GEOSTAR deep sea mission
Paolo Favali, Giuseppe Smriglio
Geostar@ingv.it
Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata, 605 - 00143 - Roma (Italy)
Abstract.

GEOSTAR(GEophysicalandOceanographic STation for Abyssal Research) is a1
Main characteristics ofGEOSTAR

scientific and technological project funded byEuropean Commission in the Marine Science and

The main aspect characterising the GEOSTAR concept

Technology Program (MAST-III CT95-0007 and(see Fig.1) is the possibility to actively deploy to theCT98-0183 contracts). This project has developed andsea-bed and then retrieve a Bottom Station (BS),tested the prototype of a deep sea multidisciplinary

designed to support operation of a wide range of sensors,benthic observatory capable to carry out long-term (upable to collect multidisciplinary data on the same spot,.

to 1 year) scientific observations at abyssal depths (upThe BS contains also the battery vessel and the Datato -4000 m) in geophysics, geochemistry and physicalAcquisition

oceanography.

management of a complete scientific mission (Gasparoni

GEOSTAR system includes twoandControlSystemtoallow

themodules: the Bottom Station, that is the Observatory

et al., 2001).

equipped with sensors and communication system,

Accurate and safe positioning at seafloor, re-entry andand the Mobile Docker which was designed andrecovery capabilities of the BS are ensured by arealised specifically to handle the Bottom Station fromdedicated cable suspended thrustered module, hereafter

the sea surface during the deployment and thereferred as Mobile Docker (MD). This is a system able

recovery.

to carry heavy loads (up to 5 tons) at abyssal depths,

GEOSTAR Observatory, successfully deployed lastdeploy them within the range of 5% of the water depth

September 23rd, 2000 in Southern Tyrrhenian Sea (38and retrieve them at the end of a scientific mission.

32'N; 12 46' E) at a depth of about 2,000 m, is now

The solution adopted overcomes typical limitations of

performing its first long term mission lasting till lateother systems like the need of neutral asset in water,

Spring 2001.

free-falling deployment (very imprecise and rough),short autonomy and limited payload.
Communication capabilities are ensured by threesystems located on the BS and by a Near Real Time
Communication System (Marvaldi et al., 2001):

Fig. 1. GEOSTAR concept. Cable connection is an option not implemented in the prototype version.

40 Mbytes, contains about 40 Data Records of•(Messenger/E)

maximum size of 850 Kbytes generated hourly.

periodically released by the BS and able to transmit

The Data Records contain the complete data

their data to a shore station over a satellite link; thevolume produced by all the sensors.

Expendable

data

capsulesE-type, with capacity of 32 Kbytes, is used to store

Two-way acoustic communication system to allowand transmit about 30 Summary Messages,

data exchange between users, on board a surface

generated daily, whose maximum size is 640 bytes.

ship, and the BS.

The Summary Messages are composed by datablocks••

containing

thebasicstatistics•

The

Near-Real-Time

Communication

System(NRTCS) includes the surface buoy, the antenna

ofmeasurements and a set of technical operating

andparameters of the BS.

communicate data through the satellite link. The

Recoverable

highstorage

capacity

andtheenergy

sourcetocommunication between the observatory, the buoy

capsulesand the shore station occurs in a interactive way.

(Messenger/S) released by the BS on request ofuser from surface ship; the S-type, with capacity oftransducer,Thecharacteristics

ofthemainsubsystems

ofGEOSTAR developed within the project and the actual
scientific payload, hosted by the BS, are summarised:

•

•

•

•

Bottom Station- Dim. 3500 x 3500 x 2900 mm- Weight 3100 kg (in air), 1475 kg (in water)- Material Al 5083, Ti grade 5- Battery pack 24 V, 2400 Ah- Mass memory 4 Gbyte (hard disk), 144 Mbyte(PCMCIA)

2Mobile Docker- Dim. 2878 x 2348 x 1540 mm- Weight 1050 kg (in air), 850 kg (in water)- Material Al, Stainless Steel- Power 25 kW- Thrust 2x2000 N (lateral), 2x700 N (vertical)- Telemetry 2 video, 12 RS232 lines- Video 3 b&w, 1 color- Lighting 4 x 250 W (+ 1 optional)- Sonar, Altimeter

verifying its performances and reliability (Favali et al.,Communication System- 3 Expendable Messengers (32 kByte memory,ARGOS transmitter)- 2 Storage Messengers (40 Mbyte memory,
ARGOS positioning)- Multimodulation Acoustic Modem (12 kHz, up to
2400 bit/s bidirectional link with a ship ofopportunity and a buoy equipped with asatellite transmitter for connection to shore)
Scientific Payload- Three axis broad-band seismometer- Scalar (proton) magnetometer- Fluxgate (x-y-z) magnetometer- 300 kHz Acoustic Doppler Current Profiler(ADCP)- Conductivity, Temperature and Depth sensor(with pump) (CTD)- Transmissometer

GEOSTAR 1

The GEOSTAR project develops in two phases. The
first phase (1995-1998), named GEOSTAR 1, wasaimed at designing and realising the prototype and at
1998, Jourdain, 1999). GEOSTAR observatory wasdeployed in Adriatic Sea from August 13th to September
2nd, 1998 at about 40 km East of Ravenna (Italy) and at a
depth of 42 m. During the 3 week mission theacquisition system recorded continuous 440 hours(97.8% of the total time). A magnetic observatory andthree broad band seismic stations were installed on land
to integrate the geophysical measurements. The mission
demonstrated reliability, both of the MD, and of thesensors and efficiency of the communication system BSsurface user.
The recorded data during the first mission in AdriaticSea (Fig. 2) gave the opportunity to verify the quality ofthe installation procedures selected in the design phasefor specific sensors (Beranzoli et al., 2000).
The good quality of the magnetometers recordings isrevealed by the comparison with the time series ofCastello Tesino (CT) observatory (300 km far fromGEOSTAR 1 site), and of the temporary station of-Gravity Meter

Bosco Mesola (BM) (Ferrara, about 57 km far from

-Space seismometer (three axis broad-band)Single point current meter (3D)
Chemical Package (NH3, pH)
Water sampler

GEOSTAR 1 site). It was also possible to grossly
estimate the magnetic influence of the GEOSTARobservatory frame and of the other equipment to theA high precision clock ensures a long-term highly stablemagnetometers. The results in terms of the geomagnetic

and accurate time reference for all sensors, mainly

deep sounding technique applied to the time variations

required by the seismic measurements.

of the horizontal and vertical components of theFig. 2. a) Recordings of the Slovenia earthquake (31/8/1998, Ml 4.9, ∆= 232 km.) at one land temporary station (CSN) andGEOSTAR observatory. b) Recordings of the GEOSTAR scalar magnetometer during a disturbed day compared with the data of theCasatello Tesino ground Observatory, located 300 km far from GEOSTAR site, and of the Bosco Mesola temporary station. c) Time
series collected with the CTD (water, temperature and pressure) over the days of mission. d) Absolute velocity of the water: currentin cm/s versus depth from the seafloor, over the duration of the mission.

magnetic field provided interesting results in theprocedure and the coupling of the sensor with the sea

framework of the regional tectonics (De Santis et al,bottom were fulfilled. The spectral analysis of the1999). The performances of the seismological package

seismic background noise, showed that the effect of thewith respect to the detection of regional and teleseismic

thick sediment layer below the GEOSTAR 1 mission

events, demonstrated that the seismometer deployment

site reduced considerably the detection capabilities oflocal earthquakes. This fact was confirmed by thecomparison with the seismic background noise of
Cesena (CSN), the on land temporary station closest toGEOSTAR, sited on a ground with almost similar geotechnical characteristics.
During GEOSTAR 1 mission the oceanographic sensors(ADCP and CTD) recorded correctly. The CTD sensor
demonstrated that the acquisition of temperature andpressure data worked properly, but conductivity andtransmissometer data suffered for fouling due tosedimentation.
Fig. 3. GEOSTAR system during the deployment in the3

GEOSTAR 2

The second phase of the project – named GEOSTAR 2
and started in 1999 - has the purpose to perform the first

Tyrrhenian Sea. Top side: the Mobile Docker, the dedicatedvehicle for surface assisted deployment/recovery of theobservatory. Bottom side: The Bottom Station (BS) hosting thesensors, the data acquisition and control system and the batteryvessel. The communication systems are located on the BS andlong-term scientific mission at abyssal depths for a

include the messengers (their antennas are clearly visible), data

period of 6-8 months. The deployment site is located in

capsules periodically released by the observatory. In thethe Southern Tyrrhenian Sea, 30 km WSW of Ustica

foreground a releasing arm with a benthosphere, containing aisland (Sicily) at about a depth of 2000 m. From amagnetometer.

geological and environmental point of view this site
represents an optimal observation point, in order to•

Messengers, to verify the status of the observatory

obtain relevant information about geodynamics andand to acquire scientific data samples.; till now 3

oceanography of the whole Mediterranean basin(Beranzoli et al., 1998).
The long term scientific mission started on 23
September 2000 (Fig. 3); the GEOSTAR observatory
will be recovered during April 2001.

release and recovery of E-Type and S-Type

Messengers were successfully recovered.
•near-real-time communication with bi-directionalconnection between a shore operator and the BS,
through the NRTCS buoy (Fig. 4). Various links
were successfully established with the observatory,

Objectives of the mission are:allowing the request of data from a shore station•

continuous, long-term acquisition of geophysicaland a correct transmission of data from the(seismic activity, earth magnetic field, earth gravity

observatory.

field) and environmental parameters (current,temperature, salinity, etc.);

At the end of the GEOSTAR 2 phase, the observatory
will be qualified and made available to the scientificcommunity for other long-term scientific missions indeep-sea marine environments.

Beranzoli L., T. Braun, M. Calcara, D. Calore, R.
Campaci, J.-M. Coudeville, A. De Santis, G.
Etiope, P. Favali, F. Frugoni, J.L. Fuda, F.
Gamberi, F. Gasparoni, H. Gerber, M. Marani, J.
Marvaldi, C. Millot, C. Montuori, P. Palangio, G.
Romeo, and G. Smriglio, European Seafloor
Observatory offers new possibilities for deep-sea
study, EOS, 81 (5): 45-49, 2000.
De Santis A., D. Di Mauro, P. Favali, P. Palangio, G.
Romeo, and G. Smriglio, GEOSTAR Project:
The performed seafloor mission in the AdriaticSea, Proceedings 2nd International Conference
on Marine Electromagnetics, Brest, July 5-7,219-230, 1999.

Fig. 4. The Near Real Time Communication System buoy

The partnership of the project includes:
Istituto Nazionale di Geofisica (Italy) Co-ordinator,
Tecnomares.p.a.

(Italy),IFREMER(France),

Laboratoire de Oceanographie et de Biogeochimie

Favali P., G. Smriglio, L. Beranzoli, T. Braun, M.
Calcara, G. Etiope, F. Frugoni, C. Millot, J.L.
Fuda, M. Marani, F. Gamberi, J.V. Dobson, andN. Marshall, GEOSTAR - Scientific goals of theproject and results of the first test phase,
Proceedings (on CD-ROM) of the IEEE
Conference and exhibition «OCEANS 98», Nice,France. September 28 - October 1, 1998.
Gasparoni F., D. Calore, and R.Campaci, From ABEL toGEOSTAR: development of the first euoropean
deep-sea scientific observatory, ScienceTechnology synenergy for research on marine
environment: challenges for the XXI Century,
Developments in Marine Technology Series, inpress.

(France), ORCA Instrumentation (France), Institut deTechnische

Jourdain J.Y., First trial of GEOSTAR, the geophysicaland oceanographic European station for abyssal
research,
EuropeanCommission
Project
information booklet EUR18885, 31 pp., editedby Gilles Ollier, 1999.

Beranzoli L., A. De Santis, G. Etiope, P. Favali, F.
Frugoni, G. Smriglio, F. Gasparoni, and A.
Marigo, GEOSTAR: a Geophysical andOceanographic Station for Abyssal Research,
Phys. Earth Plan. Inter., 108, 175-183, 1998.

Marvaldi J., Y. Aoustin, J.Blandin, G. Loaec, Ch.
Podeur, J.M. Coudeville, G. Ayela, D. Barbot, D.
Fellmann, and A. Priou, Design and realisation ofcommunication systems for the GEOSTAR
Project, Science-Technology synergy for researchon marine environment: challenges for the XXICentury, Developments in Marine Technology
Series, in press.

Physique du Globe de Paris (France), TechnischeUniversitat

Berlin(Germany),

Fachhocschule Berlin (Germany).

4References