Watch the final Delta IV Heavy rocket launch secret cargo into space today

The United Launch Alliance's (ULA) last Delta rocket is scheduled to launch today (March 28) at 2:45 p.m. ET (6:45 p.m. GMT) on a classified mission for the U.S. National Reconnaissance Office (NRO) — and you can watch it live right here.

The launch will end a 64-year run for the Delta rocket fleet, which was designed to lift large payloads into space. The Delta IV Heavy rocket, which is the 16th of its kind to launch since 2004, will carry a secret cargo as it lifts off one last time from Space Launch Complex-37 at Cape Canaveral Space Force Station in Florida.

The ULA has not disclosed the nature of the payload that is blasting off into space, but it likely consists of a sophisticated satellite, according to Live Science's sister site Space.com. The NRO is an agency within the U.S. Department of Defense tasked with designing and operating surveillance satellites, and it rarely makes the nature and purpose of its reconnaissance systems known to the public. 

All we know about the current mission is its name, NROL-70, and when it is scheduled to lift off, which you can watch live on a ULA webcast, embedded below. The livestream is scheduled to start at 1:15 p.m., with live updates provided in the meantime. 

"The NROL-70 mission will strengthen the NRO's ability to provide a wide-range of timely intelligence information to national decision makers, warfighters, and intelligence analysts to protect the nation's vital interests and support humanitarian efforts worldwide," representatives of the ULA wrote in a mission statement.

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It is uncertain whether the Delta rocket will actually take off at the announced time, as ground winds and cumulus clouds have created unfavorable conditions, already resulting in delays. The 45th Weather Squadron forecasts a 30% chance that the weather will settle down enough for launch on Thursday and a 60% chance of favorable conditions on Friday (March 29), according to Spaceflight Now.