Tuesday, May 24, 2016

Soyuz Soars into Space with Two Galileo Navigation Satellites

Arianespace has successfully launched a Soyuz ST-B rocket into orbit carrying two latest navigation satellites for Europe’s Galileo network. Liftoff occurred as planned at 4:48 a.m. EDT (8:48 GMT) from the Soyuz Launch Complex (ELS) in Sinnamary, French Guiana. Credit: Arianespace

Arianespace has successfully launched on Tuesday a Soyuz ST-B rocket into orbit carrying two latest navigation satellites for Europe’s Galileo network. Liftoff occurred as planned at 4:48 a.m. EDT (8:48 GMT) from the Soyuz Launch Complex (ELS) in Sinnamary, French Guiana. After liftoff, the rocket carrying a total payload of 3,525 lbs. (1,600 kg) started its routine vertical ascent until the vehicle’s four booster were jettisoned nearly two minutes into the flight. Then the central core stage fired its engine to continue accelerating the launch vehicle.

Approximately three minutes and 39 seconds after liftoff, the payload fairing separated from the rocket, unveiling the mission’s two passengers. With satellites exposed, the launch vehicle continued the flight for slightly more than one minute when the central core stage detached from the third stage.

The stack was flying towards the designated orbit for about four and a half minutes until the third stage separated from the launch vehicle. Fregat began its first burn approximately one minute later, starting a three-hour journey to deploy the spacecraft. The upper stage was fired for the second time about three hours and 38 minutes into the flight. Nearly ten minutes later Fregat accomplished its mission by releasing the Galileo satellites.

The spacecraft will now lower their altitudes to reach the operational circular medium-Earth orbit (MEO) at an altitude of 14,616 miles (23,522 km), inclined 57.4 degrees. The rocket’s three stages and the payload fairing will fall back into the sea, while Fregat will be passivized.

“Once we have contact, we’ll begin health checks, and we’ll be particularly interested in verifying the satellite attitudes, communication status, that power is flowing from the array and that no part of either satellite is too warm,” said Christelle Crozat, the lead Spacecraft Operations Manager at the European Space Agency (ESA).

During the first nine days after launch, the teams will prepare the satellites for handover to the Galileo Control Centre near Munich, Germany for routine operations, and ESA’s Redu Centre in Belgium, for detailed payload testing.

“In these nine days, we will make three maneuvers with each satellite, when we fire the thrusters to get them into their ‘drift’ orbit before handover for commissioning,” said Hélène Cottet, co-flight director at the French Space Agency (CNES).

Launch campaign for the mission started in March this year when the teams started first tests of the rocket’s Fregat upper stage. The satellites arrived in French Guiana on Apr. 5 to begin initial checkouts. 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 was conducted on May 23.

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.

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.

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 that was employed for Tuesday’s mission 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 was 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.

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.

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