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| Titel |
GIADA: extended calibration activities before the comet encounter |
| VerfasserIn |
Mario Accolla, Roberto Sordini, Vincenzo Della Corte, Marco Ferrari, Alessandra Rotundi |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250097952
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| Publikation (Nr.) |
 EGU/EGU2014-13581.pdf |
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| Zusammenfassung |
| The Grain Impact Analyzer and Dust Accumulator – GIADA – is one of the payloads
on-board Rosetta Orbiter. Its three detection sub-systems are able to measure the speed, the
momentum, the mass, the optical cross section of single cometary grains and the dust flux
ejected by the periodic comet 67P Churyumov-Gerasimenko.
During the Hibernation phase of the Rosetta mission, we have performed a dedicated
extended calibration activity on the GIADA Proto Flight Model (accommodated in a clean
room in our laboratory) involving two of three sub-systems constituting GIADA, i.e. the
Grain Detection System (GDS) and the Impact Sensor (IS). Our aim is to carry
out a new set of response curves for these two subsystems and to correlate them
with the calibration curves obtained in 2002 for the GIADA payload onboard the
Rosetta spacecraft, in order to improve the interpretation of the forthcoming scientific
data.
For the extended calibration we have dropped or shot into GIADA PFM a statistically
relevant number of grains (i.e. about 1 hundred), acting as cometary dust analogues. We have
studied the response of the GDS and IS as a function of grain composition, size
and velocity. Different terrestrial materials were selected as cometary analogues
according to the more recent knowledge gained through the analyses of Interplanetary
Dust Particles and cometary samples returned from comet 81P/Wild 2 (Stardust
mission). Therefore, for each material, we have produced grains with sizes ranging
from 20–500 μm in diameter, that were characterized by FESEM and micro IR
spectroscopy.
Therefore, the grains were shot into GIADA PFM with speed ranging between 1 and 100
ms-1. Indeed, according to the estimation reported in Fink & Rubin (2012), this range is
representative of the dust particle velocity expected at the comet scenario and lies within the
GIADA velocity sensitivity (i.e. 1-100 ms-1 for GDSand 1-300 ms-1for GDS+IS 1-300
ms-1).
The response curves obtained using the data collected during the GIADA PFM extended
calibration will be linked to the on-ground calibration data collected during the instrument
qualification campaign (performed both on Flight and Spare Models, in 2002). The final aim
is to rescale the Extended Calibration data obtained with the GIADA PFM to GIADA
presently onboard the Rosetta spacecraft.
In this work we present the experimental procedures and the setup used for the calibration
activities, particularly focusing on the new response curves of GDS and IS sub-systems
obtained for the different cometary dust analogues. These curves will be critical for the future
interpretation of scientific data.
Fink, U. & Rubin, M. (2012), The calculation of AfÏ and mass loss rate for comets,
Icarus, Volume 221, issue 2, p. 721-734 |
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