A Soyuz ST-B rocket will take to the skies on Tuesday, May 24, to orbit a duo of European Galileo navigation satellites. The spacecraft, designated Galileo 13 and 14, are slated to be lifted off at 4:48 a.m. EDT (8:48 GMT) from the Soyuz Launch Complex (ELS) in Sinnamary, French Guiana.
The mission, designated VS15, will be the fourth flight this year carried out by Arianespace. The mission itself will last about three hours and 47 minutes, ending in deploying the satellites into a circular medium-Earth orbit (MEO) at an altitude of 14,616 miles (23,522 km), inclined 57.4 degrees.
“Once the satellites separate into free flight, the solar wings will deploy automatically, we’ll be waiting very anxiously for receipt of the first signals via the tracking station at Dongara, Australia, and Kerguelen Island, in the Indian Ocean,” said Liviu Stefanov, lead flight director from the European Space Agency (ESA).
Launch campaign for the mission started in March this year when the teams started first tests of the rocket’s Fregat upper stage at the Soyuz launcher preparation building (MIK). The satellites arrived in French Guiana on Apr. 5 to begin initial checkouts.
April was a busy month for engineers as they conducting fueling operations of the Fregat upper stage and started the integration process of the first two Soyuz’s stages.
On May 2, pneumatic and electrical tests on the lower three stages of the launch vehicle commenced. One day later, the teams began fueling the duo of Galileo spacecraft.
The integration of the third stage took place on May 10. It was followed by the mating of the satellites with Fregat. Afterwards, the stack was encapsulated in the payload fairing. On May 20, this upper composite was installed on the launcher. On the same day, the rocket was rolled out to the launch site.
Final launch verification was carried out on May 21, along with functional tests and checks of the upper composite. The launch readiness review will be conducted one day before planned liftoff.
Galileo 13 and 14 were named Danielè and Alizée after children who won a painting competition organized by the European Commission. The spacecraft were built by OHB-System while the payload was provided by SSTL. Each satellite has a liftoff mass of about 1,576 lbs. (715 kg) and dimensions: 8.86 x 3.94 x 3.6 feet (2.7 x 1.2 x 1.1 meters). The spacecraft can generate up to 1,900 W of onboard power and are designed to operate for more than 12 years.
“We are extremely proud of our contribution to Europe’s new navigation system, and we are all looking forward to the day that the new service comes on stream, and we can start using it in our daily lives,” said John Paffett, Director of Telecommunications and Navigation at SSTL.
Galileo satellites are equipped with two passive hydrogen maser atomic clocks; two rubidium atomic clocks; a clock monitoring and control unit; one 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 telecommand as well as one search and rescue antenna. The spacecraft are fitted with two deployable solar arrays.
„We have proven that both of our satellites will be able to withstand the anticipated loads arising during launch and during transfer to their target orbit and cope with the harsh conditions existing in space on a long-term basis,” said Wolfgang Paetsch, OHB Navigation Director.
The two newest Galileo satellites belong to the Full Operational Capability (FOC) phase. This phase includes an initial operational capability phase of 18 operational satellites. The full system will consist of 30 satellites, control centers located in Europe and a network of sensor stations and uplink stations installed around the globe. First Galileo satellites were launched atop a Soyuz rocket on Oct. 21, 2011, while first two FOC spacecraft were orbited on Aug. 22, 2014.
Galileo is a European project that is currently creating a new global satellite navigation system, carried out on behalf of the European Commission, under a contract with ESA. Under civilian control, Galileo is planned to deliver high-precision positioning services. The network is designed for interoperability with the U.S.’ GPS and Russian GLONASS global positioning systems.
The Soyuz St-B rocket currently offered by Arianespace is a four-stage launch vehicle which includes the following: four boosters (first stage), a central core (second stage), third stage, and a restartable Fregat upper stage (fourth stage). It also includes a payload adapter/dispenser and fairing.
The booster’s RD-107A engines are fueled by kerosene with liquid oxygen as the oxidizer; the same propellants are used on each of the lower three stages.
The central core is similar in construction to the four boosters, with a special shape to accommodate the boosters. A stiffening ring is located at the interface between the boosters and the core. This stage is fitted with an RD-108A engine, also comprising four combustion chambers and four nozzles.
The third stage uses an RD-0124 engine in the ST-B version. The third stage engine’s thrust enables the stage to separate directly from the central core.
The Fregat upper stage is an autonomous and flexible stage that is designed to operate as an orbital vehicle. It extends the capability of the Soyuz launcher, now covering a full range of orbits. To ensure high reliability for the Fregat stage from the outset, various flight-proven subsystems and components from previous spacecraft and rockets are used. The upper stage consists of six spherical tanks (four for propellants, two for avionics) arranged in a circle and welded together.
Tuesday’s mission will be the 53rd orbital flight conducted by Arianespace for ESA. By the end of the year, the company will launch four Galileo FOC satellites on a single mission, using an Ariane 5 ES booster.
“The quadruple launch will be a major change for the mission control team, as we will have to conduct the critical early orbit phase for the four satellites in parallel,” said Stefanov.
Arianespace’s next planned mission is currently scheduled for June 8, when an Ariane 5 ECA launcher will lift off from Kourou, French Guiana with two communications satellites: EchoStar 18 and BRIsat.