Screenshot from ULA Webcast of the launch of SBIRS GEO-5. Choppy waves means it’s windy
Mission Rundown: Atlas V 421 - SBIRS GEO-5
Written: September 3, 2021 - Edit: November 29, 2022
The Little Red Rocket Flame
United Launch Alliance (ULA) Atlas V rocket carrying the Space Based Infrared System Geosynchronous Earth Orbit (SBIRS GEO) Flight 5 mission for the U.S. Space Force’s Space and Missile Systems Center (SMC) lifted off on May 18 at 13:37 EDT from Space Launch Complex-41 at Cape Canaveral Space Force Station. To date ULA has launched 144 times with 100 percent mission success.
The mission launched on an Atlas V 421 configuration rocket that included a 13.7-ft (4-m) Extra Extended Payload Fairing (XEPF). The Atlas booster for this mission was powered by the RD AMROSS RD-180 engine supported by two AJ-60A solid rocket boosters. Aerojet Rocketdyne provided the RL10C-1-1 engine for the Centaur upper stage.
This was the 87th launch of the Atlas V rocket and the 72nd Atlas V to launch from Space Launch Complex-41 in Florida.
The SBIRS GEO-5 Payload
SBIRS GEO-5 is the fifth satellite in the program, which was designed to replace the Defense Support Program, Northrop Grumman’s system of early warning satellites, which has been in operation since the 1970s.
The first of the SBIRS satellites was launched in 2011, with subsequent satellites being launched in 2013, 2017, and 2018. The final satellite in the program, the SBIRS GEO-6 is scheduled for launch in 2022, also on an Atlas V rocket.
While this is the 5th SBIRS spacecraft to be built by Lockheed Martin, it is the first to be built on the company’s LM 2100 combat bus, which provides enhanced security features, and improved power, propulsion, and electronics. The SBIRS GEO-6 satellite will also be built on the LM 2100M bus.
An Atlas V rocket will be used to take the satellite to the Geostationary Transfer Orbit (GTO), after which the satellite will use its own propulsion system to gradually raise its orbit to geosynchronous orbit.
The Space Based Infrared System (SBIRS) is a network of satellites and hosted payloads in Geosynchronous Earth Orbit (GEO) and Highly Elliptical Orbit (HEO), which utilize scanning and staring infrared sensors to provide early missile warnings.
SBIRS is managed by the Production Corps at the Space and Missile Systems Center at Los Angeles Air Force Base. The 460th Space Wing at Buckley AFB, Aurora, Colorado, operates the SBIRS constellation.
The SBIRS program delivers timely, reliable and accurate missile-warning and infrared surveillance information to the president, secretary of Defense, combatant commanders, intelligence community and other key decision makers.
The system enhances global missile launch detection capability, supports the nation’s ballistic missile defense system, expands the country’s technical intelligence gathering capacity and bolsters domain awareness for warfighters on the battlefield.
SMC is the center of excellence for acquiring and developing military space systems. SMC’s portfolio includes space launch, global positioning systems, military satellite communications, a meteorological satellite control network, range systems, space-based infrared systems, and space situational awareness capabilities.
Each SBIRS GEO spacecraft utilizes a suite of two advanced sensors, allowing them to detect short- and mid-wave infrared signals, providing data that can be used to track missile launches from around the world. According to Lockheed Martin, the constellation has quickly proven its worth; the SBIRS system detected nearly 1,000 worldwide missile launches in 2019 alone.
When GEO-5 was ordered alongside GEO-6, the two spacecraft were initially supposed to be identical to the four SBIRS High satellites that have preceded them, which used Lockheed Martin’s A2100 satellite bus.
During the development of GEO 5 and 6, it was decided to instead use the modernized LM2100M (Modernized Military) bus, which is developed specifically for military operations. A satellite bus is the basic frame with propulsion, station keeping, solar power, batteries and avionics to keep the military ‘payload’ in the right place.
The LM2100M is designed to be more resilient to cyber attacks and contains an upgraded suite of power and propulsion equipment.
The Space and Missile Systems Centre will also be flying the EZ-3 and EZ-4 flight systems as a part of the mission, which will support the deployment of two Technology Demonstration Orbiters, TDO-3 and TDO-4. The payloads will deploy from the aft bulkhead carrier prior to the SBIRS GEO-5 and will provide experimental data that can be used to improve future missions.
The Atlas V 421 launch
ULA will launch the SBIRS GEO-5 satellite on a Atlas V rocket in the 421 configuration for the United States Space Force’s Space and Missiles Systems Center. The rocket is scheduled to lift off from Space Launch Complex-41 at Cape Canaveral Space Force Station, Florida, USA at 13:37 EDT - 17:37 UTC on May 18, 2021.
At T+00:01:36 the SRB burned out and was separated at T+00:02:09, while the 1st stage kept burning to T+00:04:14 Main Engine Cut Off MECO. Stage separation took 3-4 seconds to allow leeway before 2nd stage first Main Engine Start MES-1 began at T+00:04:29 where it continued to burn for 11m 53s to T+00:15:07 beginning its coast faze toward equator, while deploying the two CubeSats EZ-3 and EZ-4.
At T+00:31:05 the 2nd stage second Main Engine Start MES-2 began initiating the transfer burn to 35 753 km apogee from a 925 km perigee on the equator and turning the angle on equator from 26.18 to 21.1 degree. After a 3m 20s burn, the second Main Engine Cut Off MECO-2, a coast faze, began until payload deployment at T+00:42:47.
SBIRS GEO-5 will now, under its own power, complete the geostationary orbit. The 2nd stage however will conduct a third Main Engine Start MES-3 at T+01:19:27 with the last remaining fuel reserves for only 13 seconds lowering the apogee from 35 749 km to 4500 km, this is a reduction of height by 88% which is impressive. The much lighter empty 2nd stage is now a derelict piece of space debris orbiting between 180 km and 4 500 km.
The Atlas V rocket
The Atlas V is an expendable medium lift launch system and member of the Atlas rocket family. The rocket is one of the most reliable in the world, having more than 76 launches (As of November 2020) with no complete failures.
The Atlas V 421 rocket, designated AV-091 is standing 59.1 meters - 194 feet tall on launch pad SLC-41.
The rocket has two stages. The first is a Common Core Booster (CCB), which is powered by an RD-180 engine with two bells and burns kerosene (RP-1) and liquid oxygen (LOX). This is accompanied by up to five strap-on solid rocket boosters. The second stage is the Centaur upper stage, which is powered by one or two RL10 engines and burns liquid hydrogen (LH2) and liquid oxygen (LOX).
Atlas V rocket is filled with 344 472 liter - 91 000 gallons of RP-1, liquid oxygen and liquid hydrogen. Question is now how much goes to fill each stage and the four tanks. Together they can contain 344,47 m3 RP-1, cryogenic oxygen and cryogenic hydrogen.
The Common Core Booster holds 184 728 liter - 48 800 gallon liquid oxygen chilled to below -182,96 0C Celsius or -297,33 0F Fahrenheit that can fit in a 184,73 m3 oxygen tank.
The Common Core Booster holds 94 635 liter - 25 000 gallon RP-1 highly refined kerosine at room temperature that can fit in a 94,64 m3 fuel tank.
The Centaur upper stage holds about 49 400 liter - 13 050 gallons of liquid hydrogen chilled to -252,8 0C Celsius or -423 0F Fahrenheit that can fit in a 49,40 m3 hydrogen tank.
The Centaur upper stage holds about 15 709 liter - 4 150 gallons of liquid oxygen chilled to below -182,96 0C Celsius or -297,33 0F Fahrenheit that can fit in a 15,71 m3 fuel tank.
Still to find is data on Helium gas, pressures used and number of COPV to store it. And are there tanks to store propellant used to maneuver during ascent and in orbit.
In the 421 configuration, the Atlas V is capable of carrying up to 14,067 kg to Low Earth Orbit (LEO), and 6,890 kg to Geostationary Transfer Orbit (GTO).
The Atlas V 421 rocket has a three number configuration code.
The first number represents the fairing diameter size in meters, so in this instance there is a 4 meter XEPF fairing. The second number denotes the number of solid rocket boosters (SRBs), which attach to the base of the rocket. The number of SRBs for a 4 meter fairing can range from 0 – 3. In this case there will be 2 SRBs attached to the center core.
The third number shows the number of engines on the Centaur Upper Stage, which is 1 in this configuration. So this means that this rocket will have a 4 meter faring, 2 solid rocket boosters, and 1 engine bell on the Centaur Upper Stage.
