Why Martian radiation is hard to escape
Radiation on Mars comes mainly in two forms. Galactic cosmic rays are extremely energetic particles arriving from beyond the solar system; they are difficult to stop completely. Solar particle events are bursts of energetic particles from the Sun. These can be intense but are more episodic, giving a habitat some chance to shelter occupants during an event.
Earth’s global magnetic field deflects many charged particles, and its thick atmosphere absorbs much of what gets through. Mars has neither a planet-wide magnetic shield nor a comparably dense atmosphere. Its surface therefore receives more energetic radiation than Earth’s, and the exposure accumulates over time—an important concern for people living there, not just for a brief landing.
Turning local material into shelter
The most direct defense is to put material between people and the sky. A habitat built underground, or covered with Martian soil called regolith, would use the planet itself as shielding. Water can also help: it contains hydrogen, which is effective at slowing some incoming particles. Water stores or tanks placed around living spaces could serve both a practical purpose and a protective one.
This creates an engineering tradeoff. Carrying heavy shielding from Earth is costly, so a settlement would have strong reason to use local soil. But digging, moving regolith, and designing a structure that remains safe and livable beneath it are substantial construction challenges. Shielding also has to account for different radiation sources; no simple layer makes the environment equivalent to Earth’s.
A possible helper, not a ready-made shield
Radiation-tolerant fungi have attracted research interest because some can survive conditions that damage many organisms. That does not mean a thin coating of fungus could protect a crew: living material would need to provide enough mass, remain stable, and be tested against the radiation encountered on Mars. For now, the dependable concept is physical shielding—especially using soil or water—not relying on biology.
The practical consequence is architectural: a Martian home may be designed less like a glass-domed outpost and more like a sheltered structure under a protective layer of the planet itself.
