The silhouette of the United Launch Alliance (ULA) Delta II rocket, with the NASA Ice, Cloud and land Elevation Satellite-2 (ICESat-2) onboard, is seen in the fog shortly after the mobile service tower at SLC-2 was rolled back, Saturday, Sept. 15, 2018, at Vandenberg Air Force Base in California. The ICESat-2 mission will measure the changing height of Earth's ice. Photo Credit: (NASA/Bill Ingalls)