Arianespace tallies up another successful mission with launch of two telecom satellites
More than a month after its initial planned launch was delayed by a “social movement” in the French South American overseas department, Arianespace‘s Flight VA236 finally departed from the Guiana Space Center and delivered two telecommunication satellites to geostationary transfer orbit (GTO). Lifting off at 5:50 p.m. EDT (21:50 GMT) May 4, 2017, the Ariane 5 continued its string of successful missions and deployed Brazil’s SGDC and South Korea’s KOREASAT-7 satellites.
SOCIAL MOVEMENT RESOLVED
Flight VA236 was originally to have launched on March 21, 2017, but a series of protests and organized work stoppages caused Arianespace to delay the mission until the situation could be resolved.
Though there was widespread displeasure over the economic disparity between mainland France and Guiana, nowhere was that contrast clearer than at the Guiana Space Center. Blockades erected by protesters effectively closed off access to the South American spaceport, forcing Arianespace to indefinitely delay its launch manifest.
A series of negotiations between French politicians and Guianan MPs culminated in an agreement in which France would provide substantial economic assistance and emergency relief to French Guiana. With the accord in place, protestors stood down, allowing the French multinational launch provider to resume operations.
To add to the turmoil that had embroiled the region during the protests, the countdown for flight VA236 was further delayed for about 80 minutes by a minor technical hitch. However, the break in the launch calendar had no apparent ill-effects on the launch team, with flight engineers working to resolve the issue within the nearly 3-hour launch window.
At the rescheduled launch time of 6:50 p.m. local time (21:50 GMT), the Ariane’s flight computers commanded the core stage’s Vulcain 2 engine to roar to life.
The cryogenically fueled engine’s turbopumps began supplying liquid hydrogen and liquid oxygen to the Vulcain’s combustion chamber, and following a brief health check, the computer ignited the two P241 solid rocket boosters (SRBs) seven seconds later.
With a combined 2.92 million pounds-force (13,000 kilonewtons) of liftoff thrust, the 180-foot (54.8-meter) tall Ariane 5 leapt off the pad and soared into a partly cloudy late afternoon sky.
Shortly after clearing the launch tower, the Ariane initiated its attitude adjustment maneuvers so that it could attain the proper flight trajectory as the vehicle and its pair of satellites climbed to GTO.
BURNOUT AND SEPARATION
As the rocket ascended, atmospheric pressure reached its maximum impact on the vehicle’s structure. This region of high stress is called “max Q” and is a function of the vehicle’s speed combined with the pressure exerted by the surrounding air. Nearly simultaneously, the rocket surpassed Mach 1 – the speed of sound – as it continued its steady climb to orbit.
Slightly more than two minutes after ignition, and nearly 44 miles (70 kilometers) in altitude, the Ariane’s twin P241 SRBs exhausted their solid fuel and were jettisoned. The spent motors splashed down into the Atlantic Ocean and were not recovered.
With the vehicle weighing a fraction of its 1.72 million pounds (780 metric tons) liftoff weight, the core stage’s Vulcain engine continued to accelerate the rocket and its payload to orbital velocity.
Almost three-and-a-half minutes into the flight, and approximately 68 miles (110 kilometers) in altitude, the Ariane shed its protective payload fairing. Though the aerodynamic shell protects the vehicle and its payload in the lower, thicker parts of the atmosphere, it becomes unnecessary mass – and a hindrance to payload deployment – once in the vacuum of space.
The Vulcain main engine powered the vehicle for nearly nine minutes, and, once the core stage was emptied of propellant, it separated from the ESC-A (second) stage and fell into the Atlantic Ocean off the coast of Africa in the Gulf of Guinea.
The ESC-A’s highly efficient HM-7B engine, burning a cryogenic mixture of liquid hydrogen and liquid oxygen, started its nearly 16-minute long burn to precisely place the two satellites in their intended orbital drop-off point.
More than 28 minutes after lifting off, the second stage was in a position to deliver the first of its two passengers to the 155-mile (250-kilometer) by 22,323-mile (35,926-kilometer) transfer orbit.
SGDC was the first to separate from the SYLDA payload carrier. After the Brazilian satellite was clear of the vehicle and at a safe distance, SYLDA was jettisoned, exposing KOREASAT-7 and providing the South Korean satellite a clear path to deploy.
Following a 9 minute coast, during which time SYLDA drifted away, the second satellite was released. KOREASAT-7, like its SDGC launch mate, was now flying free of the ESC-A upper stage.
Both satellites will steadily raise their orbit with their onboard propulsion system and will undergo a set of checkout procedures by the ground crew before being declared operational.
Flight VA236 marks Arianespace’s second Ariane 5 launch of 2017. Their next scheduled launch, Flight VS17, is for their Europeanized Soyuz rocket carrying the SES-15 communications satellite. That mission is tentatively scheduled for May 18, 2017.
Video courtesy of Arianespace
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.