AstroRad Vest Cut Modeled Astronaut Radiation Exposure by 60% in Artemis I Test

Earth's atmosphere and magnetic field shield people from cosmic radiation, but crews travelling to the Moon or Mars lose that protection. Because thickly shielding an entire spacecraft adds too much weight, Israeli company StemRad worked with Lockheed Martin, NASA, the German Aerospace Center and the Israel Space Agency to build a wearable alternative: the AstroRad vest, which protects an astronaut's most radiation-vulnerable organs instead of the whole cabin.

The vest was tested during NASA's 25-day, uncrewed Artemis I mission around the Moon in November 2022. Two mannequin-like torso phantoms, each fitted with more than 5,600 radiation sensors and modeled on adult female anatomy, rode inside the Orion capsule; one, named Zohar, wore the 57-pound AstroRad vest, while the other, Helga, flew unprotected. The vest uses hexagonal rods of high-density polyethylene, a hydrogen-rich plastic that absorbs radiation without the extreme mass of metals like lead, concentrated over the bone marrow, lungs, stomach, colon, breasts and ovaries.

Orion did not fly through a live solar storm, so researchers compared its Van Allen radiation belt readings against two historic solar storms. Modeled on the August 1972 storm, the vest cut radiation exposure from 222 millisieverts to 87.5 millisieverts, a 60.7% drop equal to sparing an astronaut 193 days of deep-space background radiation; the team had expected only a 45% reduction. Modeled on the October 1989 storm, the vest cut radiation by 38.5%, equal to 131 days spared.

Because the results rely on models rather than live data, the vest's real performance remains unproven, and future space weather may not match either historic storm. AstroRad is meant as emergency gear for radiation spikes, not daily wear. StemRad is now partnering with aerospace firm Redwire to explore 3D-printing the shielding in space using recycled polyethylene.