NASA says its hydrogen leak fixes worked, meaning Artemis I may launch this month

NASA put its Space Launch System through its paces with this week's tanking test.
Chris Young
NASA's SLS rocket on the launch pad.

 NASA / Twitter 

NASA announced its Space Launch System (SLS) tanking test on Wednesday, September 21, was a success, paving the way for the launch of Artemis I.

The test was held this week to determine whether fixes NASA had applied to the SLS rocket, following a second failed launch attempt, had done their job. The second launch attempt of SLS, on September 3, was scrubbed due to a hydrogen leak issue.

Yesterday's tanking test did see a reoccurrence of liquid hydrogen leaks, though NASA ultimately greenlit SLS's next launch attempt.

NASA's day-long SLS tanking test

NASA's day-long tanking test at Kennedy Space Center’s Launch Complex 39B saw ground teams fill the SLS core stage and upper stage with liquid hydrogen and liquid oxygen propellants. Important steps included the "kickstart bleed" of liquid hydrogen into the core stage as well as a "pre-press" test of the liquid hydrogen tank.

Ultimately, the tests were carried out to discern whether replacement seals and other changes to SLS would prevent hydrogen leaks during the next launch attempt.

Early on in the test, NASA did report a liquid hydrogen leak in the tail service mast umbilical. The section of NASA's massive moon-bound rocket transfers liquid hydrogen from ground systems to the core stage. However, NASA did find that warming the connection of the umbilical to the core stage before cooling it again did seem to work, as the leak fell below the limit of four percent concentration of hydrogen.

Another leak was also reported during the pre-press test on another, smaller liquid hydrogen line, with concentrations at roughly five percent. That leak, however, diminished over time as the test continued. Ultimately, NASA said the test went well, though it didn't go as far as confirming it would go ahead with the next launch attempt on September 27. The space agency said it will review the data from the test before announcing the next launch date.

Will Artemis I launch on September 27?

NASA's Artemis I mission will kickstart its Artemis program, which eventually aims to send humans back to the surface of the moon and serve as a stepping stone for the eventual colonization of Mars.

Before the mission can launch, however, SLS and the Orion capsule must be cleared for takeoff once more. Aside from the hydrogen leak issue, there are one or two other factors that could cause further delays.

Firstly, a tropical storm is expected in Florida over the next few days, which could force NASA to roll SLS back to the Vehicle Assembly Building (VAB). Secondly, NASA is hoping to secure a waiver from the U.S. Space Force for the SLS flight termination system. If it secures the waiver, and the weather behaves, it will not have to send SLS back to the VAB to recharge the system's batteries. That process would likely set the launch back several weeks — only transporting SLS back to the VAB takes an entire day.

The U.S. Space Force is expected to make a decision on that waiver following the results of the tanking test. Stay posted for more updates on the launch of Artemis I.

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