Video replay: Parker Solar Probe launches atop Delta 4-Heavy

With the Atlas 5 rocket that will boost it into space now assembled and waiting, a $408 million NASA communications satellite is in final preparations for its science data relay mission.

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.

Launching the Wideband Global SATCOM 9 satellite purchased by allied nations in collaboration with the U.S. military’s worldwide communications network, a United Launch Alliance Delta 4 rocket thundered away from Cape Canaveral at 8:18 p.m. EDT (0018 GMT).