ULA is now targeting the launch of the highly-secretive NROL-44 mission on their mammoth 235-foot-tall (72-meter) Delta IV Heavy rocket from Cape Canaveral no earlier than Sep 26, following two scrubs over the past month, the latter of which being a dramatic hot-fire abort just as the rocket’s engines were lighting up at T-3 seconds on Aug 29.
As detailed previously by AmericaSpace, the snakebitten NROL-44 already had its launch date shifted from June to August, for reasons which remain unclear, before suffering the two scrubbed attempts to get airborne late last month. Postponed 24 hours past its original August 26 target, at the NRO’s request, an attempt to fly on the 27th was itself moved two days to the right in response to an issue and review of power redundancy in a critical ground-side pneumatics control system.
The Delta IV Heavy’s starboard-side Common Booster Core (CBC) had ignited as planned on Aug 29, but the requisite start conditions were not met to proceed with the ignition of the core booster. As a consequence, the Terminal Countdown Sequencer Rack (TCSR)—which carries responsibility for managing the countdown in those final few seconds, including the ignition and ramp-up of the three RS-68A engines and release of the rocket from the pad—automatically halted the launch attempt at T-3 seconds.
After reviewing all data and ground support equipment, ULA discovered that a ground system regulator internal component failure was the cause of the on-pad abort. A regulator takes incoming pressure and adjusts the pressure levels to the correct pressure for system operation. They’ve since replaced and retested all three regulators associated with each of the giant rocket’s three common booster cores, and are now targeting liftoff on Sep 26 during a window from 12:01 – 1:35 a.m. EDT.
Another Delta IV Heavy is undergoing preparations at Vandenberg Air Force Base, Calif., for launch later this year with the classified NROL-82 mission. It is expected to undergo a fully-fueled Wet Dress Rehearsal (WDR) on Space Launch Complex (SLC)-6 before launch.
Asked about any commonalities between the issue suffered by NROL-44 and the Delta IV Heavy hardware assigned to NROL-82, ULA advised AmericaSpace that “we are ensuring we have no cross-over concerns”. They also added that no details have yet been provided on a launch date or the schedule for the WDR, citing the highly secretive nature of the mission.
– Written by Ben Evans and Mike Killian