Charging and motion of dust grains near the Moon and asteroids

N.Borisov IZMIRAN, Russia

O.E.Berg, H.Wolf, J.Rhee. Lunar soil movement registered by Apollo 17 cosmic dust experiment.

O’Brien. Review of measurements of dust motion on the Moon during Apollo, Planet Space Sci., 2011.

Lunar surface potential

SIDE results Freeman and Ibrahim, 1975

The structure of the double layer behind the Moon (Borisov and Mall, 2002)

Apollo15 subsatellite results, Anderson et al., 1972

Electron fluxes at 40, 140, 340, 800, and 2950 eV (LP results, Lin at al., 1998.

The decrease of electron fluxes related to Maxwellian core distribution ~ Exp [e Ф/T]

Formation of strong local electric fields in the shadow• Electric charge on a given dust grain on

the surface is several orders of magnitude less than the equilibrium charge on the same grain above the surface in the DL.

• Very strong electric fields (E > 100 V/cm) are required to overcome the gravity of the Moon.

Usw

Vi

( )dQ

Jdt

Charging and motion of dust grains near the terminator of the moon (Borisov and Mall, 2006)

Laboratory experiments.Wang et al. Planetary Space Sci., 2011.

Russian landers of the forthcoming Lunar missions: Luna-Resourse and Luna-Globe

The Luna-Resourse (Chandrayaan 2) project is developing according to Russian-Indian agreement. It will consist of an Indian Orbiter and a Russian Lander that will carry a small Indian rover. The Russia Luna-Globe project includes a Lunar Orbiter and a Lunar Lander.

Luna-Resourse lander

lunar dust monitor(DML)

• The lunar dust monitor (PmL) is designed to study temporal variations of two expected sources of dust in the lunar environment: charged grains lofted by strong local electric fields and ejecta production due to bombardment by micrometeorites. This instrument is included into the payload of landers of the forthcoming Lunar missions: Luna-Resourse andLuna-Globe.Impact sensor will measure pulses of charged grains. Electrostatic field sensors will measure electric potentials at the heights 20 cm and 90 cm and electric charges

1410 * /kg m s

Influence of local magnetic fields on dust chargingMitchell et al., 2008

Theory in two limiting cases:

1. Strong large-scale magnetic anomaly

1 D case (Borisov and Mall, 2003).

Strong non-monotonic variations of the electric potential above the anomaly are predicted

2. Rather weak and small magnetic anomaly :

nonmagnetized ions and magnetized electrons

.i M A eL

Dust motion near asteroids

Asteroid Eros enhanced view (NEAR-Shoemaker mission)

Details of the surface