Madrid 24 (European press)
At HSE University they developed a mathematical model that explains the height of charged dust particles on the sunlit surface of the Moon at nearly any latitude.
For the first time, the model takes into account Earth’s magnetic tail, a specific region around our planet. The research data is critical to planning the Russian space missions Luna-25 and Luna-27. The study was published in the Journal of Plasma Physics.
In space, the Moon is surrounded by plasma (ionized gas), which contains dust particles of solid matter. On the moon’s surface, dust particles, affected by photons, electrons and ions from the solar wind, acquire a positive charge. Its interaction with the surface of the moon positively charged causes it to bounce back and form dusty plasma.
Because of these factors, researchers can assume that lunar dust plasma develops only over a portion of the lunar surface (around latitudes above 76 degrees). But it is expected that dusty plasma can be observed on the sunlit part of the Moon. The authors of the article developed a physical-mathematical model of dust plasma motion in which the influence of the Earth’s magnetic tail plays an important role.
The Earth’s magnetosphere develops as a result of the interaction of the planet’s magnetic field with charged particles from space. Affected by the magnetic field, for example, the particles of the solar wind deviate from their initial path and form a region around the planet. It is asymmetric: on the day side it reaches the size of 8-14 earth rays, and on the night side it spreads out and forms a magnetic tail, the length of which is several hundred earth rays.
For about a quarter of its orbit, the Moon is in the Earth’s magnetic tail, which affects the movement of particles along the meridian: affected by the magnetic field, they begin to move from the polar region toward the equator.
Particles are also affected by gravity and electrostatic forces. The first attracts dust grains to the surface, while the other repels them. This leads to a vertical oscillation of the particles.
After that, the particles enter into a hover state. Researchers explain this effect by the long days of sunlight on the Moon: roughly 15 Earth days. During this period of time, the particle oscillation process fades away and they have enough time to go into flight.
According to researchers at the university, opposite phenomena were also observed. For example, on the moons of Mars, Phobos and Deimos, the decay time of dust grains oscillation is longer than that of daylight, so they do not have enough time to go uphill.
“Luna-25 and Luna-27 are in preparation today, and will study the properties of dusty dust and plasma near the lunar surface. To be successful, preliminary research is essential. Today we use a simplified approach to explain the transmission of dust on the Moon’s surface by taking into account the magnetic fields in the Earth’s magnetic tail. In future studies, it will also be necessary to take into account the axial inclination and inclination of the orbit to the ecliptic plane of both the Earth and the Moon, as well as to consider more accurate parameters of magnetic tail plasma. ” In a statement issued by Sergey Poppel, Head of the Laboratory for Dusty Plasma Operations in Space Objects, Institute Space Research of the Russian Academy of Sciences.
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