by European Space Agency

Credit: ESA/NASA

Earth's magnetosphere protects us from the most harmful cosmic rays that bombard our planet but beyond this natural shield, astronauts are subjected to radiation that is a hundred times more than at sea level.

The risks of radiation are in the spotlight of ESA's research efforts. The first 'radiation summer school' took place last year to train students and stimulate novel ideas for research into the effects of space radiation on humans.

Young researchers received an introduction to radiation physics and biology and had to think of biological experiments to run in a number of ESA's partner particle accelerators around Europe. The best proposals won the opportunity to fire up the accelerator and shoot atomic particles at their experiment.

Irradiating stem cells

The first prize of the 2019 radiation summer school went to Emiliano Bolesani, a researcher based in Germany, who is eager to identify the patho-physiological response of heart cells when exposed to cosmic radiation. To do this, Emiliano proposed to use stem cells for growing structures of heart tissue that will then be placed at the receiving end of the particle accelerator of the GSI Helmholtz centre for heavy ion research in Darmstadt, Germany.

The novelty of this approach is growing heart microtissues to mimic the cellular composition of the human heart.

Artist impression (not to scale) idealising how the solar wind shapes the magnetospheres of Venus (top), Earth (middle) and Mars (bottom). Unlike Venus and Mars, Earth has an internal magnetic field that deflects the charged particles of the solar wind as they stream away from the Sun, carving out a ‘bubble’ – the magnetosphere – around the planet. At Mars and Venus, which don’t generate an internal magnetic field, the main obstacle to the solar wind is the upper atmosphere, or ionosphere. Just as on Earth, solar ultraviolet radiation separates electrons from the atoms and molecules in this region, creating a region of electrically charged – ionised – gas: the ionosphere. At Mars and Venus this ionised layer interacts directly with the solar wind and its magnetic field to create an induced magnetosphere, which acts to slow and divert the solar wind particles around the planet. Credit: ESA

Emiliano wants to find out what type of cells are most susceptible to radiation damage—cardiomyocytes, endothelial cells, smooth muscle cells or fibroblasts—and identify how they influence one another. The data will help create an analytical model to predict how the cells will interact with each other in the face of radiation.

"I am hopeful that the system could also be used in the future to screen for molecules that might prevent cells from radiation damage," says Emiliano, from the Hannover Medical School.

"It is exciting to use the exclusive facilities on offer, but even more that this research could have direct implications in limiting unwanted effects on the cardiovascular system after radiotherapy. This strategy could be extended to other organs in the future and may help in safeguarding astronauts' health while exploring deep space."

• Cosmic radiation could increase cancer risks during long duration missions. Damage to the human body extends to the brain, heart and the central nervous system and sets the stage for degenerative diseases. A higher percentage of early-onset cataracts have been reported in astronauts. Earth’s magnetic field and atmosphere protect us from the constant bombardment of galactic cosmic rays – energetic particles that travel at close to the speed of light and penetrate the human body. A second source of space radiation comes from unpredictable solar particle events that deliver high doses of radiation in a short period of time, leading to ‘radiation sickness’ unless protective measures are taken. Credit: ESA

• The SIS-18 ring accelerator can shoot ions at targets including biological cells, recreating cosmic radiation. Analysing how the ions interact will help mission designers to develop new ways of minimising the risks of cosmic radiation. The ions are accelerated with magnets to 90% of the speed of light, or 270 000 km/s. This image shows a beam diagnosis element, which allows scientists to analyse the shape of the ion beam as it passes through. Credit: Gabi Otto/GSI Helmholtzzentrum für Schwerionenforschung GmbH

• A new international accelerator, the Facility for Antiproton and Ion Research (FAIR), now under construction near Darmstadt, Germany, at the existing GSI Helmholtz Centre for Heavy Ion Research (GSI), will provide particle beams like the ones that exist in space and make them available to scientists for studies that will be used to make spacecraft more robust and help humans survive the rigours of spaceflight. For example, researchers will be able to investigate how cells and human DNA are altered or damaged by exposure to cosmic radiation and how well microchips stand up to the extreme conditions in space. FAIR’s central element will be a new accelerator ring with a circumference of 1100 m, capable of accelerating protons to near-light speeds. The existing GSI accelerators will repurposed to serve as pre-accelerators for the new FAIR facility. This image shows the high-tech equipment that generates the particles, which are then injected into the GSI and FAIR accelerator systems. Credit: GSI Helmholtzzentrum für Schwerionenforschung GmbH/Jan Michael Hosan 2018

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Next… astronaut cells

Emiliano has worked with a team to propose a more detailed idea for collecting cells from astronauts before and after a spaceflight. Tissues and organs grown from the astronauts' cells could be placed under the beam of a particle accelerator to see their reaction to simulated space radiation.

This study could shed light on the cellular and molecular clues underlying the individual response to space radiation.

"Each of us has a different susceptibility to radiation," explains Emiliano, "this is a problem for radiation therapy as it can influence how efficient treatments are on Earth, as well as having implications for astronauts exposed to space radiation.

"The other question behind this potential follow-on study is whether cells adapt during spaceflight and 'remember' after coming back to Earth—are epigenetic and physiological changes longer lasting? In other words, is spaceflight "captured" as a footprint in our DNA?"

Provided by European Space Agency