SpaceX launched the NROL-172 mission aboard a Falcon 9 Block 5 rocket from Space Launch Complex 4 East (SLC-4E) at Vandenberg Space Force Base at 0213 UTC on Tuesday (May 12). The flight carried a batch of classified intelligence-gathering satellites for the National Reconnaissance Office (NRO), marking the 13th mission supporting the agency’s "proliferated architecture" constellation.
The first-stage booster, B1097 (flown for the 9th time), successfully landed on the drone ship 'Of Course I Still Love You' approximately 8.5 minutes after liftoff. It was the second launch and landing for this particular booster, according to a SpaceX mission description. SpaceX's livestream ended shortly thereafter, at the request of the NRO.
This mission is part of the National Security Space Launch (NSSL) Phase 3 Lane 1 contract, managed by the Space Systems Command (SSC), and follows previous proliferated architecture launches such as NROL-145, NROL-48, and NROL-105.
"To stay ahead of the competition and ensure it can continue to operate in a heightened threat environment, the NRO is modernizing its architecture in space and on the ground — delivering more capability faster with increased resilience," agency officials wrote in the NROL-172 press kit.
"A greater number of satellites — large and small, government and commercial, in multiple orbits — will deliver an order of magnitude more signals and images than is available today," they added.
The NRO did not disclose the exact quantity of satellites, but they are part of a constellation including electro-optical, radar, and relay satellites contributed by the Geospatial Intelligence Systems Acquisitions Directorate (GEOINT). These relay satellites enable inter-satellite optical communications and support the Department of War’s space-data network.
The NRO utilizes this proliferated architecture to provide greater revisit rates, increased coverage, and resilience by eliminating single points of failure. The satellites for the new network were built by SpaceX and Northrop Grumman. Their exact purpose, location in orbit or number remain classified.
The use of Falcon 9 for these missions allows for shorter, more responsive timelines compared to traditional major system acquisitions. All of the proliferated architecture satellites have reached orbit atop the SpaceX rockets flying out of Vandenberg, which sits on California's scenic but often foggy central coast. The first such launch, NROL-146, lifted off in May 2024. The most recent before today, NROL-105, took place this past January.
This was the second flight under the NSSL Phase 3 Lane 1 contract for SpaceX, following NROL-145 in April 2025. The mission was originally targeted for May 11 but was delayed to May 12 due to weather or technical checks, with propellant loading commencing successfully on the night of May 11.
NROL-172 was the 55th Falcon 9 launch of the year. The vast majority of the rocket's liftoffs so far in 2026 — 44 of 55 — have been dedicated to building out Starlink, SpaceX's broadband megaconstellation in low Earth orbit.
