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A stratospheric balloon experiment to test the Huygens atmospheric structure instrument (HASI) |
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| Authors: | M Fulchignoni A Aboudan M Antonello C Bettanini G Colombatti E Flamini N Ghafoor A-M Harri PF Lion Stoppato JC Zarnecki |
| Institution: | a LESIA, Observatoire de Paris, 5, Place Jules Janssen, 92195 Meudon, France b Université Denis Diderot - Paris 7, 2 Place Jussieu 75005 Paris, France c CISAS, Center of Activities and Science for Space, Università di Padova, via Venezia 1, I-35131 Padova, Italy d Agenzia Spaziale Italiana (ASI), via di villa Patrizi, 13 00161 Roma, Italy e Planetary and Space Sciences Research Institute, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK f Finnish Meteorological Institute (FMI), Kaisaniemenkatu 10, PO Box 503, SF-00101 Helsinki, Finland |
| Abstract: | We developed a series of balloon experiments parachuting a 1:1 scale mock-up of the Huygens probe from an altitude just over  to simulate at planetary scale the final part of the descent of the probe through Titan's lower atmosphere. The terrestrial atmosphere represents a natural laboratory where most of the physical parameters meet quite well the bulk condition of Titan's environment, in terms of atmosphere composition, pressure and mean density ranges, though the temperature range will be far higher.The probe mock-up consists of spares of the HASI sensor packages, housekeeping sensors and other dedicated sensors, and also incorporates the Huygens Surface Science Package (SSP) Tilt sensor and a modified version of the Beagle 2 UV sensor, for a total of 77 acquired sensor channels, sampled during ascent, drift and descent phase.An integrated data acquisition and instrument control system, simulating the HASI data-processing unit (DPU), has been developed, based on PC architecture and soft-real-time application. Sensor channels were sampled at the nominal HASI data rates, with a maximum rate of  . Software has been developed for data acquisition, onboard storage and telemetry transmission satisfying all requests for real-time monitoring, diagnostic and redundancy.The mock-up of the Huygens probe mission was successfully launched for the second time (first launch in summer 2001, see Gaborit et al., 2001) with a stratospheric balloon from the Italian Space Agency Base “Luigi Broglio” in Sicily on May 30, 2002, and recovered with all sensors still operational. The probe was lifted to an altitude of  and released to perform a parachuted descent lasting  , to simulate the Huygens mission at Titan. Preliminary aerodynamic study of the probe has focused upon the achievement of a descent velocity profile reproducing the expected profile of Huygens probe descent into Titan.We present here the results of this experiment discussing their relevance in the analysis of the data which will be obtained during the Huygens mission at Titan. |
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