Giant solar eruption felt on Earth, Moon and Mars

A coronal mass ejection erupted from the Sun on 28 October 2021 and was so big that Mars and Earth, while on opposite sides of the Sun, both received an influx of solar energetic particles.

This marks the first time that a solar event was measured by an international fleet of spacecraft both in orbit and on the surfaces of the Earth, the Moon and Mars: ESA’s ExoMars Trace Gas Orbiter (TGO), NASA’s Curiosity Mars rover, the CNSA Chang’e-4 Moon lander, NASA’s Lunar Reconnaissance Orbiter (LRO), and DLR’s Eu:CROPIS mission and others in Earth orbit. The event was also detected by ESA’s BepiColombo craft, on its way to Mercury, and detected and imaged by the ESA/NASA Solar and Heliospheric Observatory (SOHO).

Radiation dose measurements by these missions show that the bodies are protected against space radiation in different ways. Earth has an internally generated magnetic field protecting us from particle radiation. The Moon has no magnetic field or atmosphere while Mars has only a weak magnetic field induced by interaction with the solar wind, so solar particles can reach their surface more easily. Interaction with the soil can even generate additional secondary radiation. Mars does have a thin atmosphere which stops most of the lower energetic solar particles and slows down the highly energetic ones.

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