SpaceX has issued a warning over "sonic booms" as Elon Musk 's firm gears up for another Falcon 9 launch. It comes after several successful launches involving the Falcon 9 rocket this month, including one on March 14 which propelled a crew towards the International Space Station (ISS) to relieve beleaguered astronauts Butch Wilmore and Suni Williams. The next Falcon 9 launch is scheduled for today at 11.49pm Pacific Time (6.49am GMT tomorrow). The rocket will launch the NROL-57 mission from Space Launch Complex 4 East at Vandenberg Space Force Base in California , US . If something goes wrong with the initial launch, SpaceX will try again at 11.31pm PT on Friday, (6.31am GMT Saturday). In a statement ahead of the launch, SpaceX warned residents of the nearby counties of Santa Barbara (including Prince Harry and Meghan Markle ), San Luis Obispo, and Ventura that "sonic booms" might ring out after take-off. The space firm said: "There is the possibility that residents of and visitors to Santa Barbara, San Luis Obispo, and Ventura counties may hear one or more sonic booms during the launch, but what residents experience will depend on weather and other conditions." A sonic boom is a loud, explosive sound similar to thunder, caused by an object traveling faster than the speed of sound. It is a shockwave created as the object moves through the air, as the pressure waves combine to form a loud noise. The SpaceX statement added: "This is the fourth flight for the first stage booster supporting this mission, which previously launched NROL-126, Transporter-12, and SPHEREx. Following stage separation, Falcon 9 will land on Landing Zone 4 (LZ-4) at Vandenberg Space Force Base." This comes after Wilmore and Williams finally left the ISS in a SpaceX capsule on Tuesday, before parachuting into the Gulf of Mexico and splashing down off the coast of Tallahassee, Florida. The duo found themselves stuck in space after launching on Boeing's new Starliner crew capsule on June 5 last year. What was intended to be an eight-day trip to the space station was extended to nine months after the Starliner encountered problems with its propulsion system, leading NASA to send it back to Earth without any crew aboard. NASA astronaut Nick Hague and Roscosmos cosmonaut Aleksandr Gorbunov also joined the pair on their return home. They lifted off on September 28, 2024, on a SpaceX Falcon 9 rocket from Cape Canaveral Space Force Station in Florida. They joined Wilmore and Williams on the ISS the next day. "We are thrilled to have Suni, Butch, Nick, and Aleksandr home after their months-long mission conducting vital science, technology demonstrations, and maintenance aboard the International Space Station," said NASA acting Administrator Janet Petro. "Per President Trump’s direction, NASA and SpaceX worked diligently to pull the schedule a month earlier. This international crew and our teams on the ground embraced the Trump Administration’s challenge of an updated, and somewhat unique, mission plan, to bring our crew home. "Through preparation, ingenuity, and dedication, we achieve great things together for the benefit of humanity, pushing the boundaries of what is possible from low Earth orbit to the Moon and Mars."