ROSETTA and the mysteries of comets
Rosetta is a Cornerstone mission of the ESA Horizon 2000 program dedicated to the exploration of small bodies in the Solar System. It was launched March 2, 2004, he made a successful fly-by of the asteroid Steins (2008) and performed a fly-by of the asteroid Lutetia on July 10, 2010, but his primary goal is to make a series of detailed investigations on the characteristics of the comet 67P / Churyumov-Gerasimenko in 2014. The ROSETTA spacecraft consists of an orbiter, where can be found the sensors for experiments in remote sensing and a lander called PHILAE which was released on the surface of the comet to make a series of measurements of the physical characteristics of the surface and to investigate the internal structure of the nucleus.
The main scientific objective of the Rosetta mission is the understanding of the origin of comets and the relationship between their composition and interstellar matter as fundamental elements to be able to trace the origins of the solar system. The search for intact materials is achieved through the exploration of the comet as the outer zones of the Solar System contain rich material in volatile compounds that have not been tried in inland areas characterized by high temperatures.
The exploration of the comet is the characterization of the nucleus and the coma, the determination of their dynamic properties, the study of the morphology and composition. In particular, the study of mineralogy and isotopic ratios of volatile elements and refractory core will provide valuable information on the composition of the nebula, in current models, is believed to have been the origin of the Solar System.
To achieve these objectives, the spacecraft will orbit around the comet, following his journey into the interior of the planetary system, and the Philae lander will carry out in-situ measurements and sample of the material to the surface of the core to a chemical analysis detailed mineralogical.
The Italian participation in the mission ROSETTA orbiter consists of three scientific instruments: VIRTIS (Visual and InfraRed Thermal Imaging Spectrometer) whose PI is Dr. Fabrizio Capaccioni from IAPS (INAF Rome), JADE (Grain Impact Analyser and Dust Accumulator) whose PI (principal investigator) is Dr. Alessandra Rotundi from “Parthenope” University of Naples and WAC (Wide Angle) of OSIRIS of Prof. C. Barbieri from University of Padova (PI Dr. Uwe Keller, Max Planck Institute fur Sonnensystem).
Onboard the lander, is the Italian system of acquisition and distribution of samples (SD2), made by Galileo Avionics and whose PI is Prof. Amalia Ercoli Finzi, Politecnico di Milano, and the subsystem of solar panels (Polytechnic University of Milan). Italy has also provided the manpower Lander Project Team.
VIRTIS (Visible and Infrared Thermal Imaging Spectrometer): combines 3-channel of observation in a single instrument, two of which will be used in the reconstruction of the nucleus spectral map. The third channel is dedicated to high-resolution spectroscopy. With these observations the scientists will try to determine the nature of the solid parts that make up the nucleus of the comet and trace its thermal characteristics. These data, combined with data collected by other instruments, will be used to select the area on which to place the lander. GIADA (Grain Impact Analyzer and Dust Accumulator) is a tool that can analyze dust and small grains of material in the comet’s coma by measuring the physical properties and dynamics, including the size, the relationship between granular material and as well as the gaseous material, the speed of the particles. OSIRIS / WAC (Optical, Spectroscopic, and Infrared Remote Imaging System): OSIRIS is the main instrument of the Rosetta mission to collect images of the comet. It consists of two channels: NAC (Narrow Angle Camera), optimized to obtain high-resolution maps of the comet nucleus, up to 2cm per pixel, with a capacity of focus from 2 km infinite and 1 to 2 km; WAC (Wide Angle Camera), which is optimized to obtain a high resolution overview map of the gas and dust material around the nucleus of the comet.
The channel of OSIRIS WAC is the Italian responsibility and is designed for the accurate study of the gaseous emissions of the comet that are visible in the UV band. The images captured by this channel will be used to select the area where the lander will be placed.