A year’s worth of Falcon 9 Ascent sonic boom measurements in Southern California

Falcon 9 rockets launched from Vandenberg Space Force Base (VSFB) with a southeastern heading can create a sonic boom whose carpet includes parts of Santa Barbara, Ventura, and Los Angeles Counties. Because the Falcon 9 may soon launch from VSFB up to 100 times per year, the need to understand these booms is pressing. Beginning in June 2024, between 16 and 30 microphones were placed in an area spanning 500 square miles to characterize these sprawling booms for 18 launches. Despite logistical challenges, patterns have begun to emerge. First, for the same launch heading, the boom focal line shifts from Santa Barbara in fall, winter, and spring down to Ventura in the summer, producing less impact on land overall. Second, boom peak overpressures are typically lower during the summer than the fall. From the perspective of impact on coastal communities, these results suggest that the more southeastern trajectories should be flown during the summer, when there is a lower likelihood of impact. Work sponsored by SLD-30 at VSFB.