2 sonic booms possible in California? Artemis II splashdown, SpaceX launch

• Hours after Artemis II splashdown off the coast of San Diego, California, SpaceX could launch a rocket from Vandenberg Space Force Base.

• What is a sonic boom? Brief, thunder-like noises often heard from the ground when a spacecraft or aircraft travels faster than the speed of sound.

• NASA Artemis II splashdown will be about 8:07 pm ET Friday, April 10, 2026, off the coast of San Diego, California.

A sonic boom will herald the end of the record-setting Artemis II mission after a California splashdown.

Hours later, there might be another one.

The U.S. Geological Survey said to expect a sonic boom after NASA Artemis II's Orion capsule streaks through the atmosphere during its return to Earth in a planned water landing off the coast of San Diego.

The thunderous vibration will likely take place between 5 p.m. and 5:15 p.m. Pacific Time, the USGS wrote in a post on X.

The boom, USGS said, may be heard throughout Southern California as four astronauts complete a 10-day voyage to circle the moon and travel farther in space than anyone in history.

The Orion spacecraft, carrying Reid Wiseman, Christina Koch, Victor Glover and Jeremy Hansen, is expected to splash down about 8:07 p.m. ET in the Pacific Ocean off the California coast, according to NASA.

The USGS is asking anyone who hears the sonic boom to report it here or visit https://earthquake.usgs.gov/earthquakes/eventpage/tellus.

Is there a SpaceX rocket launch today in California?

Hours after the Artemis II astronauts are due to splash down off the coast of San Diego, California, SpaceX could launch a rocket about 200 miles north.

A Falcon 9 rocket is due to get off the ground at 10:39 p.m. ET Friday, April 10, 2026, from Space Launch Complex 4-East (SLC-4E) at the Vandenberg Space Force Base in Santa Barbara County, California. The rocket will fly at a southern trajectory.

After liftoff, the Falcon 9 will deploy 25 SpaceX Starlink broadband internet satellites into low-Earth orbit, an altitude nearer Earth's atmosphere where they're able to circle the planet quickly. The rocket's booster will then aim to land on a SpaceX drone ship, nicknamed "Of Course I Still Love You," in the Pacific Ocean. This allows for SpaceX personnel to recover the booster so it can be reused in future spaceflights.

The launch window for the Friday, April 10, 2026, SpaceX Falcon 9 Starlink 17-21 mission is due to open shortly after the four Artemis II astronauts' planned splashdown in the Pacific Ocean.

A Federal Aviation Administration operations plan advisory suggests a backup opportunity is available the next day if the SpaceX Falcon 9 rocket launch were to be postponed.

What is a sonic boom? Will there be sonic booms from SpaceX Falcon 9 rocket launch in California?

According to the U.S. Air Force, a sonic boom is caused by an object moving faster than sound - about 750 miles per hour at sea level.

Residents of Santa Barbara County, San Luis Obispo County and Ventura County often stand to be the most likely to hear sonic booms, SpaceX said.

The sonic booms - brief, thunder-like noises that are often heard from the ground when a spacecraft or aircraft travels faster than the speed of sound - could last for up to 10 minutes after liftoff, Vandenberg has added.

"Areas local to Vandenberg Space Force Base will hear the initial low rumble of take-off," Vandenberg has also said.

"An aircraft traveling through the atmosphere continuously produces air-pressure waves similar to the water waves caused by a ship's bow," according to the Air Force. "When the aircraft exceeds the speed of sound, these pressure waves combine and form shock waves which travel forward from the generation or 'release point.'"

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