ULA Successfully Conducts NROL-107 Launch, Marking the Final Atlas NRO Mission
United Launch Alliance (ULA) successfully launched its Atlas V rocket on Sunday for the classified NROL-107 Silent Barker mission. This mission, a joint project between the National Reconnaissance Office (NRO) and the United States Space Force, has been in development for three years and aims to provide the capability to search, detect, and track objects from a space-based sensor for timely custody and event detection. Silent Barker will form a constellation of satellites used for tracking other countries’ activities in geostationary orbit.
Unlike the current method of geostationary tracking using ground-based assets, Silent Barker can track smaller objects and continuously observe their position and movement. The exact number of satellites onboard the Atlas V rocket is classified, but it is expected to be one of two launches for the initial constellation. The NRO will operate the constellation, which is scheduled to be operational by 2026.
The Silent Barker payload was launched into a near-geosynchronous orbit with zero inclination, positioned at the 105-degree East slot. This places the satellites around 7,000 kilometers above a proper geosynchronous orbit. The specific maneuvers that the satellites will perform following deployment are unknown.
The Atlas V rocket used for this mission was in its most powerful active configuration, known as Atlas V 551. The first stage booster, five GEM-63 solid rocket motors (SRMs), and the Centaur upper stage were stacked together before the payload was installed. A wet dress rehearsal was performed to simulate launch day activities and ensure the integrated launch vehicle and ground support systems were ready for launch.
On launch day, the Atlas V rocket was loaded with cryogenic propellants including liquid oxygen and liquid hydrogen. The RD-180 engine on the first stage burned RP-1 fuel and liquid oxygen, while the Centaur second stage’s RL-10C-1-1 engine burned liquid hydrogen and liquid oxygen. The countdown entered a planned hold at T-4 minutes to perform a final go/no-go poll of all flight controllers. At T-2.7 seconds, the RD-180 engine ignited, and the vehicle lifted off from the launch pad at T+1 second.
Thanks to the high thrust of the five GEM-63 SRMs, the Atlas V rocket went supersonic just over 35 seconds after liftoff. The SRMs burned out and were jettisoned at one minute and 44 seconds after launch, followed by the jettisoning of the payload fairing at T+3 minutes and five seconds. Based on previous Atlas V 551 flights, it is inferred that the first stage should burn out and separate around four and a half minutes into the flight.
The Centaur second stage will then begin its burns to bring the payload into a low-Earth parking orbit. After coasting for some time, the RL-10 engine on the Centaur will ignite for a second time to send the stack into a geostationary transfer orbit. Near apogee, the Centaur will ignite its RL-10 engine for the third time to boost Silent Barker into a near-geosynchronous orbit. The satellites will then deploy, and the Centaur will either vent the remaining propellants or ignite its engine for a final time, entering a graveyard orbit for disposal.
This mission marks the 98th launch for Atlas V and the second launch this year for United Launch Alliance. It also signifies the end of NRO payloads launching on the Atlas V, as future reconnaissance missions will fly on ULA’s upcoming Vulcan rocket.
To wrap it up, ULA’s successful launch of the Atlas V rocket carrying the classified NROL-107 Silent Barker mission demonstrates the advancement in space-based tracking capabilities. This joint project between the NRO and the United States Space Force will provide enhanced surveillance of objects in geostationary orbit, allowing for timely custody and event detection. With the Silent Barker constellation, smaller objects can be tracked continuously, improving monitoring capabilities. The launch of this mission, using the most powerful active configuration of the Atlas V rocket, marks an important milestone in the history of Atlas V and sets the stage for future reconnaissance missions on ULA’s upcoming Vulcan rocket.
