NASA yesterday admitted that with the decision to return SLS to the vehicle assembly building (VAB) before completing its dress rehearsal countdown, it is now impossible to launch SLS in the June launch window as planned, and that the earliest the rocket could launch would be July.
This summary of the issues that dogged the rocket during the three attempts to complete that dress rehearsal illustrates the likelihood that SLS has many engineering loose ends still unresolved:
On April 3 it was malfunctioning fans on the Mobile Launcher needed to clear hazardous fumes. On April 4, it was a defective helium check valve on the Interim Cryogenic Propulsion Stage, ICPS, the Space Launch System’s second stage. On April 14, it was a hydrogen leak on the SLS first stage, or Core Stage.
Once again, having such problems during the first countdown of a new rocket is not unusual. What is questionable is only finding them now, at the very end of the rocket’s development.
I predict the launch will be further delayed until the fall, at which time NASA might face a much more serious issue regarding SLS’s two strap-on solid rocket boosters. During the shuttle era NASA had always placed a one year limit on their use once they were stacked, because it was believed that standing in a vertical position for too long could warp and distort the solid rocket fuel, thus causing it to burn improperly during launch.
These boosters were first stacked near the end of 2020, so their use-by date should have been January 2022, at the latest. Not launching until the fall will place them nine to eleven months past that date. And since these boosters are taller than the one’s used by the shuttle, they are heavier which makes extending that lifespan even riskier.
Thus, if NASA decides it must replace the boosters, that will likely delay the launch another three to six months, pushing it into ’23 at the earliest. If NASA decides to go with these boosters, it poses a real risk of failure during launch, a failure that will certainly destroy the rocket.
