Humanity is on the threshold of a new era of space exploration, with ambitious plans to return to the Moon and take the first steps on Mars. While engineers and scientists are developing powerful rockets and advanced life support systems, one of the biggest and most insidious challenges remains invisible to the naked eye – space radiation. Outside the protective magnetic field of Earth, astronauts are exposed to a constant bombardment of high-energy particles that pose a serious threat to their health. In orbit around our planet, at a location like the International Space Station (ISS), crews are still partially protected. However, a journey into deep space, towards the Moon or the Red Planet, exposes them to the full force of cosmic radiation, making the development of effective protection an absolute priority. It was precisely on the ISS, in the unique environment of microgravity, that crucial testing of an innovative solution that could be decisive for the future of human spaceflight was conducted – the AstroRad protective vest.

This vest, developed in a collaboration between the American aerospace giant Lockheed Martin and the Israeli company StemRad, represents a revolutionary approach to personal radiation protection. Instead of bulky and impractical shields that would encompass the entire spacecraft, AstroRad offers targeted protection, focusing on the most sensitive organs and tissues in the human body, while preserving the mobility and functionality of the astronauts. The testing on the ISS was not only aimed at verifying its radiation-blocking capabilities but also at its ergonomics – a key factor for daily life and work in space.

The invisible enemy in deep space

Space radiation comes from two primary sources: galactic cosmic rays (GCRs) and solar energetic particles (SEPs) released during solar storms. GCRs are remnants of ancient supernovae, heavy, high-energy atomic nuclei that have been stripped of their electrons and travel through the galaxy at nearly the speed of light. Due to their immense energy, these particles act like microscopic cannonballs, piercing through the hull of a spacecraft and human tissue, causing significant damage at the cellular and molecular level. Long-term exposure to GCRs significantly increases the risk of developing cancer, can cause damage to the central nervous system, and lead to degenerative diseases of the heart and other organs.

Solar events, on the other hand, are unpredictable and can release enormous amounts of radiation in a very short time. Although less penetrating than GCRs, they can cause acute radiation sickness, a condition with symptoms ranging from nausea and fatigue to severe damage to the bone marrow and internal organs, which can be fatal without adequate protection. Earth's magnetic field and atmosphere act as a natural shield that protects us from most of these threats, but in deep space, there is no such protection. Therefore, finding ways to mitigate these risks is essential for enabling long-duration missions, such as a journey to Mars, which could last up to three years.

AstroRad: Targeted protection for vital organs

The concept behind the AstroRad vest is based on the principle of selective protection. Analyses have shown that certain organs, such as bone marrow, lungs, stomach, colon, and female reproductive organs, have a significantly higher sensitivity to radiation. Instead of encasing the entire body in heavy materials, which would drastically restrict movement, AstroRad is designed to protect precisely these critical areas. The vest is made of layers of hydrogen-rich materials, such as polyethylene, which have proven to be extremely effective at stopping and fragmenting the heavy ions of galactic cosmic rays into less harmful particles. Its modular and ergonomic design allows for adaptation to different astronaut body types and ensures that wearing the vest does not interfere with the performance of daily tasks.

The partnership between StemRad, which possesses expertise in radiation protection developed for the needs of emergency services on Earth, and Lockheed Martin, with decades of experience in space technology, was key to adapting this technology to the extreme conditions of space. Through their joint work, a product was created that not only offers protection but is also practical for use in zero gravity, which was one of the main goals of the testing on the International Space Station.

Testing in real conditions on the ISS

The International Space Station served as the perfect laboratory for validating the AstroRad vest. Although ground-based tests could simulate many aspects, it was only in the real space environment that it was possible to assess how the vest behaves during the routine activities of astronauts. NASA astronaut, Kayla Barron, was one of the crew members tasked with wearing the vest and providing detailed feedback. During the multi-week trial, astronauts wore the AstroRad while exercising on equipment, performing scientific experiments, and conducting regular station maintenance.

Their feedback was invaluable. Scientists and engineers on Earth received crucial data on the vest's comfort, its fit, the ease of putting it on and taking it off, and its impact on the range of motion. Every detail, from the design of the buckles to the arrangement of the protective panels, was carefully analyzed to ensure the vest was as unintrusive as possible. Successfully demonstrating its functionality in microgravity was a critical step, transitioning from a prototype to an operational technology ready for implementation on future deep space missions. The ISS National Lab program played a key role, providing companies like StemRad with access to this unique platform for research and development.

Proving itself on the way to the Moon

The testing on the ISS was just the beginning. The real test of the AstroRad vest's ability to block the actual radiation of deep space occurred during the Artemis I mission, an uncrewed test flight of the Orion spacecraft around the Moon. Inside the capsule were two anatomical phantoms, named Helga and Zohar, equipped with thousands of radiation-measuring sensors. These phantoms, modeled on female physiology due to its greater sensitivity to radiation, were at the center of the MARE (Matroshka AstroRad Radiation Experiment). The key difference was that Zohar wore the AstroRad protective vest, while Helga was unprotected.

During the 25-day journey around the Moon and back, the sensors collected a vast amount of data, providing scientists with the most detailed map to date of the radiation environment on the trajectory to the Moon. Comparing the data from Helga and Zohar allowed for a precise quantification of the vest's effectiveness. The results confirmed that AstroRad significantly reduces the radiation dose received by vital organs. This experiment was a monumental step forward, providing concrete evidence that targeted, wearable protection is a viable and effective concept for future astronauts who will travel as part of the Artemis program and, eventually, to Mars.