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Research | Space Research | Planetary research - Rosetta - Permittivity Probe
Permittivity Probe
Permittivity Probe (PP) is designed to measure the complex permittivity, i.e., electrical conductivity and dielectric polarizability, of the cometary nucleus at the landing site of the Rosetta Lander, down to a depth of a few meters. PP is an active instrument that measures the influence of a material upon the electrical coupling between two dipoles in contact with its surface. Unlike all microwave techniques (e.g., radar, interferometry, and antenna impedance measurements), the PP is operated in a frequency domain, below 10 kHz, where the electrical signature of the material is the most influenced to the presence of water ice.
Primary scientific objectives
Conductivity and polarizability are very sensitive to the temperature of the material, the frequency of the applied electric field, and below 10 kHz to the presence of water, which is the only common rock-forming substance which has a marked polarizability.Permittivity measurements will therefore help answering such fundamental questions as:
- what is the water content of the ice mixture which forms the cometary material?
- how does sublimation of ice control the evolution of the nucleus?
- does sublimation take place at the surface or deep below the dust mantle?
- why is the surface temperature of the nucleus so high?
- how does the mantle evolve as function of solar illumination and heliocentric distance?
Secondary scientific objectives
In the passive mode, this experiment has also the capability of a plasma wave investigation. As a secondary objectiv it is consequently used to detect the electric fields of electrostatic and electromagnetic waves with frequencies up to 10 kHz, which are generated by the interaction of the solar wind with the charged dust and ionized outgassing products of the nucleus. Sampling the total intensity of plasma waves every few second, these measurements will consequently provide a continuous monitoring of the nucleus activity.
More information:
, tel. 358 9 1929 4658
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The Rosetta Lander
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