Titan 4-B launched: Payload top secret

A Titan 4-B -- like the one seen here -- was launched Friday from Vandenberg Air Force Base in California.

VANDENBERG AIR FORCE BASE, California (CNN) -- A Titan IV rocket blasted off from this base Friday carrying a top-secret payload, one that intelligence experts believe contains satellite imaging equipment -- which could be used to spy on suspected terrorists.

The launch went off without a hitch at 5:21 p.m. EDT after being postponed several times in recent days because of technical problems.

The mission was planned long before the September 11 terrorist attacks against the United States that left thousands dead, but takes on new significance in the current atmosphere.

The Titan IV, built by Lockheed Martin, is the most powerful, expendable space launch vehicle in the country.

Its payload belongs to the National Reconnaissance Office, which operates satellites for the U.S. military and the intelligence community.