Nasa cuts short third attempt at Moon rocket fuel test

Hydrogen leak blamed for latest delay

Nasa’s Space Launch System Moon rocket during a “wet dress” rehearsal for launch at Kennedy Space Center in Florida (Nasa)

Nasa cut short its third attempt to test the fueling of its Space Launch System (SLS) Moonrocket on Thursday after leaks appeared during the loading of liquid hydrogen fuel.

Known as a “wet dress rehearsal,” Nasa began loading liquid oxygen into the SLS rocket on Thursday morning. The plan was to load the entire core stage of the rocket with both liquid oxygen and liquid hydrogen propellant and then complete a simulated launch countdown.

But Nasa halted the test around 5.10pm Eastern on Thursday when the ground team discovered a leak in the umbilical carrying liquid hydrogen into the rocket.

Nasa has attempted a wet dress rehearsal three times since rolling the SLS and the Orion spacecraft at its top to launch complex 39B at Kennedy Space Center on 17 March.

A 3 April attempt to load propellant into the SLS rocket was scrubbed after fans used to mitigate the leakage of hazardous gasses on the mobile launcher platform holding the rocket malfunctioned.

Nasa tried again on 4 April, but only loaded about 50% of the liquid oxygen necessary into the rocket before a pressure valve malfunction on the mobile launches caused the team to scrub the test attempt.

Another faulty valve, this one managing helium flow in the rocket’s upper stage, was discovered following the 4 April attempt, leading Nasa to modify Thursday’s test to only load the core stage with propellant. During a media call about the helium valve, Nasa officials could not say if they would need to test fueling the upper stage later on, but noted they would have to return the SLS rocket to the Vehicle Assembly Building at Kennedy Space Center in order to replace the helium valve.

Nasa officials were due to hold another media briefing on Friday afternoon to discuss the latest setback in the SLS test schedule.

SLS and Orion are the cornerstones of Nasa’s Artemis Moon program, which aims to return humans to the Moon by 2025. But before humans can ride the rocket to space, Nasa must complete Artemis I, the first uncrewed test flight of both the SLS rocket and Orion Spacecraft.

While Nasa had been targeting a May launch window for Artemis I earlier this year, it’s not yet clear how much the thrice aborted wet dress rehearsal will set back that launch schedule. In media briefings following the aborted 4 April wet dress rehearsal, Nasa officials began mentioning launch windows as late as later July and early August.