NASA counts down to within 29 seconds of launching the large SLS rocket

Enlarge / NASA's Space Launch System rocket, reflected in the turn basin at the Kennedy Space Center in Florida, rolls out for a fourth attempt at a wet dress rehearsal on June 6, 2022. (credit: Trevor Mahlmann)

NASA tried three times during April to complete a critical fueling test of its large Space Launch System rocket. And three times, due to about half a dozen technical problems, the space agency failed.

And so NASA made the difficult decision to roll the large rocket back into the Vehicle Assembly Building for repairs, adding a couple of months of delays to a program already years behind schedule. After this work was complete in early June, NASA rolled the SLS rocket and Orion spacecraft back out to the launch pad for a fourth try.

The painful decision turned out to be the correct one. Over the course of more than 14 hours on Monday, NASA largely succeeded in completing this fueling test, loading hundreds of thousands of gallons of liquid oxygen and hydrogen into the first and second stages of the SLS rocket.