Spaceflight Radiation Exposure Tested with Onboard Sensors and Mannequins, Reports Reuters

By Will Dunham

WASHINGTON – Utilizing mannequins named Helga and Zohar along with sensors installed in a spacecraft, scientists have gathered crucial data regarding radiation exposure for astronauts venturing beyond Earth’s protective magnetic field. This research is essential for enhancing safety during long space missions, such as those aimed at Mars exploration.

Initial measurements detailing radiation levels encountered inside NASA’s Orion spacecraft were released following its 25-day uncrewed Artemis I mission in 2022, which circled the moon before returning to Earth. Continuous radiation data was captured using instruments like NASA’s HERA and sensors from the European Space Agency.

Radiation poses a significant threat that must be addressed for astronauts engaged in extended missions outside of Earth’s protective reach. The Artemis program intends to return astronauts to the lunar surface within this decade and establish a base there as a precursor to human exploration of Mars.

Various sources of radiation, including galactic cosmic rays and solar flare particles, can increase the risk of radiation sickness, elevate lifetime cancer risk, and contribute to neurological and degenerative diseases among astronauts.

Helga and Zohar were designed to simulate the female human body and served as substitutes for astronauts in the Orion capsule. They were equipped with sensors that measured radiation exposure on their skin and internal organs, with Zohar wearing a radiation protection vest while Helga did not.

"Helga and Zohar are ‘radiation phantoms’—advanced mannequins that replicate the human body’s response to radiation, outfitted with sensors throughout to measure dosage across different organs," explained Stuart George, a physicist from NASA’s Space Radiation Analysis Group. He noted the phantoms were specifically designed to account for the higher sensitivity that women generally have to radiation, providing valuable insights into radiation deposition during various phases of the mission.

The regions of radiation known as the Van Allen belts envelop Earth, contributing to the complex radiation environment that astronauts will face on long journeys.

"We are currently finalizing data analysis for Helga and Zohar, with comprehensive results expected to emerge in the coming months," remarked Thomas Berger, lead author of the study and a radiation physicist at the Institute of Aerospace Medicine in Cologne.

The areas within Orion that featured the most radiation shielding, including a designated "storm shelter" for astronauts during radiation events like solar flares, offered up to four times more protection compared to less shielded sections. This discovery reaffirmed the spacecraft’s design plans for future missions.

Data indicated that radiation exposure inside Orion from galactic cosmic rays—high-energy particles traveling through space—was approximately 60% lower than that recorded by earlier uncrewed probes. This underscores the advantages of a spacecraft designed with radiation shielding.

"The cosmic rays encountered during interplanetary flights are especially significant, as they represent the primary exposure risk for lengthy missions, making this data crucial for extended stays on the moon and future missions to Mars," George stated.

The spacecraft’s orientation during its flight also influenced radiation exposure, with levels dropping by half when Orion executed a 90-degree turn while passing through the inner Van Allen belt.

"This reduction is due to the directional nature of Van Allen belt radiation, where altering the spacecraft’s orientation shielded it more effectively," George added.

Earth’s magnetic field creates a protective barrier against space radiation, with the International Space Station orbiting within this field. The Artemis I mission enabled Orion to travel further than any human-rated spacecraft, moving beyond the magnetic shielding of Earth.

While there is ample data on radiation exposure from crewed missions in low-Earth orbit, very few measurements exist for those beyond the protective magnetic field. Previous data primarily stemmed from planetary science missions that employed significantly lighter radiation shielding than what is utilized in crewed spacecraft like those for the Artemis program.