The billionaire class has sold Mars as a destination. A frontier. A backup drive for humanity. But before we talk about domes and dust storms, we need to talk about the radiation challenges of traveling to Mars. Because the trip itself may be the most dangerous part.
We Live in a Bubble
People live in space today.
Astronauts aboard the International Space Station circle Earth every ninety minutes. They float. They conduct experiments. They post beautiful photos of our blue world. But they are not in deep space.
They are still inside Earth’s magnetic field—the magnetosphere. That magnetic shield deflects a significant portion of charged cosmic radiation and solar particles. It’s an invisible armor humanity evolved beneath.
Even the astronauts who traveled to the Moon during NASA’s Apollo program only left that protection briefly. The journey took about three days each way. Their exposure window was short.
A Mars mission is different.
You’re looking at roughly six months in transit. Six months outside the magnetic cocoon that has protected life on Earth for billions of years. That’s where the real radiation challenges of traveling to Mars begin.
What’s Actually Hitting You Out There
Interplanetary space is not empty.
It’s saturated with:
- Galactic Cosmic Rays (GCRs): high-energy particles from outside our solar system—mostly protons, but also heavier nuclei like iron.
- Solar Particle Events (SPEs): bursts of protons and charged particles from the Sun during solar flares and coronal mass ejections.
These particles travel at a significant fraction of the speed of light. When they hit the human body, they don’t politely deposit energy like an X-ray.
They punch through.
A single high-energy heavy ion can tear through cells, damaging DNA and cellular structures along its path. Think microscopic shrapnel moving at relativistic speeds. The biological term is “linear energy transfer.” The practical term is tissue destruction.
And this isn’t a one-time exposure. It’s cumulative. Every hour. Every day. For half a year.
Why You Can’t Just “Add More Shielding”
Shielding is the obvious answer. Just wrap the spacecraft in something thick enough to block the radiation, right?
The main problem is mass.
Every kilogram you launch from Earth costs fuel. Every kilogram you accelerate toward Mars requires more propellant. Thick metal walls quickly become impractical.
On top of that, heavy metals like aluminum can actually make things worse. When high-energy cosmic rays strike dense shielding, they can generate secondary radiation—cascades of subatomic particles that spread inside the spacecraft. In trying to block the bullet, you create a fragmentation grenade.
Materials rich in hydrogen—like water or polyethylene—are better at slowing and absorbing certain types of radiation. That’s why some mission concepts propose lining crew quarters with water tanks, food supplies, even waste containers. But you can’t eliminate exposure entirely. You can only reduce it. And “reduce” doesn’t mean “safe.”
Your Brain on Deep Space
One of the more unsettling aspects of the radiation challenges of traveling to Mars is neurological damage.
Unlike skin or blood cells, neurons don’t regenerate well. If high-energy particles damage brain tissue, those changes may be permanent. Animal studies suggest that exposure to cosmic-ray-like radiation can impair cognition—memory, decision-making, learning speed. Exactly the capacities you need when landing on another planet.
So here’s the uncomfortable question: after six months of bombardment by near-light-speed particles, will the crew be thinking clearly enough to execute a complex planetary landing?
Science fiction—including my novel Ares—often explores leadership under stress. But radiation adds a layer of biological uncertainty. What if the crew isn’t just stressed or sleep-deprived? What if their neural circuitry has been physically altered?
The Kidney Problem (And the Rest of You)
Radiation doesn’t limit its damage to the brain. Emerging research suggests that deep-space radiation may significantly increase the risk of kidney damage. Animal models exposed to simulated galactic cosmic rays show structural changes in renal tissue. That matters in a closed environment where medical evacuation is impossible.
Add elevated cancer risk. Cardiovascular damage. Immune system suppression. Then remember: this is before you even arrive.
Before dust storms. Before low gravity muscle loss. Before isolation begins to grind down morale.
That’s Just the Transit
Let’s say you make it.
You survive six months of radiation exposure. Your shielding did its job—mostly. Your cognition holds. Your kidneys still function. Your DNA is damaged, but not catastrophically.
You step on to Mars. That’s where the marketing brochures start—and a whole new set of challenges. In Part Two, we’ll look at the reality of living on Mars, and why surviving the journey may be the easy part.
Jayson L. Adams is a technology entrepreneur, artist, and the award-winning and best-selling author of two science fiction thrillers, Ares and Infernum.
Jayson writes sci-fi thrillers that explore what extreme situations reveal about who we really are. His novels combine high-stakes science fiction with deeper questions about identity, courage, and human nature. You can see more at www.jaysonadams.com.