Breakthrough Study Maps Solar Proton Energy Spectrum in Martian Space
A team of international scientists has successfully constructed the first complete energy spectrum of high-energy protons produced during a solar eruption in Martian space. The achievement represents a major step in understanding the radiation environment on Mars, which is critical for future exploration missions and astronaut safety.
Historic SEP Event Detection and Multi-Institution Collaboration
On February 15, 2022, a significant solar energetic particle (SEP) event was detected simultaneously by several key missions monitoring Mars: China’s Tianwen-1 orbiter, the European Space Agency’s Trace Gas Orbiter (TGO), NASA’s Mars Atmosphere and Volatile Evolution Orbiter (MAVEN), and the Curiosity rover on Mars’ surface. This was the first time so many spaceborne and surface-based detectors recorded the same SEP event at Mars, marking a unique opportunity for coordinated analysis.
The study was led by researchers from the University of Science and Technology of China, the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS), the Lanzhou Institute of Physics, and Germany’s University of Kiel. Their findings, published as the cover article in Geophysical Research Letters, provide a more comprehensive view of how high-energy protons behave in Martian space.
How Solar Proton Events Threaten Space Missions
Solar energetic particle (SEP) events are intense bursts of high-energy charged particles generated by solar eruptions. On Earth, the planet’s magnetic field and atmosphere protect its surface from these dangerous particles. Mars, however, has no such protection, as it lacks a global magnetic field and has only a thin atmosphere. This makes the Martian surface and orbiting spacecraft particularly vulnerable to radiation, posing significant challenges for future crewed Mars missions.
During an SEP event, the flux of high-energy particles can increase suddenly, threatening spacecraft electronics, disrupting communications, and exposing astronauts to harmful radiation. As a result, studying SEP particle behavior around Mars is essential for designing protective measures for future exploration missions.
How the First Complete Energy Spectrum Was Built
Data from multiple detectors played a vital role in constructing the proton energy spectrum for the February 2022 SEP event. The Tianwen-1 Mars Energy Particle Analyzer (MEPA), which measures particles in the 2–100 MeV range, provided critical data. Meanwhile, MAVEN supplied complementary data on medium-energy particles, and the Curiosity rover contributed insight into high-energy particles that had penetrated the Martian atmosphere.
To fill in gaps in the observed spectrum, the researchers employed particle transport simulations for Mars’ atmosphere. By fitting the combined data from these sources, they successfully reconstructed the complete proton energy spectrum, which spanned a wide range of 1 to 1000 MeV.
Implications for Martian Radiation Protection
Beyond scientific discovery, the practical applications of this study are significant. The researchers used the newly constructed energy spectrum to calculate the radiation dose on Mars’ surface and in orbit during the event. Their model results aligned closely with actual radiation dose measurements, underscoring the accuracy of the Tianwen-1 MEPA data and the robustness of the Martian radiation transport model.
This validation demonstrates the importance of continuous, coordinated monitoring of space weather conditions on Mars. Future human missions to the Red Planet will require precise radiation forecasts to protect astronauts from sudden SEP events.
The successful construction of a complete energy spectrum for high-energy protons in Martian space marks a significant advancement in space weather research. The February 2022 event, recorded by multiple spacecraft and surface-based detectors, provided a rare opportunity for cross-mission data analysis. The findings offer a valuable reference for future Mars exploration, radiation protection strategies, and the development of spacecraft shielding for human missions.