Highlights

• Novel analysis of energetic charged protons from TW-1/Mars Energetic Particle Analyzer (MEPA) provides fresh insights into the heliosphere’s underlying particle acceleration and propagation processes.
• Findings suggest that the double-power-law feature in particle spectra is intrinsic to shock-based acceleration, challenging previous assumptions about particle transport and potentially reshaping our understanding of space radiation.
• Ongoing data collection by TW-1/MEPA in its elliptical orbit holds promise for revolutionizing the radiation shielding design for future crewed Mars missions, offering key parameters critical for spacecraft and astronaut safety.

Summary

The Tianwen-1 mission, with its Mars Energetic Particle Analyzer (MEPA), marked a significant milestone in space science by detecting a major solar energetic particle (SEP) event on November 29, 2020. This event, linked to coronal mass ejections (CME)-driven shocks, provides crucial insights into particle acceleration and transport processes, vital for understanding the challenges of space exploration.

Mars, the fourth planet from the Sun and the second smallest in our solar system is a prime target for exploration. However, its exploration is hindered by the planet’s harsh radiation environment, posing significant risks to astronauts and spacecraft. SEPs, particularly those associated with CMEs, are a key concern due to their potential to cause severe radiation damage.

To better understand these risks, scientists conducted a detailed analysis by comparing MEPA and near-Earth spacecraft data. This collaboration shed light on particle acceleration and propagation mechanisms. Surprisingly, findings from this research challenge the existing theories of space radiation. The observed double-power-law feature in particle spectra indicates a direct link to the acceleration process at the shock front rather than being solely a result of particle transport, as previously thought. This revelation could significantly alter future research in this area.

MEPA’s ongoing data collection is crucial for designing effective radiation shielding for manned Mars missions. The insights from MEPA’s data are vital for astronaut safety, offering a practical application of scientific discovery. Additionally, the research revealed a notable relationship between proton energy and radial distance, where higher proton energy corresponds to lower peak intensity at greater distances. This finding is essential for mission planning and risk assessment.

In summary, the collaborative efforts in analyzing proton flux measurements from MEPA and near-Earth spacecraft have enhanced our understanding of the space radiation environment. This joint analysis has improved the accuracy of space research models and predictive tools and significantly contributed to informed decision-making in future space missions.

S. Fu et al., “First Report of a Solar Energetic Particle Event Observed by China’s Tianwen-1 Mission in Transit to Mars,” ApJL, vol. 934, no. 1, p. L15, Jul. 2022, doi: .