Arianespace to close out June with Flight VA238 launch of two satellites
Artist’s rendering of the Hellas Sat 3 / Inmarsat S EAN satellite in orbit. Image Credit: Thales Alenia Space
Final preparations are underway for the launch of two satellites aboard Arianespace’s workhorse Ariane 5 rocket for delivery to geosynchronous transfer orbit (GTO). GSAT-17 and Hellas Sat 3 / Inmarsat S EAN are scheduled to lift off from the spaceport in Kourou, French Guiana, on Wednesday, June 28, 2017, during a 77-minute window opening at 4:59 p.m. EDT (20:59 GMT).
The Mission
The ISRO-built GSAT-17 satellite undergoes pre-launch processing. Photo Credit: ESA / CNES / Arianespace
A mainstay of the Ariane 5 mission is the launch of two satellites on a single vehicle, and Flight VA238 is no different. Sitting atop the nearly 180-foot (54.8-meter) tall rocket is a pair of satellites destined to provide telecommunications and direct-to-home (DTH) television services to their respective markets.
Encased in the 55.8-foot (17-meter) tall RUAG-manufactured fairing are the GSAT-17 and Hellas Sat 3 / Inmarsat S EAN satellites. GSAT-17, a 7,665-pound (3,477-kilogram) telecommunications satellite built by-and-for India, will launch in the lower position of the SYLDA payload adapter.
Sitting in the payload carrier’s top spot is the 13,000-pound (5,900-kilogram) Hellas Sat 3 / Inmarsat S EAN satellite. The spacecraft is dubbed a “condosat” as there will be two discrete payloads housed within a single chassis, each providing services in their designated areas.
Sharing a single ride to orbit offers cost saving opportunities to the customers and is something at which Arianespace has become very adept. Indeed, the France-based multinational launch provider has been a leader in launching two large satellites to GTO for nearly 20 years and has earned a reputation for success over that time.
The Spacecraft
GSAT-17, designed and built by the Indian Space Research Organization (ISRO), is constructed on the indigenous I-3K satellite bus. The chassis is outfitted with twin solar panels, capable of producing up to a total of 6,500 watts of DC power, tapering to 5,200 watts at the end of its 15-year design life.
The satellite will provide telecommunications services, as well as support data relay and government functions, from its position at 93.5 degrees East via multiple C-band transponders. Several of GSAT-17’s predecessors have used the I-3K bus, and all have launched aboard an Ariane 5 as India has no vehicle capable of launching such a massive satellite to GTO.
Playing the heavyweight on Flight VA238 is the Hellas Sat 3-Inmarsat S EAN satellite. The ungainly named spacecraft was built by Thales Alenia Space on their Spacebus 4000C4 architecture. The spacecraft has twin solar panels, capable of generating up to 16,000 watts, and has a design life of more than 15 years.
Originally set to launch with SpaceX, Inmarsat moved the launch to Arianespace after the U.S.-based NewSpace launch provider experienced delays with their launch schedule.
The core stage of the Ariane 5 gets positioned for launcher build-up. Photo Credit: ESA / CNES / Arianespace
Though housed in a single structure, Hellas Sat 3-Inmarsat S EAN is really two payloads in one.
The first, Hellas Sat 3, was built for and will be operated by Hellas Sat. It will provide telecommunications and DTH television services to customers in Europe, the Middle East, and Sub-Saharan African countries.
The second member of the condosat’s payload is the Inmarsat S EAN telecommunications hardware. Designed to enhance Inmarsat’s European Aviation Network (EAN), the satellite will provide backhaul via S-band transponders to support advanced Wi-Fi service to airlines.
Hellas Sat 3-Inmarsat S EAN will be the 149th Thales Alenia Space-built satellite to be launched by Arianespace and will operate from 39 degrees East.
The Rocket
Lofting two heavy satellites to GTO is a task only a big rocket can handle, and Arianespace has once again called upon its reliable Ariane 5 to get the job done. Though Flight VA238 won’t be a record-setting mission – that award goes to Flight VA237 – its 20,408 pounds (9,257 kilograms) of payload is more than any other active commercial launch vehicle can deliver to GTO.
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 216,000 pounds-force (960 kilonewtons) of sea-level thrust, increasing to 312,000 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 VA238 will feature the Ariane 5 in its ECA – Evolution Cryotechnique type A – configuration; it will mark the 63rd overall launch of that variant of the Ariane 5 and the fourth of 2017. The mission will be broadcast live via Arianespace’s website. Coverage will begin 15 minutes before the scheduled liftoff.
Curt Godwin
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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