SLS fully powered for the first time despite a leak

A full moon is seen from Launch Complex 39B at NASA’s Kennedy Space Center in Florida on June 14, 2022. The Artemis I Space Launch System (SLS) and Orion spacecraft, atop the mobile launch vehicle, were in preparatory classes for a wet dress rehearsal with timelines and practice procedures for the launch. The first in a series of increasingly complex missions, Artemis I will test SLS and Orion as an integrated system before crewed flights to the Moon. Thanks to Artemis, NASA will land the first woman and first person of color on the lunar surface, paving the way for a long-term lunar presence and using the Moon as a stepping stone on the way to Mars. Credit: NASA/Ben Smegelsky

The Artemis I wet dress rehearsal ended yesterday (June 20, 2022) at 7:37 p.m. EDT (4:37 p.m. EDT) at T-29 seconds into the countdown. This test marked the first time the team had fully loaded all of the Space Launch System rocket’s propellant tanks and counted down the terminal launch, when many critical activities come in quick succession.

NASA Space Launch System Rocket and Orion Spacecraft Mobile Launcher with umbilical lines

An artist’s rendering of the mobile launch vehicle with umbilical lines installed on the tower and attached to NASA’s Space Launch System rocket and Orion spacecraft. Credit: NASA

During propellant loading operations earlier today, launch controllers encountered a hydrogen leak in the quick disconnect that connects an umbilical from the mobile launcher’s tail service mast to the rocket’s core stage. . The team attempted to repair the leak by reheating the quick disconnect and then cooling it to realign a seal, but their efforts did not fix the problem.

Launch controllers then devised a plan to mask data associated with the leak that would trigger a hold by the launch ground sequencer, or launch computer, in a real launch day scenario, to allow them to go as far as possible in the countdown. The time required to come up with the plan necessitated an extended wait time during the countdown activities, but they were able to resume with the last 10 minutes of the countdown, known as the terminal countdown. During the terminal count, the teams performed several critical operations that must be accomplished for launch, including switching control from the ground-based launch sequencer to the automated launch sequencer controlled by the rocket’s flight software, and a step important that the team wanted to accomplish.

This second dress rehearsal for Artemis I began on June 18, 2022. After the launch team arrived at their stations inside the launch control center at[{” attribute=””>NASA’s Kennedy Space Center in Florida at approximately 5 p.m. EDT to begin the wet dress rehearsal test for NASA’s Artemis I mission. The countdown began 30 minutes later at 5:30 p.m. or L-45 hours, 10 minutes before the initial target T-0 of 2:40 p.m. on Monday, June 20.

Overnight from June 18th to the 19th, engineers powered up the Orion spacecraft and the Space Launch System’s core stage. Teams also configured several systems on the ground, rocket, and spacecraft and performed activities to prepare umbilicals that connect the rocket and spacecraft to the mobile launcher and are used to provide power, communications, coolant, and propellant.

On the morning of June 20, the launch control team began chill down operations and resumed the countdown clock ahead of flowing super cold liquid oxygen (LOX) into the core stage tank. The T-0 time for today’s test is now 4:38 p.m. EDT for the first of the two terminal count runs for the wet dress rehearsal.

The process for filling the core stage tank begins with the chill down, or cooling, of the propellant lines to load the liquid oxygen and liquid hydrogen in preparation for tanking. The team will slowly fill liquid oxygen into the core stage tank with the fast fill beginning soon after. Teams will then proceed to slowly fill the core stage’s liquid hydrogen tank followed by fast fill.

 

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