The Rosetta spacecraft is beeing prepared for an ambitious robotic
space mission to Comet Wirtanen.
The objective of the CONSERT experiment is to study a comet at close
quarters by placing a lander on its surface and chasing, with an orbiter,
the comet for millions of kilometers through space. Comets - among the
oldest (4.6 billion years!) and last altered objects in the solar system -
are regarded as the building blocks from the planets formed. Thus the
Rosetta's discoveries will allow the scientists to learn about the birth
and evolution of the planets and about the origin of life on the Earth.
The Rosetta mission is a major effort to experimentally study a a cometary
nucleus. The comet's spatial structures and material characteristics are
determined by the processes by whichmaterial condenced out of the solar
nebula. Gravitation, collisions, and adherence between dust grains, solar
radiation and the solar wind plasma effects were processes active in shaping
the comet's nucleus.
In the mission a spacecraft will orbit the nucleus, and another spacecraft,
a Lander, will settle on its surface.With a large varity of experiments
measurements will be made of the solar wind, the cometary coma, the comet's
surface and near surface layers. Only one experiment, CONSERT, will provide
measurementsof the deep interior of the cometary nucleus.
In CONSERT (COmet Nucleus Sounding Exprtiment by Radiowave Transmission)
radio waves are transmitted through the nucleus. The phase and amplitude
changes in the radio signal reflect electrical properties and spatial
structurs of the cometary materials. Measurments of the radio signal will
allow to infer the following parameters:
The mean permittivity and mean absorption of the comet are used to identify
the comatary materials.
The spatial correlation length of the phase and amplitude are related to
the size of irregularities and spatial structures inside the comet.
The volume scattering coefficient is a measure of the homogeneity of
the comet interior.
The reflection coefficients of internal surfaces are related to
permittivity gradients and spatial scales of cometesimals.
The surface reflection cefficient and the surface scattering
characteristics are used to derive the electrical properties and
irregularity structure of the surface
The CONSERT expriment will contribute to the understanding of the composition
and internal structure of the comet nucleus.