Thursday, November 17, 2016

Ariane 5 Booster Soars into Orbit with Four Galileo Navigation Satellites

Europe’s 15th, 16th, 17th, and 18th Galileo satellites lifted off from Europe’s Spaceport in French Guiana atop an Ariane 5 launcher (VA 233 / Galileo M-6). Photo & Caption Credit: Stephane Corvaja / ESA

Thundering off from the launch pad at the Guiana Space Center in Kourou, French Guiana, an Ariane 5 rocket took to the skies on Thursday, Nov. 17, to replenish Europe’s Galileo navigation network. The booster, carrying four Galileo FOC (Full Operational Capability) satellites, lifted off at 10:06 a.m. local time (8:06 a.m. EST / 13:06 GMT).

The liftoff started a four-hour-long ride into space tasked with delivering four Galileo FOC spacecraft into orbit, namely: FM7 (Antonianna), FM12 (Lisa), FM13 (Kimberley), and FM14 (Tijmen). The satellites, each named after a child that had won the European Commission’s Galileo drawing competition, will reside in an operational circular medium-Earth orbit (MEO) at an altitude of 14,430 miles (23,222 kilometers), inclined 57.57 degrees.

This is the first time that the Galileo satellites have been delivered into orbit by Europe’s own booster, Ariane 5. All previous 14 spacecraft in the series were launched by the Russian Soyuz-STB rocket.

Preparations for the mission, designated VA 233 in Arianespace‘s numbering system, commenced in early September when the quartet of spacecraft was shipped to French Guiana. September was a busy month for engineers as they worked around the clock performing fit checks and initial checkouts of the newly arrived satellites. Later that month, the teams started the assembly of the Ariane 5 rocket.

Fueling operations of the spacecraft began in mid-October, which was followed by the integration of the payload onto the launch vehicle’s dispenser on Oct. 25–28. The rocket was delivered to the Final Assembly Building (BAF) on Oct. 26 in order to attach the satellites to it and encapsulate them in the payload fairing.

The launch vehicle was cleared for liftoff on Nov. 14 when it passed the launch readiness review. On the next day, the rocket was rolled out to the launch pad, which initiated the final phase of preparations for the launch. On Nov. 16, the engineers started fueling operations of the rocket’s cryogenic main stage, called EPC.

Countdown for the launch started 12 hours and eight minutes before the planned liftoff. About one-and-a-half hours later, checks of the electrical systems began. After completing these checks the rocket’s EPC stage was ready to be filled with liquid oxygen and hydrogen, starting at T–5 hours and seven minutes.

At approximately three-and-a-half hours before liftoff, the EPC’s Vulcain 2 engine was chilled down, and some two hours later, the teams started final checks of connections between the launcher and the telemetry, tracking, and command systems. The successful completion of these last checks allowed the mission controllers to report “all systems go”, which initiated the synchronized sequence during which the tanks are pressurized for flight and the launch vehicle is switched to onboard power mode.

The launcher ignited its two solid rocket boosters known as EAPs and lifted off from the launch pad at the ELA-3 launch complex in Kourou seven seconds after the ignition of its EPC main stage. It completed a short vertical climb before starting a roll maneuver just 17 seconds after liftoff.

The rocket was powered by the EAP boosters until the two minutes and 19 seconds into the flight when they were jettisoned. After the separation of the solid boosters, the launch vehicle was accelerated by the Vulcain 2 engine alone for nearly seven minutes, until the EPC stage was detached at about T+9 minutes. During this phase of the flight, the rocket’s payload fairing was separated some three minutes and 44 seconds into the mission, unveiling the quartet of passengers.

Ariane 5’s storable propellant upper stage, known as EPS, took control over the flight nine minutes and eight seconds after liftoff, igniting its one AESTUS engine. The first burn of this engine lasted nearly 11 minutes and was needed to send the upper stage toward the targeted operational orbit.

After the first shutdown of the EPS at approximately 20 minutes into the mission, this stage commenced its three-hour-long coast phase that sent it to the transfer orbit. At about T+3 hours and 28 minutes, the upper stage was ignited for the second time for approximately six minutes to reach the transfer orbit.

Galileo FOC FM7 and FM13 satellites were released first into space at three hours and 35 minutes after launch. Twenty minutes later, FM12 and FM14 separated from the EPS stage. The quarter of spacecraft then cruised toward the targeted MEO orbit.

“At the time that the four satellites separate two by two, we’ll have two shifts of the mission team working in the control room at the CNES (French Space Agency) center in Toulouse, France, each shift managing two satellites – so it will be an intense period,” said Liviu Stefanov, co-flight director from ESA.

The satellites are expected to reach the targeted operational circular MEO orbit in early 2017.

The four Galileo satellites launched on Thursday are almost identical. They have dimensions of 8.86 ft × 3.94 ft × 3.61 ft (2.7 m × 1.2 m × 1.1 m); however, with solar arrays deployed in space, they measure 48 feet (14.67 meters) in width. The Galileo FOC satellites FM12 and FM14 have an equal weight of 1,581 pounds (717 kilograms), whereas FM13 is 1,579 pounds (716 kilograms) and FM7 is the lightest with a weight of 1,577 pounds (715 kilograms).

Built by OHB System, the satellites feature two solar arrays generating up to 1,900 watts of power during the designed lifetime of at least 12 years. The spacecraft are equipped with two passive hydrogen maser atomic clocks, two rubidium atomic clocks, a clock monitoring and control unit, one navigation signal generator unit, an L-band antenna for navigation signal transmission, a C-band antenna for uplink signal detection, two S-band antennas for telemetry and telecommand, and one search and rescue antenna. The payload was provided by SSTL.

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 highly precise positioning services. The network is designed for interoperability with the U.S. GPS and Russian GLONASS global positioning systems.

The satellites that were launched on Thursday belong to the Full Operational Capability phase of the constellation, which include the initial operational capability phase of 18 operational satellites. The full system should consist of 30 satellites, control centers located in Europe, and a network of sensor stations and uplink stations installed around the globe.

The first Galileo satellites were launched on Oct. 21, 2011, atop a Soyuz rocket, whereas the first two FOC spacecraft were sent into orbit on Aug. 22, 2014. Arianespace will conduct two more Galileo missions in the future, sending four satellites each. These flights are planned for the third quarter of 2017 and 2018.

With a mass of 770 metric tons, the Ariane 5 in its ES configuration, employed on Thursday’s launch, is an evolution of the initial Ariane 5 generic launcher. The 166-foot (50.5-meter) tall rocket has all the performance improvements of the well-known Ariane 5 ECA variant but replaces the ESC-A second stage with the restartable EPS. The ES version is capable of delivering up to 21 metric tons into a low-Earth orbit (LEO).

The Ariane 5 ES rocket was mainly used for launching ESA’s Automated Transfer Vehicle (ATV) to the International Space Station (ISS). From now through 2018, it will be utilized to send four Galileo navigation satellites into orbit on one mission. First flight of this variant took place in March 2008 when it launched the maiden ATV spacecraft named Jules Verne.

Thursday’s mission was the 234th liftoff of an Ariane vehicle from the Kourou Spaceport. It was the sixth Ariane 5 launch of 2016 (the 89th Ariane 5 launch overall) and the ninth of 11 flights planned this year by Arianespace, utilizing its family of the heavy-lift Ariane 5, the medium-lift Soyuz, and the lightweight Vega.

Arianespace’s next launch is scheduled for Dec. 5 when it is expected to deliver into space the Gokturk-1 reconnaissance satellite for the Turkish Armed Forces. That mission will be performed by the Vega launcher, lifting off from Kourou.

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