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Published July 27, 2006 | Published
Journal Article Open

Overview of the coordinated ground-based observations of Titan during the Huygens mission


Coordinated ground-based observations of Titan were performed around or during the Huygens atmospheric probe mission at Titan on 14 January 2005, connecting the momentary in situ observations by the probe with the synoptic coverage provided by continuing ground-based programs. These observations consisted of three different categories: (1) radio telescope tracking of the Huygens signal at 2040 MHz, (2) observations of the atmosphere and surface of Titan, and (3) attempts to observe radiation emitted during the Huygens Probe entry into Titan's atmosphere. The Probe radio signal was successfully acquired by a network of terrestrial telescopes, recovering a vertical profile of wind speed in Titan's atmosphere from 140 km altitude down to the surface. Ground-based observations brought new information on atmosphere and surface properties of the largest Saturnian moon. No positive detection of phenomena associated with the Probe entry was reported. This paper reviews all these measurements and highlights the achieved results. The ground-based observations, both radio and optical, are of fundamental importance for the interpretation of results from the Huygens mission.

Additional Information

© 2006 by the American Geophysical Union. Received 17 November 2005; revised 29 March 2006; accepted 24 April 2006; published 27 July 2006. The decision to support and coordinate a series of optical ground-based observations was taken at the time of the Huygens Science Working Team in October 2003 in Graz. We thank all participants, especially Athena Coustenis and Dennis Matson, for their support. We thank the observatory directors and telescope allocation panels for their endorsement of all these observations. We thank the European funded network EUROPLANET for its support. This research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. We appreciate the support provided by the National Radio Astronomy Observatory (NRAO) and the Australia Telescope National Facility (ATNF). NRAO is operated by Associated Universities, Inc., under a cooperative agreement with the NSF. The ATNF, managed by the Commonwealth Scientific and Industrial Research Organization (CSRIO), The Joint Institute for VLBI in Europe, is funded by the national research councils, national facilities and institutes of Netherlands (NWO), the United Kingdom (PPARC), Italy (INAF), Sweden (Onsala Space Observatory, National Facility), Spain (IGN), Germany (MPIfR), and China (National Astronomical Observatories, CAS). The Huygens e-VLBI demonstration would have been impossible without the efforts of the networking community, who on very short notice provisioned a dedicated light path between Australia and JIVE. We thank George McLaughlin, Steve Maddocks, Mark Prior, and Alan Cowie (AARNet),- Shaun Amy (CSIRO), Craig Russell (CeNTIE), Hervé Guy and Damir Pobric(Canarie), Bill Mar (Pacific Northwest GigaPoP), Geoff Lakeman (University of Washington), Caroline Carver (MANLAN), and Dennis Paus(SURFnet). Part of this work was funded through grants AST-0205893 from the National Science Foundation and NNG05GH63G from NASA to the Univ. of California, Berkeley. David Luz acknowledges financial support from Fundação para a Ciência e a Tecnologia, Portugal (fellowship PRAXIS XXI/BPD/3630/2000 and project POCI/CTE-AST/57655/2004). Alberto Negraõ is supported by the FCT Ph.D. scholarship SFRH/BD/8006/2002. HIPWAC measurements were supported by the NASA Planetary Astronomy Program. Olivier Witasse thanks Sushil Atreya for useful suggestions.

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