A 19-story-tall rocket launched from Vandenberg Air Force Base late Thursday night, carrying a secret payload for the U.S. government.
An Atlas V rocket blasted off from Space Launch Complex 3 at 11:15 p.m. PST, lighting up the night sky as it roared into orbit.
The mission was carried out by United Launch Alliance, a joint venture of aerospace giants Lockheed Martin Corp. and Boeing Co., for the National Reconnaissance Office.
The government agency operates the nation's system of spy satellites. As usual, it has not disclosed any information about the mission, called NROL-39.
United Launch said that 12 small spacecraft, called CubeSats, were also sent up as part of the mission.
The Army disclosed Friday that it developed four of the nanosatellites, which will remain on orbit for "several years" supporting experiments before burning up in the Earth's atmosphere. The spacecraft represents the first U.S. Army-designed and -built satellites in more than 50 years, it said.
The launch took place even though temperatures had dipped below 50 degrees at Vandenberg.
It was the 11th launch of the year at the base, located about 150 miles northwest of Los Angeles.
Whereas Cape Canaveral, Fla., is the launch site for NASA's civilian space program, Vandenberg has been the primary site of military and intelligence space launches for more than half a century because of its ideal location for putting satellites into a north-to-south orbit.