Shukla’s Ax-4 mission data provides new insights into space risks

Data collected during the Axiom-4 space mission, which included Indian astronaut Captain Shubhanshu Shukla, has provided a detailed picture of the radiation environment that astronauts encounter during human spaceflight.

The findings, published in the peer-reviewed journal Scientific Reports on August 13, could help improve radiation risk assessment, protect astronaut health and future space medicine research.

Radiation is one of the major environmental risks in human spaceflight. Prolonged exposure has been linked to an increased risk of cancer, cardiovascular and neurological disorders, tissue damage and DNA changes, making close monitoring important for both mission planning and astronaut safety.

Axiom-4 was an 18-day mission to the International Space Station (ISS) carried out in June-July 2025. Shubhanshu Shukla, an Indian Air Force officer, served as pilot of the Dragon spacecraft that transported the four-member crew from Florida to the ISS and back to Earth.

The study looked at radiation exposure throughout the mission, which covered the astronauts’ stay aboard the International Space Station and the transportation phases aboard the Dragon spacecraft.

The researchers found that most of the total absorbed radiation dose accumulated during the habitation phase of the ISS. Spacecraft transfer stages accounted for an average of 8.5 percent of the total mission dose, while still contributing significantly to the overall exposure.

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Scientists used custom-designed RadNano-1K dosimeters and RadNanoPlus detectors placed at multiple locations to continuously record radiation levels and environmental data throughout the mission.

The researchers said the continuous, high-resolution measurements allowed them to reconstruct variations in radiation dose rates and calculate cumulative absorbed doses across the full mission profile.

Astronauts in low Earth orbit are exposed to a combination of galactic cosmic rays, radiation trapped in the Earth’s magnetosphere, and occasional solar particle events. These radiation fields can also generate secondary particles when they interact with spacecraft structures, creating a complex and uneven radiation environment.

The researchers said that radiation data from private astronaut missions remains relatively limited despite the increasing frequency of such missions. Direct measurements from missions such as Axiom-4 could therefore help improve understanding of radiation exposure and enhance risk assessments for future human spaceflight.

The results can also support the evaluation of smaller, advanced dosimeters that can be deployed during operational missions.

With commercial human spaceflight expected to expand, researchers said continuous radiation monitoring will remain important to assess health risks and develop safer environments for astronauts on future missions.