Ariane 5 rocket places 2 satellites into orbit despite telemetry anomaly
Arianespace conducted its first mission of 2018 by launching its workhorse Ariane 5 booster with the SES-14 and Al Yah 3 communications satellites. However, the outcome of the flight remained a mystery for several hours as telemetry cut off just after ignition of the upper stage of the rocket.
The Ariane 5 lifted off at 5:20 p.m. EST (22:20 GMT) Jan. 25, 2018, from Ariane Launch Complex No. 3 (ELA 3) in Kourou, French Guiana. The flight lasted 35 minutes and ended with the deployment of the dual payload. However, confirmation of a successful mission didn’t come immediately.
Seconds after the upper stage ignited (occurring some 9 minutes into the launch) to finish placing the two communications satellites into a geostationary transfer orbit (GTO), a tracking station in Natal, Brazil, was not able to acquire launch telemetry.
Arianespace said this lack of telemetry lasted throughout the rest of the powered portion of the flight. With no information as to the fate of the launcher and its expensive payload, the company’s CEO, Stephane Israel, made an announcement about an hour after liftoff confirming there had indeed been an anomaly.
“Up to now, our customers do not have contact with the satellite,” Israel said. “We need now some time to know if they have been separated, and where they are exactly, to better analyze the consequences of this anomaly.”
This caused many to assume the launch had indeed failed, a rarity for the Ariane 5. Of the 96 previous flights, only two failed completely, with another two having been partial failures. The last failure occurred on flight 14 back in December of 2002.
A failure would have serious ramifications for the future of the Ariane 5 launch manifest, which includes the European Space Agency’s $2 billion BepiColombo mission bound for Mercury in October of 2018 and NASA’s $8 billion James Webb Space Telescope slated for liftoff in spring of 2019.
However, some two hours after the anomaly announcement, Ariancespace confirmed the two satellites’ operators had indeed established contact with their spacecraft and they were in orbit. What was not disclosed, however, was if they were in their expected orbits.
The launch campaign
The 180-foot (54.8-meter) tall rocket rolled out to the launch pad Wednesday, Jan. 24. After that, engineers were ready to start the final countdown 11 hours, 23 minutes ahead of planned launch. During the countdown campaign the last checks of electrical systems were performed and the launch vehicle was filled with propellants.
Seven minutes before the launch, all systems were reported “go” and a synchronized sequence was initiated, which led to the ignition of the rocket’s cryogenic main stage (EPC). About six seconds later, Ariane 5’s solid boosters came to life and the launcher soared into the sky.
Ariane 5 completed a short vertical ascent and began its pitch and roll maneuvers within first 10 seconds after liftoff. The initial phase of the flight lasted for 2 minutes, 19 seconds before the two solid boosters were jettisoned at an altitude of approximately 43 miles (70 kilometers). This left the launch vehicle being powered by the EPC stage alone.
Just over three minutes into the ascent, the protective payload fairing was detached, unveiling the mission’s two passengers. The EPC powered the flight until nearly nine minutes after liftoff, when this stage separated from the launch vehicle. Shortly after, the ESC-A cryogenic upper stage fired its HM7B engine and took control over the flight.
While Arianespace has not confirmed if the upper stage performed as expected despite the telemetry dropout, if all was nominal the ESC-A would have continued the trek toward a GTO for another 16 minutes.
The SES-14 satellite would have been the first to be deployed at about 27 minutes into the flight. Six minutes, 17 seconds later, the SYLDA dual-payload adapter was jettisoned to reveal the Al Yah 3 spacecraft, which would have been released 35 minutes after liftoff.
If the spacecraft are confirmed in their initial GTO, the next step will be for each satellite to use their onboard propellant to circularize their orbit into a geostationary orbit. SES-14 will reside at 47.5 degrees West while Al Yah 3 will be at 20 degrees West.
SES-14, built by Airbus Defence and Space, is a telecommunications satellite weighing approximately 4.4 metric tons. It has dimensions of 23 x 17.7 x 8.86 feet (7 x 5.4 x 2.7 meters). It is based on the E3000 EOR spacecraft platform with an onboard power of 16 kilowatts and is fitted with two deployable solar arrays.
The spacecraft will be operated from orbit by the Luxembourg-based telecommunications satellite operator SES for a designed lifetime of some 15 years. SES-14 will offer its services to Latin America, the Caribbean, North America and the North Atlantic region with its C- and Ku-band wide beam coverage, as well as Ku-band high-throughput spot beams coverage.
“SES-14’s C-band wide beams are designed to expand the reach of SES’s second cable neighborhood in Latin America, while its Ku-band HTS spot beams will serve the dynamic aeronautical market and other traffic-intensive applications such as maritime, cellular backhaul and broadband services,” SES wrote on its website. “The Ku-band wide beams will also serve growing direct-to-home and VSAT services in the Americas and the North Atlantic.”
SES-14 also carries the Global-Scale Observations of the Limb and Disk (GOLD) as a hosted payload for NASA. The main goal of this payload is to advance humanity’s understanding of the space environment. GOLD is designed to examine the response of the upper atmosphere to forces from the Sun, the magnetosphere, and the lower atmosphere.
“The upper atmosphere is far more variable than previously imagined, but we don’t understand the interactions between all the factors involved,” said Richard Eastes, GOLD principal investigator at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder. “That’s where GOLD comes in: For the first time, the mission gives us the big picture of how different drivers meet and influence each other.”
Al Yah 3
Al Yah 3 was built by Dulles, Virginia-based Orbital ATK for the United Arab Emirate’s (UAE) Al Yah Satellite Communications Company (Yahsat). The spacecraft has a mass of nearly 3.8 metric tons and its dimensions are 17 x 11 x 9.4 feet (5.18 x 3.35 x 2.87 meters). The vehicle is based on the GEOStar-3 bus and has two deployable solar arrays and an onboard power of 8.0 kilowatts. It is designed to be operational for 15 years.
The satellite is equipped to transmit in 53 active Ka-band user beams and four gateway beams. Al Yah 3 will provide its services to Brazil and Africa. Additionally, it will offer two-way communications services to facilitate high-speed delivery of data to end-user applications such as broadband Internet and corporate networking as well as IP backhaul for telecommunications service providers.
“The launch of Al Yah 3 extends the coverage to another 20 markets, reaching 60 percent of Africa’s population and marks our entry into Brazil, covering more than 95 percent of the population,” said Muntasir Abdullah Murad Al Mazem, the Senior Network Operator at Yahsat.
The Ariane 5 in its ECA configuration, which was used for the Jan. 25 launch, is the heavy-lift rocket Arianespace uses for missions to GTO and usually carries two telecommunications satellite payloads.
The flight, designated VA241, was the 241st Ariane launch conducted by the Arianespace. The company’s next mission is currently scheduled for March 1, when a Soyuz ST-B launcher is slated to orbit a quartet of O3b satellites.
Video courtesy of NASA
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