Fiery scenes from a Sept. 24, 2022, liftoff of a Delta IV Heavy rocket. Video by United Launch Alliance The Delta IV Heavy burns ultracold liquid hydrogen, which is a high-performance fuel.

SpaceX's Falcon rocket family is close on Delta's heels and could surpass the 389-flight milestone later this year. However, there's an important distinction to make with the Delta IV rocket ...

The United Launch Alliance's (ULA) Delta IV Heavy rocket lifted off from Space Launch Complex-37 (SLC-37) at Cape Canaveral Space Force Station in Florida at 12:53 p.m. EDT (1653 GMT) on April 9 ...