Projet MoVeGra

Project  “Mobile Underwater Vector Gravity Sensor” (MoVeGra)

The objective of MoVeGra is to mature the technology of a novel type of vector gravity sensor to be used on Autonomous Underwater Vehicles (AUV). This proposal is the follow-up of a larger project, GRAVIMOB, which developed and built the first prototype and tested it during a cruise (GRAVIMOB 2016, funded by the French Oceanographic Fleet-FOF).

the objectives of ANR research axis 01 as this new sensor will allow:

  • improving the knowledge of the crustal structure (porosity, alteration) and fluid circulation associated with hydrothermal vents, which impact the fluxes of diverse elements, and,
  • evaluating the economic potential of the mineral deposits associated with these environments.

The concept of GRAVIMOB is based on direct measurements of accelerations along three axes (De Saint Jean, 2008). The system is composed of six accelerometers mounted in two co-linear triads, integrated on a glass sphere, which also holds the data loggers and additional sensors (Figure 1). It is therefore a vector gravity meter allowing, after data processing, to determine the three components of the gravity acceleration.

GRAVIMOB sensor (left), sphere in a frame for AUV AsterX (centre), AUV AsterX (right) AUV AsterX @IFREMER

Main partners: LGO  ESGT (Le Mans)

Collaborations: IGN, SHOM, IFREMER
Prototype built by  MAPPEM Geophysics, funded by CPER Bretagne

Test cuise GRAVIMOB (NO Europe, AUV AsterX), May 2016, funded by FOF, Labex MER, LGO

Cruise evaluation (CNFH)

Cruise operational report

Cruise scientific report

Test cruise GRAVIMOB-2 (NO Europa, AUV) evaluated A+ by the French Coastal Fleet Committee (CNFC)

Cruise evaluation (CNFC)

Bibliography

Roussel, C., J. Verdun, J. Cali, M. Maia, and J. F. d’EU. “Integration of a strapdown gravimeter in an autonomous vehicle.” ISPRS – International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL– 5/W5 (April 9, 2015) : 199–206. doi :10.5194/isprsarchives-XL-5-W5-199-2015

Thèse (DGA): Roussel, C. Expérimentation d’un gravimètre mobile léger et novateur pour la mesure du champ de gravité en fond de mer, 2017 (https://tel.archives-ouvertes.fr/tel-01635884)

Thin blade workshop

The LGO litholamellage and milling plant includes sawing and grinding rock equipment as well as equipment for manufacturing thin sections and polished sections.

Optical microscopy systems

The laboratory is equipped with several polarizing microscopes for the observation of thin sections in transmitted or reflected light, as well as several binocular microscopes for the observation and sorting of minerals or fossils. A high definition digital camera allows the acquisition of high quality images.

Means in sedimentology

Sedimentology means of the LGO are common with the GEOMER laboratory.

The palynology laboratory – micropalynology

A laboratory for microfossil extraction has been in place at IUEM since 2016, financed by CPER credits during the installation of the Paleoclimatology and Paleontology team. It allows the chemical processing of sedimentary rock and sediment samples for microfossil extraction, in connection with research programs in palynology and micropaleontology. This laboratory is backed by a microscopy room that includes three interferential contrast research microscopes, with a photomicroscopy equipment (digital camera and digital reflex). This equipment allows the analysis of slides prepared after palynological and / or micropaleontological treatments. Two binocular loupes are also installed in this room, for the observation and sorting of microfossils (essentially planktonic and / or benthic foraminifers).