Proton-M launcher soars skyward with communications satellite
International Launch Services (ILS) conducted a successful launch of its Proton-M booster carrying a communications satellite for Intelsat. The rocket, with the Intelsat 31 spacecraft (also known as DLA-2), lifted off at exactly 3:10 a.m. EDT (07:10 GMT) on June 9 from Launch Pad 24 at the Baikonur Cosmodrome in Kazakhstan.
The launch of the mission was primarily scheduled for May 28; however, an issue with the upper stage’s thermal control system forced ILS to postpone the planned liftoff. The flight was delayed again on June 8 due to a faulty electrical system on the launch pad itself.
The Proton-M rocket, adhering to a routine flight profile, completed a short vertical ascent before turning eastward. The first stage of the launch vehicle powered the mission by utilizing its six engines for about two minutes. Next, the second stage assumed control over the flight and accelerated the rocket for approximately two-and-a-half minutes until it separated from the launch vehicle.
The third stage then ignited its engine to continue the flight for about five minutes until it separated from the launch vehicle at around nine-and-a-half minutes after liftoff. Meanwhile, the protective payload fairing was jettisoned at five minutes and 47 seconds into the flight, exposing the satellite.
After separation of the third stage, the Briz-M upper stage took control of the mission, starting a long 15-hour trek to release the spacecraft.
During this long-lasting journey, the upper stage will conduct five engine burns to advance the orbital unit first to a circular parking orbit, then to an intermediate orbit, followed by a transfer orbit, and finally to a supersynchronous transfer orbit.
The last Briz-M engine burn will finish at 6:28 p.m. EDT (22:28 GMT), 15 hours and 18 minutes after liftoff. About 13 minutes later, the satellite will separate from the upper stage.
The spacecraft will be inserted into a geosynchronous orbit and will eventually reside co-located with Intelsat’s Galaxy 3C and DLA-1 satellites at 95 degrees West.
The flight is one of the longest among commercial missions in history. Usually, orbiting a communications satellite does not take more than three hours, counting from liftoff to orbital insertion.
The mission’s payload – Intelsat-31/DLA-2 satellite – has a mass of nearly 6.5 metric tons and is manufactured by Space Systems Loral (SSL). It is 28.34 feet (8.64 meters) long, making it the tallest spacecraft ever built by SSL.
“Intelsat 31, manufactured by SSL, is almost a clone of Intelsat 30. The two programs were run as one, with a single design cycle and construction timelines separated by only four months, so the same team was able to build both satellites,” Intelsat noted on its website.
Intelsat 31 is designed to provide Direct-to-Home (DTH) television services in Latin America. Although the satellite will be operated by Intelsat, the company will lease the total Ku-band capacity of the spacecraft to DirecTV Latin America, a DTH digital television services operator in Latin America.
The satellite is based on the SSL 1300 platform, available on the space industry market since the mid-1980s. This bus has a total satellite power capability ranging from 5 to 25 kilowatts and can support between 12 and 150 transponders.
According to SSL, this platform features a lightweight and high-strength structure, fuel-efficient attitude and station-keeping subsystems, high-efficiency and reliable solar arrays and batteries, as well as advanced command and control subsystems.
Intelsat 31 is equipped with 10 C- and 72 Ku-band transponders. The satellite has two deployable solar arrays capable of generating 20 kilowatts of output power throughout its designed lifetime of 15 years.
“Intelsat 31 is a 20-kilowatt class Ku- and C-band satellite. The Ku-band payload is also known as DLA-2 and will provide redundancy for DirecTV Latin America’s direct-to-home distribution services in South America and the Caribbean. The C-band payload enhances Intelsat’s existing C-band service infrastructure serving Latin America,” Sharyn Nerenberg of Intelsat told SpaceFlight Insider.
The satellite will be used for high-definition programming throughout South America and the Caribbean. Intelsat hopes that utilizing the reuse of a spot-beam frequency, along with the other advanced technologies, the Ku-band payloads will significantly expand DTH entertainment offerings in Latin America and provide backup and restoration services.
“What is unique about Intelsat 31 is that the Ku-band payload is dedicated to a single customer, DirecTV Latin America, to serve their direct-to-home distribution needs throughout South America and the Caribbean,” Nerenberg said.
The 190-foot (58-meter) tall Proton-M booster, which was used to send Intelsat 31 into space, measures some 13.5 feet (4.1 meters) in diameter along its second and third stages. The first stage has a diameter of 24.3 feet (7.4 meters). The total overall height of the Proton rocket’s three stages is about 138.8 feet (42.3 meters).
The rocket’s first stage consists of a central tank containing the oxidizer surrounded by six outboard fuel tanks. Each fuel tank also carries one of the six RD‑276 engines that provide power for the first stage. The cylindrical second stage is powered by three RD-0210 engines along with a single RD‑0211 engine.
Meanwhile, the third stage is powered by a single RD-0213 engine and a four-nozzle vernier engine. Guidance, navigation, and control of the Proton-M during operation of the first three stages is carried out by a triple redundant closed-loop digital avionics system mounted in the Proton’s third stage.
The Briz-M is powered by a pump-fed gimbaled main engine. This stage is composed of a central core and an auxiliary propellant tank that is jettisoned in flight after the depletion of the stage’s fuel.
The Briz-M control system includes an onboard computer, a three-axis gyro stabilized platform, and a navigation system.
Thursday’s launch was the third Proton mission and the 14th orbital flight for Russia in 2016. It is also the 93rd ILS Proton launch overall. The next Russian mission is currently scheduled for July 6 (July 7 Moscow time) when a Soyuz-MS spacecraft is expected to send a trio of Expedition 48 crew members to the International Space Station.
Video courtesy of Телестудия Роскосмоса (TV Roscosmos)
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