Shubhanshu Shukla's Axiom Mission Postponed: How Does Liquid Oxygen Leak Affect Take-Off? Explained

Last Updated:June 11, 2025, 12:02 IST

Liquid oxygen is oxygen that has been cooled to a point where it becomes a pale blue liquid and is used extensively in rocket propulsion systems and spacecraft life support systems

NASA’s Axiom-4 mission will “realize the return" to human spaceflight for India, Poland, and Hungary, with each nation’s first government-sponsored flight after over 40 years. (X/@NASASpaceOps)

India may have to wait a little longer to see its astronaut Shubhanshu Shukla in Space as the Axiom-4 mission to the Space Station, carrying three more astronauts, has been put off for the time being, with engineers seeking more time to repair a leak in the SpaceX’s Falcon-9 rocket.

In a post on X, SpaceX announced that it was “standing down" from the Falcon-9 launch of the Axiom-4 mission to allow repairs of the liquid oxygen leak identified during the post-static booster inspections. “Once complete—and pending Range availability—we will share a new launch date," SpaceX said.

Earlier, addressing a pre-launch press conference, SpaceX Vice-President William Gerstenmaier said engineers had fixed some snags in the Falcon-9 rocket that were discovered during the static fire test and had gone unnoticed during the post-flight refurbishment of boosters.

Gerstenmaier said engineers had discovered a lock leak that was previously seen on the booster during its entry on the last mission and was not fully repaired during the refurbishment.

WHAT IS LIQUID OXYGEN?

Liquid oxygen (LOX) is oxygen that has been cooled to a point where it becomes a pale blue liquid. It’s used extensively in rocket propulsion systems and spacecraft life support systems. LOX is essential for providing breathable air for astronauts, as well as being a key component in the fuel systems for launch.

During pre-launch preparations, a liquid oxygen leak was detected in the system that supplies the spacecraft with oxygen for both life support and propulsion. The leak itself wasn’t catastrophic, but it posed significant safety risks for the crew and the mission. Even a small leak of LOX in spacecraft systems can be dangerous because of the extremely cold temperatures of liquid oxygen (-183°C or -297°F) and the potential for it to evaporate into gaseous oxygen, creating risks for fire or explosions in the pressurised environment.

WHY DID THE LEAK DELAY THE MISSION?

Safety Concerns: The primary reason for delaying the mission was the safety of the crew. A leak in the oxygen system, especially if it couldn’t be sealed or fully contained, could lead to catastrophic failure during launch or while in orbit. Ensuring that all systems are completely operational and leak-free is critical for crewed missions, and any issue with life support or propulsion systems could jeopardize the mission.

Technical Complexities: Spacecraft systems, especially those used for crewed missions, are highly sensitive and complex. Even a seemingly minor issue, like a leak in the oxygen system, can trigger a more thorough investigation, technical fixes, and re-testing. Given the tight tolerance and precision required for these systems, any malfunction necessitates a delay to ensure that the spacecraft is fully operational and safe for launch.

Crew Oxygen Supply: The spacecraft needs a stable supply of LOX to create breathable air for astronauts during launch, orbital operations, and re-entry. If there’s a leak in the LOX system, it could compromise the crew’s oxygen supply, especially during the early phases of flight when the spacecraft is still in the lower atmosphere and the crew is exposed to high g-forces and other launch stresses.

Air Quality and Safety: In a crewed mission, any disruption to the life support system (like a leaking oxygen tank) is a serious concern. Spacecraft need to maintain precise levels of oxygen and pressure to ensure the crew’s safety, and a leak could risk causing an unsafe environment. This would prevent the mission from launching until the leak was fixed or isolated.

Launch Pad Procedures: In space missions, there are strict procedures for handling any anomaly during pre-launch, including detecting leaks in critical systems. A LOX leak detected prior to take-off would trigger an automatic halt to the launch sequence because safety is the top priority. This means that even if the leak were small, engineers would need to address it to ensure that the spacecraft could handle the extreme conditions of take-off.

Fuelling and Pre-Flight Readiness: The fuelling process for LOX can take hours, and a leak could disrupt the timing of fuel loading. If the leak were detected during fuelling, the launch would need to be scrubbed and rescheduled after repairs, further delaying the mission.

THE AXIOM MISSION

The Axiom-4 (Ax-4) mission is part of a series of private spaceflights organised by Axiom Space, a private space company, to send private astronauts to the Space Station (ISS). The Ax-4 mission is part of Axiom’s goal to commercialise space travel and provide private citizens and researchers the opportunity to experience life in orbit and conduct research aboard the ISS.

NASA’s Axiom-4 mission will “realize the return" to human spaceflight for India, Poland, and Hungary, with each nation’s first government-sponsored flight after over 40 years. While Axiom-4 marks these countries’ second human spaceflight mission in history, it will be the first time all three nations will execute a mission on board the ISS. The four crew members will be led by Axiom Space’s Director of Human Spaceflight, Peggy Whitson while Shukla will serve as the pilot in the mission.

This historic mission highlights how Axiom Space is redefining the pathway to low-Earth orbit and elevating national space programs globally. The space crew will carry out around 60 experiments during their 14-day stay in space, ranging from life science to technology demonstrations to diabetes research.

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