Atlas V 421 Launch

SBIRS GEO-5 | Atlas V 421

Lift Off tIME
May 18, 2021 17:37 UTC | 13:37 EDT
Mission Name
Launch Provider
(What rocket company launched it?)
United Launch Alliance (ULA)
(Who paid for this?)
United States Space Force
Atlas V 421
Launch Location
Space Launch Complex-41, Cape Canaveral Space Force Station, Florida, USA
Payload mass
4,500 kg (~10,000)
Where did the satellites go?
Geostationary Transfer Orbit (GTO)
Did they attempt to recover the first stage?
No, this is not a capability of ULA
Where did the first stage land?
It crashed into the Atlantic Ocean
Did they attempt to recover the fairings?
No, this is not a capability of ULA
Were these fairings new?
This was the:
– 144th mission for ULA
– 87th Atlas V launch
– 8th launch of an Atlas V in the 421 configuration

– 44th orbital launch attempt of 2021 (42nd successful launch)
Where to watch
Official replay

How did it go?

The United Launch Alliance successfully launched the SBIRS GEO-5 satellite atop an Atlas V rocket in the 421 configuration for the United States Space Force’s Space and Missiles Systems Center. This launch marked 144 successful missions for ULA.

Originally scheduled to launch on May 17, 2021, the launch was initially scrubbed. A faulty temperature sensor prevented ULA from being able to complete Centaur liquid oxygen (LOx) chilldown operations. The rocket instead lifted from Space Launch Complex-41 at Cape Canaveral Space Force Station, Florida, USA on May 18, 2021.

The Atlas V 421 carries the SBIRS GEO-5 to orbit. (Credit: ULA)

What is the SBIRS GEO-5 Mission?

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 warning and defense capabilities to the U.S Space Force’s Space and Missile Systems Center. The main aim of the program is to support missile defense, missile warning, battlespace awareness, and technical intelligence.

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 was used to take the satellite to Geostationary Transfer Orbit (GTO), after which the satellite used its own propulsion system to gradually raise its orbit to geosynchronous orbit.

The Space and Missile Systems Centre will also flew 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 deployed 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 SBIRS GEO-5 mission warning satellite during acoustic testing. (Credit: Lockheed Martin)

SBIRS GEO-5 Flight Profile

From Lift-Off
0:00:47Maximum Dynamic Pressure (Max Q)
0:02:09  SRB Jettison
0:04:10Atlas Booster Engine Cutoff 
0:04:16Atlas Centaur Separation 
0:04:26Centaur Main Engine Start (MES-1)
0:04:34Payload Fairing Jettison 
0:15:06Centaur Main Engine Cutoff (MECO-1)
0:15:37EZ-3 Deployment 
0:16:25EZ-4 Deployment 
0:31:06Centaur Main Engine Start (MES-2)
0:34:27Centaur Main Engine Cutoff (MECO-2)
0:42:26SBIRS GEO-5 Separation 
The Atlas V payload fairing which will enclose the SBIRS GEO-5 satellite. (Credit: ULA)

What is the Atlas V?

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 now flown 77 launches with no complete failures.

The rocket has two stages. The first is a Common Core Booster (CCB), which is powered by an RD-180 engine 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).

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).

What does 421 mean?

Atlas V rockets have a three number configuration code. The first number represents the fairing diameter size in meters, so in this instance there is a 4 meter 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 on the Centaur Upper Stage.

rocket white srb atlas v fairing fuel engine
A diagram of the entire Atlas V family with the SRB placement for each number shown. (Credit: NASA)

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