CONSERT - COmet Nucleus Sounding Experiment by Radio-wave Transmission
The CONSERT instrument is the only instrument of the Rosetta mission that uses equipment located on both the orbiter and the lander units. The scientific goal is to explore the interior and the internal structure of the cometary nucleus through radio waves. A radio signal is sent by the CONSERT orbiter unit towards the surface and penetrates through the nucleus. It is received and retransmitted by the instrument unit onboard the lander and after a second travel through the nucleus it is finally measured by the orbiter unit of the instrument. The signal changes allow to conclude on the internal structure of the comet. Durung the transfer of the lander from the orbiter to the comet's surface, CONSERT will be operated like a "normal" radar instrument.
The internal structure of a cometary nucleus is widely unknown so far. Is it a loose mixture of snow and solid particles? Does it contain smaller planetesimals, the likely building stones of the planets during the formation era of the planetary system? Are there voids and large scale structures found in the nucleus interior? Answers to these questions are expected to come from the CONSERT instrument. The following specific physical properties of the nucleus shall be determined:
- the material of the nucleus interior
- the dimensions of possible substructures in the nucleus
- the presence and thickness of intrinsic layers in the nucleus
- the permittivity of the top layer near landing site
The CONSERT-antenna on the orbiter consists of two crossed dipole-antennas with reflectors (1500g); the antenna on the lander consists of two crossed monopole-antennas (300g). This is complemented by the necessary electronics. Both antennas - on the orbiter and the lander - serve as sender and receiver of the instrument signals. The instrument uses radio frequencies of 90 MHz with a band width of 8 MHz.
Three institutions have contributed to the CONSERT instrument hardware: the Laboratoire de Planétologie de Grenoble, the Ruhr-Universität Bochum and the MPS. The MPS was responsible for the antenna concept, design, building, testing, and verification of the antenna units, while the French colleagues developed the respective instrument electronics. Principla investigator of the instrument is Wlodek Kofman from the Laboratoire de Planétologie de Grenoble.