Did ISRO Play Role In Axiom Mission Delay?

'ISRO recommended to carry out in-situ repairs or replacement and conduct a low-temperature leak test to validate system performance and integrity, before proceeding with the launch.'

India seems to have had a major say in delaying the flight of SpaceX's Falcon 9 rocket so that the leaking booster is sealed properly and the four international astronauts can travel on the Dragon spacecraft atop the rocket, as gleaned from ISRO statements.

The SpaceX's Falcon 9 rocket with Dragon spacecraft carrying Commander Peggy Whitson of the US, Mission Pilot Subhanshu Shukla of India, Mission Specialist Sławosz Uznański-Wiśniewski of the European Space Agency/Poland, and Mission Specialist Tibor Kapu of Hungary was supposed to fly to the ISS on June 11.

The flight -- Axiom Mission 4 or Ax-4 Mission -- was managed by the US company Axiom Space.

The mission was aborted as one of the Falcon 9's boosters leaked liquid oxygen during post-static fire Falcon 9 rocket inspections.

It is reported that the leak was due to a weld crack.

The rocket uses rocket grade kerosene as fuel and super cooled liquid oxygen as oxidiser.

According to the Indian Space Research Organisation, the liquid oxygen leakage in the engine bay was observed during the preparation for a hot fire test conducted on June 8.

Anticipating the quick resolution of the LOx leak issue, the launch was rescheduled to June 11, 2025, ISRO said.

'NASA, Axiom Space, and SpaceX are standing down from the launch opportunity on Wednesday, June 11, of Axiom Mission 4 to the International Space Station to allow additional time for SpaceX teams to repair a liquid oxygen leak identified during post-static fire Falcon 9 rocket inspections,' National Aeronautics and Space Administration (NASA) said on June 10.

"Standing down from tomorrow's Falcon 9 launch of Ax-4 to the @Space_Station to allow additional time for SpaceX teams to repair the LOx leak identified during post-static fire booster inspections. Once complete -- and pending Range availability -- we will share a new launch date,'; SpaceX had said on June 10.

On its part, ISRO had demanded replacement of the leaking booster with a new one or carry out in-situ repairs.

'During the appraisal of technical issues by Axiom & SpaceX to ISRO delegation on June 10, 2025 (a day prior to the launch), ISRO recommended to carry out in-situ repairs or replacement and conduct a low-temperature leak test to validate system performance and integrity, before proceeding with launch clearance,' ISRO said.

"As part of launch vehicle preparation to validate the performance of the booster stage of the Falcon 9 launch vehicle, a seven second hot test was carried out on the launch pad. It is understood that LOX (liquid oxygen) leakage was detected in the propulsion bay during the test,' ISRO Chairman Dr V Narayanan tweeted on June 11.

'Based on discussions by the ISRO team with Axiom and SpaceX experts it has been decided to correct the leak and carry out necessary validation tests before clearing for the launch. Hence the launch of Axiom 04 slated for 11th June 2025 for sending the first Indian Gaganyatri (astronaut in Hindi) to the ISS is postponed,' Dr Narayanan added.

Dr Narayanan is an expert in liquid fuel powered rocket engines and a team of ISRO experts is in the US in connection with the Ax-4 mission.

As per the sequence of developments given by ISRO, there have been some technical glitches even prior to the liquid oxygen leak.

Giving a sequence of the developments relating to the human mission, ISRO said the launch, originally targeted on May 29, 2025 was deferred to June 8, due to observation in the electrical harness in the Crew Dragon Module.

'The launch was postponed by one day to June 9, 2025 due to delay in preparedness of the Falcon 9 vehicle for the launch,' ISRO said.

The launch date was further postponed to June 10, 2025, due to unfavourable weather in the ascent corridor.

'Additional observation of oxygen leakage in the engine bay was observed during the preparation for hot fire test conducted on June 8, 2025. Moreover, there was an observation of an anomaly in one of the engine actuators which was replaced along with the controller,' ISRO said.

Anticipating the quick resolution of the liquid oxygen leak, ISRO said the launch was rescheduled to June 11, 2025.

'During the appraisal of technical issues by Axiom & SpaceX to ISRO delegation on June 10, 2025, ISRO recommended to carry out in-situ repairs or replacement and conduct a low-temperature leak test to validate system performance and integrity, before proceeding with launch clearance,' the Indian space agency added.

Earlier at a media interaction, SpaceX Vice President-Build and Flight Reliability William Gerstenmaier said that the liquid oxygen leak was seen on the booster during its entry on its last mission.

Gerstenmaier had said the leak was not repaired when the booster was refurbished for the next flight or the leak was not detected then.

According to SpaceX, the Ax-4 Mission will be the second flight for the first stage booster. It was previously used for the Starlink mission. The company reuses its booster to save on costs.

"Leaks in a liquid propulsion system are typical. Even after testing, such observation could happen due to nano particles settling at valve seats or something like that," a senior ISRO scientist said.

The solution, the ISRO source said, is to replace, clean up, retest and proceed. It requires time and facility support and there is nothing to worry about if the issues are corrected.

Meanwhile at the ISS, Zvezda the Russian service module too experienced some leak.

'On June 11, 2025, NASA informed that they are working with Roscosmos to evaluate a new pressure signature indicating a leak in the aft most segment of the ISS Zvezda Russian service module, after the recent repair attempt. In order to assess the situation and determine the need for further troubleshooting, the launch of Axiom-4 mission is being postponed,' ISRO said.

On June 14 NASA said: 'SpaceX teams have repaired a liquid oxygen leak identified during post-static fire Falcon 9 rocket inspections. Following the repairs, the company completed a wet dress rehearsal of the Falcon 9.'

'NASA, Axiom Space, and SpaceX are reviewing launch opportunities no earlier than Thursday, June 19, for the fourth private astronaut mission to the International Space Station, Axiom Mission 4,' the US space agency added.

The Ax-4 Mission can be launched on any day till June 30, said Dana Weigel, manager, ISS Programme, NASA, and there are launch opportunities from the second week of July.

Venkatachari Jagannathan can be reached at venkatacharijagannathan@gmail.com

Feature Presentation: Aslam Hunani/Rediff