Before trips to Mars, we need better protection from cosmic rays
The Invisible Threat to Space Travel: Cosmic Rays
Cosmic rays, consisting of protons, helium nuclei, heavy ions, and electrons, are a hidden menace to space travelers. These high-energy particles stream in from exploding stars (galactic cosmic rays) and our very own sun (solar particle events). They don't discriminate, carrying so much energy and moving so fast that they can knock electrons off atoms and disrupt molecular structures of any material.
The Earth's Shield: A Protective Bubble
The Earth's magnetic field and atmosphere shield us from most of this danger. However, outside Earth's protection, space travelers will be routinely exposed. In deep space, cosmic rays can break DNA strands, disrupt proteins, and damage other cellular components, increasing the risk of serious diseases such as cancer.
The Research Challenge: Measuring the Effects of Cosmic Rays
The research challenge is straightforward: measure how cosmic rays affect living organisms, then design strategies to reduce their damage. Ideally, scientists would study these effects by sending tissues, organoids (artificially made organ-like structures), or lab animals (such as mice) directly into space. That does happen, but it's expensive and difficult. A more practical approach is to simulate cosmic radiation on Earth using particle accelerators.
Simulating Cosmic Rays on Earth
Cosmic ray simulators in the US and Germany expose tissues, plants, and animals to different components of cosmic rays in sequence. A new international accelerator facility being built in Germany will reach even higher energies, matching levels found in space that have never been tested on living organisms. However, these simulations aren't fully realistic. Many experiments deliver the entire mission dose in a single treatment, which is like using a tsunami to study the effects of rain.
A More Realistic Approach: Multi-Branch Accelerators
My colleagues and I have suggested building a multi-branch accelerator that could fire several tuneable particle beams at once, recreating the mixed radiation of deep space under controlled laboratory conditions. For now, though, this kind of facility exists only as a proposal.
Physical Shields: A Limited Defense
Physical shields seem like the obvious first defense. Hydrogen-rich materials such as polyethylene and water-absorbing hydrogels can slow charged particles. Although they are used, or planned to be used, as spacecraft materials, their benefits are limited. Particularly galactic cosmic rays, the ones that arrive from far exploding stars, are so energetic that they can penetrate through physical shielding. They can even generate secondary radiation that increases exposure.
Biological Strategies: Nature's Armor
That's why scientists are exploring biological strategies. One approach is to use antioxidants. These molecules can protect DNA from harmful chemicals that are produced when cosmic rays hit living cells. Supplementing with CDDO-EA, a synthetic antioxidant, reduces cognitive damage caused by simulated cosmic radiation in female mice.
Learning from Organisms with Extraordinary Abilities
Hibernating organisms become more resistant to radiation during hibernation. The mechanisms on how hibernation protects from radiation are not fully understood yet. Still, inducing hibernation-like conditions in non-hibernating animals is possible and can make them more radioresistant. Tardigrades, microscopic creatures also known as water bears, are also extremely radioresistant, especially when dehydrated.
Supporting Organisms' Own Stress Responses
Stressors on Earth, such as starvation or heat, have driven organisms to evolve cellular defenses that protect DNA and other cellular components. In a recent preprint, my colleague and I suggest that activating these mechanisms through specific diets or drugs may offer additional protection in space.
The Road Ahead: A Multifaceted Approach
Physical shields alone won't be enough. But with biological strategies, more experiments in space and on Earth, and the construction of new dedicated accelerator complexes, humanity is getting closer to making routine space travel a reality. With current speed, we are probably decades away from fully solving cosmic-ray protection. Greater investment in space radiation research could shorten that timeline.
Conclusion
The ultimate goal is to journey beyond Earth's protective bubble without the constant threat of invisible, high-energy particles damaging our bodies and our spacecraft. As we continue to explore the vastness of space, we must also continue to explore the mysteries of cosmic rays and develop strategies to protect ourselves and our technology from their effects.
Source: https://www.space.com/astronomy/mars/before-trips-to-mars-we-need-better-protection-from-cosmic-rays
