HSE University researchers have developed a mathematical model. It will explain the levitation of charged dust particles over the sunlit lunar surface for almost any latitude. The model takes into account the Earth’s magnetotail, for the first time. Earth’s magnetotail is a particular area around our planet. The study is important for planning the Luna-25 and Luna-27 space missions. The study has been published in Physics of Plasmas.
The Moon is surrounded by plasma, in space. It contains solid-matter dust particles. Dust particles are impacted by solar wind photons, electrons and ions get a positive charge, on the lunar surface. The interaction with the positively charged lunar surface causes them to rebound, move and make up the dusty plasma.
Scientists assumed that lunar dusty plasmas evolve only above part of the lunar surface, because of these factors. But it is expected that dusty plasmas will be observed above the whole sunlit part of the Moon. Scientists developed a physical-mathematical model of dust plasma motion. In that the impact of Earth’s magnetotail plays an important role.
Earth’s magnetosphere evolves because of the interaction. The planets magnetic field has with charged particles from space. It is impacted by the magnetic field. The solar wind particles deviate from their initial trajectory. They make up an area around the planet. It is asymmetrical. It achieves the size of 8-14 Earth radiuses. It is extended and makes up a magnetotail, on the night side. It is several hundred Earth radii-long.
The Moon is in Earth’s magnetotail, during about one-fourth of its orbit. It impacts particles’ movement along the meridian which is impacted by the magnetic field. They start moving from the polar area to the equator.
The particles are impacted by gravitation and electrostatic forces. The first attracts the dust grain to the surface and the other repels it. Vertical oscillation of particles happens because of this.
Particle’s transit into a condition of levitation. Scientists explained this effect by long sun days on the Moon which is 15 Earth days. The process of particle oscillation fades away, over this time period. They have enough time to transfer into levitation. Opposite phenomena are also observed. The time of dust grain oscillation dying out is longer than the light day, on Martian moons, Phobos and Deimos. This is why they do not have enough time to transfer into levitating condition.