The second and third stages of the Orbital ATK Pegasus XL rocket are offloaded from a transport vehicle at Building 1555 at Vandenberg Air Force Base in California. The rocket is being prepared for NASA's Ionospheric Connection Explorer, or ICON, mission. ICON will launch from the Kwajalein Atoll aboard the Pegasus XL on Dec. 8, 2017. ICON will study the frontier of space - the dynamic zone high in Earth's atmosphere where terrestrial weather from below meets space weather above. The explorer will help determine the physics of Earth's space environment and pave the way for mitigating its effects on our technology, communications systems and society.