NASA Conducts Unannounced SLS Hydrogen Leak Test

NASA is currently performing a test at the Kennedy Space Center involving the loading of liquid hydrogen onto its Space Launch System (SLS) moon rocket. This operation, which was not publicly announced, is intended to verify repairs made to a leaky umbilical.

The objective is to determine the effectiveness of new seals installed in the launch pad umbilical.

Test Purpose and Procedure

The test involves loading liquid hydrogen into the core stage's fuel tank. A NASA spokesperson stated that engineers are testing the seals by flowing liquid hydrogen across the interface and partially filling the core stage liquid hydrogen tank. The data collected from this will inform the timeline for the next wet dress rehearsal.

Recalling Previous Challenges

During a previous Wet Dress Rehearsal (WDR) on February 2, the launch team encountered hydrogen leaks from the umbilical that supplies propellant to the rocket. Despite managing to fully load the propellant tanks during that test, the countdown was halted due to a significant increase in hydrogen leakage when the fuel tank was pressurized in the final minutes. Liquid hydrogen is notably difficult to handle; its small molecules can escape through minor imperfections in the propellant system, and it is highly explosive when mixed with air.

Repairs Undertaken

Following the February 2 dress rehearsal, technicians disconnected the hydrogen lines, which are part of a structure on the mobile launcher. Engineers subsequently removed and replaced the seals on two hydrogen lines located on a tail service mast.

Outlook

Should the hydrogen testing prove successful, NASA may schedule a second Wet Dress Rehearsal as early as the following week. The results of this test are critical for advancing the SLS launch preparations.