A geometrical arrangement of spikes opens the door to extreme science at the nuclear level. This setup is part of a galactic cosmic ray simulator at the GSI accelerator facility in Darmstadt, Germany.

For the first time in Europe, researchers are accelerating charged atoms up to around 90% the speed of light to recreate the full spectrum of cosmic radiation in one of the most powerful particle accelerators in the world. A network of rings and pipes stretching several hundred metres can deliver high-energy ion beams at 270 000 km/s.

The core structure of this new device is a combination of slab modulators (flat panels to induce fragmentation of the primary beam) and complex modulators (a set of 3D-printed thin pins to modulate the velocity of the fragments). The geometry, composition and thickness of the modulators are optimised to reproduce on Earth the spectrum of cosmic rays in deep space.

In outer space, high-energy particles coming from beyond our Solar System hit every cell of an astronaut’s body. Known as galactic cosmic rays, these particles emanate from dying stars and pose serious risks for missions to the Moon or Mars.

The impact can damage our cells and lead to cancer, cardiovascular disease and disorders of the central nervous system. Electronics on board spacecraft are also at risk. There is nowhere to hide from this invisible threat, and extra shielding is not the solution. When cosmic rays strike metal walls, they can trigger showers of secondary particles that may be even more harmful than the original radiation. Understanding and mitigating the biological impact of cosmic radiation is essential for a sustainable human presence in space.

The GSI research team, in collaboration with ESA, used the high-energy accelerator to bring the Universe into the lab. By precisely tuning its beams, scientists generated a mixed radiation field that replicated what astronauts would experience inside a spacecraft. The experiment allowed researchers to measure radiation doses that affect both human tissue and space components.

The benefits of this technology go beyond astronaut safety. This same accelerator will be available to external researchers, and can be used for cancer therapy with charged particles on Earth.

ESA and GSI give students an insight into the fundamentals of biophysics with heavy ions for both terrestrial and space applications during the annual ESA-FAIR Space Radiation School. The next edition will take place in August 2026 and registration is open until April 12.