CONSERT

CONSERT (COmet Nucleus Sounding Experiment by Radiowave Transmission) is a scientific experiment on board the European Space Agency's Rosetta mission, launched in 2004, which will provide information about the deep interior of the comet 67P/Churyumov-Gerasimenko upon the probe's rendezvous with the comet in 2014.

The CONSERT radar will perform tomography of the nucleus by measuring electromagnetic wave propagation from the Philae lander and the Rosetta orbiter throughout the comet nucleus in order to determine its internal structures and to deduce information on its composition. The related lander and orbiter electronics were provided by France and both antennas were constructed in Germany. The experiment was designed and built in France by Laboratoire de Planétologie de Grenoble (LPG now IPAG) and by Service d'Aéronomie in Paris (SA now LATMOS), in Germany by Max Planck Institut of Aeronomy (MPAE and now MPS) in Lindau/Katlenburg. The Principal Investigator of CONSERT is Dr. Wlodek Kofman (IPAG), Director of Research at CNRS.

The scientific objectives of the CONSERT experiment are the determination of the main dielectric properties and, through modelling, to set constraints on the cometary composition (materials, porosity, etc.), to detect large–size structures (several tens of meters) and stratification, to detect and characterise small–scale irregularities within the nucleus.

A detailed analysis of the radio–waves which have passed through all or parts of the nucleus will put real constraints on the materials and on inhomogeneities and will help to identify blocks, gaps or voids. From this information, scientists will attempt to answer some fundamental questions of cometary physics. How is the nucleus built up? Is it homogeneous, layered or composed of accreted blocks (cometesimals, boulders)? What is the nature of the refractory component? Is it chondritic as generally expected or does it contain inclusions of unexpected electromagnetic properties?

In more detail, the purpose of CONSERT experiment is to measure the following quantities:

The basic principle of the experiment consists in using the electromagnetic propagation (90 MHz VHF radio) through the cometary interior. An electromagnetic wave–front propagates through the cometary nucleus at a smaller velocity than in free space and loses energy in the process. Both the change in velocity and the energy loss depend on the complex permittivity of the cometary materials. They also depend on the ratio of the wavelength used to the size of any inhomogeneities present. Thus, any signal that has propagated through the medium contains information concerning this medium. The change in velocity of the electromagnetic wave induced by propagation through the cometary material is calculable from the time taken by the wave to travel between the orbiter and the lander, while the loss of energy is deducible from the change in signal amplitude.

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