GRGS > The GRGS > Memorandum of Agreement

Bureau des longitudes Centre national d’études spatiales Institut national de l'information géographique et forestière - Laboratoire LAREG Observatoire de Paris Institut national des sciences de l'Univers Observatoire de la Côte d'Azur Service Hydrographique et Océanographique de la Marine Observatoire Midi-Pyrénées Université de la Polynésie Française Ecole Supérieure des Géomètres et Topographes - Conservatoire national des arts et métiers Ecole et Observatoire des Sciences de la Terre

The GRGS was created by the Bureau des Longitudes, the Centre National d'Etudes Spatiales, the Institut Géographique National and the Observatoire de Paris, known as founding members, who have signed the memorandum establishing the group on Feb. 17, 1971 (in the Appendix).

The GRGS is a scientific consortium, which brings together teams in France (or parts of teams) who work in space geodesy. Initially, they dealt with celestial mechanics applied to artificial satellites (or space mechanics), the reference systems (celestial and terrestrial) for geodesy, Earth rotation, its gravitational field, as well as the creation of measuring instruments, the collection of observation data and prospective studies of new systems in order to determine these scientific subjects (or their constitution). These activities were subsequently extended to applying space geodesy to other domains, particularly oceanography (satellite altimetry) and planetology (where these methods and similar techniques are used for the global study of other bodies in the solar system). These objectives continue to be our main focus.

Parallel to the creation of additional space research groups by CNES and CNRS, the founding members created this consortium in order to carry out activities that were needed to develop space geodesy in our country---activities that could not be done, at least not quickly, or whose continued existence would not be ensured, within the standard framework of existing agencies. To do this, members began - and continue-- to share staff and operating resources, and they specifically contribute to projects and space experiments as well as their data processing. However, the staff generally continue to work at the premises of their home organization and are subject to its regulations. The informal and flexible character of the group has been preserved and other institutions, seeing its benefits and its efficiency, and the quality of results obtained, have decided to join the GRGS: the Institut National des Sciences de l'Univers [National Institute of Sciences of the Universe] in 1987, the Observatoire de la Cote d'Azur [Observatory of the Cote d’Azur] in 1988, the Service Hydrographique et Océanographique de la Marine [Hydrographic and Oceanographic Department of the Navy] in 1993, the Observatoire Midi-Pyrénées [Observatory of the Midi-Pyrenees] in 1997, the Université de Polynésie Française [University of French Polynesia] in 2003, the École Supérieure des Géomètres et Topographes du Conservatoire National des Arts et Métiers [School of Land Surveyors and Topographers of the National Academy of Arts and Crafts] in 2007 and the Ecole et Observatoire des Sciences de la Terre [School and Observatory of the Earth Sciences] in 2013.

Research considered to be “GRGS” has thus been, in principle, those projects conducted by one or more member institutions that nevertheless interest all of them. In particular, the CNES, in accordance with its statutes, has regularly funded activities carried out by all or part of the teams that are members of GRGS. This allows CNES to guide such research without the overhead of a highly specialized laboratory. Of course, since some of these activities are in the domain of research, the same result could have been obtained using successive grant "programs," which would be much more open and accessible to others. However, since many of these activities – for example in the field of pre-operational developments and observatory work of a more permanent nature-- need to be carried out on a long-term basis, they could not be done as successive grant programs. Organizations within the GRGS can only agree to allocate staff and to work in such fields with the guarantee of a long-term commitment from CNES.

GRGS has gained recognition and status internationally, and the agreements that link us with, for example, the Royal Observatory of Belgium and the German GeoForschungs Zentrum (preferred partners with whom these agreements are have just been renewed) are further encouragement to pursue the work we have begun.

Over the years, the expansion of space geodesy towards the sciences that rely on it (solid Earth geophysics, oceanography, glaciology, and planetary science) has increased. Yet this broadening of application, which, on the one hand enriched the GRGS, also weakened its visibility by making its boundaries increasingly blurred. Conversely, the geosciences have developed numerous sub-disciplines that rely on space geodetics, and new groups (such as AGRET, G2) have emerged to coordinate their development and to better organize the community of users, broadly defined, of geodesy and its products.

Member agencies of the GRGS therefore wished to redefine the objectives and scope of activities of GRGS and its teams, which is the purpose of this memorandum which replaces the previous one.

Furthermore, successive Scientific Assessment Panels have conducted in-depth evaluations of GRGS and its scientific production every three years. Their reports have occasionally questioned the delimitation of the consortium’s activities, but never the scientific quality of the research, which have always been rated as excellent.

From this, it follows that

Le Bureau des Longitudes

Le Centre National d’Études Spatiales

L’Institut Géographique National

L’Observatoire de Paris

L’Institut National des Sciences de l’Univers

L’Observatoire de la Côte d’Azur

Le Service Hydrographique et Océanographique de la Marine

L’Observatoire Midi-Pyrénées de l'Université Paul Sabatier

L’Université de Polynésie Française

L’Ecole Supérieure des Géomètres et Topographes du Conservatoire National des Arts et Métiers

L'Ecole et Observatoire des Sciences de la Terre

hereafter called member organizations or parent organizations,


  • the interest shown by these organizations in research, both theoretical and in instrumentation, in the field of space geodesy and its applications
  • the need to coordinate efforts in this area at the national level
  • the existence of the GRGS since 1971
  • the important results that have been obtained from the cooperation of its researchers, engineers and technicians within the framework of the GRGS or under its leadership
  • the emergence of organized groups, users of space geodesy and its products

And moreover, considering that

  • space experiments in geodesy- or involving geodesy, that are in progress, and the need for treatment and increased visibility of their data,
  • new space missions dedicated to geodesic objects (e.g., Earth’s gravitational field) or their applications,
  • increased precision and resolution in describing these objects with appropriate physical models, requiring extensive ongoing research,
  • the demand for these models, products of space geodesy, by user communities,
  • the considerable involvement of French teams in international systems and services based largely on the techniques of space geodesy,
  • the need to continue work in the future in different sectors of space geodesy, to find and develop new approaches, both instrumental and methodological,

To continue to ensure that French teams working in cooperation in the field of space geodesy have the framework and the necessary stability through the renewal of the Space Geodesy Research Group (GRGS), to which they strive to commit the maximum amount of resources, compatible with their respective abilities.

The GRGS is placed under the authority of a Steering Committee composed of the presidents or directors of member agencies or their representatives.

The operating cycle of the structural elements of the GRGS is four years. This method of functioning has been defined by the organizational chart attached to this Memorandum.

GRGS Teams and Their Objectives

GRGS’ specific objectives are the acquisition and discussion of geodetic measurements, terrestrial or planetary, obtained by spatial techniques. These techniques that are themselves objects of research for the construction of models (the products of space geodesy), which are then used in various fields of geophysics in the broadest sense. These goals could also include acquiring other kinds of data when the methods of space geodesy play an essential role in obtaining them, or use of such data when they are essential to the development of geodetic products.

Thus the definition of GRGS teams that fall into this framework takes into account the entire research process – from initial design and research up to development of geodetic products-- as well as the end use that other research groups and institutes (which GRGS may belong to) make of these products.

The list of teams, each with their own objectives and personnel, is annexed to this Memorandum. It will be updated annually and presented to the Steering Committee of the GRGS.

Admission of New Members

The admission of new members will be described in an addendum to this memorandum.

Duration, Termination

The MOU, first signed in 2004 and valid for four years, is renewable automatically. It may be terminated at any time by any of the parties, whose participation in GRGS ceases at the end of the Steering Committee meeting following such termination, provided they have fulfilled all the commitments made before their departure.