Photos: Another SBIRS soars atop Atlas 5

United Launch Alliance crews at Cape Canaveral have topped off an Atlas 5 rocket for liftoff Monday with the U.S. military’s next infrared sentinel to join a satellite fleet designed detect missile launches around the world.

The U.S. Space Force is planning for an airborne launch of a solid-fueled Pegasus rocket over the Pacific Ocean by early summer after quietly awarding Northrop Grumman a contract for the mission last year.

A Russian-built Soyuz booster arrived at its tropical launch pad in South America on Friday and was joined with a European weather satellite for launch Tuesday night.