NASA is preparing to roll its Artemis II Space Launch System (SLS) rocket and Orion spacecraft back to the Vehicle Assembly Building (VAB) at Kennedy Space Center (KSC) in Florida as early as , to address a helium flow issue discovered over the weekend. The problem has further delayed the highly anticipated mission to send four astronauts on a flight around the moon, pushing the launch no earlier than .
The issue centers on the rocket’s upper stage, known as the Interim Cryogenic Propulsion Stage (ICPS). Helium is a critical component in the SLS system, used to control engine environmental conditions and to pressurize fuel tanks – both essential for a safe and successful launch. According to NASA, engineers were unable to achieve the necessary helium flow during testing.
This latest setback follows a successful wet dress rehearsal on , where the team demonstrated the ability to safely fuel the SLS with over 700,000 gallons (2.6 million liters) of cryogenic propellants – supercold liquid hydrogen and liquid oxygen. The successful rehearsal initially led to optimism, with NASA targeting a potential launch as early as next week.
The Artemis II mission represents a pivotal step in NASA’s broader Artemis Program, aiming to establish a sustained human presence on the moon and eventually pave the way for missions to Mars. The program has faced numerous challenges, including previous hydrogen leaks, highlighting the inherent complexities of returning humans to the lunar surface after a 50-year hiatus.
The rollback to the VAB is necessary to allow engineers to thoroughly investigate the helium flow problem and implement the required repairs. NASA is currently examining several potential causes, including the interface between the ground and rocket lines used to route helium, a filter between those lines, and a valve within the upper stage itself. The agency is also reviewing data from the Artemis I mission, the uncrewed precursor to Artemis II, which experienced helium-related pressurization issues before its successful launch in .
Helium’s role in the ICPS is multifaceted. Beyond engine purging and propellant tank pressurization, it ensures the proper functioning of critical systems during the flight. The inability to achieve adequate helium flow raises concerns about the reliability of these systems and necessitates a cautious approach to ensure astronaut safety.
The SLS rocket itself underwent a similar rollback to the VAB prior to the Artemis I launch. This experience suggests NASA has established procedures for addressing issues discovered on the launchpad, and the agency expressed hope for a relatively quick turnaround to preserve the launch window. However, the complexities of spaceflight mean that further delays remain a possibility.
NASA Administrator Jared Isaacman explained on X (formerly Twitter) that the team was unable to achieve helium flow through the vehicle on . He further clarified that the helium bottles are used not only for engine purging but also for pressurizing the liquid hydrogen and liquid oxygen tanks.
The Artemis II mission is designed to be a rigorous test of the SLS and Orion systems, preparing them for the Artemis III mission, which aims to land astronauts on the moon in . The crew will consist of four astronauts, including the first woman and the first person of color to travel to the moon. The mission will involve a 10-day flight around the moon, providing valuable data on system performance and astronaut health in deep space.
Currently, NASA has identified three potential launch windows in : , , and . The agency will continue to assess the situation and provide updates as the investigation progresses. NASA’s Moon to Mars program manager, Lori Glaze, expressed the team’s excitement for the mission prior to the discovery of the helium issue, stating, “Every night I look up at the Moon and I see it, and I get real excited because I can feel she’s calling us and we’re ready.”
