By Georgia Barrington-Smith
Have you ever wondered what the main risks of space travel are?
Hollywood films like The Martian and Apollo 13 often portray the dramatic risks of space travel, such as mechanical failures, life support issues, and unpredictable space weather.
However, as astronauts journey far from home, venturing into the cold, unforgiving vacuum of space, they face a far more hostile environment, one where even the protection of their spacecraft offers only limited safety.
Beyond the thin walls of their vessel, amid the seemingly empty void, lies a hidden and invisible danger—space radiation.
This invisible threat arises from high-energy, ionising particles that travel from the Sun, distant stars, and galaxies. When these particles pass through the human body, they ionise atoms and molecules, triggering a cascade of biological damage that particularly effects our very DNA.
Galactic particles and double-strand breaks
On Earth, we are largely shielded from cosmic radiation by the combined effects of Earth’s atmosphere and magnetic field. Astronauts travelling beyond these protective barriers must contend with high-energy space radiation that can easily penetrate spacecraft, spacesuits, and human tissue, causing silent damage to the complex building blocks of our bodies — our DNA.
Double-strand breaks (DSB) – a type of early DNA damage where both strands of the double helix are broken – can be caused by exposure to radiation. Depending on the radiation field, DSBs can be extremely difficult for cells to repair correctly. If the repair process fails, it can result in mutations, cancer, or even cell death.
As we look to establish a long-term human presence beyond Earth, it’s essential to understand and mitigate the biological risks posed by prolonged exposure to space radiation. Nanodosimetry helps us to do just that.
Tracing space radiation damage at the molecular level
Space agencies worldwide, including NASA, currently estimate radiation risk using models that apply adjustments based on particle type and energy to estimate effective dose. One of the drawbacks of this method is that it doesn’t directly assess early DNA damage.
To address this shortcoming, the developing field of nanodosimetry studies radiation effects at the nanometre scale, where actual DNA damage occurs. Thanks to advances in physics, computing, and molecular biology, researchers can now simulate in-silico how individual particles interact with DNA molecules and predict the early DNA damage.
One of the key tools at the heart of this effort is Geant4-DNA—a specialised Monte Carlo simulation framework. By combining this framework with detailed three-dimensional DNA models, scientists can trace the full journey of space radiation, from its impact on the lunar surface down to the molecular havoc it wreaks inside a single cell.
Developing a framework for future lunar radiation protection
AINSE PGRA scholar Jay Archer, PhD student of the University of Wollongong, in collaboration with ANSTO and CENBG, Bordeaux, France, is pioneering efforts to improve how we monitor and understand space radiation exposure on the lunar surface.
Together, Jay and the team developed the first complete simulation pipeline to assess DNA damage from space radiation on the Moon. Their research into the effects of space radiation comprises of three key pillars:
- Monte Carlo simulations of early DNA damage from space radiation,
- Validation of these simulations through radiobiological experiments performed at the ANTARES beamline at ANSTO, and
- Characterisation of silicon radiation detectors for improved dosimetry.
1. Modelling radiation impact: from the lunar surface to DNA damage
Jay and collaborators built a multiscale simulation to track galactic cosmic radiation (GCR) and its interactions on three distinct scales: the Moon’s surface, a virtual human body model (phantom), and a detailed cell and DNA structure.
- Simulating space radiation on the Moon
First, the team modelled how GCRs hit the lunar surface and affect astronauts standing on it. This modelling helped to determine the types and intensity of radiation exposure. - Tracking radiation through the body
Using a 3D phantom, the team traced how radiation penetrates organs and tissues in the human body, calculating doses to critical biological systems. - Zooming into the DNA level
Finally, the team scaled their model down to simulate double-strand breaks in DNA—pinpointing exactly how and where radiation-induced molecular damage occurs.
Thanks to the use of this simulation pipeline from macro to nanoscale, Jay and the team obtained an understanding of the early DNA damage in astronauts without needing to conduct real-life experiments. It also allowed them to test the design of new different spacecraft shielding or spacesuit materials under different conditions, to help make safer missions for future space exploration.
2. Validating Simulations Through Radiobiological Experiments
While simulations provide valuable predictions, verifying their accuracy is essential. To this end, Jay performed radiobiological experiments using human skin cells exposed to controlled radiation beams at ANSTO’s Centre for Accelerator Science (CAS) to verify the performance of their initial simulations.
After exposure on the ANTARES beamline, Jay and team used a fluorescent marker (γ-H2AX) to stain DNA double-strand breaks and imaged the cells using a confocal microscopy. By comparing these three-dimensional visualisations with the simulated damage results from Geant4-DNA, the team were able to fine-tune their models and ensure their biological accuracy.
Below is a first qualitative comparison of the damage patterns from the simulations and the actual experimentswhich show a similar yield and structure of γ-H2AX foci.
3. Advancing tiny detectors for a giant leap in lunar safety
The final piece in Jay’s research was the development of more accurate sensors for detecting space radiation.
While current silicon devices can effectively detect many types of radiation, they struggle to detect low linear energy transfer (LET) radiation, which is a common component of galactic cosmic rays.
To overcome this weakness, Jay and his team explored low gain avalanche diodes (LGADs), which incorporate a “gain layer” that amplifies the radiation signal and improves detection sensitivity.
By testing LGADs on the SIRIUS beamline at ANSTO’s Centre for Accelerator Science, they evaluated the performance of these detectors across different particle types and energy levels, observing how radiation damage can also affects the detectors themselves over time.
The Bigger Picture: Integrating Models, Experiments, and Detectors
By integrating multiscale simulations, experimental biology, and cutting-edge detector technology, Jay has created a powerful framework for understanding and mitigating radiation risks facing astronauts in space.
His work is a stellar example of how interdisciplinary research, involving physics, biology, and engineering, can help pave the way for safer space exploration.
Jay’s work shows how science at the nanoscale can have a cosmic impact, helping protect future astronauts as they journey beyond Earth!
AINSE is proud to support researchers like Jay who are paving the way for safer, smarter space exploration.
Interested in being part of the next generation of space research? Explore our scholarships at ainse.edu.au/scholarships and dive into more research spotlights at ainse.edu.au/research-spotlights/.
That’s a wrap on our stellar spotlight for Lunar June—but don’t float away just yet!
Next up: Geochemistry July!
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