ULA Recalls Vulcan Upper Stage for Further Enhancements

United Launch Alliance (ULA) has sent the upper stage of its Vulcan rocket back to the factory for reinforcements after a test article exploded during a structural test. ULA engineers have determined that the upper stage needs more work, delaying the first flight of the Vulcan rocket until at least the fourth quarter of this year. The Vulcan rocket is set to replace ULA's Atlas and Delta launch vehicles and is crucial for launching the US military's critical satellites. The issue with the upper stage's fuel tank is described as a "minor reinforcement" and is expected to be relatively easy to fix.