But occasional flares are so powerful that they can make astronauts acutely sick and significantly raise their long term cancer risk.
Illustration of the inside of the Artemis I Orion spacecraft. The mannequin on the right, Zohar, is wearing the vest. Helga, on the left, has no vest. (NASA/Lockheed Martin/DLR)[Missing Credit]
Until now they've had to huddle inside the spacecraft's shielded ‘safe room’ and wait for the storm to subside, which could be anywhere from a few hours to three days.
An alternative was to wear a heavy and cumbersome whole body suit that offers them limited protection.
The AstroRad vest is a breakthrough that could allow astronauts to go about their business relatively unhindered as the storm rages.
It weighs about 26 kg (57 lb) on Earth, and it covers the torso, shielding vital organs such as bone marrow, lungs and parts of the digestive system.
The study, carried out by NASA, StemRad and other partners, concluded the vest – the first to be tested in deep space - would roughly halve the radiation dose received during some of the most severe storms.
To test the vest, two identical female torso mannequins, called Helga and Zohar, flew inside the Orion spacecraft. One wore the AstroRad, the other didn't.
The mannequins, made of materials that mimic human tissue, were also fitted with thousands of sensors to measure radiation levels.
Artemis I didn't encounter an actual solar storm, so researchers extrapolated the data collected from the mannequins and calculated what doses of radiation Zohar (with the vest) and Helga (without the vest) would have received if there had been one.
A side-by-side comparison showed the vest would have reduced radiation by between around 40% and 60%.
The authors of the study believe there's a long-term benefit to their vest. They estimate that AstroRad's extra protection could allow astronauts to remain in space far longer – by as much as six months.
NASA limits the days an astronaut can spend in space depending on the radiation they encounter.
Oren Milstein, StemRad’s CEO and a co‑author of the study, said such personal shielding could be “particularly important for future lunar and Mars missions”.
Dr Oren Milstein (StemRad)[Missing Credit]
He said the Artemis I mission had been “a formative test for AstroRad in deep space and a significant milestone for StemRad”.
He said he hoped the vest “will become an ongoing Israeli contribution to NASA’s manned space programme… and help pave the way for the participation of additional Israeli astronauts in future missions.”
Artemis I, on which the vest was tested, was the first US mission to the moon since Apollo 17 in December 1972. It flew without a crew.
It was followed by Artemis II, carrying four astronauts, which lifted off in February 2026 and which will fly by the moon but won't land.
Future Artemis missions will be crewed and will land on the moon, but it is not yet clear if they will include the AstroRad.
StemRad, which developed the vest, is an Israeli-American startup founded in 2011, that specialises in personal radiation protection technology for medical, emergency and space applications.
The AstroRad vest was co-developed with US aerospace giant Lockheed Martin.
