SLS dress rehearsal countdown scrubbed an hour before T-0
Yesterday’s first dress rehearsal countdown for NASA’s SLS rocket managed to get within an hour of T-0 with its oxygen tanks half full when mission control scrubbed the countdown.
During chilldown of the lines in preparation for loading the liquid hydrogen, the teams encountered an issue with a panel on the mobile launcher that controls the core stage vent valve. The purpose of the vent valve is to relieve pressure from the core stage during tanking. Given the time to resolve the issue as teams were nearing the end of their shifts, the launch director made the call to stop the test for the day. A crew will investigate the issue at the pad, and the team will review range availability and the time needed to turn systems around before making a determination on the path forward.
No word as yet when they will attempt the next full dress rehearsal. The delays with SLS have so far caused several further delays for Axiom’s private mission to ISS, since NASA has given SLS priority over the range. It has now been pushed back to April 8th.
Note that none of these problems should be a surprise. This is the first time the rocket and mobile launcher have been placed under flight conditions, so minor issues should be expected. At the same time, dealing with these issues now, just before actual launch, rather than earlier in development, illustrates the backwards way NASA’s management has run this program. You can never design anything new perfectly. You need to test and fail and fix along the way. NASA avoids testing because it can’t build anything at a reasonable cost. The result is that when it comes time to launch, lots of previously unidentified minor issues pop up that need fixing.
Yesterday’s first dress rehearsal countdown for NASA’s SLS rocket managed to get within an hour of T-0 with its oxygen tanks half full when mission control scrubbed the countdown.
During chilldown of the lines in preparation for loading the liquid hydrogen, the teams encountered an issue with a panel on the mobile launcher that controls the core stage vent valve. The purpose of the vent valve is to relieve pressure from the core stage during tanking. Given the time to resolve the issue as teams were nearing the end of their shifts, the launch director made the call to stop the test for the day. A crew will investigate the issue at the pad, and the team will review range availability and the time needed to turn systems around before making a determination on the path forward.
No word as yet when they will attempt the next full dress rehearsal. The delays with SLS have so far caused several further delays for Axiom’s private mission to ISS, since NASA has given SLS priority over the range. It has now been pushed back to April 8th.
Note that none of these problems should be a surprise. This is the first time the rocket and mobile launcher have been placed under flight conditions, so minor issues should be expected. At the same time, dealing with these issues now, just before actual launch, rather than earlier in development, illustrates the backwards way NASA’s management has run this program. You can never design anything new perfectly. You need to test and fail and fix along the way. NASA avoids testing because it can’t build anything at a reasonable cost. The result is that when it comes time to launch, lots of previously unidentified minor issues pop up that need fixing.