EurOCEAN 2000 - Vlaams Instituut voor de Zee

GEOPHYSICAL AND OCEANOGRAPHIC STATION FOR ABYSSAL
RESEARCH: GEOSTAR 2 – ENHANCEMENTS OF THE SYSTEM
FOR THE DEEP SEA SCIENTIFIC MISSION
INTRODUCTION
660
Paolo Favali 1 , Giuseppe Smriglio 1 , Caterina Montuori 1
1 Istituto Nazionale di Geofisica, Roma
GEOSTAR 2 (GEophysical and Oceanographic STation for Abyssal Research) is a scientific
and technological project funded by the European Commission in the framework of Marine
Science and Technology Programme (MAST-III CT98-0183). The ongoing 2 nd phase continues
the first GEOSTAR phase (CT95-0007) ended in the 1998. The main objectives of both
GEOSTAR projects are to realise and test an autonomous benthic observatory able to collect
geophysical, geochemical and oceanographic data for long-term (up to1 year) in deep-sea
(4000 m). GEOSTAR realised also a dedicated deployment/recovery system, based on a
mobile docker concept, linked with the ship by an electromechanical cable (Beranzoli et al.,
1998). The deployment/recovery procedure has been derived from the so called “two-module”
concept successfully applied by NASA in many space missions (Apollo, Space Shuttles) where
the Mobile Docker is both the carrier and a 2 way communication Surface-Bottom Station
during all phases (e.g. for instruments check). The station is conceived to have a broad range of
sensors. The simultaneous acquisition of a set of various measurements with a unique time
reference can make GEOSTAR to be the first element of a future multiparametric ocean
network. The presence of such a network is important considering, for example, that the
present distribution of land-based geophysical observatories is inadequate for addressing
important scientific issues related to many features of our planet both at global and regional
scale.
The first phase (1995-1998), named GEOSTAR 1, was aimed at designing and realising the
system and at verifying its performances and reliability (Favali et al., 1998, Jourdain, 1999).
GEOSTAR 1 was deployed in Adriatic Sea from August 13 th to September 2 nd , 1998 at about
40 km East of Ravenna and at a depth of 42 m. During the 3 weeks mission the acquisition
system recorded continuously for 440 hours (97.8% of the total time). A magnetic observatory
and three broad band seismic stations were installed on land to integrate the geophysical
measurements. The mission demonstrated reliability of the deployment/recovery vehicle, of the
sensors and efficiency of the communication system Bottom Station-surface.
The second phase - started in 1999 - has the purpose to perform the first long-term scientific
mission at abyssal depth for a period of at least 6-8 months. After geological and geotechnical
surveys, done during the first phase, the deployment site was located in the Southern
Tyrrhenian Sea at 25-30 km NNE of USTICA Island, at a depth of 3400 m. From the
geological and environmental point of view this site represents an optimal observation point in
order to obtain relevant information about geodynamics and oceanography of the whole
Mediterranean basin. GEOSTAR 2 will carry new equipment for geophysical and chemicalphysical
analyses not available in the first phase.