NASA Declares Tanking Test of SLS Megarocket a Success

NASA declared Wednesday's test a success after a demonstration to confirm a hydrogen leak. Engineers still need to review the results, but the space agency could be on track to perform its third launch attempt of its SLS megarocket in just six days.

The ground teams began loading more than one million gallons of propellant into the megarocket. The rocket stood at Launch Pad 39B at Kennedy Space Center in Florida for today's test.

Two previous launches ended in scrubs for different reasons. The first scrub was caused by a faulty sensor that recorded incorrect engine temperature readings, while the second scrub was caused by a hydrogen leak, which NASA traced to damaged seals at the quick connect fitting between a liquid hydrogen fuel. The mixture of oxygen and liquid hydrogen has a tendency to leak due to its small atomic stature.

Tom Whitmeyer, deputy associate administrator for common exploration systems development at NASA, told reporters on Monday that the primary goal of the test was to look at the two new seals. Key wet dress objectives, such as going into the terminal count phase of the countdown, were not included in Wednesday's test.

A key strategy for the test was for ground teams to use a softer approach to tanking Engineers thought a slower approach would reduce the chance of thermal shock as components come into contact with ultra-cold propellants. It is possible that thermal shock caused the hydrogen leak on September 3, but the true cause is not known.

The ground teams transitioned from slow fill to fast fill at 10:00 a.m. The teams reported a hydrogen leak at the quickDisconnect between the rocket and the tail service mast umbilical. After signing off on the plan to warm the line and reset the connection point, the teams were back to work. "You could kind of feel the room deflate a bit, but as the ground teams got past it, you could feel a certain lifting of the room."

The thermal conditioning of the rocket's four engines happened shortly before 1:00 p.m., and the tanking moved quickly and smoothly after that. The upper stage and the core stage were filled with propellants. The pre-pressurization test had been completed by the time the de-tanking activities started. The test was declared complete 20 minutes later after NASA said all objectives had been met.