Recently, a team of international scientists led by Prof. JIAN Zhang from the University of Science and Technology of China (USTC) has made a significant breakthrough in understanding Mars' radiation environment. The research team focused on the solar energetic particle event (SEP) that occurred on February 15, 2022, and reconstructed the energy spectrum of this event for Mars for the first time. The study was published in Geophysical Research Letters.

Mars, with its thin atmosphere and lack of a global magnetic field, is exposed to significant space radiation. This radiation poses a considerable threat to both human health and spacecraft hardware during future missions. Understanding the Martian radiation environment, especially during large SEP events, is essential for the safety and success of these endeavors.

Building on the above critical need, the study delved into the intricacies of a significant solar energetic particle event on February 15, 2022. This event was not only intense but also posed substantial risks to potential future missions, as it demonstrated the harsh space radiation conditions that Mars can experience due to its thin atmosphere and lack of a global magnetic field.

The research team faced the daunting task of piecing together the complex radiation puzzle across different energy levels and from various vantage points around Mars. To achieve this, they harnessed data from a network of detectors, including the Mars Energetic Particle Analyzer (MEPA) on China's Tianwen-1 spacecraft, which provided valuable insights into high-energy protons up to 100 MeV. Also, they relied on data from ESA's Trace Gas Orbiter, NASA's Mars Atmosphere and Volatile Evolution spacecraft, and the Curiosity rover to create a comprehensive picture of the SEP event.

By integrating these diverse data streams, the researchers were able to reconstruct the energy spectrum of the event up to 1 GeV, a first for Mars. This reconstruction was crucial for modeling the radiation doses at Mars's orbit and surface, which are essential for assessing the radiation hazards faced by both human explorers and spacecraft electronics.

After data collection, another challenge was accounting for the shielding effects of Mars's atmosphere and the spacecraft's structures on the radiation doses. The team addressed this by developing sophisticated models that considered these factors, allowing for a more accurate estimation of the radiation doses experienced during the SEP event. These models were then validated against the actual dosimetry data recorded by the detectors, ensuring the reliability of the study's findings.

Finally, the successful integration of data from multiple detectors and the development of accurate modeling techniques have resulted in a significant leap forward in our ability to understand and predict the radiation environment on Mars. This research not only enhances our knowledge of the immediate radiation risks but also provides a foundation for developing mitigation strategies to protect future Mars missions.

The SEP event that occured on February 15, 2022 was simultaneously detected by China's Tianwen-1 orbiter, ESA's Trace Gas Orbiter (TGO), NASA's Mars Atmosphere and Volatile Evolution (MAVEN) orbiter, and the Curiosity rover (MSL) on the surface of Mars. (Image from USTC)

Paper Link:https://doi.org/10.1029/2024GL111775

(Written by LI Qige, Edited by WU Yuyang, USTC News Center)