Read moreAfter a two-hour delay, workers lifted a United Launch Alliance Delta 4 Heavy rocket to the vertical position on the launch pad.
When it lifts off in the spring, it will be only the second time one of these has ever been launched from Cape Canaveral Air Force Station.
A United Launch Alliance Delta 4-Heavy rocket will launch the 23rd and final Defence Support Program missile-warning satellite, from SLC-37B, Cape Canaveral Air Force Station, Florida on April 1st.
The launch window extends from 16:00 to 20:00 GMT.
The vehicle will deliver the DSP 23 satellite 35,970 kilometres above the earth in a geosynchronous orbit.