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Atlas carries twin sats to orbit

October 4 at 5:36 pm E.T. from SLC-41 at Cape Canaveral Space Force Station

With much of the state still flooded and left in devastation from the recent hurricane Ian, space operations are beginning to move forward with the cadence. This evening ULA (United Launch Alliance) lifted off an Atlas V rocket in the 531 configuration to bring SES-20, and SES-21 to orbit for SES of Luxembourg. Going into a near circular, near geosynchronous orbit at 1.9 degrees of inclination. Once separated these twin satellites will use their on-board propulsion systems to circularize their orbits at 22,300 miles above the equator. This comes ahead of two other launches slated for this week, the Crew-5 mission on Wednesday, and the Galaxy 33 & 34 mission Thursday evening.

SES-20 and SES-21 are both all electric 702 Small Platform satellites equipped with C-band payloads which will operate over the United States. These will help usher in the Federal Communications Commission’s 5G Fast initiative, requiring operators like SES to quit using the lower 300MHz from 200 MHz of the C-band system to make way for 5G mobile services. They each have a mass of 3500 kg, include two solar arrays and a lifespan of fifteen years. The main goal is to provide North America with digital broadcasting services.

Built by Boeing with thousands of narrow and steerable beams and the capability to isolate interference sources, these two spacecrafts provide SES and future customers the ability to extend or even change the satellites coverage areas and mission throughout its life. Using proven hardware along with next generation technology these were created with affordable and lightweight materials enabling them both to be launched from a single rocket. They also mark the first satellites delivered by the company since the start of the global Covid-19 pandemic. After going through environmental testing (vibration, thermal vacuum, electromagnetic, and acoustic) at Boeings factory in El Segundo, CA they were integrated into a dual launch configuration platform also built by Boeing.

You may already know about the Atlas V rocket, but if not here’s what makes ULA so great. The Atlas V rocket is an expendable medium lift launch vehicle with two stages and multiple configurations depending on the mission parameters. The first part of the Atlas V is a common core booster, powered by and RD-180 engine that burns kerosene and liquid oxygen. This stage is accompanied by up to five solid rocket boosters to provide additional thrust. The second stage of the rocket is the Centaur upper stage, powered by one or two RL10 engines that burn liquid hydrogen and liquid oxygen. The 531 configuration simply means the fairing is five meters in diameter, there will be three Solid Rocket Boosters, and a single Centaur engine on the upper stage. The booster for the rocket, or common core will provide 860,200 lbs. of of thrust at sea level and with each SRB (Solid Rocket Booster) providing an additional 371,550 lbs. of thrust totaling the amount of thrust at lift off to 1,974850 lbs. at sea level.

Today’s launch marks the ninety-sixth flight of an Atlas V, and the fifth Atlas V to launch using the 531 configuration. Now there are only twenty Atlas Vs set to launch before the company phases them out for the newest ULA launch vehicle. Delta has slowing been retired and only two Delta IV Heavy’s now remain. Once Atlas and Delta are gone ULA will begin using the new Vulcan Centaur which is said to be less expensive and more capable than its predecessors.

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