

by Chris Bergin and William Graham

Arianespace have launched, at the second attempt, their debut Soyuz ST-B from the European Spaceport “Centre Spatial Guyanais (CSG)” in Kourou, French Guiana, following a scrub during Thursday’s tanking. The launch – was on schedule at 10:30am GMT on Friday – lofting two European “Galileo” navigation satellites into orbit from the specially built launch site.

Thursday’s Scrub:

A ground support system leak during third stage fueling of the Soyuz launcher was the cause of the delay for this medium-lift vehicle’s inaugural flight from French Guiana. Such issues are not uncommon, as seen during Ariane 5 countdowns.

Arianespace Chairman and CEO Jean-Yves Le Gall said the leak was in a launch pad pneumatic system that activates the pre-planned disconnection of fueling lines to Soyuz’ third stage before the vehicle lifts off.

“During the final phase of third stage fueling, there apparently was a change in pressure in this pneumatic system, and we observed the unplanned disconnection of the two connectors that enable the fueling of Soyuz’ third stage with liquid oxygen and kerosene,” Le Gall said in a statement after the scrub.

“The problem apparently is due to a valve leak in this pneumatic system, and we have taken the decision to empty the launcher and replace the valve.”

Le Gall underscored that the identified anomaly is in the ground-based pneumatic system, not on the launch vehicle.

Fueling of the Soyuz is performed inside the mobile service gantry, which continues to remain in place on the launch pad. The launcher and its payload of two Galileo IOV (In-Orbit Validation) satellites are in a safe mode, as is the ELS launch site.

With the valve in question soon replaced, a decision to aim for the next attempt – on Friday – was made, with the lift-off time moving four minutes earlier to 10:30am GMT.

Soyuz at CSG – The Launch Site:

Construction of the launch site began in 2007, as Arianespace advanced their plans to add two launch vehicles to their family. With Ariane 5 continuing to be the flagship in Kourou, Arianespace are first debuting the veteran Soyuz launcher, prior to including the smaller Vega launch vehicle next year.

The Spaceport’s Soyuz launch site combines the proven design elements from the long-existing site at Baikonur Cosmodrome with satellite integration procedures that are in concert with the spacecraft processing used for Ariane missions.

Located 12 kilometers northwest from the existing Ariane 5 launch complex, the new Soyuz facility extends the Spaceport’s operational zone further up the French Guiana coastline.

The launch vehicle’s assembly building is 92 meters long, 41 meters wide, and 22 meters tall, allowing the vehicle to be assembles horizontally, prior to rolling out to the launch site, which is configured after the Russian Baikonur and Plesetsk Cosmodromes, albeit with a new mobile launch service tower.

The Soyuz’ transfer to the Spaceport’s launch zone is performed with the launcher riding horizontally atop a transporter/erector rail car.  Soyuz was then raised into position on the pad, and in contrast with the Baikonur Cosmodrome processing flow, is protected by a gantry that moves into place for payload integration.

Soyuz at CSG – The Launch Vehicle:

The more powerful Soyuz-ST configuration will be the standard version launched from French Guiana, with the additional performance of the Soyuz ST-B variant – including a Fregat-MT upper stage – being used to deliver the Galileo IOV satellites into their final circular 23,222 km orbit.

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 is making its maiden flight during Thursday’s launch. The Soyuz-ST is optimised to fly from Kourou, and also incorporates a flight termination system and a modified telemetry system.

With the Soyuz ST-B utilizing the RD-0124 third stage engine, an additional 34 seconds of specific impulse (Isp) will significantly increase the vehicle’s overall launch performance.

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The RD-0124 is a staged-combustion engine powered by a multi-stage turbopump, which is spun by gas from combustion of the main propellants in a gas generator. These oxygen-rich combustion gases are recovered to feed the four main combustion chambers where kerosene – coming from the regenerative cooling circuit – is injected.

Attitude control is provided by main engine activation along one axis in two planes. Liquid oxygen (LOX) and kerosene tanks are pressurized by the heating and evaporation of helium coming from storage vessels located in the LOX tank. Avionics for the Soyuz launcher are carried in the vehicle’s third stage, and are located in an intermediate bay between the oxidizer and fuel tanks.

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.

The new Soyuz fairing has a diameter of 4.11 meters and an overall length of 11.4 meters – enabling it to accommodate the full range of payloads in the launch vehicle’s performance category. Arianespace is planning to further enhance the Soyuz’ mission flexibility with the development of a structure to accommodate small secondary payloads.

Called the ASAP-S, this system continues the auxiliary platform concept previously developed for Ariane missions, which have enabled “piggyback” passengers to be flown for the past 20-plus years.

The ASAP-S has external positions for four micro-satellites, along with volume inside the center structure for a fifth payload. The ASAP-S’ external configuration accommodates spacecraft weighing up to 200 kg, while the internal position is designed to accept a payload with a maximum mass of 400 kg.

The Fregat upper stage is an autonomous and flexible upper stage designed to operate as an orbital vehicle.  Flight qualified in 2000, it extends the Soyuz launcher’s capability to provide access to a full range of orbits (medium-Earth orbit, Sun-synchronous orbit, geostationary transfer orbit, and Earth escape trajectories).

Fregat consists of six spherical tanks arrayed in a circle (four for propellant, two containing the avionics), with trusses passing through the tanks to provide structural support. The stage is independent from the Soyuz’ lower three stages, having its own guidance, navigation, control, tracking, and telemetry systems.

The Fregat uses storable propellants (UDMH/NTO) and can be restarted up to 20 times in flight – enabling it to carry out complex mission profiles. It can provide 3-axis stabilization or perform a spin-up of the spacecraft payload.
The Fregat first flew in 2000, and has been used on Soyuz-U, Soyuz-FG, Soyuz-2 and Zenit rockets.

Soyuz in CSG – The Passengers:

This launch marks the first orbital elements of Europe’s global satellite navigation system. The four satellites – both launched by Soyuz, the second of which will launch next year – are called the Galileo In-Orbit Validation (IOV) satellites, will form the operational nucleus of the full 30-satellite constellation.

Fully representative of the others that will follow them into orbit, these first four IOV satellites will prove that the satellites and ground segment meet many of Galileo’s requirements and will validate the system’s design in advance of completing and launching the rest of the constellation.

The 700 kgs birds sport two Passive Hydrogen Maser atomic clocks; two Rubidium atomic clocks; Clock monitoring and control unit; Navigation signal generator unit; L-band antenna for navigation signal transmission, C-band antenna for uplink signal detection, two S-band antennas for telemetry and telecommands; Search and rescue antenna.

Galileo’s highly-accurate atomic clocks are at the heart of the system. Each satellite emits a signal containing the time it was transmitted and the satellite’s orbital position.

The very first atomic clock, developed in England in 1955, was the size of a room. For satellite navigation, the challenge was coming up with a design that was compact and robust enough to fly in space.

Based on ESA research and development dating back to the early 1990s, two separate atomic clock technologies have been developed and qualified in Europe, then proved suitable for the harsh environment of space by the two GIOVE missions.

GIOVE-A launched on a Soyuz rocket from Baikonur Cosmodrome in Kazakhstan on 28 December, 2005, followed by GIOVE-B – again on a Soyuz rocket from Baikonur – on 27 April, 2008.

These two clocks are the Passive hydrogen maser clock and the Rubidium clock, which need to be synchronised regularly with a network of even more stable ground-based reference clocks. These include clocks based on the caesium frequency standard, which show a far better long-term stability than rubidium or passive hydrogen maser clocks.

Control Centers are located with CNES in Toulouse, France with the support of ESOC in Darmstadt, Germany for Launch and Early Operations Phase (LEOP). Satellite control transferring to Oberpfaffenhofen Galileo Control Centre in Germany while Redu in Belgium performs the In-Orbit Test campaign.

Thursday’s 3 hour, 49 minute flight will deploy the two Galileo satellites into a circular medium-Earth orbit at an altitude of 23,222 km, inclined 54.7 degrees.

(Images via ESA, Arianespace and Roscosmos).

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