Centaur modifications cause further delay for first Vulcan launch.

United Launch Alliance (ULA) has delayed the inaugural launch of its Vulcan Centaur rocket to make "minor reinforcements" to the Centaur upper stage. ULA identified the root cause of an anomaly during a March 29 test of a Centaur at NASA’s Marshall Space Flight Center and said that Centaur’s thin-walled pressure stabilized tanks require minor reinforcement at the top of the forward dome prior to flight. The Cert-1 launch, when it does take place, will carry as its primary payload Astrobotic’s Peregrine lunar lander.