Spaceflight Insider

Ariane 5 Flight VA237 set for record launch with heavy telecom satellites

EUTELSAT-172B satellite on Flight VA237

Artist’s rendering of the EUTELSAT 172B satellite to be launched on Flight VA237. Image Credit: Airbus Defence and Space

France-based multinational launch provider Arianespace looks to go six-for-six near 2017’s midpoint after being sidelined by a “social movement” earlier in the year. Flight VA237 will see the workhorse Ariane 5 launch two telecommunications satellites – ViaSat-2 and EUTELSAT 172B – from the spaceport in Kourou, French Guiana, to geosynchronous transfer orbit (GTO) during a 1-hour window opening at 7:45 p.m. EDT (23:45 GMT) on June 1, 2017.

EUTELSAT-172B / Flight VA237

EUTELSAT 172B. Photo Credit: S. Martin / ESA / CNES / Arianespace

The Mission

In what has become a commonplace mission profile for Arianespace, VA237 will see another pair of large telecommunications satellites deployed on a single Ariane 5 launch vehicle. This ridesharing arrangement offsets the higher cost of the European rocket, bringing per-customer costs to levels comparable to Arianespace’s competition.

Flight VA237 will see ViaSat-2 and EUTELSAT 172B ride atop the nearly 180 foot (54.8-meter) tall Ariane 5, with the former sitting above the latter in the SYLDA payload adapter. Together, the pair weigh-in at 21,978 pounds (9,969 kilograms) and are near the upper-end of the vehicle’s capacity to GTO. In fact, the total orbited mass (satellites plus adapter and other hardware) of 23,953 pounds (10,865 kilograms) marks the heaviest launch for the Ariane 5 to date.

Ridesharing has proven so effective over the vehicle’s nearly 20 years of existence that customers will sometimes opt to pay a somewhat higher premium to take advantage of the launch provider’s proven flight history rather than riding solo elsewhere. Indeed, ViaSat-2 was originally intended to be launched on SpaceX’s Falcon Heavy in late 2016, but ViaSat re-booked with Arianespace for Flight VA237 due to schedule uncertainties with the U.S.-based NewSpace launch provider.

The Spacecraft

Occupying the top spot on the SYLDA payload adapter is the Boeing-built ViaSat-2 telecommunications satellite. The 14,149-pound (6,418-kilogram) spacecraft is built on the Boeing 702HP satellite bus and will provide broad-based and high-bandwidth communications services via Ka-band transponders to North, Central, and South America from its position at 70 degrees West above the equator.

Ariane 5 / Flight VA237

The Ariane 5 for Flight VA237 is transferred to the Final Assembly Building to have the ViaSat-2 and EUTELSAT 172B payloads attached. Photo Credit: ESA / CNES / Arianespace

Once ViaSat-2 becomes operational, it will provide more bandwidth – at higher speeds and at greater capacity – than any other commercial satellite.

“ViaSat-2 is designed to combine both deep, high-capacity bandwidth and wide coverage, and flexibility to move bandwidth to where demand requires it,” notes ViaSat in a release issued by the company. “ViaSat-2 will be our first big step toward spreading high-capacity coverage worldwide for fixed broadband and mobility services for aviation and maritime.”

Riding below ViaSat-2 is the EUTELSAT 172B satellite. Like its larger counterpart on this flight, the Eutelsat spacecraft will provide high-bandwidth telecommunications services, though through a collection of C- and Ku-band transponders, and will reside at 172 degrees East.

The 7,829-pound (3,551-kilogram) satellite is built on the Airbus Defense and Space Eurostar E3000e spacecraft bus and marks the first all-electric satellite built in Europe.

“EUTELSAT 172B is based on the highly reliable Eurostar E3000 platform from Airbus Defence and Space, in its latest EOR (Electric Orbit Raising) evolution,” states Airbus Defence and Space in a release. “This version relies exclusively on electric propulsion for initial orbit raising and all on-station manoeuvres, with the consequent reduction in mass enabling the satellite to be launched in the Ariane 5 lower position, resulting in lower launch costs.”

The Rocket

Arianespace has tapped its reliable Ariane 5 to launch a pair of communications satellites to geosynchronous transfer orbit (GTO). The European launcher is one of only two active and mission-proven heavy-lift rockets in the world today and is capable of lofting 44,000 pounds (20,000 kilograms) to low-Earth orbit (LEO) or 23,667 pounds (10,735 kilograms) to GTO. Flight VA237 will push the limits of that GTO capability.

Ariane 5’s first stage is powered by a single liquid-fueled Vulcain 2 engine, along with a pair of side-mounted P241 solid-fueled boosters. The trio produces 3.4 million pounds-force (15,120 kilonewtons) of thrust at liftoff, with more than 92 percent of that coming from the P241 boosters.

The boosters will operate for slightly more than 2 minutes, after which they will be jettisoned and fall into the Atlantic Ocean.

Supplying the remaining eight percent of liftoff power is the core stage’s Vulcain 2 cryogenic engine. Burning a mixture of liquid hydrogen and liquid oxygen, the hydrolox powerplant provides 220,000 pounds-force (960 kilonewtons) of sea-level thrust, increasing to 310,000 pounds-force (1,390 kilonewtons) as it climbs into the vacuum of space.

The second stage is outfitted with a single HM7B cryogenic engine, which produces 15,000 pounds-force (67 kilonewtons) of vacuum thrust for up to 945 seconds.

Flight VA237 will feature the Ariane 5 in its ECA – Evolution Cryotechnique type A – configuration; it will mark the 62nd overall launch of that variant of the Ariane 5 and the third of 2017. The mission will be broadcast live via Arianespace’s website. Coverage will begin 15 minutes before the scheduled liftoff.

Video courtesy of ViaSat



Curt Godwin has been a fan of space exploration for as long as he can remember, keeping his eyes to the skies from an early age. Initially majoring in Nuclear Engineering, Curt later decided that computers would be a more interesting - and safer - career field. He's worked in education technology for more than 20 years, and has been published in industry and peer journals, and is a respected authority on wireless network engineering. Throughout this period of his life, he maintained his love for all things space and has written about his experiences at a variety of NASA events, both on his personal blog and as a freelance media representative.

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