🚀 Space Radiation Basics – Part III
An Introduction to Radiation Beyond Earth's Protection
In our last post, we explored radiation sources trapped within Earth's magnetic field, those sneaky particles that orbit along the Van Allen Belts. But what happens when we move beyond Earth’s protective bubble?
As we venture into deep space or design satellites for higher orbits, we enter an environment filled with even more dangerous types of radiation. These are high-energy particles that don't get trapped, they fly straight through space, often at nearly the speed of light, interacting directly with whatever crosses their path.
Let’s explore them.
🌞 Solar Radiation: The Sun's Constant Embrace
As we’ve seen, the Sun is more than just a source of light, it becomes a major player in the harsh environment of space.
Up there, we face the solar wind, a constant flow of charged particles, mainly electrons and protons, streaming from the Sun’s outer atmosphere, the corona, at speeds of up to 1.6 million kilometers per hour. This wind shapes the heliosphere and can interact with spacecraft electronics, charging surfaces and sometimes degrading sensitive components.
Satellites must first endure the trapped particles in the Van Allen Belts [see previous post]. But those positioned farther out, like geostationary satellites, leave the protection of Earth's magnetic field behind. Out there, they face high-energy solar radiation with no natural shielding. Exposure to solar radiation becomes a constant design challenge, and even the steady flow of the solar wind can influence satellite operations and longevity.
And the Sun isn’t always calm, sometimes, it decides to shout with a solar flare.
Credits: NASA
🔗 Read more:
💥 Solar Flares and Coronal Mass Ejections (CMEs)
Solar flares are sudden, intense bursts of radiation that erupt from active regions near sunspots. They release enormous amounts of energy across the electromagnetic spectrum, from radio waves to X-rays and gamma rays, in just minutes.
When a solar flare erupts, it may also be accompanied by a coronal mass ejection (CME), a massive burst of plasma and magnetic fields hurled into space. Unlike the solar wind, CMEs are more like solar storms. When directed toward Earth, they can compress the magnetosphere, disturb GPS and communication systems, and in extreme cases, damage power grids.
These events also generate solar energetic particles (SEPs), high-energy protons and heavier ions (anything heavier than a helium nucleus), that can reach Earth in under an hour. For spacecraft and astronauts outside of Earth's magnetic shield, SEPs pose serious radiation hazards.
The risk isn’t just about power surges or electronic failures. Solar storms are a key factor in space weather forecasting, influencing everything from satellite design to launch windows.
Credits: ESA
🔗 Read more:
🌌 Galactic Cosmic Rays: The Universe's High-Energy Messengers
Beyond the influence of our Sun lies an infinite universe, and with it, a persistent and powerful source of radiation: Galactic Cosmic Rays (GCRs). These high-energy particles originate from outside our solar system and are a constant presence in space, posing serious challenges for both spacecraft and astronaut safety.
GCRs are primarily composed of ionized particles, mostly protons, along with a mix of heavier elements like helium, carbon, and iron. In space, we receive many of these heavy ions, which are believed to be accelerated to near-light speeds by violent astrophysical events such as supernovae, black holes, and neutron stars.
When GCRs reach Earth’s atmosphere, they collide with atmospheric particles and produce cascades of secondary particles, including muons, neutrons, and electrons. These particle showers can be detected on the ground and have been studied for decades to better understand their origins and how they interact with matter.
For spacecraft operating beyond Earth's magnetic field, GCRs present a major hazard. Their high penetration power allows them to pass through most shielding, potentially damaging electronics and significantly increasing the radiation dose absorbed by astronauts. This becomes especially critical for long-duration crewed missions to the Moon, Mars, or deep space.
🔗 Read more:
🌌 How Do We Quantify This Environment?
Luckily, many brilliant researchers have worked hard to build models that help us understand and simulate this harsh environment, a critical step if we want to design technology for space.
Here are a few examples:
For solar particles, we can use the Emission of Solar Protons (ESP) model.
For solar particles and flares, we can use the Solar Accumulated and Peak Proton and Heavy Ion Radiation Environment (SAPPHIRE) model.
For Galactic Cosmic Rays (GCRs), we can use models like CREME96 or ISO-15390, which estimate GCR fluxes depending on solar activity and particle energy levels.
If you want to learn more about how these models work, I invite you to explore them through OMERE, or check out these helpful resources:
🔗 SPENVIS – Flare Model Background
🔗 SPENVIS – GCR Model Background
🛠️ Playing with OMERE
This time, I invite you to try something different. I created a GPT agent to help you explore and experiment with OMERE. I figured it would be helpful to have a tutor you can access 24/7, someone who can guide us through the learning process in a more interactive and fun way. I’m still training the GPT, so I’d love to hear your feedback.
🔗 Here’s the link to the GPT: OMERE Space Radiation Tutor
🧪 Try asking it this:
“Show me how to simulate the radiation environment for a GEO satellite.”
🛰️ What’s Next?
In this post, we explored the invisible forces that shape the radiation environment beyond Earth’s protection. But understanding where radiation comes from is just one side of the challenge.
In the next article, I plan to dive into how these particles affect electronic components, from subtle performance degradation to sudden failures, and what engineers can do to protect spacecraft systems from them.
