In a truly remarkable cosmic occurrence, a massive solar eruption unleashed its energy upon Earth, the Moon, and Mars simultaneously, marking the first time such an event has been observed.
The incident in question occurred on October 28, 2021, when a powerful coronal mass ejection (CME) erupted from the Sun. Astonishingly, the eruption was so extensive that its effects reached both Mars and Earth, despite the staggering distance of approximately 250 million kilometers between the two planets, which were situated on opposite sides of the Sun.
Published in the Geophysical Journal Letters, a study examining this extraordinary solar event reveals that this occurrence, known as a “ground level enhancement,” is incredibly rare. It refers to instances when solar particles possess sufficient energy to penetrate Earth’s protective magnetic field. Unlike Earth, neither the Moon nor Mars possess intrinsic magnetic fields, enabling solar particles to directly impact their surfaces. However, Mars possesses a thin atmosphere that serves as a barrier against lower-energy solar particles, while also slowing down higher-energy ones.
Given the burgeoning interest in human space exploration, particularly concerning the Moon and Mars, comprehending the implications of these solar events on human health is of paramount importance, as highlighted by the European Space Agency. The implications can be dire, as astronauts exposed to radiation doses exceeding 700 milligray might experience radiation sickness due to bone marrow destruction. Symptoms encompass infections and internal bleeding, with a milligray serving as a unit for gauging radiation absorption.
Exposing astronauts to more than 10 gray of radiation practically ensures their survival chances are grim, with a duration of mere weeks. During the active Apollo missions in 1972, a potent solar burst released enough radiation to expose lunar-surface astronauts to such levels. Providentially, this event occurred between the Apollo 16 and Apollo 17 missions, sparing the astronauts from its potentially severe consequences.
