Today, Sep. 10 at 12:47 UTC, United Launch Alliance (ULA) successfully launched the NROL-107 mission, a joint collaboration between the National Reconnaissance Office (NRO) and the United States Space Force (USSF). The launch was previously scheduled for August 29, but the Hurricane Idalia postponed the liftoff. The payload was sent into a near-geosynchronous orbit with the Atlas V 551, marking the final launch of this rocket for the NRO. The new ULA’s Vulcan Centaur rocket will take its place once it becomes operational.
The NROL-107 mission, also called Silent Barker, is a classified joint mission between NRO and USSF, and the only readily available information comes from ULA, where the company states that the satellite will “improve space domain awareness”.
This launch was the first out of two and carried several satellites onboard, meaning that the Silent Barker mission will set up a constellation of satellites in geosynchronous orbit, to track foreign objects that would not otherwise always be monitorable due to weather conditions.
According to the disclosed launch specifications, the Silent Barker payload is scheduled to be placed into an orbit ranging from 41,849 to 42,479 kilometers, featuring zero inclination. This will position the satellites at the 105-degree East orbital slot, approximately 7,000 kilometers above the standard geosynchronous orbit.
The Atlas V 551 rocket, originally designed by Lockheed Martin and now operated by United Launch Alliance, is the most powerful rocket of the Atlas series, able to carry 3,850 kg in GEO and 8,900 kg in GTO.
The rocket uses 5 solid rocket boosters (SRBs) mounted around a standard common core booster, a Centaur upper stage in a single-engine configuration, and a 5m-diameter payload fairing in a carbon composite bi-sector design.
The common core booster, called “Atlas V Booster”, is powered by the RD-180 main engine, a liquid oxygen/liquid kerosene, two-thrust-chamber engine, fully equipped with thrust vector gimbaling, pneumatics and hydraulics for control valve actuation, and a thrust frame to distribute loads. In this particular mission, the rocket will be equipped with five Aerojet Rocketdyne SRBs, to ensure maximum thrust.
Ultimately, the Centaur upper stage is one of the world’s highest-performing ones. The pressure-stabilized tanks combined with the lightweight Aerojet Rocketdyne RL10C-1 engine provide the industry’s best thrust-to-weight ratio.