With astronauts venturing beyond the protection of Earth’s magnetic field exposed to high levels of cosmic radiation, the European Space Agency (ESA) has teamed with Germany’s GSI (Gesellschaft für Schwerionenforschung) particle accelerator in the search for materials to shield future astronauts going to the Moon, the asteroids and Mars, or manning a space station beyond the Moon. Amongst the candidates being assessed are Moon and Mars soil.
As well as galactic cosmic radiation consisting of atomic nuclei produced by dying stars, deep space also exposes astronauts to harmful radiation produced by the Sun in “solar particle events,” – but these are made up of protons that can be shielded relatively easily. Thankfully, the Earth’s magnetic field protects us, and those aboard the International Space Station (ISS) that orbits within the field, from the bulk of the harmful ionizing radiation that originates beyond our Solar System. But venture outside the magnetic field without protection and your cells are sure to take a beating.
Simply producing thicker and denser metal radiation shielding to protect astronauts isn’t necessarily the answer because high-ionizing high-energy particles – or HZEs – can produce showers of even more harmful secondary particles when striking metal shields.
This is why the ESA is conducting a two-year project to assess the most promising materials to provide shielding from this damaging radiation. Formally known as ROSSINI (Radiation Shielding by ISRU (In-Situ Resource Utilisation) and/or Innovative Materials for EVA, Vehicle and Habitat), the project is using the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, which is the only European facility capable of simulating the high-energy heavy atomic nuclei found in galactic cosmic radiation.
However, the first round of testing was recently performed at NASA’s Space Radiation Laboratory at Brookhaven in New York. The team has assessed various promising materials, including aluminum, water, polyethylene plastic, multilayer structures and simulated Moon and Mars material. The last two were chosen for examination due to their accessibility for planetary expeditions.
“We have also confirmed a new type of hydrogen storage material holds particular promise,” said Alessandra Menicucci, who is overseeing the project and notes that, “in general, the lighter a material’s atomic nuclei the better the protection.”
Using the Geant4 toolkit to simulate particles striking matter, the researchers found that water and polyethylene performed better than aluminum, while new hydrogen-rich materials originally developed by U.K.-based Cella Energy for storing hydrogen fuel performed even better.
The research will continue with the results to be made available for the planning of future manned space missions.