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100th flight of Ariane 5 rocket orbits 2 telecommunications satellites

Arianespace's 100th Ariane 5 rises off the pad on Sept. 25, 2018. Photo Credit: Arianespace

Arianespace’s 100th Ariane 5 rises off the pad on Sept. 25, 2018. Photo Credit: Arianespace

KOUROU, French Guiana — Europe’s flagship heavy-lift Ariane 5 rocket flew to space for the 100th time in history on Tuesday, delivering the Horizons 3e and Azerspace-2/Intelsat 38 telecommunications satellites into orbit.

The mission was initially targeting a 6:53 p.m. local time (21:53 GMT / 5:53 p.m. EDT) launch. This historic mission got underway on Sept. 25, 2018, with the flight lifting off from the Ariane Launch Complex No. 3 at Kourou. However, a hold was called within two minutes of reaching T-zero because of a technical issue with a ground-based system. A new time was set for 7:38 p.m. local time, which was at the end of the 45-minute launch window. This time, everything went as expected and the rocket took to the skies.

“With this sixth launch of the year, Arianespace is proud to have placed its 100th Ariane 5 mission at the service of our American, Japanese and Azeri customers,” Arianespace CEO Stephane Israel said shortly after the mission was declared a success. “It clearly symbolizes the long string of successes achieved by our heavy launcher on the commercial export market, representing more than half of all satellites it has orbited.”

Horizons 3e satellite.

Horizons 3e satellite. Photo Credit: Intelsat

Designated VA243 in Arianespace’s numbering system, the mission was initially scheduled to get underway on May 25, 2018. However, GSAT-11 was sent back to India in late April for additional checks and inspections after communication was lost with another spacecraft in that series—GSAT-6A—shortly after its launch on March 29, 2018.

Arianespace rescheduled VA243 to Sept. 7 and replaced GSAT-11 with Horizons 3e. The flight was delayed one more time, by about 2 and a half weeks, making Sept. 25 the new launch date.

The launch campaign for the mission commenced with the arrival of Azerspace-2/Intelsat 38 and Horizons 3e in French Guiana on Aug. 6 and Aug. 8 (respectively). Throughout August engineers were busy conducting fit checks and other initial checkouts of the satellites. The two spacecraft were fueled in the latter weeks of August.

Horizons 3e was integrated with the rocket’s payload fairing first. On Sept. 5, the satellite was installed into the payload adapter and encapsulated in the fairing. On Sept. 16, the team also finished the integration of Azerspace-2/Intelsat 38 with the stack.

On Sept. 18, the fairing with the satellites inside was attached to the launch vehicle and various checks were performed. A launch rehearsal was conducted on the following day, with the mission passing its launch readiness review on Sept. 21 – giving a green light for the rocket’s roll out to the pad on Sept. 24.

The countdown began 11 hours and 23 minutes before the planned liftoff. About 50 minutes later, checks of the electrical systems commenced. After completing these checks, the rocket’s cryogenic main stage known as the EPC was ready to be filled with liquid oxygen and hydrogen. This began at T-minus 4 hours, 38 minutes. Fueling operations for ESC-A—Ariane 5’s cryogenic upper stage—started some 50 minutes later.

EPC’s Vulcain 2 engine was chilled down at T-minus 3 hours, 18 minutes. Some two hours later, engineers performed final checks on connections between the launch vehicle and telemetry, tracking, and command systems. These last checks allowed mission controllers to report “all systems go,” initiating the synchronized sequence during which the tanks were pressurized for flight and the launch vehicle was switched to onboard power mode, leading to the ignition of EPC.

The EPC was ignited at T-plus 1 second. Six seconds later, the rocket’s twin solid boosters came to life, lifting the rocket off the ground. The launch vehicle then completed a short vertical ascent before beginning its pitch and roll maneuvers 10 seconds after leaving the pad.

The initial phase of the flight lasted for about two minutes, 19 seconds and concluded when the two solid boosters were jettisoned at an altitude of approximately 43 miles (70 kilometers), leaving the Ariane 5 to be powered by the EPC stage alone.

The EPC continued powering the mission until about nine minutes after launch, when it was also separated from the launch vehicle. At T-plus 3 minutes, 19 seconds in, the protective payload fairing was detached unveiling the two car-sized passengers.

Next, the ESC-A stage fired its HM7B engine and took control of the flight. This started the longest phase of the mission, which was tasked with delivering its dual payload into space. Horizons 3e was deployed first, some 28 minutes into the flight. Azerspace-2 / Intelsat 38 was separated some 14 minutes later.

Azerspace-2/Intelsat 38 satellite.

Azerspace-2/Intelsat 38 satellite. Photo Credit: Intelsat

The satellites were initially put into the targeted transfer orbit at an altitude of 155 by 22,000 miles (250 by 35,726 kilometers), inclined 6 degrees. Both spacecraft will reside in a geosynchronous orbit at 45 degrees East (Azerspace-2/Intelsat 38) and 169 degrees East (Horizons 3e).

Built by Boeing Satellite Systems, Horizons 3e is a high-throughput telecommunications satellite owned by a joint venture between US-based Intelsat and the Japanese company SKY Perfect JSAT. The spacecraft, based on Boeing’s BSS-702MP platform, has a mass of about 6.44 metric tons, features two deployable solar arrays and is equipped in high-throughput C- and Ku-band transponders.

Horizons 3e is expected to operate for 15 years, offering 30 gigabits per second of bandwidth for fixed and mobile customers. It is a replacement for the Intelsat 805 satellite and is expected to provide high-throughput services to the Asia-Pacific region and expand coverage in the Pacific Ocean.

Horizons 3e is the first High Throughput Satellite (HTS) for SKY Perfect JSAT and will lead to the expansion of our next generation business in the Asia and Pacific region,” SKY Perfect JSAT wrote in a press release.

Azerspace-2/Intelsat 38 was manufactured by SSL. Weighing some 3.5 metric tons, it is a multi-mission telecommunications satellite based on the SSL-1300 bus featuring two deployable solar arrays. The satellite will be jointly operated by Intelsat and Azercosmos Open Joint Stock Company, a satellite operator based in Azerbaijan for more than 15 years.

Intelsat plans to use Azerspace-2/Intelsat 38 to provide Ku-band capabilities and deliver continuity of service for the Intelsat 12 satellite. The spacecraft is designed to host leading Direct-to-Home television platforms for the fast-growing Central and Eastern Europe and Asia-Pacific regions.

For Azercosmos, the satellite is expected to expand the current capacity of the previous spacecraft in the series—Azerspace-1. It will also increase the coverage area and spectrum of services provided by Azercosmos. The newly-launched spacecraft is Azerbaijan’s second geostationary satellite.

“This satellite, along with the expansion of the coverage zone, will become a reserve for Azerspace-1, which will allow Azercosmos to provide customers with even more reliable services. To meet the growing demand for network services of the public and private sectors in the region, Azerspace-2 will provide strong technical capabilities, affordable coverage and quality services,” Azercosmos wrote on its website.

The Ariane 5 in its ECA configuration is the heavy-lift rocket Arianespace uses for missions to geostationary transfer orbits and usually carries two telecommunications satellite payloads. The 180-foot (54.8-meter) tall ECA is an improved version of the launcher. It is designed to deliver payloads, primarily communications satellites, that weigh up to 10 metric tons.

Tuesday’s mission also marked the fourth flight of an Ariane 5 rocket in 2018 and the sixth launch for Arianespace this year. The company’s next planned flight is scheduled for Oct. 19, when another Ariane 5 is slated to send the BepiColombo spacecraft on a journey to Mercury.

Video courtesy of Arianespace




Tomasz Nowakowski is the owner of Astro Watch, one of the premier astronomy and science-related blogs on the internet. Nowakowski reached out to SpaceFlight Insider in an effort to have the two space-related websites collaborate. Nowakowski's generous offer was gratefully received with the two organizations now working to better relay important developments as they pertain to space exploration.

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