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| Titel |
The BepiColombo mission to Mercury and the role of the ISA accelerometer in the Radio Science Experiments: status and perspectives |
| VerfasserIn |
Valerio Iafolla, David M. Lucchesi, Sergio Nozzoli, Francesco Santoli, Roberto Peron, Emiliano Fiorenza, Carlo Lefevre |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250055577
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| Zusammenfassung |
| Mercury’s exploration is one of the most important challenges of modern planetary sciences.
The results of such an exploration — in particular in the context of BepiColombo mission —
are a way to constrain the physics of the terrestrial planets formation and, at the end, of the
whole solar system. Moreover, as the closest body, among the planets, to the Sun, Mercury
represents a unique “laboratory” in order to verify Einstein’s theory of general
relativity with respect to other metric and non-metric theories of gravitation. The
level of knowledge that can be reached in the above fields is strongly conditioned
by the accuracy of the Radio Science Experiments (RSE) that will be performed
using Earth–bound radar tracking stations. Such very ambitious objectives need an
onboard accelerometer in order to measure and remove, a posteriori, the complex to
model, strong and subtle, non–gravitational accelerations of the very severe radiation
environment the probe will face. To this purpose, the Italian Spring Accelerometer
(ISA) has been selected to fly onboard the BepiColombo Mercury Planetary Orbiter
(MPO). After a brief review of the RSE objectives, we describe the advantages
arising from the new position of ISA inside the MPO, away from the spacecraft
center–of–mass. We then focus on the accelerometer characteristics and performance, its
functional tests, and on the accelerometer calibration with special emphasis on the
precise determination of the sensing axes directions with respect to the body of the
spacecraft. We then describe additional gravimetric measurements that can be achieved
with the accelerometer under favorable flight conditions. We finally describe the
accelerometer capability to measure the MPO speed variations during the onboard reaction
wheels desaturation manoeuvres. These manoeuvres directly impact on the accuracy
of the propagated state-vector of the satellite at the beginning of the subsequent
observed arc, with an overall degradation of the RSE accuracy. ISA measurements
of the speed variations, both in time and frequency domains, will be an essential
ingredient in order to preserve the accuracy of the BepiColombo RSE and of the
pointing accuracy of other onboard instruments. This additional capability of ISA
strengthens once more the key role of the accelerometer in the BepiColombo mission. |
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