United Launch Alliance’s Delta IV Heavy rocket launched Saturday with the mysterious NROL-71 mission for the National Reconnaissance Office from SLC-6 at Vandenberg Air Force Base in California. A series of technical and weather-related scrubs hampered the launch attempts, prior to a lengthy stand down to fix a hydrogen leak that scrubbed the final attempt of 2017 with just seconds remaining in the count. With the issue fixed, the launch was realigned for January 19, with the window opening at 11:05 AM local time (19:05 UTC). Launch occurred slightly into the window at 11:10 AM local time.
