Photos: Atlas launch seen from press site

When the next Delta 4 rocket flies in July, as well as all future ones to come, the enhanced RS-68A main engine will power the boosters off the launch pad.

The step-by-step stacking of United Launch Alliance’s final Delta 2 rocket was completed in June at Vandenberg Air Force Base in California for liftoff Sept. 15 with an Earth science satellite for NASA.

When the first Delta 2 rocket took off on Valentine’s Day 1989, ideas like navigating by smartphone and driving robots on Mars were science fiction. More than 150 launches over the last 30 years helped change all that.