Less than two months since the rousing launch of the Automated Transfer Vehicle (ATV)-4 “Albert Einstein,” another mammoth Ariane 5 booster stands ready at the Guiana Space Centre in Kourou, French Guiana, primed to loft India’s latest meteorological and search-and-rescue satellite, the Insat-3D, and Europe’s largest and most sophisticated communications satellite, the Alphasat. Launch of Mission VA-214—the 214th flight by Arianespace’s rocket family since the maiden voyage of its Ariane 1 in December 1979—is scheduled to occur within a 78-minute “window” on Thursday, 25 July. The window opens at 4:53 p.m. local Kourou time (3:53 p.m. EDT).
The upcoming launch also marks the 70th mission by the Ariane 5 variant, which first flew back in June 1996. Standing 171 feet tall and weighing close to 1.7 million pounds, the two-stage rocket is one of the world’s most powerful launch vehicles currently in operational service. Since its ill-fated maiden voyage—which succumbed to a software glitch and was remotely destroyed by the flight termination system when it began to veer off-course—it has supported dozens of missions, only four of which have been classified as total or partial failures. Ariane 5’s second mission, in October 1997, suffered a premature shutdown of its core stage and failed to achieve orbit, whilst two others in July 2001 and December 2002 also underperformed. However, the vehicle has maintained an unblemished record ever since.
Thursday’s flight is the third Ariane 5 launch of 2013, coming hard on the heels of ATV-4 in June and the Amazonas-3 and Azerspace-1/Africasat-1A dual-satellite mission in February. The VA-214 launch campaign got underway in earnest at the South American site with the erection of the rocket stages, and in mid-June the Insat-3D and Alphasat payloads arrived for final pre-flight processing. Both satellites’ on-orbit propulsion systems were fueled in early July, and they were loaded aboard the Ariane 5—with Insat atop the cryogenic core stage and Alphasat above it—ahead of “encapsulation” within the bullet-like payload shroud on 17 July. This intricate process took place inside the 295-foot Final Assembly Building (BAF) at the Guiana Space Centre.
A standard Launch Readiness Review took place Tuesday, 23 July, and the VA-214 vehicle was due to be rolled out from the BAF to the ELA-3 (Ensemble de Lancement Ariane) launch complex early today (Wednesday), as this preview article was being prepared. In the final hours before tomorrow’s launch, the rocket’s electrical systems will be checked, and at T-4 hours and 50 minutes the lengthy process to load 260,000 pounds of liquid oxygen and 50,000 pounds of liquid hydrogen into the 100-foot-tall “cryotechnic main stage” will begin. These propellants will feed the stage’s French-built Vulcain-2 engine. Ariane’s tanks will be pressurized for flight at T-4 minutes and the vehicle will transition to internal power supplies. In the final seconds, the on-board systems will assume primary command of all critical functions and the guidance systems will be unlocked to flight mode.
At T-zero, the Vulcain-2 will ignite and 7.3 seconds of engine-check operations will be conducted, ahead of the command to fire Ariane 5’s twin side-mounted solid-fueled boosters. Powered by the Vulcain’s 300,000 pounds of thrust and supplemented by the boosters—each of which produces a 1.4-million-pound propulsive yield—Mission VA-214 will be committed to flight. Five seconds after leaving ELA-3, guided by two computers inside the rocket’s Vehicle Equipment Bay (VEB), Ariane will commence a pitch and roll program maneuver, rotating toward the east and establishing itself onto the proper azimuth to inject its twin satellite cargoes into orbit. “It maintains an attitude that ensures the axis of the launcher remains parallel to its velocity vector,” noted Arianespace in its VA-214 launch kit, “in order to minimize aerodynamic loads throughout the entire atmospheric phase, until the solid boosters are jettisoned.”
The departure of the boosters will take place at T+142 seconds, after which the vehicle will continue to climb, under the impulse of the Vulcain engine. At three and a half minutes, the bullet-shaped payload fairing will be released, exposing Insat-3D and Alphasat to the harsh space environment for the first time. The Vulcain will shut down and the core stage will be discarded about nine minutes after launch, descending toward a splashdown zone off the coast of Africa, in the Gulf of Guinea. Meanwhile, the second stage—powered by a restartable, 6,100-pound-thrust Aestus engine—will pick up the baton for the final push. Fed by unsymmetrical dimethyl hydrazine and nitrogen tetroxide, the Aestus will deliver both satellites into their preliminary orbits: Alphasat will depart at 27 minutes into the flight, and Insat-3D will follow about five minutes later. Both satellites will play an enormous role in their respective areas of meteorology and telecommunications.
The inaugural contracts to build Alphasat were signed in Paris, France, between the European Space Agency (ESA) and the International Maritime Satellite Organisation (INMARSAT), back in November 2007. It marked the first commercial customer to utilize the new “Alphabus” satellite platform, which has been developed jointly by Astrium and Thales Alenia Space. The platform is described as “a co-ordinated European response to the increased market demand for larger telecommunications payloads for new broadband, broadcasting, and mobile communications services.”
In May 2009, Arianespace was chosen to launch Alphasat. The 14,600-pound satellite will be located at an inclination of 25 degrees East, from which it will spend up to 15 years providing extended coverage to Africa, Europe, the Middle East, and parts of Asia, supplementing INMARSAT’s current constellation. An advanced integrator processor provides payload flexibility and, coupled with its L-band transponder suite, enables robust communications in crisis and disaster emergencies, potentially connecting homes, schools, and businesses in remote locations.
Alphasat is equipped with a large deployable antenna reflector, measuring over 36 feet in diameter, and will also carry three ESA-supplied technology demonstrators. The latter include an advanced star tracker with active-pixel technology, an optical laser terminal for high-data-rate geosynchronous and low-orbit communications, and a dedicated payload to characterize performance in the Q-V band to prepare for possible future commercial exploitation. The satellite generates electrical power by means of two large gallium arsenide solar arrays, which have a total wingspan of 130 feet when fully unfurled in orbit.
Insat-3D carries advanced meteorological instruments, including a six-channel imager and a 19-channel sounder. These provide vertical profiles of temperature, humidity and integrated ozone from the surface to the top of the “sensible” atmosphere. A Middle Infrared capability enables Insat to acquire night-time images of low cloud and fog patterns, whilst imaging in two Thermal Infrared bands allows for sea surface temperatures to be pegged with great accuracy. The satellite is also equipped with a C-band data-relay transponder to receive meteorological, hydrological and oceanographic data from remote locations, whilst a 406 MHz Satellite-Aided Search-And-Rescue transponder will pick up and relay alert signals from distress beacons of maritime, aviation and land-based users and route them to the Indian Mission Control Centre at ISRO’s Telemetry, Tracking and Command Network in Bangalore. The 4,400-pound satellite—based upon India’s I-2K “bus”—has been developed by the Indian Space Research Organisation (ISRO), headquartered in Bangalore. It was originally expected to fly aboard a home-grown Geosynchronous Satellite Launch Vehicle (GSLV), but in December 2010 ISRO decided to manifest Insat-3D aboard an Ariane 5.
Its primary mission goal is “to provide an operational, environmental, and storm warning system to protect life and property and also to monitor Earth’s surface and carry out oceanic observations.” After insertion into geosynchronous orbit, at an altitude of more than 22,000 miles, Insat-3D will be maneuvered into its operational “slot” of 82 degrees, which will enable it to cover the entire Indian subcontinent. According to Shailesh Naik of India’s Ministry of Earth Sciences, the new satellite should “achieve more accuracy levels within a few years in short-term and long-term weather forecasts.”
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