ON A POSSIBLE DUST-PLASMA INTERACTION AT MARS

According to present theoretical models, material ejected from the Martian satellite Phobos due to meteoroid bombardment and tidal coupling can stay for a long time in circular orbits near the planet, forming a dust belt. The dust particles are moving through various plasma domains of the Martian magnetosphere and may undergo electrostatic disruption there, producing very fine motes in the range 0.005-0.1 mum which can stay positively charged for a time comparable with the orbital period. A negatively charged spacecraft will attract such particle and an ion spectrometer with wide enough mass range (1-10(8) amu/Q, where Q is the particle charge) may detect these grains. Our model can explain observations made by the ASPERA mass spectrometer during the PHOBOS mission when signals in the num channels 10(3)-10(7) amu were detected inside the Martian magnetosphere. The evolution of a grain orbiting Mars is shown in a diagram of the particle size-particle potential. Such a diagram a qualitative picture of the grain interaction with the Martian plasma environment.