The most recent Delta IV launch from Cape Canaveral wasn't without challenges. This was a classic case of a mature launch system where everything looked relatively smooth through the Aerospace President's Review and the SMC commander's Flight Readiness Review. But in the days leading up to launch and all through the countdown, numerous issues with ground systems, launch vehicle systems, and range support assets cropped up.
Among other things was a two-day launch slip from March 13 to March 15, resulting from an anomaly during second-stage hydrazine loading that required the system to be off-loaded and reloaded over the weekend. All health checks were nominal, and the system was restored to a nominal flight configuration.
On launch day, the launch was initially delayed 14 minutes due to a launch tower swing arm problem that delayed cryogenic operations. During those operations, automated ground system issues required part of the operation to be transitioned to manual control to support a new launch time nearly 50 minutes into the window.
At that point, it was determined that a tracking and data relay satellite (TDRS) was unable to provide mandatory telemetry coverage. Fortunately, the ground station at White Sands subsequently reconfigured the antennas, enabling the launch to proceed.
After overcoming all of these challenges, the 10th Wideband Global SATCOM (WGS) spacecraft was successfully launched on a Delta IV M+(5,4) launch vehicle — configured with a 5-meter fairing and four solid rocket motors — at 8:26 p.m. EDT on Friday, March 15, 90 minutes into the launch window.
The military communications spacecraft was delivered to the desired orbit, with all five orbital parameters within 0.52 sigma of preflight predictions. Sigma is a statistical term commonly used in many engineering calculations: The higher the number, the farther the result is from expected accuracy. Below 1 sigma for the five parameters is considered very good, and less than 0.52 sigma is unusually accurate.
Dr. Malina Hills, senior vice president of Space Systems Group sent her congratulations to the Aerospace team: "I would like to recognize the significant accomplishments, dedication, and exemplary support of the entire spacecraft and launch vehicle teams for this successful launch of a critical national security space mission."