SpaceX scrubs final-minute launch of 21 SDA missile-tracking satellites

SpaceX scrubbed its launch attempt for the Space Development Agency’s Tranche 1 Transport Layer A mission on Monday, aborting the Falcon 9 countdown in the final minute, Spaceflight Now reported (https://spaceflightnow.com/2026/10/04/live-coverage-spacex-to-launch-21-data-transport-satellites-for-the-space-development-agency/).

The countdown was halted at 4:28 a.m. EDT (08:28 UTC) as the rocket shifted into its automated startup sequence. SpaceX gave no immediate reason for the abort.

The mission, dubbed T1TL-A, is the fourth production flight for the SDA’s Proliferated Warfighter Space Architecture, which will provide missile tracking and secure communications for the US military and its allies. The 21 satellites were built by Northrop Grumman — the first Tranche 1 batch from the company. The earlier missions used satellites from York Space Systems (T1TL-B in September 2025 and T1TL-E in July 2026) and Lockheed Martin (T1TL-C in October 2025). Sixty-three Tranche 1 satellites are already in orbit.

Liftoff is now targeted for no earlier than Tuesday 6 October at 1:17 a.m. PDT from Space Launch Complex 4 East at Vandenberg Space Force Base in California. The mission will reuse Falcon 9 booster B1103 on its sixth flight, with a planned landing at Landing Zone 4 — which would be the 37th LZ-4 landing and the 668th Falcon booster landing overall.