A SpaceX Falcon 9 rocket launched 10 Tranche 0 demonstration satellites for the U.S. military’s Space Development Agency. The launch was the first of two Falcon 9 missions to carry SDA demonstration spacecraft for a future constellation of military missile tracking and data relay satellites. The Falcon 9’s first stage booster returned to Landing Zone 4 at Vandenberg. Delayed from Sept. 24. Delayed from Sept. 29 by payload supply chain issues. Delayed from January due to satellite issue. Delayed following an abort at T-3 seconds on Mar. 30. Our live coverage.