Photos: Atlas 5 rocket soars from West Coast

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.

The most powerful Atlas rocket to ever fly from the West Coast is poised for launch Thursday to deliver a secret payload into orbit while debuting a new upper stage engine.

China has launched its 10th space mission of the year, deploying three civilian-operated Earth observation satellites with cameras to help monitor natural disasters, survey natural resources and assist in infrastructure planning.