Photos: Atlas 5 rocket aims for International Space Station

Carrying a $2.7 billion NASA mission to Mars, a United Launch Alliance Atlas 5 rocket took off July 30 from Cape Canaveral and fired into a summer sky powered by four powerful solid rocket boosters and a kerosene-burning main engine.

A commercial rocket under development by Firefly Aerospace will conduct its first orbital test flight in 2019 from a launch pad at Vandenberg Air Force Base in California that will become vacant with the retirement of the venerable Delta 2 booster later this year, the company announced Tuesday.

This gallery of U.S. Air Force photos show technicians, wearing protective SCAPE suits, initially check for hazardous hypergolic fuel vapors around the X-37B spaceplane on the Shuttle Landing Facility runway and the subsequent tow of the vehicle to its newly-renovated hangar at the Kennedy Space Center.