NASA will not load fuels in SLS upper stage in next dress rehearsal countdown attempt
In the next attempt to complete the first “wet dress rehearsal” of NASA’s SLS rocket tomorrow, April 11th, the dress rehearsal will not be as wet as originally planned.
NASA said April 7 that engineers found a problem maintain helium purge pressure in the ICPS [SLS’s upper stage] after changing out a regulator in the mobile launch platform. At that time, the agency said it was able to restore normal pressure but was still studying the source of the problem, now linked to the faulty valve in the ICPS itself.
Because that issue, NASA now plans to limit the amount of liquid oxygen and liquid hydrogen propellant loaded into the ICPS during the WDR. NASA said the countdown rehearsal will be modified with “minimal propellant operations” on the ICPS, but didn’t elaborate on how much propellant would be transferred into the upper stage.
As usual, NASA officials are now making believe that they will achieve all their goals for the dress rehearsal if they complete it without completely fueling the upper stage. This is intellectually dishonest. This dress rehearsal was intended to test all aspects of the rocket’s launch countdown, including the fueling of all its stages. If they complete it without successfully fueling the upper stage, they will not achieve all their goals. Period.
The plan right now is to attempt this revised launch rehearsal tomorrow, then return the rocket to the vehicle assembly building where engineers will replace the faulty valve. At that point it is unclear what the agency will do next.
Though this incomplete test will have taught them a lot, if they do not redo the dress rehearsal with full loading of all stages but instead proceed to a launch attempt in the present target window from June 6 to June 16, they will be doing so with a greater risk. Of course, if the new valve works during that launch attempt, then all should be well. In fact, this risk appears quite reasonable.
Nonetheless, the fundamental problem remains: NASA is under pressure to launch, and held off this kind of testing until very late in the program. Finding these problems now puts serious limits on the ability of the agency to fix them. This in turn puts serious limits on the reliability of SLS.
In the next attempt to complete the first “wet dress rehearsal” of NASA’s SLS rocket tomorrow, April 11th, the dress rehearsal will not be as wet as originally planned.
NASA said April 7 that engineers found a problem maintain helium purge pressure in the ICPS [SLS’s upper stage] after changing out a regulator in the mobile launch platform. At that time, the agency said it was able to restore normal pressure but was still studying the source of the problem, now linked to the faulty valve in the ICPS itself.
Because that issue, NASA now plans to limit the amount of liquid oxygen and liquid hydrogen propellant loaded into the ICPS during the WDR. NASA said the countdown rehearsal will be modified with “minimal propellant operations” on the ICPS, but didn’t elaborate on how much propellant would be transferred into the upper stage.
As usual, NASA officials are now making believe that they will achieve all their goals for the dress rehearsal if they complete it without completely fueling the upper stage. This is intellectually dishonest. This dress rehearsal was intended to test all aspects of the rocket’s launch countdown, including the fueling of all its stages. If they complete it without successfully fueling the upper stage, they will not achieve all their goals. Period.
The plan right now is to attempt this revised launch rehearsal tomorrow, then return the rocket to the vehicle assembly building where engineers will replace the faulty valve. At that point it is unclear what the agency will do next.
Though this incomplete test will have taught them a lot, if they do not redo the dress rehearsal with full loading of all stages but instead proceed to a launch attempt in the present target window from June 6 to June 16, they will be doing so with a greater risk. Of course, if the new valve works during that launch attempt, then all should be well. In fact, this risk appears quite reasonable.
Nonetheless, the fundamental problem remains: NASA is under pressure to launch, and held off this kind of testing until very late in the program. Finding these problems now puts serious limits on the ability of the agency to fix them. This in turn puts serious limits on the reliability of SLS.