Rosetta/CONSERT

Science goals

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:

1. The mean permittivity and mean absorption of the comet are used to identify the comatary materials.
2. The spatial correlation length of the phase and amplitude are related to the size of irregularities and spatial structures inside the comet.
3. The volume scattering coefficient is a measure of the homogeneity of the comet interior.
4. The reflection coefficients of internal surfaces are related to permittivity gradients and spatial scales of cometesimals.
5. 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.