Research Spotlights

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:

1. Monte Carlo simulations of early DNA damage from space radiation,
2. Validation of these simulations through radiobiological experiments performed at the ANTARES beamline at ANSTO, and
3. 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 findings revealed that while LGADs can better detect low LET radiation, the amplification of the radiation signal is dependent on the particle type, energy and the amount of radiation damage suffered by the detector. This can make it difficult to accurately determine the radiation dose.

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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By Georgia Barrington-Smith

In the quest to unravel one of life’s greatest mysteries—how it all began—scientists are looking beyond our planet, to the vastness of space, in search of the molecular seeds that might have sown life on Earth.

One key stop on that journey is Titan—Saturn’s largest moon.

For nearly two decades, NASA’s Cassini spacecraft orbited Saturn, collecting stunning data about the planet’s rings, moons, and magnetic environment. Accompanying it was the European Space Agency’s Huygens probe, which parachuted down to Titan’s surface, becoming the first spacecraft to land on a world in the outer Solar System.

What it found was astonishing!

This mission revealed that Titan isn’t just a frozen, foreign world, it’s a chemical treasure trove. Its atmosphere contains more than twenty complex organic molecules. Among the most intriguing are nitrogen-rich compounds that could serve as stepping stones in the formation of prebiotic molecules, the very kind that may have paved the way for microbial life on early Earth.

How Titan’s co-crystals could hold clues to life’s beginnings

New research suggests that Titan’s icy temperatures and dense, organic-rich atmosphere create ideal conditions for the formation of co-crystals: solid structures made up of two or more molecules arranged in a fixed, orderly pattern (Cable et al. 2021). These ordered molecular arrangements provide a scaffold that allows close interactions between complex compounds, providing stepping stones toward biologically relevant molecules.

Therefore, studying these co-crystals, which can stabilise these fragile complex molecules, is critical for understanding how prebiotic chemistry (the chemical processes that generate life’s building blocks, such as amino acids and nucleotides) develops and survives in harsh extraterrestrial environments.

One compound of particular interest is pyridine, a nitrogen-containing aromatic compound thought to exist in Titan’s atmosphere. Pyridine interacts with hydrocarbons like acetylene to create stable co-crystals, which are believed to act as precursors to nucleobases (the building blocks to DNA and RNA). This makes pyridine a promising candidate for exploring how co-crystal formation might contribute to prebiotic chemistry on Titan.

Larissa investigates Titan’s prebiotic potential

Larissa Lopes Cavalcante, an AINSE PGRA scholar, in collaboration with ANSTO and the University of Otago, is investigating pyridine-based co-crystals and their potential role in forming prebiotic molecules. Her research focuses on combining pyridine with key molecules found in Titan’s atmosphere, like acetylene, diacetylene, ethane, and acrylonitrile.

By using techniques such as X-ray diffraction, infrared and Raman spectroscopy, mass spectrometry, and computational modelling, Larissa aims to characterise these co-crystals and uncover the pathways that might lead to life’s building blocks.

Simulating Titan’s atmosphere to explore prebiotic molecules

One focus of Larissa’s research is the pyridine: acetylene system, previously shown to form stable co-crystals under Titan-like conditions. She studied the reactivity of this mixture under such conditions to determine if it can give rise to more complex organic molecules.

To test the systems reactivity, the team exposed both amorphous (disordered) and crystalline (ordered) pyridine: acetylene ices to vacuum-ultraviolet (VUV) radiation, simulating the high-energy conditions in Titan’s atmosphere (Lopes Cavalcante et al. 2024).

Under VUV exposure, pyridine and acetylene reacted to form nitrogen-containing polycyclic aromatic hydrocarbons (NPAHs)—complex molecules that may serve as intermediates in the formation of life-related compounds.

Interestingly, the crystalline co-crystal form showed lower reactivity than its amorphous counterpart. This greater chemical stability makes it better equipped to withstand Titan’s extreme conditions. Maintaining the stability of the co-crystal is crucial for preserving pyridine, a key molecule in prebiotic chemistry. Once the co-crystal reaches Titan’s surface, pyridine could be released and become available to interact with other chemical species present there. Even more intriguing is the possibility that these surface molecules could be transported to Titan’s subsurface ocean, where conditions may allow for more complex, Earth-like prebiotic chemistry to unfold.

The role of pyridine: diacetylene in Titan’s prebiotic chemistry

Larissa and the team also explored the pyridine: diacetylene system for its potential role in Titan’s prebiotic chemistry.

Diacetylene, a hydrocarbon abundant in Titan’s atmosphere, is notoriously unstable and prone to polymerisation. Therefore, to safely study it, researchers at ANSTO’s Australian Centre for Neutron Scattering (ACNS) developed an advanced gas delivery system for neutron diffraction experiments. This innovative system enabled researchers to securely handle diacetylene and accurately deliver it without premature reactions, establishing a foundation for future studies on the formation of co-crystals involving highly flammable, toxic, and reactive molecules at Titan-relevant temperatures (-180°C). A major challenge with diacetylene is its tendency to polymerize upon contact with oxygen, forming unstable and potentially explosive materials. One of the most significant improvements introduced by this new gas delivery system is its ability to minimize that risk—while handling diacetylene still requires caution, the system offers far greater control and safety, drastically reducing the likelihood of hazardous reactions.

Using the WOMBAT powder diffractometer at ACNS, along with X-ray diffraction (University of Sydney) and Raman spectroscopy (Jet Propulsion Laboratory, Caltech), the team determined the crystal structure of pure diacetylene under Titan-like cryogenic conditions.

After characterising diacetylene in isolation, the team started a new series of experiments to investigate its interactions when combined with pyridine. The results revealed the formation of a new crystalline phase. This newly identified solid crystal structure corroborates earlier infrared spectroscopic data. It may represent a novel class of co-crystal pertinent to Titan’s chemistry, suggesting that, if such co-crystals exist on Titan, they could influence the storage, preservation, or synthesis of complex organic molecules in its environment.

Unexpected behaviour with ethane and acrylonitrile

In addition to studying pyridine mixed with acetylene and diacetylene, Larissa and her collaborators also investigated what happens when pyridine is combined with ethane and acrylonitrile.

Surprisingly, instead of forming co-crystals, these combinations triggered a phase transition in pyridine, a change in its physical state or structure. This unexpected behaviour adds complexity to the understanding of Titan-like chemical systems and highlights the diverse ways organic molecules may interact in such extreme environments.

Looking ahead: Titan’s chemistry and the ongoing search for the origins of life

Together, Larissa and the team’s findings not only deepen our understanding of Titan’s unique environment but also shed light on the broader question of whether life could have started elsewhere in the solar system.

Pyridine-based mixed ices show promise to form the building blocks of life, such as nucleobase precursors and other key organic molecules. On the other hand, the stability of co-crystals in Titan’s harsh conditions suggests they could protect organic compounds for long periods, potentially allowing them to be transported to places where prebiotic chemistry could take place.

This research is especially relevant for upcoming missions like NASA’s Dragonfly, which prepare to explore Titan’s surface investigating its chemical and astrobiological potential for life. 

AINSE are proud to spotlight Larissa for her stellar work!

If you, like Larissa, are curious about studying the chemistry of our solar system, visit ainse.edu.au/scholarships to see how AINSE can support you.

Join us on your next stop for this lunar journey as we spotlight Jay Archer’s groundbreaking research on the effects of lunar space radiation.

While you wait, read some more out of this world research, at ainse.edu.au/research-spotlights/ and explore the rest of our catalogue.

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