A secret satellite for the National Reconnaissance Office was launched into orbit from California yesterday by a giant Titan 4B rocket, the US Air Force said.
The launch had been delayed since Monday by technical problems.
Outside experts have said the satellite was likely equipped with a digital camera able to pick out objects as small as four inches (10cm) across on the ground.
The NRO builds and operates the nation’s spy satellites. Prior to 1996, it did not publicly disclose the launches of its satellites.
The launch was the 33rd of a Titan 4, the nation’s largest unmanned launch vehicle. Four Titan 4 launches have failed, including a string of three in 1998 and 1999.
Built by Lockheed Martin, Titan 4s can put a 47,800lbs payload into low-Earth orbit or more than 12,700lbs into geosynchronous orbit 22,300 miles above the Earth.