NASA's massive Moon rocket sidelined by a hydrogen leak

It's another return to the drawing board for NASA scientists and engineers working on the Artemis I mission, which was due to lift off on Saturday until a hydrogen leak led to a last-minute scrubbing. The team has ruled out any imminent further launch attempts and is now assessing their next steps, which may include returning the massive Space Launch System (SLS) to the Vehicle Assembly Building for repairs.

Saturday’s scrubbing comes after NASA’s first attempt to launch the Artemis I mission last Monday was foiled by engine trouble, with the team unable to bring one of the rocket engines down to the required temperature for launch. After reviewing the data, the team settled on Saturday afternoon for a second bite of the cherry, but again ran into trouble in the buildup to lift-off.

As engineers were slowly filling the rocket’s liquid hydrogen tanks, a leak was detected in the quick disconnect device, an interface between the hydrogen line and the rocket that keeps the fuel secure until the very last moment before lift-off. Problems with the quick-disconnect had plagued the wet dress rehearsal for the SLS, which the team addressed first by warming the device to realign the seal, and then ultimately replacing the hardware altogether.

A hydrogen leak in the quick disconnect also featured as part of last Monday’s attempt, but engineers were able to safely manage the leak by manually adjusting the flow of propellant. They had no such luck this time, first attempting to warm up the quick disconnect for a tighter seal, then applying pressure to it with helium for the same effect. A third troubleshooting effort involved again warming it up to reseat the seal, but to no avail.

This led launch director Charlie Blackwell-Thompson to call off the attempt, with the team now investigating the issue. One possibility is that an inadvertent command sent during loading operations raised pressure in the propulsion system and contributed to the leak, but that warrants further examination. Next, engineers will decide whether to perform repairs and testing with the rocket in place on the pad, or haul it back to Vehicle Assembly Building.

In any case, no further launch attempts will be made in early September. Because launch windows are dictated by the Moon’s position in its lunar cycle, among other factors, the next window of opportunity for lift-off will be from September 19 to October 4.

Source: NASA