Vandenberg Space Force Base, Calif.—A privately designed, unmanned rocket built to carry satellites was destroyed in an explosive fireball after suffering an “anomaly” off the California coast during its first attempt at reaching Earth’s orbit. Firefly Aerospace’s Alpha rocket was “terminated” over the Pacific Ocean shortly after its 6:59 p.m. Thursday liftoff from Vandenberg Space Force Base, according to a base statement. Video from the San Luis Obispo Tribune showed the explosion. Firefly said an “anomaly” occurred during the first-stage ascent that “resulted in the loss of the vehicle” about two minutes, 30 seconds into the flight. Vandenberg said a team of investigators will try to determine what caused the failure. The rocket was carrying a payload called DREAM, or the Dedicated Research and Education Accelerator Mission. It consisted of items from schools and other institutions, including small satellites and several demonstration spacecraft. “While we did not meet all of …