US defense satellite to be launched from Calif.

VANDENBERG AIR FORCE BASE, Calif. (AP) -- A powerful rocket carrying a National Reconnaissance Office satellite is expected to be launched into orbit Wednesday from the California coast.

The 235-foot Delta IV Heavy rocket is scheduled to lift off from Vandenberg Air Force Base at 10:52 a.m., according to United Launch Alliance.

The rocket is set to send a classified spacecraft into orbit for the NRO, which is in charge of U.S. intelligence-gathering satellites.

Air Force security and police have closed nearby locations as a precaution.

It's the second time that a Delta IV Heavy rocket will be launched from Vandenberg. In January 2011, a sound wave as loud as a freight train swept over nearby Lompoc, a town of about 43,000. Some people reported hearing the rocket's roar as far away as 50 miles.

United Launch Alliance is a joint venture of Lockheed Martin Corp. and The Boeing Co. to provide space launch services to the U.S. government with their Atlas and Delta rocket programs.