KENNEDY SPACE CENTER, Fla.—America’s space agency on Saturday sought to launch a rocket largely cobbled together from the space shuttle, which itself was designed and built more than four decades ago.

As the space shuttle often was delayed due to technical problems, it therefore comes as scant surprise that the debut launch of NASA’s Space Launch System rocket scrubbed a few hours before its launch window opened. The showstopper was an 8-inch diameter line carrying liquid hydrogen into the rocket. It sprang a persistent leak at the inlet, known as a quick-disconnect, leading on board the vehicle.

Valiantly, the launch team at Kennedy Space Center tried three different times to stanch the leak, all to no avail. Finally at 11:17 am ET, hours behind on their timeline to fuel the rocket, launch director Charlie Blackwell-Thompson called a halt.