In an interview with the Haydan website, Dr. Oren Milstein, CEO and founder of StemRad, explains how Artemis 1 data was used to assess the effectiveness of the AstroRad vest, why wearable protection does not replace spacecraft protection – and how the project may open additional doors for the Israeli space industry.
A vest that specifically protects the body's most sensitive organs could reduce the radiation dose astronauts absorb during a solar particle storm by 40%–60%. This is according to a study published in the journal Science Advances, based on data collected on NASA's Artemis 1 mission.
However, it is important to note that no major solar storm occurred during the mission. The reduction rates are not the result of direct exposure to such an event, but rather of computer simulations validated using measurements collected when the Orion spacecraft crossed the inner Van Allen belt.
"We have proven that wearable personal protection works and can be a very significant factor in long-term journeys in deep space," said Dr. Oren Milstein, CEO and founder of StemRad, which developed the AstroRad vest, in an interview with the Hidan website.
Two dolls, one with a vest
In the MARE experiment, two mannequins – “Zohar” and “Helga” – simulating the body of an adult woman – were launched on the Orion spacecraft. Zohar wore the AstroRad vest, while Helga flew without the vest.
"We sent two dummies around the moon with NASA," Milstein explained. "One dummie was equipped with a vest and one dummie was not, and we compared the absorption of radiation by their bodies."
The dolls, called "phantoms" in the study, were built from materials that simulate bones, soft tissues, and internal organs. More than 12 passive detectors and 34 active detectors from the German Aerospace Center, DLR, and NASA were installed inside and on their surfaces. The detectors were placed in areas such as the bone marrow, lungs, stomach, and uterus. According to DLR, it was the most comprehensive radiation experiment conducted to date beyond low Earth orbit.
The Artemis 1 mission lasted about 25.5 days in November and December 2022. In the absence of a significant solar storm, the researchers used measurements collected during the passage through the Van Allen belt, where energetic protons are trapped, to test the model for calculating the passage of particles through the spacecraft, the vest, and the human body.
Once the model matched the actual measurements well, the researchers ran simulations of two historical solar particle events. The storm-like event of August 1972 yielded a reduction in effective dose of about 60%, while a scenario similar to the October 1989 event—where the particles were more energetic and penetrating— yielded a reduction of nearly 40%.
The researchers calculated that in some scenarios the reduction could be equivalent to up to 193 days of normal deep space exposure. This does not mean that the vest automatically extends a mission by this many days, but it could prevent a single short event from consuming a significant portion of an astronaut's allowed radiation budget.
Not a spacesuit and not a replacement for spacecraft protection
AstroRad is not intended to be used as a spacesuit for activities outside the spacecraft. Initially, it is intended to be worn inside the crew compartment, primarily when an alert is received about an increase in radiation levels.
According to Milstein, operational use depends on the duration of the mission, the phase of the solar cycle, and the degree of protection provided by the spacecraft itself. On a short mission in a relatively protected spacecraft, the risk is lower; on missions lasting weeks or months, or on a lander with poorer protection, the need for personal protection increases.
"The mass comes in place of other things, and the mass is very limited," Milstein said. That's why it's not enough to show that the vest reduces radiation: NASA will have to decide that the health and operational benefits justify its weight.
The model tested on Artemis 1 weighed about 26 kilograms on Earth. It is made primarily of high-density polyethylene, a hydrogen-rich material suitable for slowing down energetic particles. Thousands of small shielding elements are arranged in a modular structure, and their thickness varies depending on the sensitivity of the tissues underneath.
Instead of distributing the shielding evenly across the body, the vest provides thicker protection to the bone marrow and organs such as the lungs, stomach, colon, breasts, and ovaries. According to the study, targeted use of the same shielding mass improved the effective dose reduction by about 30% compared to a uniform shielding layer.
Milstein emphasized in the interview the importance of the bone marrow, where blood cells are formed. Women are also considered to be at higher risk for certain types of radiation-induced cancer, partly because of the sensitivity of the breasts and ovaries. Therefore, Zohar and Helga were designed from the start with a female body structure.
The operational advantage: getting out of the radiation shelter
A wearable vest is not intended to replace a protected "storm shelter" inside the spacecraft. Its advantage is its ability to allow astronauts to exit the shelter, move around the crew compartment, and continue to perform essential tasks while radiation levels are high.
Milstein believes that operational adoption will become more likely as deep space stays get longer. Future missions that involve extended stays around the moon, on its surface, and later on the way to Mars will increase the chance of a solar particle event occurring while the crew is outside the protection of Earth's magnetosphere.
In this sense, the study does not prove that the vest is ready for regular operational use. It provides data-based validation of the protection method, but a decision on its integration into future missions will depend on further testing, in accordance with NASA's teams and priorities.
The significance for the Israeli space industry
The experiment illustrates how an Israeli company specializing in a narrow field can be integrated into an international flagship mission through cooperation between space agencies and large companies.
According to Milstein, the roots of the project lie in a cooperation agreement signed in 2015 between the Israel Space Agency and NASA. Later, DLR and Lockheed Martin, which built the Orion spacecraft, joined. In 2018, the agreement was signed to integrate the vest into the Artemis 1 experiment.
Because Artemis 1 was an unmanned mission, the spacecraft had enough mass to launch the two dummies, the vest, the detectors, and the experimental equipment—a total payload that Milstein says weighed about 250 pounds. He estimates that if StemRad had been required to fund an independent lunar experiment of this magnitude, the cost could have exceeded $100 million.
From the perspective of Israeli industry, the important achievement is not just flying the Israeli flag on a spacecraft. It demonstrates a path in which government investment and international cooperation enable the technology of a relatively small Israeli company to reach an experiment that is usually within the reach of only large space companies.
However, publishing scientific research is not equivalent to a commercial order or a commitment from NASA to use the vest. The next test will be whether the results will translate into operational integration in future missions and further collaborations for StemRad and other Israeli space companies.
Milstein noted that the same concept of targeted shielding was first developed for first responders to nuclear incidents, has been expanded to military uses, and is now being tested for astronaut protection. For him, the Moon is an intermediate stage: the destination where radiation protection will be especially essential is a manned mission to Mars.
Official responses
In a response published by the Ministry of Innovation, Science and Technology, Minister Gila Gamliel said that the results express Israel's ability to contribute to space exploration through technology of human significance.
The director of the Israel Space Agency, Ran Levena, noted that the experiment marks a transition from measuring the radiation environment to examining practical countermeasures under mission conditions.
Questions and Answers
What was actually proven in Artemis 1?
The detectors measured the radiation environment and the vest's effect during the flight and during the Van Allen belts. No strong solar storm occurred, so the 40%–60% reduction was calculated using a model that was validated against measurements.
Does AstroRad protect against all types of space radiation?
No. The vest is primarily intended to reduce exposure to protons from solar particle events. It does not eliminate the risk of galactic cosmic radiation and does not replace spacecraft shielding.
Why does the vest only protect part of the body?
The launch mass is limited. Therefore, the shielding is concentrated in the bone marrow and organs most sensitive to radiation. According to the study, this approach is more effective than uniform shielding of the same mass.
Has NASA already decided to use the vest?
No decision on operational use has been made. The study provides a scientific basis for examining its integration, but the decision will depend on the duration of the mission, the expected risk, the mass of the vest, and the protection alternatives.
More of the topic in Hayadan:
- Israeli development at the heart of the Artemis 1 mission: Dummies on which the AstroRad vest will be tested
- NASA will launch a radiation protection suit developed in Israel into space
- Artemis II returns humans to lunar orbit – and radiation becomes a major challenge
- Artemis II on its way back after orbiting the moon
For the scientific article: Opening the scientific article
