Compositional Mapping of a Satellite Surface with a Dust Mass Spectrometer

Abstract:

Measuring the composition of cosmic dust in the vicinity of icy satellites provides unique insight into the physical and chemical conditions at its origin as demonstrated by Cassinis dust detector [4, 3]. Information about the geological activities on and below a moons surface is contained in the types and amounts of organic and inorganic components embedded in the dominant surface material. The basic idea of the proposed compositional mapping [2] is that moons without an atmosphere are wrapped in clouds of dust particles (roughly micron sized) ejected by micro-meteroid impacts from the moons surfaces [1]. The composition of these dust particles can be analysed by an orbiter instrument. The ejecta particles move on ballistic trajectories and most of them recollide with the moon. As a consequence, an almost isotropic dust cloud forms around the moon. From the statistics of the particles in the cloud, one can constrain their location of origin on the surface. Thus, from their composition one can conclude, with given probability, on the composition of a certain part of the surface. In this way, recording a large sample of dust grains with an orbiter, it will be possible to resolve compositional variations on the surface and relate them to topological features.

[1] Krueger et al., Nature, 399, 1999.
[2] Postberg et al., Planetary and Space Science, 59, 2011.
[3] Postberg et al., Nature, 459, 2009.
[4] Postberg et al., Icarus, 183, 2006.