Last flight of the Titan

After unusual concentrations of hydrogen around the rocket foiled a launch attempt Dec. 19, United Launch Alliance said Friday that the company’s powerful Delta 4-Heavy launcher and a U.S. government spy satellite will remain grounded in California until at least Jan. 6 as engineers troubleshoot a small fuel leak.

SpaceX launched a Falcon 9 rocket at 5:37 a.m. PDT (8:37 a.m. EDT; 1237 GMT) Monday from Vandenberg Air Force Base in California with the third set of 10 new-generation satellites for Iridium’s voice and data relay network. The Falcon 9’s first stage booster successfully landed on a platform in the Pacific Ocean a few minutes after liftoff.

The 32-story-tall mobile service tower is retracted from the Delta 4 rocket at Vandenberg’s Space Launch Complex 6 pad for the NROL-45 flight that will place a surveillance satellite into orbit for the U.S. National Reconnaissance Office.