Artemis II Wet‑Dress Rehearsal Halted by Persistent Hydrogen Leaks on Feb 18, 2026

Updated 2026-02-18 19:13:12+00:00 (2 articles)

Hydrogen Leak Forces Test Abort Early‑February fueling of the Space Launch System revealed super‑chilled liquid hydrogen escaping at the launch pad, prompting controllers to repeatedly stop fuel flow and ultimately abort the full wet‑dress rehearsal [1]. The leak persisted despite attempts to vent and repressurize, preventing the crew‑size test from proceeding as scheduled [1]. NASA officials announced the cancellation of the rehearsal while engineers investigate the source [1].

Leak History Mirrors Prior Artemis and Shuttle Missions Similar hydrogen seepage delayed the uncrewed Artemis I launch in 2022 and has been documented throughout the Space Shuttle program, underscoring a long‑standing engineering challenge [1]. Engineers noted that the pattern of leaks follows historical trends, suggesting systemic issues with hydrogen handling on large launch vehicles [1]. The recurrence has raised concerns about schedule impacts for upcoming Artemis flights [1].

Technical Constraints Keep Hydrogen as Propellant Hydrogen’s ultra‑low density yields the highest specific impulse, making it the most efficient rocket propellant despite its propensity to escape containment [1]. At roughly 14 times lighter than air, it provides superior thrust‑to‑weight performance essential for the SLS’s heavy lift capability [1]. Congressional mandates to reuse Shuttle hardware compel the SLS to retain hydrogen on all stages, limiting alternatives [1].

Mitigation Steps Include Seal Replacement and Leak‑Rate Limit Technicians swapped PTFE seals around two propellant lines in the Tail Service Mast Umbilical, aiming to reduce leakage [1]. Launch director Charlie Blackwell‑Thompson set a leak‑rate ceiling of 16 % during fueling, and a recent partial‑fill test showed measurable progress toward that target [1]. Engineers acknowledge that material limits make a permanent fix unlikely without a redesign, but the current measures aim to keep the program on track [1].

Sources

1.
CNN: NASA’s Artemis II Wet‑Dress Test Stalled by Persistent Hydrogen Leaks – Details the February 2026 leak that halted the rehearsal, links the issue to historic Artemis I and Shuttle problems, explains hydrogen’s performance advantages, and describes seal replacements and the 16 % leak‑rate limit set by Charlie Blackwell‑Thompson .
2026-02-18 19:13:12+00:00

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Timeline

1980s‑2000s – Hydrogen seepage repeatedly troubles the Space Shuttle program, prompting extensive engineering fixes that later inform SLS design constraints [1].

2011 – Congress mandates reuse of Shuttle‑derived hardware and workforce for the Space Launch System, cementing hydrogen‑fuel architecture and its associated leak risks in the new rocket [1].

2022 – Artemis I’s uncrewed launch slips after a hydrogen leak forces a delay, marking the first modern SLS mission to encounter the same propellant‑handling issue that now resurfaces [1].

Jan 21, 2026 – Astronauts Reid Wiseman, Victor Glover, Christina Koch and Jeremy Hansen begin a 21‑day quarantine in preparation for an early‑February Artemis II launch, later released when the schedule shifts [2].

Early Feb 2026 – During the wet‑dress rehearsal, cold‑weather fueling of the SLS reveals super‑chilled liquid‑hydrogen escaping at the launch pad; the countdown stops at T‑5 minutes and the test aborts, prompting technicians to replace Tail Service Mast Umbilical (TSMU) PTFE seals and set a 16 % leak‑rate ceiling [1][2].

Feb 3, 2026 – NASA announces a new launch window targeting early March, stating “We expected challenges given the three‑year gap between SLS flights,” says Administrator Jared Isaacman, and outlines a second wet‑dress rehearsal, crew re‑quarantine two weeks before launch, and a review of whether to roll the vehicle back to the VAB for battery work [2].

Feb 2026 (mid‑month) – Post‑seal‑swap partial‑fill test shows reduced leak rates, confirming progress but underscoring that PTFE material limits make a permanent fix unlikely without a redesign [1].

March 2026 (potential dates Mar 6, 7, 8, 9, 11) – NASA plans the earliest possible Artemis II launch, contingent on a successful second wet‑dress rehearsal and final leak‑rate verification; crew will re‑enter quarantine about two weeks prior, and launch directors keep the option to roll the SLS back to the Vehicle Assembly Building under review [2].

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