CRISISBOOM

VANDENBERG AIR FORCE BASE, Calif. — The largest rocket ever launched from the West Coast blasted off Thursday with a classified defense satellite on board.

The 235-foot-tall Delta IV Heavy Launch Vehicle lifted off at 1:10 p.m. carrying a payload for the National Reconnaissance Office.

The booster rose into the sky over California’s central coast and arced over the Pacific Ocean, a spectacle visible over a wide area.

United Launch Alliance, the joint venture of rocket builders Lockheed Martin Corp. and Boeing Co., said in a statement that the launch was a success.

The launch was pushed back two minutes to avoid an object in space that could have been in the path of the rocket, said Michael J. Rein, a ULA spokesman.

No payload details were released. The NRO operates satellites that provide information to the Central Intelligence Agency and Department of Defense.

This was the fifth launch of a Delta IV but the first from the West Coast. The other four launches were at Cape Canaveral, Fla.

Capable of generating nearly 2 million pounds of thrust, the liquid-fuel rocket has a central core booster and two strap-on boosters that make the assembly 50 feet wide. An upper second stage takes over when the first stage is exhausted.

Preparing for the launch took three years and $100 million in infrastructure upgrades at Vandenberg, 130 miles northwest of Los Angeles.

The launch director, Lt. Col. Brady Hauboldt, said in a statement before the liftoff that the launch would mark a milestone by restoring heavy lift capability in the nation’s western range. The last heavy lift Titan IV-B was launched at Vandenberg in 2005.

In its past, the launch complex was once configured for West Coast space shuttle launches, which were canceled after the 1986 Challenger disaster, and the Air Force’s Manned Orbiting Laboratory program, which was canceled in 1969. It was last used in 2006.