Centaur Has to Go Back to the Shop

When I was a kid, almost everyone knew that when the TV wasn't working the bad news was when the repair tech couldn't fix it and would have to say, "the set has to go back to shop."  Just like that, the TV was going away and no one knew when it would be back.  No TV!   

Today we learned the Centaur upper stage for the first Vulcan Centaur test flight has to go back to the shop.  In the last update on the Vulcan's failure investigation two weeks ago, it wasn't clear that they were going to do this, but they made the decision to do the same fix to this Centaur as they're doing to newly made ones.  I honestly don't know why they didn't just say this would be the case two weeks ago.  

In a statement, ULA described the work needed on the Centaur V upper stage as “minor reinforcement at the top of the forward dome,” or the uppermost section of the liquid hydrogen tank. The changes will add strength to the tank, which contains super-flammable fuel chilled to minus 423° Fahrenheit (minus 253° Celsius).

Since it's impossible to tell by looking at a picture whether that Centaur stage on the right is going up or down, I should tell you the pic was taken back in February when it was on the way up.   ULA Photo

The failure analysis after the March explosion of the Centaur test article showed that was ultimately caused by a liquid hydrogen leak on the forward bulkhead of the Centaur V upper stage.  That hydrogen found an ignition source and that's all it took. 

“The super thin, high performance steel skin needs to be a little thicker near the top of the dome,” tweeted Tory Bruno, ULA’s chief executive. The steel walls of the Centaur upper stage’s pressure-stabilized propellant tanks are as thin as 0.02 inches, or half a millimeter, in some places.

It's not impossible that this Cert-1 flight could take place before the end of this year, but the two flights required to certify Vulcan Centaur for US Military National Security payloads will extend well into '24.  The Vulcan booster or first stage has passed all of its qualification tests, with the successful Flight Readiness Firing earlier in the month.  The payloads for this flight, Astrobotic's Peregrine lunar lander and a pair of test satellites for Amazon's Kuiper constellation are also ready and waiting for launch.  Ironically, the Centaur that's getting modified here is the oldest part of the design, or at least has the longest history.  This Centaur V is a larger, updated, twin-engine version of the Centaurs that have flown on 268 missions since 1962.