The exploration of the cosmos has been one of humankind’s most enduring ambitions. It’s a journey of discovery that’s both thrilling and fraught with challenges. One of the most significant, and less discussed, challenges is the exposure of astronauts to cosmic radiation during their voyages to the Moon and Mars. The issue of radiation exposure is a considerable health risk, capable of causing severe damage to cells, DNA, and can contribute to long-term health problems like cancer.
Cosmic radiation, unlike the radiation we experience on Earth, primarily consists of atomic nuclei stripped of their electrons, moving at near light-speed. This high-energy radiation comes from two main sources. One is solar particle events (SPEs), high-energy particles ejected by the Sun, particularly during solar flares. The other source, galactic cosmic rays (GCRs), originates from outside our solar system and is far more energetic and penetrative.
When astronauts journey to the Moon or Mars, they leave the protective cocoon of Earth’s magnetosphere, a magnetic shield that deflects a significant portion of cosmic radiation. Once outside this shield, astronauts face higher levels of radiation exposure. Research using data from the Mars Science Laboratory’s Curiosity Rover, for instance, indicated that a round-trip human mission to Mars could expose astronauts to a cumulative radiation dose of about 1.01 sieverts. Such exposure is associated with a 5% increase in the risk of fatal cancer over a lifetime.
Given these risks, how do we protect astronauts venturing into the unknown? There are three primary ways: shielding, medications, and forecasting.
Shielding
Shielding is the most obvious countermeasure. It involves the use of physical barriers to block or reduce radiation. Traditional radiation shields, like those made from lead, are heavy and impractical for space missions where every pound matters. Modern spacecraft use light materials such as aluminum, but they provide limited protection, especially against GCRs. However, research in advanced materials offers promising alternatives. Materials such as hydrogenated boron nitride nanotubes (BNNTs) and polyethylene have shown potential in laboratory tests to absorb or deflect more radiation than aluminum.
Innovative shielding concepts are also under study. One approach is to use water as a radiation shield. Since water is composed of hydrogen and oxygen, and hydrogen is particularly good at absorbing cosmic rays, water stored in the spacecraft for consumption or fuel could double as a radiation barrier. Another idea is to create a “magnetic shield” that replicates Earth’s magnetosphere, repelling charged particles.
Medications
Medications also play a vital role in mitigating radiation effects. These include radioprotective drugs that help protect the body’s cells from radiation damage and radiomitigators that minimize damage after exposure. However, most drugs currently available have significant side effects and are not suitable for healthy individuals. Nevertheless, research is ongoing to develop safer and more effective drugs for space travel.
Forecasting
Radiation forecasting is the third countermeasure. By predicting solar particle events, which are the primary source of radiation during solar maximum periods, astronauts can be warned to seek shelter. Advanced monitoring and forecasting systems are therefore vital components of any long-term space mission. However, this approach offers limited protection against GCRs, which are not tied to solar activity and are much more challenging to forecast.
Conclusion
There is no silver bullet for the problem of radiation exposure in space. Instead, the solution lies in a combination of countermeasures: improved shielding, better medicines, and more precise radiation forecasts. With every mission, we gather valuable data that furthers our understanding of cosmic radiation and how best to protect those who dare to venture beyond the safety of our home planet.
NASA, SpaceX, and other agencies are investing heavily in research to tackle this issue. As we stand on the brink of a new era of human space exploration, the solutions we develop will not only ensure the safety of our astronauts but also pave the way for humanity’s future in the cosmos. After all, tackling challenges is part of what makes exploration worthwhile.
