STP-3 (Atlas V)
7 December 2021
Space Launch Complex 41
Cape Canaveral Space Force Station
A United Launch Alliance Atlas V 551 rocket launched the STP-3 mission for the U.S. Space Force’s Space Systems Command from Space Launch Complex 41 at Cape Canaveral Space Force Station at 5:19 a.m. on 7 December 2021. The Atlas V is flying in its 551 configuration consisting of five solid rocket boosters, a five-meter payload fairing, and a single engine Centaur second stage.
The Solid Rocket Boosters begin to burn out.
Solid Rocket Booster separation.
Four of the five SRBs can be seen to the upper left as the rocket continues on.
The rocket, seen at lower right, leaves the SRBs behind to fall into the Atlantic Ocean.

A United Launch Alliance (ULA) Atlas V 551 rocket will launch the Space Test Program-3 (STP-3) mission for the U.S. Space Force’s (USSF) Space Systems Command. STP-3 is a co-manifested mission that matures technology and reduces future space program risk by advancing nuclear detonation detection, space domain awareness, weather and communication. Both spacecraft will be delivered to geosynchronous orbit. Liftoff will occur from Space Launch Complex-41 at Cape Canaveral Space Force Station, Florida.

Built by Northrop Grumman, the primary spacecraft is STP Satellite (STPSat)-6 and the rideshare spacecraft is the Long Duration Propulsive Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA) or LDPE-1. STPSat-6 carries nine payloads including the Space and Atmospheric Burst Reporting System 3 (SABRS-3), an operational mission from the National Nuclear Security Administration, NASA’s Laser Communication Relay Demonstration (LCRD) payload to test technologies for the next generation of data relay satellites, and several Department of Defense Space Experiments Review Board space weather and situational awareness payloads. LDPE-1 is designed for a 1-3 year mission life and carries experimental payloads. The experiments are intended for rapid risk reduction efforts to inform future programs.

The Atlas V rocket debuts several features designed to reduce risk and accumulate flight experience before use on ULA’s Vulcan rocket. The Payload Fairing is produced out of autoclave, a new manufacturing method to cure carbon fiber composites that is a more efficient production process resulting in lower cost and lower system mass while maintaining reliability and quality. The in-flight power system supplies power to the satellites’ batteries during the rocket’s long-duration ascent, ensuring the spacecraft have fully charged batteries when deployed into geosynchronous orbit. Utilizing existing flight computers, GPS enhanced navigation provides GPS signals to improve Centaur’s navigation system performance and orbital accuracy. And finally, the booster rate gyro (BoRG) unit is a low- cost alternative rate gyroscope package. The design utilizes simplified processing and commercial IMUs built into a triple-channel architecture to significantly reduce unit cost and weight.

The ULA Atlas V 551configuration used for the STP-3 mission. Image credit: ULA
The flight profile for the STP-3 mission. Image credit: ULA
ULA STP-3 mission logo. Image credit: ULA
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