Moon Atmosphere Volatile to Solar Winds, Not Immune as Previously Thought, Says Swedish Scientist

The moon’s space environment is much more volatile and active than previously thought since the solar wind is seen to be affecting the crustal magnetic fields of the moon, said researcher Charles Lue at the Swedish Institute of Space Physics and Umea University in Sweden.

The solar wind is a continuous flow of plasma from the Sun which affects the planets in the Solar System, including effecting aurora on Earth. With the Swedish space instrument SARA, which has been sent aboard India’s Chandrayaan I mission, Swedish scientists were able to detect a strong and varied interaction between the Moon and solar wind.

The atmosphere on moon is too thin to show the same phenomenon and the moon also lacks a global magnetic field to regulate the solar wind. So, it has long been believed that the Moon passively absorbs solar wind without noticeably affecting its surroundings. But the new research shows that the surface of the Moon, and also local magnetic fields of the lunar crust, do reflect some of the solar wind, making the moon’s atmosphere more volatile.

“This knowledge is of great importance to the lunar space environment which is affected both on the lunar dayside and nightside surfaces,” says Charles Lue, whose dissertaion was submitted recently on the subject.

The reflected solar wind ions move in spiralling tracks taking them from the dayside of moon to the nightside, keeping the disturbances constant on its surface, he said. Areas where strong magnetism is recorded, the solar wind flow is restricted on the surface at the same time as adjacent areas receive an increased flow, affecting the Moon’s surface in the long run.

The long term effects may result in elevated levels of ground water on moon. “The effects can even be seen in the form of visible light – like bright swirls imprinted on the surface of the moon,” says Charles Lue.

The particle instrument SARA (Sub-keV Atoms Reflecting Analyzer), which has helped the Swedish scientists observe the moon surface was developed at the Swedish Institute of Space Physics and was sent to the Moon on board the Indian satellite Chandrayaan-1.

SARA continued its study of the solar wind interaction with the Moon since 2009, and the observations made by the instrument have since been analysed by researchers, including Charles Lue. “The observations help us map and understand the variations in the lunar space environment. They also give us clues about the physical processes involved and the long-term effects they have on the lunar surface,” he said.

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