SLS dress rehearsal countdown ends at T-29 seconds
NASA’s fourth attempt to complete a full dress rehearsal countdown of its giant SLS rocket today ended at T-29 seconds, just short of the complete countdown.
It appears the countdown had one issue — a hydrogen fuel leak at the point where the umbilical fuel line attaches to the rocket — that mission control decided to ignore (or “mask” to use their word) so that they could proceed into the count as far as possible. It was this decision however that caused the two-hour delay in the countdown. They then resumed the countdown at T-10 minutes, the beginning of terminal count.
During the terminal count, the teams performed several critical operations that must be accomplished for launch including switching control from the ground launch sequencer to the automated launch sequencer controlled by the rocket’s flight software, and important step that the team wanted to accomplish.
NASA will hold a press conference tomorrow at 11 am (Eastern) to discuss the results of this dress rehearsal. While the leak is concerning, I expect NASA to decide that this dress rehearsal was a success, that they will roll the rocket back to the vehicle assembly building where they will fix this problem, after which the agency will declare the rocket ready to launch by the end of August.
While risky, doing otherwise likely raises other risks. If they decide to do another dress rehearsal the launch faces more delays. And waiting much longer continues to increase the danger that the solid rocket side boosters will not function as intended because they have been stacked almost a year longer than their accepted use-by date.
If this turns out to be the plan, expect the actual launch countdown to be as plagued with issues and delays and scrubs. NASA has yet to demonstrate it can do this smoothly with no problems. Worse, this level of mediocre performance has been par for the course for this entire SLS program.
If that launch should go smoothly it will be a welcome and unprecedented event.
NASA’s fourth attempt to complete a full dress rehearsal countdown of its giant SLS rocket today ended at T-29 seconds, just short of the complete countdown.
It appears the countdown had one issue — a hydrogen fuel leak at the point where the umbilical fuel line attaches to the rocket — that mission control decided to ignore (or “mask” to use their word) so that they could proceed into the count as far as possible. It was this decision however that caused the two-hour delay in the countdown. They then resumed the countdown at T-10 minutes, the beginning of terminal count.
During the terminal count, the teams performed several critical operations that must be accomplished for launch including switching control from the ground launch sequencer to the automated launch sequencer controlled by the rocket’s flight software, and important step that the team wanted to accomplish.
NASA will hold a press conference tomorrow at 11 am (Eastern) to discuss the results of this dress rehearsal. While the leak is concerning, I expect NASA to decide that this dress rehearsal was a success, that they will roll the rocket back to the vehicle assembly building where they will fix this problem, after which the agency will declare the rocket ready to launch by the end of August.
While risky, doing otherwise likely raises other risks. If they decide to do another dress rehearsal the launch faces more delays. And waiting much longer continues to increase the danger that the solid rocket side boosters will not function as intended because they have been stacked almost a year longer than their accepted use-by date.
If this turns out to be the plan, expect the actual launch countdown to be as plagued with issues and delays and scrubs. NASA has yet to demonstrate it can do this smoothly with no problems. Worse, this level of mediocre performance has been par for the course for this entire SLS program.
If that launch should go smoothly it will be a welcome and unprecedented event.