Radiation Vest Could Cut Astronaut Dose by 60 Percent
Measurements from an uncrewed mission around the Moon show that a 26-kilogram vest would cut an astronaut's radiation dose by about 60 percent in a solar storm as strong as the one from 1972.
A protective radiation vest that flew around the Moon inside the Orion capsule in 2022 would have cut an astronaut’s radiation dose by about 60 percent during a solar storm as strong as the one that struck in 1972. The measurements were published on August 12, 2026 in the journal Science Advances, in a paper offering the first estimates of wearable radiation protection for human deep space exploration. The lead author is Jordan Hurie of the company StemRad.
Outside Earth’s magnetic field, an astronaut has none of the shielding that people on the ground take for granted. In an event called a solar particle event, the Sun hurls out protons at high energy, and exposure to this kind of radiation raises the risk of several types of cancer. That is one of the questions standing between today’s missions and a base on the Moon, where a stay would last weeks rather than the days astronauts spent there during the Apollo program.
How Zohar and Helga measured the dose
The vest was worn by one of two female mannequins that flew on the Artemis 1 mission, an uncrewed flight around the Moon that lasted 25 days. The mannequins were strapped into the passenger seats of the Orion capsule. Zohar wore the vest, while Helga had no protection at all. Both stand about 90 centimeters tall, from the head to the lower torso, and are packed with thousands of radiation sensors, so the dose is read out at specific points inside the body rather than just at the skin.
The vest is called AstroRad. It weighs 26 kilograms and is made of high-density polyethylene. It was developed by the American-Israeli company StemRad together with Lockheed Martin, modeled on the gear worn by nuclear-accident response teams, and an earlier version was tested aboard the International Space Station before this flight. It covers the organs most sensitive to radiation:
- bone marrow
- lungs
- the digestive tract
- breasts
- ovaries
Both mannequins are female because women are considered more susceptible to radiation-induced cancer.
How much dose would the vest actually shed?
No solar storm occurred during the entire mission. So the figures in the paper are not a measured level of protection during an actual storm, but a calculation: the team took the data collected as Orion passed through the inner Van Allen belt and applied it to two well-documented past events, from August 1972 and October 1989.
For the 1972 scenario, the dose would have dropped from 222 to 87.5 millisieverts, a reduction of about 60 percent. For the stronger 1989 event, the reduction would be around 40 percent. Those two figures correspond to 193 and 131 days, respectively, of unnecessary radiation exposure in deep space.
“The dose reduction we saw was surprising,” Hurie said.
The scale becomes clearer with two more reference points. A person on Earth’s surface receives about 3 millisieverts a year from natural sources. NASA, the American space agency, caps the total dose an astronaut may receive over an entire career at 600 millisieverts. A dose of 222 millisieverts from a single storm would burn through a third of that career budget, which means the difference the vest makes is really a difference in how many missions one person is allowed to fly.
Why the vest didn’t fly on Artemis 2
The vest was not aboard Artemis 2, the four-person flight that looped past the Moon in April 2026. That flight lasted 10 days, and there was no room for it in the capsule. The idea was never for the vest to be worn constantly anyway, but to be put on during a solar flare with high radiation output. At that moment, the crew retreats into a shielded area of the spacecraft, and whoever is wearing the vest could keep handling tasks that cannot wait.
The team is now working on a modular version, a single base vest that would adjust to different body types, cutting the mass that needs to be launched. Zohar and its vest are on display at the Kennedy Space Center in Florida.
What this doesn’t prove
The paper does not show that the vest protected anyone during an actual solar storm, because there was no storm during Artemis 1. What it shows is how much radiation passed through the shielded mannequin and the unshielded one inside the Van Allen belt, with the rest left as a calculation for two historical events. A mannequin is not a human being and says nothing about how the body responds to the dose it receives, only how much energy reached specific organs.
The shielding is aimed at the organs listed above, not the whole body, and it addresses solar particle events, which are only one part of the radiation present in deep space. How much such equipment would actually lower the cancer risk for a crew spending months on the Moon cannot be worked out from a single flight without a storm.
