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ULA prepares for 100th launch with Morelos-3 mission

Atlas V 421 payload fairing for Morelos-3 communications satellite Astrotech facilities ULA photo posted on SpaceFlight Insider

United Launch Alliance is planning on sending one of the company’s Atlas V 421 boosters to orbit with the Morelos-3 communications satellite in the early hours on Friday, Oct. 2. Photo Credit: ULA

CAPE CANAVERAL, Fla — United Launch Alliance (ULA) is preparing one of the company’s Atlas V 421 rockets for use as the delivery vehicle for Mexico’s Secretaria de Comunicaciones y Transportes (Ministry of Communications and Transportation) Morelos-3 satellite. The 421 booster was provided by Lockheed Martin Commercial Launch Services and is currently on track to be launched on Friday, Oct. 2. ULA has twenty minutes to get the Morelos-3 spacecraft launched and into the Florida skies, with the window opening at 6:08 a.m. EDT (10:08 GMT).

United Launch Alliance Atlas V 421 rocket Cape Canaveral Air Force Station Space Launch Complex 41 Morelos-3 EPF payload fairing communications satellite ULA photo posted on SpaceFlight Insider

The Morelos-3 satellite being encapsulated in its payload fairing. Photo Credit: ULA

The launch site for the Atlas V 421 is Cape Canaveral Air Force Station’s Space Launch Complex 41 in Florida. This version of the rocket is not one of the usual versions of the launch vehicle employed by the Colorado-based firm.

Each of the numbers at the end of the Atlas V’s designation reveals the features of that configuration and the rocket’s payload capability.

The first number, “4”, stands for the size of the payload fairing (in meters; it always has a value of “4” or “5”). The second digit denotes the number of Aerojet Rocketdyne AJ-60A solid rocket boosters the rocket uses (in this case 2). The final number indicates the number of engines in the boosters Centaur Upper Stage (in this case, a single RL-10C – also produced by Aerojet Rocketdyne).

The Atlas V 421 will use these assets to send the Morelos-3 spacecraft into a geosynchronous transfer orbit (2,588 x 19,323 nmi).

Morelos-3 will be shielded during ascent through Earth’s turbulent atmosphere by Atlas’ Extended Payload Fairing (EPF). This top, conical section of the booster comprises two parts and is made up of aluminum skin with stringer construction with vertical split-line longerons. With the additional 31 feet (9 meters) of the EPF, the Atlas V 421 stands an impressive 195 feet (59 meters) in height.

That is just the proverbial tip of the iceberg, however.

The Atlas V booster itself measures some 10 feet (3 meters) in diameter and 41.5 feet (13 meters) in height. The tanks containing the propellant are made of a pressure-stabilized, corrosion resistant stainless steel.

The core stage of the Atlas V measures some 12 and a half feet (four meters) in diameter. Without the EPF, the rocket stands 106.5 ft (32 meters) in height.

Tanks within the booster are composed of barrel sections made of isogrid aluminum panels welded together, and one-piece spun-formed aluminum forward and aft domes. The intertank skirts are made of aluminum isogrid with aluminum ring frames. The resulting construction is structurally rigid.

Despite the appearance that the rocket has two engines, lent by Atlas’ twin thrust chambers, it uses a single RD-180 rocket engine – which is a dual-combustion chamber, dual-nozzle design – in its first stage. The Russian-made RD-180 burns RP-1, a highly refined version of kerosene, with LOX (liquid oxygen) as the oxidizer.

The RD-180 is listed as being able of imparting 860,200 lbf (3.83 MN) of thrust at sea level and is produced by NPO Energomash.

Each of the two AJ-60A solid rocket boosters imparts 380,000 lbf (1.69 MN) of thrust. These SRBs are required for heavier payloads and can be configured anywhere between 1-5 boosters on the Atlas V, depending on the requirements of the mission.

Tomorrow’s flight will be guided, in large part, by the Centaur avionics system. During the boost and Centaur phases of the Morelos-3 mission, this system will be responsible for flight control, guidance, as well as sequencing functions.

United Launch Alliance Atlas V 421 rocket Cape Canaveral Air Force Station Space Launch Complex 41 Morelos-3 EPF payload fairing communications satellite ULA photo posted on SpaceFlight Insider

Two Aerojet Rocketdyne AJ-60A solid rocket boosters will be used to help get the Morelos-3 spacecraft out of Earth’s atmosphere and into orbit. Photo Credit: ULA

The rocket’s Centaur upper stage uses a single RL-10C rocket engine, which is capable of generating some 22,300 lbf (99.2 kN) of thrust. Centaur is fueled by liquid hydrogen with liquid oxygen (LOX) as the oxidizer, which are contained in tanks insulated with helium-purged insulation blankets, radiation shields, and spray-on foam insulation (SOFI).

Much of the Centaur upper stage’s stability is provided by the Centaur forward adapter (CFA). The CFA also has the structural mountings used for the booster’s avionics system as well as the structural and electrical interfaces with the Morelos-3 satellite.

While the rocket engine in the first stage was built in Russia, most of the remainder of the launch vehicle’s components are made in the U.S. The rocket’s EPF and the Centaur fairing are made in Texas, and the AJ-60A is made in California. The RL-10C used in the Centaur upper stage is manufactured in West Palm Beach, Florida, with the rocket’s core stage being built in Decatur, Alabama.

At present, there is a 70 percent chance of favorable conditions for launch. The current, primary causes for concern are solar weather as well as high winds during liftoff.

When it is on orbit, Morelos-3 will be the second of three communications satellites that will comprise the Mexsat communications satellite system.

The MEXSAT system is designed to provide 3G+ communications services across an array of platforms. As noted, there will be three satellites in the constellation. There will also be two ground stations, the pre-requisite control centers, and other sites necessary for the operation of the system.

The Mexsat constellation will provide a wide range of services that include education and health programs, as well as voice, data, video, and internet services. Mexsat will serve to complement other services to rural regions of the country.

The satellite poised for launch on Friday is built by Boeing based on the 702HP geomobile satellite and will run off of 14 kilowatts of power provided by the satellite’s 5-panel solar arrays. These arrays are composed of ultra triple-junction gallium arsenide solar cells.

Morelos-3 will utilize a 22-meter L-band reflector, providing the capability of connecting to handheld devices, which will be complimented by a two-meter Ku-band antenna. If everything goes as plan, Morelos-3 will function for 15 years.

Friday’s launch will be the only commercial, non-NASA mission that United Launch Alliance has on its 2015 launch manifest. This, however, is not perhaps the most notable aspect of the mission.

While this marks the 5th launch overall of an Atlas V 421 and the 57th flight of the Atlas V overall, it will be the 100th ULA since the firm was formed in 2006 from elements of Boeing and Lockheed Martin.

“Our thanks to the entire launch team, including our suppliers, as well as our mission partner — the Ministry of Communications and Transportation of Mexico — for their hard work and commitment to mission success,” said the representatives with ULA and Lockheed Martin Launch Services.

United Launch Alliance Atlas V 421 rocket Cape Canaveral Air Force Station Space Launch Complex 41 Morelos-3 EPF payload fairing communications satellite ULA photo posted on SpaceFlight Insider

Tomorrow’s planned launch will be the fifth for the 421 configuration of the Atlas V – and the 57th of the rocket overall. Photo Credit: ULA


Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology,, The Mars Society and Universe Today.

Reader Comments

Good luck to the fine folks at ULA!

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