With the performance hit on the Atlas 5 rocket’s most recent flight last month now isolated to a faulty valve, preparations to resume the manifest are underway as United Launch Alliance workers stack the next booster for blastoff this summer.

Towering more than 30 stories tall, the mobile gantry structure at the Delta 4-Heavy rocket’s launch pad at Cape Canaveral was wheeled into position for liftoff of the triple-core launcher Thursday with a classified payload for the National Reconnaissance Office.

Take a look back at the Feb. 9 launch of a 189-foot-tall (57.6-meter) Atlas 5 rocket from Cape Canaveral carrying the European-built Solar Orbiter spacecraft.