The first mission of Northrop Grumman's big new cargo spacecraft is nearly over. That freighter, known as Cygnus XL, left the International Space Station (ISS) on Thursday morning (March 12), ending a nearly six-month orbital stay for the 23rd Northrop Grumman (NG-23) resupply mission to the orbital laboratory. Secured on the station's Canadarm2 after detaching from its berth on the Earth-facing port of the Unity module, the spacecraft was released at 7:06 a.m. EST (1105 GMT). Northrop Grumman’s first Cygnus XL cargo craft is pictured installed to the Unity module’s Earth-facing port as the International Space Station orbited 262 miles (422 kilometers) above the Atlantic Ocean off the coast of South Africa. (Image credit: NASA) The NG-23 Cygnus XL launched atop a SpaceX Falcon 9 rocket on Sept. 14 , carrying about 11,000 pounds (4,990 kilograms) of scientific gear and other supplies toward the ISS.…