The 8.5-hour countdown is starting at Cape Canaveral Space Force Station for #DeltaIVHeavy  to launch #NROL44  at 6:15pmEST (2315 UTC). This is ULA's 142nd mission, our 89th for U.S. national security and 30th for the NRO. Follow along in our live blog:

LIFTOFF of the United Launch Alliance#AtlasV  rocket on a national security space mission, lifting #NROL101  for the National Reconnaissance Office. And the vehicle has cleared the tower! @NatReconOfc  @AFSpace  @AF_SMC  @45thSpaceWing 

The countdown is exactly two hours away from the #NROL44  liftoff time.

Although designed to meet the difficult specifications of U.S. national security launches, #VulcanCentaur  is well suited for commercial and civil markets, including launching dual-manifested payloads and missions across the solar system. The rocket has nearly 30 launches booked.

A pathfinder of the ULA #VulcanCentaur , the new all-American rocket designed to meet the needs of U.S. national security space launches, now stands assembled for major launch pad testing. #CountdownToVulcan  Read more in our blog: